Microbiology Case Study: A 24 year old with Sore Throat and Difficulty Breathing

Case History

A 24 year old male with a past medical history of recurrent streptococcal pharyngitis presents to the emergency department with a sore throat and dyspnea. His symptoms began three days prior and included left-sided upper neck and lower jaw pain and odynophagia. The patient’s evaluation demonstrated tachycardia, cervical lymphadenopathy, and a small left tonsillar abscess. Labs were significant for an elevated WBC count but blood cultures, Group A streptococcal and mononucleosis screens were negative. The patient was admitted for pain management and treated with a combination of IV ampicillin/sulbactam (amp/sulb) and steroids. He improved with treatment and was discharged the following day on oral amoxicillin/clavulanic acid (amox/clav). Nine days later, the patient re-presented with similar complaints. The tonsillar abscess had increased in size to 2cm. Labs were significant for leukocytosis and a now positive Group A streptococcal screen. 2mL of pus was aspirated from the lesion but no cultures were ordered. The patient’s status again improved, and he was discharged home again on oral amox/clav. The patient returned the following day and was placed on IV amp/sulb and admitted for imaging and symptom management. A neck CT with contrast revealed a now 3cm tonsillar abscess with reactive cervical lymphadenopathy (Image 1). A throat culture was collected; however, no beta-hemolytic streptococci were recovered after 48 hours of incubation. Incision and drainage of the abscess was performed at bedside, recovering an additional 10 mL of purulence that was sent to the microbiology laboratory for aerobic and anaerobic culture. The patient improved on IV amp/sulb and was switched to high dose amox/clav on day 15.  

Laboratory Identification

Gram stain of the aspirated purulence revealed many WBCs and a mixture of gram positive rods and cocci (Image 2). The aerobic culture grew a heavy amount of tiny, weakly beta-hemolytic colonies on blood agar. Smears of these colonies revealed Gram-positive coryneform rods. Biochemical testing determined the growth to be catalase-negative and MALDI-TOF MS definitively identified the organism as Arcanobacterium haemolyticum. The anaerobic culture grew oral flora.

Image 1. Computed tomography of the neck in a 24 year old male who presents with difficulty breathing. Area of large tonsillar abscess (yellow circle).
Image 2. Gram stain demonstrating small, pleomorphic gram positive rods in a background of neutrophils and Gram-positive cocci in pairs or short chains. (1000x magnification, oil immersion)
Image 3. A. haemolyticum isolate after 48 hours of incubation. The weak beta-hemolysis was not readily apparent using room (reflected) light. Placing the plate on a lightbox revealed beta-hemolysis.
Image 4. Streptococcus agalactiae exhibiting synergetic hemolysis with a beta-lysin producing strain of S. aureus (CAMP reaction, top). A. haemolyticum inhibits hemolysis by S. aureus in a CAMP-test set up (CAMP inhibition, middle). A. haemolyticum exhibits synergistic hemolysis with S. agalactiae. (Reverse CAMP, bottom).

Discussion

A. haemolyticum is an infrequently isolated  gram positive rod which is an etiologic agent of non-streptococcal pharyngitis diagnosed predominantly in adolescents or young adults. The diagnosis of A. haemolyticum can be challenging because itis often clinically indistinguishable from cases caused by beta-hemolytic streptococci. Most patients exhibit some degree of cervical lymphadenopathy, and a scarlatiniform rash can be present in up to 50% of cases. From a laboratory perspective, A. haemolyticum is slowly growing and weakly beta hemolytic after 24-48 hours on media containing sheep blood (including SBA and Strep Selective agars routinely used for screening throat cultures). The beta-hemolytic activity of A. haemoltyicum is attributed to expression of arcanolysin, a cholesterol-dependent cytolysin. Interestingly, arcanolysin more robustly binds to rabbit and human erythrocytes than those from sheep,1 which may explain the organism’s weak beta hemolysis on routine media.  In this setting, the organism can be missed or dismissed as commensal flora without careful observation. Conversely, if beta-hemolysis is observed, the colony morphology and catalase non-reactivity can lead to misidentification as beta-hemolytic streptococci in the absence of a Gram stain or other determinative methods (i.e. MALDI-TOF MS).

The beta hemolysis of this patient’s A. haemolyticum isolate is difficult to appreciate in reflected (room) light, and was best observed after 48 hours using transduced light from a light box (Image 3). A. haemolyticum displays CAMP inhibition due to the production of phospholipase D which inhibits the hemolytic activity of beta-lysin produced by S. aureus (Image 4) and is reverse-CAMP positive when perpendicular to Group B streptococci which can aid in identification.2

Erythromycin is the drug of choice for treatment of A. haemolyticum, further highlighting the need for definitive identification of this organism in settings of pharyngitis. The use of penicillin for treatment of A. haemolyticum pharyngitis can result in treatment failure, possibly due to invasion of host cells, thus establishing a reservoir,3 or due to a penicillin-tolerant phenotype.4 It is unclear in this case if source control or decreased susceptibility necessitated the multiple courses of antibiotics utilized. Fortunately, the patient’s symptoms resolved on high dose amoxicillin/clavulanic acid following thorough incision and drainage. He subsequently returned for an outpatient tonsillectomy.

References

  1. Jost BH, Lucas EA, Billington SJ, Ratner AJ, McGee DJ. 2011. Arcanolysin is a cholesterol-dependent cytolysin of the human pathogen Arcanobacterium haemolyticum. BMC Microbiology 11:239.
  2. Kang H, Park G, Kim H, Chang K. 2016. Haemolytic differential identification of Arcanobacterium haemolyticum isolated from a patient with diabetic foot ulcers. JMM Case Reports.
  3. Österlund A. 1995. Are Penicillin Treatment Failures in Arcanobacterium haemolyticum Pharyngotonsillitis Caused by Intracellularly Residing Bacteria? Scandinavian Journal of Infectious Diseases 27:131-134.
  4. Nyman M, Danek G, Thore M. 1990. Penicillin Tolerance in Arcanobacterium haemolyticum. The Journal of Infectious Diseases 161:261-265.

-Andrew Clark, PhD, D(ABMM) is an Assistant Professor at UT Southwestern in the Department of Pathology and Associate Director of the Clements University Hospital microbiology laboratory. He completed a CPEP-accredited postdoctoral fellowship in Medical and Public Health Microbiology at National Institutes of Health, and is interested in antimicrobial susceptibility and anaerobe pathophysiology.

-Clare McCormick-Baw, MD, PhD is an Assistant Professor of Clinical Microbiology at UT Southwestern in Dallas, Texas. She has a passion for teaching about laboratory medicine in general and the best uses of the microbiology lab in particular.

Microbiology Case Study: Skin and Soft Tissue Infection Caused by an Unusual Bacterium

Case History

A 20 year old female with no significant past medical history presented with a painful pruritic rash on the bilateral inner thighs that had been persistent for one month. Prior to presentation, she had been treated with oral and topical antihistamines, topical steroids, valacyclovir, and partial courses of doxycycline and cephalexin without improvement. Physical examination was notable for diffuse erythema and dermal edema of the bilateral medial thighs with superimposed exophytic papules with dark, necrotic cores, the largest of which measured 1 cm in diameter (Image 1). Punch biopsy of the lesions was taken and sent for histology. A sample from necrotic tissue was sent to microbiology laboratory for gram stain and cultures.

