Microbiology Case Study: A 30 Year Old with Worsening Right Middle Finger Pain

Case History

A thirty year old male on dialysis with past medical history of nephrotic syndrome and end-stage renal disease presented to the emergency department due to complaints of severe abdominal pain. Culture of paracentesis fluid confirmed a diagnosis of bacterial peritonitis, and he was admitted for intra-peritoneal antibiotic therapy. During his admission however, he also complained of progressive worsening right middle finger pain and swelling after smashing his finger in a door one month prior. Upon exam the finger appeared visibly swollen with slight discoloration, but exhibited full range of motion (Image 1A). Imaging revealed osteomyelitis of the intermediate and distal phalanx, including involvement of the distal interphalangeal joint (Image 1B). Additionally, a small abscess was detected (Image 1B, inset) requiring incision and drainage (I&D). Following the I&D, the patient was discharged home on broad spectrum antimicrobial therapy pending results of intra-operative cultures. The patient was readmitted the following week for severe electrolyte imbalance due to a missed dialysis session. His right middle finger continued to cause him significant pain, and the I&D site appeared poorly healing with excess fluid drainage (Image 1C).

Image 1. A: Right distal right middle finger swelling at admission. B: MRI with IV contrast of the right hand revealed osteomyelitis with small abscess formation (inset). C: Right middle figure I&D site at readmission.

Laboratory Identification

Bacterial, fungal and mycobacterial cultures of purulent material from the I&D were obtained. Following four days of incubation, creamy white yeast-like colonies appeared on blood and chocolate agar plates at 35°C (Images 2A, B). Fungal medias grew colonies which were initially white (Image 2C), but became more wrinkled with increased central dark coloration and white periphery (Image 2D) within two weeks at 30°C. Cellophane tape preparations with lactophenol cotton blue were performed for microscopic evaluation of the mature colonies from potato dextrose agar. Narrow, septate hyphae with slender, tapering conidiophores were observed (Image 3A). The conidiophores had many small, tear-shaped hyaline conidia forming “daisy-like” clusters (Image 3B). Based upon these morphologic characteristics, the organism was identified as member of the Sporothrix schenckii complex.

Image 2. Culture of purulent material obtained from right middle finger I&D. A,B: Creamy white yeast-like colonies on blood and chocolate agar plates incubated at 35°C. Small white colonies (C) matured into moist, wrinkled colonies with central dark coloration (D) on fungal medias after 2 weeks’ incubation at 28-30°C.
Image 3. Lactophenol cotton blue (LCB) prep of fungal growth from plate in Figure 2D. Thin, septate hyphae were observed with tapered conidiophores and characteristic “daisy-like” clusters of conidia.

Discussion

Sporotrichosis (also known as rose gardener’s disease) is caused by dimorphic molds belonging to the Sporothrix schenckii complex. These fungi inhabit soil, plant matter and decaying vegetation, thus explaining their traditional association with gardening. As thermally dimorphic fungi, members of the Sporothrix schneckii complex exhibit both yeast and filamentous mold forms. The yeast colonies are smooth with cream or tan coloration when grown close to body temperature (35℃). Microscopically, the yeasts appear as round, oval and fusiform budding cells3,4 best visualized with GMS or PAS stains due to their relative infrequency when observed in tissue. These are commonly referred to as “cigar bodies”, and are typically seen on histopathology, sometimes with accompanying pyogranulomatous inflammation or suppurative granulomas.2 By contrast, the mold colonies begin small, white to pale-orange and become moist, wrinkled, leathery, or velvety and often darken to a salt-and-pepper brown-black as the mold ages. Microscopically, narrow, septate hyphae with slender, tapering conidiophores can be visualized. The conidiophore apex is often slightly swollen and bears many small, tear-shaped or almost round hyaline conidia (2-3 X 2-6 µm) on delicate hair-like denticles, forming the characteristic “rosette” or “daisy-like” clusters in young cultures.1,3,4 This also illustrates the etymology of the organism: from latin, spor (spore) + thrix (hair).5

The most common presentation of sporotrichosis is a lymphocutaneous form originating from a puncture or trauma that inoculates contaminated material into the wound. A pustule forms in subcutaneous tissue followed by ulceration and development of secondary lesions via lymphatic spread in a distal to proximal fashion.2 This form often occurs in immunocompetent individuals. More uncommon forms include osteoarticular, pulmonary, and disseminated infections, usually associated with immunocompromised hosts and alcoholics. In our case of osteoarticular sporotrichosis, the patient suffered from nephrotic syndrome which is often associated with immunodeficiency. The key inciting event to the development of his infection was likely the traumatic injury to his finger which was followed by wound inoculation of soil/material containing the organism. Following his diagnosis, the patient revealed that he was an avid gardener.

In conclusion, the patient was started on oral itraconazole initially for medical management. However, due to continued pain after a few weeks of therapy, the patient opted for amputation of the involved portion of the finger. Following successful amputation, the patient is to remain on itraconazole for one year due to concern for possible surgical margin involvement. He has healed well to date, with no continued pain in the remaining portion of the finger.

References

  1. Love GL, Ribes JA. 2018. Color Atlas of Mycology, An Illustrated Field Guide Based on Proficiency Testing. College of