Laboratory diagnosis

Gram stain showed gram positive cocci in clusters. After 32 hours of incubation, tissue cultures grew white, β-hemolytic colonies which were catalase positive, coagulase negative, and pyrrolidonylarylamidase (PYR) positive. The organism was identified as Staphylococcus lugdunensis by MALDI-TOFmass spectrometry. Histology revealed eosinophilic inclusions consistent with molluscum bodies as well as inflammatory infiltrate (Image 2). Brown and Hopps stain on tissue showed Gram-positive cocci is small clusters (Image 3). A diagnosis of molluscum contagiosum superinfected with Staphylococcus lugdunensis was made based on laboratory and histologic findings.

Image 1. Lesions on left medial thigh (left) and right medial thigh (right).
Image 2. Molluscum bodies
Image 3. Brown and Hopps stain on tissue showing gram positive cocci

Discussion

S. lugdunensis is a coagulase-negative staphylococcus first isolated in 1988 that was initially thought to be a commensal skin organism but has been shown to cause skin and soft tissue infections (SSTIs), bacteremia, endocarditis, prosthetic joint infections, and osteomyelitis,2 with a virulence more similar to S. aureus than to that of other coagulase-negative staphylococci. SSTIs are one of the more common manifestations of S. lugdunensis infection; one analysis of 229 S. lugdunensis clinical isolates demonstrated that 55.4% were associated with SSTIs.3 The spectrum of S. lugdunensis-related SSTIs includes folliculitis, pustulosis, cellulitis, abscesses, and rarer secondary infection of molluscum contagiosum and hidradenitis suppurativa.5 Molluscum superinfection itself is a rare phenomenon, and when it occurs, the superinfecting agent is most often S. aureus.1 Our case suggests that S. lugdunensis should also be considered as a potential causative agent of molluscum superinfection. There is growing recognition that S. lugdunensis is a virulent pathogen that should not be disregarded as a contaminant if found on culture. Importantly, when compared with S. aureus, S. lugdunensis has a more limited resistance profile; methicillin resistance is still uncommon, and 74.6% of isolates in one recent study were penicillin susceptible.4 Awareness of this more favorable resistance profile can facilitate selection of narrower-spectrum antibiotic therapies for S. lugdunensis infections.

In our case, patient received one dose of vancomycin and metronidazole in the emergency department and was then started on cefazolin for cellulitis. After wound culture identified S. lugdunensis, the patient was discharged on cefadroxil 1g twice daily for 10 days. On follow up, the rash had resolved.

References

  1. Berger EM, Orlow SJ, Patel RR, Schaffer JV. Experience With Molluscum Contagiosum and Associated Inflammatory Reactions in a Pediatric Dermatology Practice: The Bump That Rashes. Arch Dermatol. 2012;148(11):1257–1264. doi:10.1001/archdermatol.2012.2414
  2. Douiri N, Hansmann Y, Lefebvre N, Riegel P, Martin M, Baldeyrou M, Christmann D, Prevost G, Argemi X. Staphylococcus lugdunensis: a virulent pathogen causing bone and joint infections. Clinical Microbiology and Infection, 2016;22(8):747-748. doi:10.1016/j.cmi.2016.05.031
  3. Herchline TE, Ayers LW. Occurrence of Staphylococcus lugdunensis in consecutive clinical cultures and relationship of isolation to infection. J Clin Microbiol. 1991;29(3):419–421.
  4. Taha L, Stegger M, Söderquist B. Staphylococcus lugdunensis: antimicrobial susceptibility and optimal treatment options. Eur J Clin Microbiol Infect Dis. 2019;38(8):1449–1455. doi:10.1007/s10096-019-03571-6
  5. Zaaroura H, Geffen Y, Bergman R, Avitan‐Hersh E. Clinical and microbiological properties of Staphylococcus lugdunensis skin infections. J Dermatol, 2018;45: 994-999. doi:10.1111/1346-8138.14496

-Ansa Mehreen, MD. 1st year AP/CP resident at University of Chicago hospital program based at Evanston Hospital. Her academic interests include gastrointestinal pathology.

-Erin McElvania, PhD, D(ABMM), is the Director of Clinical Microbiology NorthShore University Health System in Evanston, Illinois. Follow Dr. McElvania on twitter @E-McElvania. 

Microbiology Case Study: A 27 Year Old Man with Lumbar Pain

Clinical History

A 27 year old male with past medical history of mixed connective tissue disease was transferred from an outside hospital where he had initially presented for 6 days of progressively worsening lumbar pain preceded by 1 day of fevers up to 104 F, as well as chills and rigors. Also noted was pain and swelling in his left thumb and a mild rash present on the hands and feet. It is notable that the patient has multiple pets, including a rat.

Workup at the outside hospital included and MRI showing facet arthrosis and effusions at L4-L5 with mass effect on the S1 nerve root. Neurosurgery recommended biopsy of the lumbar spine by Interventional Radiology.

Laboratory Findings

Two sets of blood cultures at the outside hospital showed no growth at 5 days. Two sets of blood cultures obtained at our institution were positive at 15 and 29 hours, with a smear showing gram negative bacilli. The blood culture media was tested by nucleic acid hybridization and no targets were detected. When subcultured, there was only significant growth on the blood plate, with very small gray-green colonies that were not well appreciated

Image 1. Gram stain showing gram negative bacilli.
Image 2. Blood agar plate showing difficult to discern growth of very small grayish colonies.

A sample was sent to a reference lab for testing, which identified Streptobacillus moniliformis.

Discussion

In the United States, Streptobacillus moniliformis is the most common causative agent of rat bite fever, a relatively rare infectious systemic illness. This syndrome is also caused by infection with Spirillum minus, primarily seen in Asia, and rarely by Streptobacillus notomytis.1,2

S. moniliformis is a fastidious pleomorphic gram negative rod which grows slowly; in cases where there is clinical suspicion for rat bite fever, cultures can be held up to seven days. It is part of the normal nasal and oropharyngeal flora of rodents, with carriage rates of up to 100% in some rat populations. It can be found in oral, nasal, and conjunctival secretions, as well as urine, and can be transmitted to humans via bites, scratches, or oral contact. This includes kissing a pet rat or ingesting food or water that is contaminated with rat secretions.1,2

S. minus is a gram negative spirochete. It cannot be cultured on synthetic media, but may be visualized by Giemsa or Wright stain, or by using dark-field microscopy. Transmission of S. minus is similar to that of Steptobacillus spp., but has not been documented to be associated with contaminated food or water. (1, 2)

The clinical presentation of rat bite fever ranges from a mild case with only a flu-like illness to cases of severe sepsis. In untreated cases, the mortality rate is approximately 10 to 13 percent. Initial symptoms typically begin within 7 days of exposure for S. moniliformis and in 1 to 3 weeks for S. minus. These initial symptoms can include fever, myalgias, vomiting, pharyngitis, headache, and migratory arthralgias. If exposure was through a wound, it is typically resolved by the time symptoms develop, although it may reappear with ulceration, edema, and regional adenopathy in cases caused by S. minus. Cases associated with ingestion may have more severe vomiting and increased likelihood of developing pharyngitis.1,2

Symptoms may further develop to include a maculopapular rash on the extremities, and asymmetric polyarthralgias. The rash is seen most commonly on the extensor surfaces but can involve the palms and soles. Spontaneous remission may occur, but without treatment the fever can show a relapsing course, and the arthritis may last for several years. Possible complications include bacteremia, endocarditis, myocarditis, pneumonia, abscesses, septic arthritis, osteomyelitis, multiorgan failure, fulminant sepsis and death.1,2

Rat bite fever is usually diagnosed empirically based on consistent symptoms and history of rat exposure, because it is difficult or impossible to culture the causative organisms in the lab and there is no serologic test available. 16S rRNA sequencing can be used for definitive diagnosis, but only for certain sample types, and it is not always available.1,2

The empiric treatment of choice is penicillin, with the dose and duration being dependent on the clinical presentation. Ceftriaxone is also commonly used due to better ease of use in the outpatient setting, and tetracyclines are used in patients with beta-lactam allergies. For uncomplicated cases, most patients are treated for a total of 14 days; initially with IV antibiotics, and then transitioned to oral agents after 5 to 7 days if there is sufficient clinical improvement.1,2

Also remarkable in the patient’s history was a note indicating that they had been known to share drinks with his pets and instances of the pet rat licking the patient’s face. Initial treatment was vancomycin and cefepime, with vancomycin discontinued after the gram stain results. The patient was discharged before a definitive identification of the organism was made, with a plan for 6 weeks of outpatient treatment with ceftriaxone via infusion.

References

1.  King, Katherine Yudeh, MD, PhD “Rat Bite Fever.” UpToDate, Wolters Kluwer, 1 Jun. 2020. https://www.cdc.gov/rat-bite-fever/index.html

2.  “Rat-bite Fever (RBF).” Centers for Disease Control and Prevention, 1 Jun. 2020. https://www.uptodate.com/contents/rat-bite-fever?search=rat%20bite%20fever&source=search_result&selectedTitle=1~17&usage_type=default&display_rank=1

-Tom Koster, DO is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

A Resident’s Perspective of SARS-CoV-2 Testing Using the Double Diamond Model of Design Process

During the 2019-2020 residency interview season, I “courted” – no better way to describe those interactions over lunch–several potential co-residents, who were eager to know why I came to University of Chicago (NorthShore) for my residency. My answers and those of my fellow residents would help the candidates determine how high they should rank our program, so I enthusiastically recalled things I liked when I interviewed at NorthShore about a year earlier. I had also recently completed my first microbiology rotation in residency and I had enjoyed seeing all of those factors work synergistically to improve patient health outcomes through improved testing. So passionately, I shared how I fell in love with the physical structure of the department which has almost all the labs and offices one floor, the automation of the labs-especially the core and microbiology labs, the capability and regular expansion of its molecular laboratory, the people and of course, “the feel” about NorthShore.

With these experiences, I looked forward to my second microbiology in March 2020, where I would learn more about the diagnostics of various microorganisms–E. coli: Gram negative short stubby/broad shouldered rods vs. Pseudomonas aeruginosa, Gram negative long slender rods, etc. (Un)fortunately, March came, but the novel coronavirus (SARS-CoV-2) had other plans for my learning. Cases of Coronavirus disease 19 (COVID-19), caused SARS-CoV-2[1] were increasing rapidly in the US, so laboratories, including ours had rapidly implement testing. Rather than have morning rounds and other educational activities where the differential diagnoses of several clinically relevant microorganisms were discussed, we had virtual and in-person meetings discussing what to do about one virus. These continued and by the middle of March, we had become the only non-government lab in Illinois and second in the Midwest that had developed a clinical PCR test for SARS-CoV-2. I was excited to be part of that success, but more so, about learning how we achieved that as a team.

Our approach could be summarized using the Double diamond or 4D model of design process which consists of four phases: Discover, Define, Develop and Deliver (Figure 1).

Figure 1. Double diamond or 4D model of design process which consists of four phases: Discover, Define, Develop and Deliver. Plan Do Study Act (PDSA) is an iterative model of quality improvement embedded in the 4D design process.
  1. In the discover phase, a phase of divergent thought [2] and exploration, we identified from events in China and other parts of the world as well as some other states in the US that the community we care for could potentially be affected by the COVID-19 outbreak.
  2. The next phase- define- is a convergent phase where the problem to be solved, as well as the resources available and resources needed to solve it are delineated [2]. As we transitioned from the discovery to define phases-and recalling the 2009 H1N1 influenza outbreak about 10 years ago- it became evident that an epidemic of a relatively fatal respiratory virus which we knew very little about was heading our way. As clinical laboratory professionals, our objective was to help identify members of the community who had been infected through testing so appropriate steps could be taken to sequester and care for them. Among our available resources was our molecular laboratory, but like most laboratories outside the Centers for Disease Control and Prevention, CDC we lacked the reagents, primers and authorization to run the test.
  3. Develop is the next phase in the process and this is a divergent phase where the team explores and refines potential solution to the issues and selects one[2]. This is often followed by the convergent deliver phase where one of the solutions from the develop phase is implemented. Feedbacks which are used for projects are also received during this phase[2]. But, the outbreak continued to evolve rapidly [3] with briskly increasing positivity rates[4] and some of the solutions we considered would require some time to be implemented and/or have long turnaround times. For instance, since we had a roust molecular laboratory, one option was to develop our assays and test in-house, while another was to send the samples to outside labs where they could be run. Running the tests in-house would have a shorter turnaround time and would be more efficient, which is extremely important considering the severity of COVID-19.
  4. Deliver is the last phase of the process.  We decided to develop a SARS-CoV-2 RT-PCR test at our institution, but we also knew we needed to put logistics and protocols in-place to deliver our solution.  For example, COVID-19 presents with flu-like symptoms but flu is common between December and March[5-7] so it would be impractical to expect to test all patients with flu-like symptoms – at least with the limited resources we had. In any case, it was clear that we would not have an ideal amount of time or information to develop and implement the perfect solution. As such, the revolving and fluid nature of the develop and deliver phases of our response is best depicted using the Plan Do Study Act (PDSA), an iterative model of quality improvement. As shown in Fig. 1, we developed and validated our assay, as well as developed an initial protocol for screening patients and logistics for patient-centered delivery in the “Do” step. Importantly, we also reviewed the effectiveness of these operations, and made necessary changes corresponding in the “Study” and “Act” steps respectively.

The prompt decision to implement in-house COVID-19 testing at NorthShore has proven to be the right one. To date we have tested 75,000 specimens and nearly 20,000 tests have been positive. Success which was possible because of the factors which made me come to NorthShore, amongst others. The LEAN, bright and capacious design of the department limits the innate barriers of hierarchical organizational structure; encouraging seamless horizontal and vertical intradepartmental consultation and collaboration as COVID-19 led us into uncharted territory. Also, having a molecular lab that regularly expands its capability made the decision to test in-house relatively easy. In addition, having an automated microbiology lab made it easier for staff to be flexible and deal with the various demands of testing for a new bug in a pandemic. And of course, the people at NorthShore who are ready to volunteer, take up new roles or change shifts to accommodate the demands of a rapidly evolving pandemic, stay in constant communications and provide feedback, and who make everything else at NorthShore work!

References

  1. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200130-sitrep-10-ncov.pdf?sfvrsn=d0b2e480_2
  2. Council, Design. “Eleven lessons: Managing design in eleven global companies-desk research report.” Design Council (2007).
  3. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/summary.html
  4. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200324-sitrep-64-covid-19.pdf?sfvrsn=723b221e_2
  5. https://www.who.int/news-room/q-a-detail/q-a-coronaviruses#:~:text=symptoms
  6. https://www.cdc.gov/flu/symptoms/symptoms.htm
  7. https://www.cdc.gov/flu/about/season/flu-season.htm
  8. Christoff, Patricia. “Running PDSA cycles.” Current problems in pediatric and adolescent health care 48.8 (2018): 198-201.

Adesola Akinyemi, M.D., MPH, is a first year anatomic and clinical pathology resident at University of Chicago (NorthShore). He is interested in most areas of pathology including surgical pathology, cytopathology and neuropathology -and is enjoying it all. He is also passionate about health outcomes improvement through systems thinking and design, and other aspects of healthcare management. Twitter: @AkinyemiDesola

-Erin McElvania, PhD, D(ABMM), is the Director of Clinical Microbiology NorthShore University Health System in Evanston, Illinois. Follow Dr. McElvania on twitter @E-McElvania. 

Microbiology Case Study: Elderly woman with Ear Pain

An elderly woman with a past medical history significant for end-stage renal disease status post deceased donor kidney transplant in 2018 (on immunosuppression), type 2 diabetes mellitus, and recurrent urinary tract infections presented to nephrology clinic with right ear pain and rash of three weeks. She was otherwise in her usual state of health. On physical exam, there were exophytic itchy papules with hemorrhagic crust and ulcerations on the ear (Image 1) and arm. A few of these papules showed central umbilication (Image 2). Erosions were also present on the upper back, face, neck, and forearms. Patient was referred to dermatology with concern for disseminated infection versus neoplasia. Complete blood count showed mildly elevated white cells. Serologies, cultures, imaging, lumbar puncture, and biopsy were performed.

Blood studies revealed a Cryptococcus antigen titer of 1:4096 along with a CSF antigen titer of 1:2048. Additionally, the CSF gram stain demonstrated yeast and cultures grew Cryptococcus neoformans. Opening pressure was normal and protein was slightly elevated to 53 mg/mL with 36 nucleated cells with a differential including 64% lymphocytes. Biopsy culture of the left cheek was positive for C. neoformans and a left forearm biopsy showed nodular aggregates of encapsulated yeasts, surrounded by relatively sparse lymphohistiocytic inflammation (Images 3-4). A CT of the chest showed innumerable pulmonary nodules concerning for infection.

Image 1. Erythematous and crusted pink plaque with ulceration on the pinna of the ear.
Image 2. Pink, domed papule on the arm with central umbilication and crust.
Image 3. Hematoxylin and eosin stain of the arm biopsy with Cryptococcus, low magnification. Note the loss of epidermis (left-hand side) and underlying foamy stroma with numerous yeasts within the dermis.
Image 4. Hematoxylin and eosin stain of Cryptococcus, high magnification. The yeasts show variable size and some demonstrate a halo of pale staining capsule. There is no significant inflammation in the background parenchyma.

Discussion

Cryptococcus is an encapsulated basidiomycetous fungus typically found in soil and pigeon droppings.1 Two species comprise the majority of Cryptococcus infections: C. neoformans and C. gatti. C. neoformans is most commonly seen in immunosuppressed patients, particularly in the setting of AIDS.2 C. gatti infections may be seen in more immunocompetent patients and appears to be more geographically restricted to the tropics and Pacific Northwest.3 C. neoformans infections can present as lung disease associated with symptoms of fever, shortness of breath, or cough and characteristically may spread to the central nervous system to cause meningitis.4 Lumbar puncture may show significantly elevated opening pressures.5 Other features of disseminated Cryptococcus infections include rash, endocarditis, ocular lesions, or multiorgan failure.6

This case is a somewhat unusual presentation of disseminated Cryptococcus infection characterized only by skin findings without clinical features of pulmonary or CNS infection. Approximately 15% of patients with disseminated infection may show cutaneous findings but primary cutaneous cryptococcosis is rare.7 Cryptococcal skin findings are quite varied, but may present similar to molluscum contagiosum, as dome shaped papules with central umbilication.7,8 On microscopy, small variably sized round yeasts without hyphae are characteristic. These yeasts may show a clear or pale staining halo representing the capsule and are highlighted well on Grocott’s Methenamine Silver or Periodic Acid-Schiff stains. Histology may demonstrate innumerable extracellular yeasts accompanied by foamy stroma and minimal inflammation or more granulomatous tissue reaction with necrosis, ulceration, and mixed inflammation. In conclusion, disseminated Cryptococcus must be considered in the context of new skin findings in an immunocompromised patient even if typical pulmonary or CNS findings are not identified.

References

  1. Sorrell TC, Ellis DH. Ecology of Cryptococcus neoformans. Rev Iberoam Micol. 1997 Jun;14(2):42-3.
  2. Bratton EW, El Husseini N, Chastain CA, Lee MS, Poole C, Sturmer T, et al. Comparison and temporal trends of three groups with cryptococcosis: HIV-infected, solid organ transplant, and HIV-negative/non-transplant. PloS One. 2012;7(8):e43582
  3. MacDougall L, Fyfe M, Romney M, Starr M, Galanis E. Risk factors for Cryptococcus gattii infection, British Columbia, Canada. Emerg Infect Dis. 2011 Feb;17(2):193-9.
  4. Sabiiti W, May RC. Mechanisms of infection by the human fungal pathogen Cryptococcus neoformans. Future microbiol. 2012 Nov;7(11):1297-313.
  5. Abassi M, Boulware DR, Rhein J. Cryptococcal Meningitis: Diagnosis and Management Update. Curr Trop Med Rep. 2015;2(2):90–99. doi:10.1007/s40475-015-0046-y
  6. Clark RA, Greer D, Atkinson W, Valainis GT, Hyslop N. Spectrum of Cryptococcus neoformans infection in 68 patients infected with human immunodeficiency virus. Rev Infect Dis. 1990 Sep-Oct;12(5):768-77.
  7. Srivastava GN, Tilak R, Yadav J, Bansal M. Cutaneous Cryptococcus: marker for disseminated infection. BMJ Case Rep. 2015;2015:bcr2015210898. Published 2015 Jul 21. doi:10.1136/bcr-2015-210898
  8. Akram SM, Koirala J. Cutaneous Cryptococcus (Cryptococcosis) [Updated 2019 Aug 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448148/

-Dr. Stanton Miller is a second year AP/CP resident at UT Southwestern Medical Center who is interested in Dermatopathology.

-Dr. IJ Frame is a board-certified Clinical Pathologist who is completing his Medical Microbiology fellowship at UT Southwestern Medical Center.

-Dr. Dominick Cavuoti is a professor of AP and CP at UT Southwestern, specializing in infectious disease pathology, cytology and medical microbiology.

-Clare McCormick-Baw, MD, PhD is an Assistant Professor of Clinical Microbiology at UT Southwestern in Dallas, Texas. She has a passion for teaching about laboratory medicine in general and the best uses of the microbiology lab in particular.

Microbiology Case Study: A 53 Year Old Man with an Aortic Valve Mass

Case History

The patient is a 53 year old male with a past medical history of chronic obstructive pulmonary disease, who presented to the emergency department with one day of right calf pain, worse with weight-bearing, with radiating paresthesias, and a pale, cold right foot. He also endorsed a history of intermittent fatigue and knee pain. The patient works on farm and has an 82 pack year smoking history. He was diagnosed with a right popliteal artery occlusion and started on IV heparin. A transthoracic echocardiogram revealed an aortic valve mass.

Five days after admission he underwent a thromboembolectomy of the occluded vessel. A further six days later he underwent a procedure to excise the aortic valve mass, but ended up having an aortic valve replacement. Cardiothoracic surgery described a friable mass with a large base, consistent with a vegetation that might be seen in infective endocarditis, and sent the mass for surgical pathology and aerobic and anaerobic cultures. He was started on empiric vancomycin by infectious disease.

The patient denied recent fevers, chills, sweats, weight loss or changes in appetite, cough, chest pain, abdominal pain, nausea, vomiting, diarrhea, constipation, painful urination, rash, or unusual bone or joint pain. Doxycycline and rifampin were added for further coverage.

Laboratory Identification

Blood cultures drawn on admission showed no growth at 5 days. Initial gram stain of tissue from the mass showed many gram positive beaded rods. Anaerobic cultures of this tissue grew a single colony of Micrococcus and a single colony of a gram positive bacilli, which also grew aerobically and was identified by Mayo as Corynebacterium spp., not jeikeium. Serology for Bartonella was negative. Q fever serology showed elevated titers of phase I Ab IgG only.

Surgical pathology of the aortic valve mass is shown below:

Image 1. H&E stain of the removed aortic valve, demonstrating foamy macrophages. Not shown are abundant necrotic debris and dystrophic calcifications. Photo taken by Jessica Crothers, MD.
Image 2. Periodic Acid-Schiff (PAS) stain of the area depicted in Figure 2. The foamy macrophages are diffusely PAS positive. Photo taken by Jessica Crothers, MD.

GMS, B&B, AFB, and Fite staining were negative for definitive organisms.

A second set of blood cultures showed no growth and 5 days, and AFB cultures were negative, and second Q fever serology showed a decrease in the titer of phase I Ab IgG.

A PCR of residual heart valve tissue identified Tropheryma whipplei.

Discussion

The diagnosis of Tropheryma whipplei is made by T whipplei PCR, PAS stain, or T whipplei immunohistochemical staining.1 As these are all non-routine tests for a microbiology work-up, the diagnosis depends on high clinical suspicion.

Most often seen in the gut, T whipplei infection classically manifests as arthralgias, abdominal pain, weight loss, and diarrhea.2 However, it is also a rare source of culture-negative endocarditis, as seen in the case above.

The organism is a gram positive bacillus that is common in the environment and found in the saliva of up to 35% of healthy hosts.3 Furthermore, IgG antibodies to T whipplei have been detected in the blood of up to 70% of healthy individuals.4 Microscopically, there is minimal inflammatory response to this organism. Because of this and the classic symptoms, the characteristic foamy macrophages were initially thought to be indicative of a metabolic disorder.5 Once discovered and studied, it was found to most commonly affect males of European descent, which with the minimal inflammatory response to the organism led to the postulation that this population may have a heritable immunodeficiency.6 Others have suggested that the organism itself may have a role in down-regulating the immune response.7 A variety of immunologic disturbances have been associated with the disease, including down-regulation/absence of MHC II molecules and general dysfunction of monocytes/macrophages.1,7,8

Treatment varies by extent of disease, but it generally includes ceftriaxone or penicillin G followed by an extended course of TMP-SMX.1

In the case of our patient, he demonstrated symptomatic improvement after aortic valve repair followed by four weeks of ceftriaxone, with a plan to transition to TMP-SMX for one year.

References

  1. Apstein, MD, and T Schneider. “Whipple’s Disease.” UpToDate, Wolters Kluwer, 28 June 2019. Accessed 23 March 2020: https://www.uptodate.com/contents/whipples-disease?search=whipples%20disease%20children&source=search_result&selectedTitle=4~70&usage_type=default&display_rank=4#H703772001
  2. Durand DV, Lecomte C, Cathébras P. “Whipple disease. Clinical review of 52 cases.” Medicine (Baltimore). 1997;76(3):170.
  3. Street S, Donoghue HD, Neild GH. “Tropheryma whippelii DNA in saliva of healthy people.” Lancet. 1999;354(9185):1178.
  4. Raoult D, Birg ML, La Scola B, et al. “Cultivation of the bacillus of Whipple’s disease.” N Engl J Med. 2000;342(9):620.
  5. Whipple GH. “A hitherto undescribed disease characterized anatomically by deposits of fat and fatty acids in the intestinal and mesenteric lymphatic tissues.” Bull. Johns Hopkins Hosp. 1907; 18:382–391.
  6. Fenollar F, Puéchal X, Raoult D. “Whipple’s Disease.” N Engl J Med. 2007;356(1):55.
  7. Ectors NL, Geboes KJ, De Vos RM, et al. “Whipple’s disease: a histological, immunocytochemical, and electron microscopic study of the small intestinal epithelium.” J Pathol. 1994;172(1):73.
  8. Moos V, Schmidt C, Geelhaar A, et al. “Impaired immune functions of monocytes and macrophages in Whipple’s disease.” Gastroenterology. 2010;138(1):210. 

-Frederick Eyerer, MD is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Thomas Koster, DO is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

Microbiology Case Study: A 70 Year Old with Altered Mental Status

Clinical History

A 70 year old patient with a history of sarcoidosis, diabetes mellitus type 2, and interstitial lung disease on prednisone presented to an outside hospital with subacute altered mental status and dizziness. Head imaging showed 3 ring-enhancing lesions most concerning for intracranial abscesses and the patient was transferred to a larger institution for management. Upon further imaging and physical examination, 3 additional lesions were found, one in the abdominal wall and two subcutaneous lesions on the extremities. An IR-guided biopsy of the abdominal wall lesion was performed and the specimen was sent for bacterial culture and smear.

Laboratory findings

An initial gram stain was interpreted as many neutrophils and no bacteria seen; however, Acridine Orange staining demonstrated the presence of fungi or bacteria on the smear. Further review of the gram stain showed many neutrophils with few filamentous beading and branching gram positive bacilli predominantly in the thick regions of the smear (image 1).

Image 1. A gram smear from the patient’s abdominal wall abscess at 100x magnification showing filamentous beading and branching gram positive organisms.
Image 2. A modified Kinyoun staining demonstrates that the organism is weakly acid fast positive (100x magnification).

Discussion

Nocardia encompasses a group of delicate aerobic gram positive and weakly acid fast positive rod-shaped bacteria that, due to their branching appearance, were once thought to be fungi. The N. farcinica species are not found in normal flora, but instead in soil around the world and are most often associated with decaying vegetation. It is the bacteria’s ability to become airborne on dust particles that may result in inhalation and lead to the most common presentation, pulmonary nocardiosis. Other modes of entry include ingestion and cutaneous disease after traumatic inoculation. CNS involvement is a common site for secondary infection.1

The pathogenicity of Nocardia is the result of several mechanisms that the bacteria possess to evade the host’s defense system. Nocardia are often resistant to phagocytosis when they are in their log-phase. If the bacteria are phagocytosed, some species have the ability to inhibit the lysosome-phagosome fusion. Nocardia farcinica, in particular, is especially important to identify as it is more likely to progress to disseminated disease and has a higher rate of antimicrobial resistance.2

Most cases of nocardiosis, as with ours above, are in immunocompromised patients either by disease states such as HIV, diabetes, and malignancy or iatrogenically with corticosteroids or other immunosuppressing or immunomodulating drugs. The clinical presentation of nocardiosis is non-specific and is dependent on the site of infection, but the diagnosis should be on the differential for immunocompromised patients with a suspected CNS abscess, particularly if they have concurrent cutaneous, soft tissue, or pulmonary infections.3

Therapy is based on site of infection and species of nocardia isolated; however, trimethoprim-sulfamethoxazole is accepted as part of the first-line treatment. Severe disease, such as that exhibited in our patient, warrants combination therapy and may include a carbapenem, third generation cephalosporin, or an extended spectrum fluoroquinolone.4 Our patient was originally treated with trimethoprim-sulfamethoxazole and imipenem, but the trimethoprim-sulfamethoxazole was discontinued due to hyperkalemia and the patient was started on Linezolid.

References

  1. Spelman, Denis. “Microbiology, epidemiology, and pathogenesis of nocardia”. UpToDate, Wolters Kluwer, May 08, 2019. https://www.uptodate.com/contents/microbiology-epidemiology-and-pathogenesis-of-nocardiosis?search=nocardiosis&source=search_result&selectedTitle=3%7E94&usage_type=default&display_rank=3. Accessed on March 10, 2020.
  2. Bell M, McNeil MM, and Brown JM. Nocardia species (Nocardiosis). 2014. http://www.antimicrobe.org/b117.asp. Accessed on March 24, 2020.
  3. Spelman, Denis. “Clinical manifestations and diagnosis of nocardiosis”. UpToDate, Wolters Kluwer, May 08, 2019. https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-nocardiosis?search=nocardiosis&source=search_result&selectedTitle=1~94&usage_type=default&display_rank=1. Accessed on March 10, 2020.
  4. Spelman, Denis. “Treatment of nocardiosis”. UpToDate, Wolters Kluwer, November 11, 2019. https://www.uptodate.com/contents/treatment-of-nocardiosis?search=nocardiosis&source=search_result&selectedTitle=2~94&usage_type=default&display_rank=2. Accessed on March 24, 2020.

-Kayla Elliott, MD is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

Microbiology Case Study: A 29 Year Old Man with Fevers and Chills

Case History

A 29 year old African American male presented to the emergency department for a 3 day history of fever, chills, and night sweats, approximately four weeks after returning home from a trip to Uganda. He denied any diarrhea, vomiting, cough, abdominal pain, nausea, or sick contacts. His past medical history was non-contributory. A complete blood count (CBC) was performed, which revealed anemia and low platelets. The patient’s blood was also analyzed through Giemsa stain on a thin smear preparation (Image 1). Findings revealed only several platelets present. In addition, the patient’s red blood cell morphology was varied and atypical. The cells appear smaller than normal (microcytic) with several shapes and form being present: acanthocytes (burr cells), schistocytes (fragmented red blood cells), and bite cells (red blood cells which appear as if a “bite” has been taken out of them). In addition, many red blood cells contained a delicate ring form with either a central chromatin dot or two dots in a “headphone” arrangement (Image 2). This ring form was the only form identified in the thin smear. In addition, it was only present inside the red blood cells (with no forms present outside the cells) and the red blood cells with the ring form were the same size as those blood cells without the ring form. Finally, several red blood cells were seen occupied by more than one ring form. A thick smear of the patient’s blood was prepared in order to lyse the red blood cells so that the cellular contents could be analyzed with increased sensitivity. Findings on the thick smear revealed the similar delicate ring form structure found inside the red blood cells on the thin smear. These were the only forms identified and they also contained either a central chromatin dot or two bi-lobed dots (“headphone” forms) (Image 3).

Image 1. Thin smear with variable red blood cell morphology (acanthocytes, schistocytes, and bite cells) and lowered platelet number.
Image 2. Delicate ring form with a central chromatin dot inside a red blood cell.
Image 3. Numerous delicate ring forms with either a central chromatin “dot” or bi-lobed “dots.”

Diagnosis

The main differential diagnoses of ring forms present in red blood cells include two parasitic organisms: Babesia and Plasmodium species. Endemic regions for Babesia include the Midwest and Eastern United States, the majority of Europe, and parts of central Asia and Far East Asia. In addition, the ring forms of Babesia are pleomorphic (varying in size and shape from cell-to-cell) with rare distinctive “Maltese cross” forms (indicative of asexual budding).

Plasmodium, on the other hand, is endemic to South America, most of Sub-Saharan Africa (including Uganda), and parts of Asia (such as India, Southern China, and Indonesia). The most common Plasmodium sub-species in Uganda is P. falciparum, which accounts for over 90% of Plasmodium cases. The ring forms of Plasmodium are monomorphic. Considering the patient’s travel history, as well as the findings on the thin smear and thick smear of the patient’s blood, the organism was confirmed as Plasmodium falciparum through polymerase chain reaction (PCR).

Discussion

Malaria is caused by the single-cell parasitic protozoan Plasmodium species, which is transmitted through an arthropod vector (Anopheles mosquito). Approximately 40% of the world’s population lives in endemic areas, 300-500 million clinical cases occur world-wide per year, resulting in 1.5-2.7 million deaths (90% of which are in Africa). However, this is an increasing problem even in non-endemic areas, considering the ease and flexibility of international travel, vague generalized clinical symptoms which could cause a delay in diagnosis, and drug resistance to the main active agents against the protozoan.

The Anopheles mosquito injects a sporozoite form of the parasite into humans, which then penetrates liver cells and matures into a schizont. The schizont then breaks through the liver cell and enters the blood stream as a merozoite, which invades red blood cells. The trophozoite form then matures in the red blood cells (as a “ring form”), which then re-enters the blood stream as a merozoite form. Finally, the merozoite matures into macrogametocytes and microgametocytes, which are taken up by the Anopheles mosquito.

The onset of symptoms usually occurs within 1 month (for patients that are not endemic to the region) or up to 6 months (for patients who have lived in Plasmodium regions and have presumably developed some sort of an immune tolerance to the parasite). These symptoms are characterized as “paroxysmal” and “cyclical,” which include chills, fever, sweats, and resolution, followed by another cycle of symptoms. Studies have shown that symptoms correlate with the release of merozoites into the blood stream, causing tissue necrosis factor release from circulating white blood cells. Patients may also develop anemia, splenomegaly, and acute renal failure. A unique complication of P. falciparum is its ability to infect a large number of mature red blood cells, rather than only young red blood cells. This results in high levels of parasitemia and increased clumping of red blood cells due to the induction of proteins in the cell that cause agglutination to other cells. This may result in “cerebral” malaria, which may cause altered mental status, coma, or even death.

References:

  1. Laboratory diagnosis of malaria: Plasmodium falciparum. CDC Laboratory Identification of Parasites of Public Health Concern. https://www.cdc.gov/dpdx/resources/pdf/benchAids/malaria/Pfalciparum_benchaidV2.pdf
  2. Kerlin, Douglas and Gatton, Michelle. Preferential Invasion by Plasmodium Merozoites and the Self-Regulation of Parasite Burden. Public Library of Science. 2013; 8(2): e57434. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3584029/

Jamaal Rehman, MD is a 4th year anatomic and clinical pathology resident at University of Chicago (NorthShore) program based at Evanston Hospital, Evanston, IL. His academic interests include Surgical pathology, specifically Gastrointestinal pathology. He will be matriculating to the University of Iowa for a Gastrointestinal pathology fellowship following residency training.

-Erin McElvania, PhD, D(ABMM), is the Director of Clinical Microbiology NorthShore University Health System in Evanston, Illinois. Follow Dr. McElvania on twitter @E-McElvania. 

Microbiology Case Study: A 57 Year Old Man with an Infected Drain Site

Clinical History

The patient is a 57 year old male with a history of traumatic brain injury in 2005 resulting in quadriplegia and subsequent neurogenic bladder with chronic spasms. In 2016 the patient underwent cystoprostatectomy, proctectomy, and ureteroenteric anastomosis to colon. The post-operative period was complicated by the formation of a presacral abscess consisting of MSSA and E. coli. Drain placement failed to resolve the abscess and drain studies showed the formation of a fistula to the patient’s rectal stump. The subsequent 3-year period consisted of repeat drain placements and laparotomy to drain and wash out multiple small collections of fluid seen on imaging. Bacterial cultures during this interval grew mixed gram positive and gram negative enteric bacteria, treated primarily with ertapenem. In January of 2020, the patient underwent exploratory laparotomy with debridement and drainage of pelvic abscess. Tissue cultures from the procedure grew MRSA and vancomycin was prescribed for treatment. Vancomycin was switched to daptomycin for more favorable dosing and ertapenem was added to his treatment plan. Four weeks after his operation, the patient reported pain at his drain site and the fluid in his Jackson-Pratt (JP) drain had turned green. Fluid from the JP drain was submitted for microbiological work-up.

Laboratory Findings

Gram stain of the fluid from the JP drain showed neutrophils, many gram negative bacilli, and beaded gram-positive bacilli. Modified Kinyuon testing was positive for acid-fast bacilli (AFB) and cultures were ordered for mycobacteria as well as Nocardia. The gram negative bacilli was isolated and identified as Pseudomonas aeruginosa by MALDI-ToF. The beaded gram-positive bacilli were isolated on CNA agar and identified by MALDI as Mycobacterium chelonae. Concordant morphology was observed on mycobacterial culture. Nocardia culture was overgrown by P. aeruginosa.

Image 1. Gram stain of specimen taken from the patient’s JP drain.
Image 2. CNA agar plate growing gram positive bacilli.
Image 3. 7H11 plate growing acid fast bacilli.

Discussion

Rapidly growing mycobacteria (RGM) include the three most common clinically relevant species: Mycobacterium abscessus, Mycobacterium fortuitum, and Mycobacterium chelonae.

The RGM are environmental organisms found worldwide that usually grow in subculture within one week (eg, rapidly, as compared with other mycobacteria). M. abscessus is the most commonly encountered species of this group isolated from clinical respiratory specimens, M. fortuitum is the most common from non-respiratory specimens, and M. chelonae primarily impacts immunosuppressed patients and may also cause surgical wound infections.

Postoperative infections with RGM have occurred following various procedures including cosmetic surgery procedures, augmentation mammoplasty, laser in situ keratomileusis (LASIK), and heart surgery.1-8 Infection is characterized by multiple recurrent abscesses around the surgical wound.

Diagnosis for non-pulmonary disease is made by culture of the specific pathogen from drainage material or biopsy of the affected site. The isolation of organisms from sterile, closed sites, such as bone marrow or blood or from a skin biopsy (in the setting of multiple lesions), is diagnostic of the disease. Once an isolate has been identified as a nontuberculous mycobacteria (NTM), the species should be identified. However, identification of RGM in most laboratories is either incomplete or imprecise. M. abscessus isolates are frequently identified simply as “M. chelonae/abscessus complex,” or if they are specifically identified as “M. abscessus,” they are not accurately sub-speciated.

Susceptibility testing should be performed against a number of antibacterial agents, however, there is no established minimum inhibitory concentration (MIC) cutoff for susceptibility or resistance. M. chelonae is typically treated with Macrolide antibiotics, particularly azithromycin and clarithromycin. M. fortuitumM. abscessus, and M. chelonae are resistant to the antituberculosis agents rifampinethambutol, and isoniazid, so susceptibility testing of RGM should not be performed with these.

The clinicians in our case suspected that the M. chelonae culture from the patient’s JP drain was most likely a contaminant as the same organism was never isolated from previous tissue or fluid cultures. He was continued on daptomycin, ertapenem, and ciprofloxacin was added to cover P. aeruginosa. The patient responded well with resolution of his localized symptoms at the site of the JP drain. Unfortunately, he continues to suffer from multiple, recurring presacral abscesses.

References

  1. Rimmer J, Hamilton S, Gault D. Recurrent mycobacterial breast abscesses complicating reconstruction. Br J Plast Surg 2004; 57:676.
  2. John T, Velotta E. Nontuberculous (atypical) mycobacterial keratitis after LASIK: current status and clinical implications. Cornea 2005; 24:245.
  3. Freitas D, Alvarenga L, Sampaio J, et al. An outbreak of Mycobacterium chelonae infection after LASIK. Ophthalmology 2003; 110:276.
  4. Sampaio JL, Junior DN, de Freitas D, et al. An outbreak of keratitis caused by Mycobacterium immunogenum. J Clin Microbiol 2006; 44:3201.
  5. Edens C, Liebich L, Halpin AL, et al. Mycobacterium chelonae Eye Infections Associated with Humidifier Use in an Outpatient LASIK Clinic–Ohio, 2015. MMWR Morb Mortal Wkly Rep 2015; 64:1177.
  6. Toy BR, Frank PJ. Outbreak of Mycobacterium abscessus infection after soft tissue augmentation. Dermatol Surg 2003; 29:971.
  7. Centers for Disease Control and Prevention (CDC). Mycobacterium chelonae infections associated with face lifts–New Jersey, 2002-2003. MMWR Morb Mortal Wkly Rep 2004; 53:192.
  8. Wallace RJ Jr, Brown BA, Onyi GO. Skin, soft tissue, and bone infections due to Mycobacterium chelonae chelonae: importance of prior corticosteroid therapy, frequency of disseminated infections, and resistance to oral antimicrobials other than clarithromycin. J Infect Dis 1992; 166:405.
  9. Wallace RJ Jr, Brown BA, Onyi GO. Susceptibilities of Mycobacterium fortuitum biovar. fortuitum and the two subgroups of Mycobacterium chelonae to imipenem, cefmetazole, cefoxitin, and amoxicillin-clavulanic acid. Antimicrob Agents Chemother 1991; 35:773.

-Will Humphery, MD is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.

An Asymptomatic 52 Year Old Female with a Surprise Finding on Colonoscopy

Case Presentation

A 52-year-old female with no significant past medical history is seen for a routine annual examination and is scheduled for a colonoscopy due to her age being over 50 years. The colonoscopy was performed and an isolated single worm was found within the cecum (Images 1-2). The worm was removed with cold forceps and subsequently placed in paraffin and sectioned (Images 3-5).

Image 1. The worm is depicted within the cecum attached to the mucosal wall by its anterior end.
Image 2. The worm is captured using cold forceps.
Image 3. Hematoxylin and eosin stained section of the worm.
Image 4. Higher power magnification, showing eggs with distinctive characteristic bilateral polar plugs and barrel shape.
Image 5. Higher power magnification, showing eggs with distinctive characteristic bilateral polar plugs and barrel shape.

Discussion

The worm was identified as Trichuris trichiura. The common name for this organism is the whipworm. It belongs to the Nematode classification of parasites, which are commonly referred to as roundworms. Adults measure up to 5 cm in length and have a tapered or whip-like anterior end. The eggs measure 50 x 25 µm, and have brownish thick shells on stool smear. The eggs also have a barrel shape and distinctive protruding polar plugs at each end. These morphologic characteristics of the egg are diagnostic of Trichuris trichiura. The lack of a tissue migration phase and a relative lack of symptoms characterize whipworm infection, with only those with a heavy parasite burden becoming symptomatic. If these symptoms do arise, they are usually mild, ranging from loose stools with minimal blood loss and nocturnal stools, to iron deficiency anemia and vitamin deficiency. As parasite burden increases, however, symptoms can progress to dysentery, colitis, or rectal prolapse. Prolapse is more frequent in the Pediatric population, but has been described in adults as well.

Trichuris trichiura has one of the simplest of the Nematode life cycles. Eggs are unintentionally ingested, hatching in the small intestine by way of exploitation of signaling molecules from the intestinal microbiome. The larvae then burrow through the villi and continue maturing in the wall of the small intestine. They then return to the intestinal lumen, migrating to the cecum and subsequently into the large intestine, where they finish the process of maturation. Finally, the worm uses its anterior end to anchor into the bowel mucosa, where it feeds on tissue secretions and uses its posterior end for reproduction and laying eggs. Female worms can live from 1-5 years and can lay up to 20,000 eggs per day.

Whipworm infection is principally a problem in tropical Asia and, to a lesser degree, in Africa and South America. Children are most commonly infected, and can experience failure to thrive as well as cognitive and developmental defects. Transmission is by the fecal-oral route, explaining the large incidence of infection in children from developing countries, as they are far more likely to be in physical contact with soil and environmental contaminants, with subsequent placement of their fingers in their mouths. The fecal-oral route can also be facilitated by improper washing and cooking of fruits and vegetables, as well as overall poor hygiene, no matter what the geographical location. In the United States, whipworm infection is exceedingly rare. When it does happen, it is most commonly seen in the rural Southeast. Although it is rare, the incidence of infection is reported to be as high as 2.2 million individuals within the United States, with 1-2 billion cases worldwide.

Studies often reveal eosinophilia in nematode infections from ongoing tissue invasion. However, the lack of a tissue migration phase in Trichuris life cycles makes this a rare laboratory finding. Other studies such as anemia can give an indication to the presence of the worm. Characteristic egg morphology on stool smear remains the cheapest and easiest way to diagnose infection, but polymerase chain reaction using new sequencing techniques are now available in some laboratories to detect the presence of Trichuris with great sensitivity and specificity. The parasite burden can be quantified per gram of stool by the Kato-Katz technique. This procedure filters stool through mesh, with the filtered sample being placed within a template on a glass slide. The template is then removed and the remaining fecal material is removed with a piece of cellophane soaked in glycerol, leaving only eggs on the slide.

Discovery of T. trichiura in our patient was an unexpected finding, as our patient had no symptoms.  Asymptomatic detection of T. trichiura has been described in the past, so this finding is not unique. The medication of choice is mebendazole, showing a cure rate of 40-75%. The drug works well by inhibiting glucose uptake from the gastrointestinal tract of the helminth. However, this drug is very expensive, and as a result is difficult to obtain. The patient is currently receiving an alternative drug called albendazole as outpatient therapy and will be switched to mebendazole as soon as resources become available should the need remain. The patient is following up with her primary care physician and is expected to make a full recovery.

References

  1. Donkor, Kwame; Lundberg, Scott;
    https://emedicine.medscape.com/article/788570-overview. Trichuris trichiura (Whipworm) Infection (Trichuriasis).
  2. Sunkara T, Sharma SR, Ofosu A. Trichuris trichiura-An Unwelcome Surprise during Colonoscopy. Am J Trop Med Hyg. 2018 Sep;99(3):555-556. doi: 10.4269/ajtmh.18-0209. PubMed PMID: 30187847; PubMed Central PMCID: PMC6169157.

-Cory Gray, MD is a second year resident in anatomic and clinical pathology at the University of Chicago (NorthShore). His interests include hematopathology and molecular and genetic pathology, as well as medical microbiology.

-Erin McElvania, PhD, D(ABMM), is the Director of Clinical Microbiology NorthShore University Health System in Evanston, Illinois. Follow Dr. McElvania on twitter @E-McElvania.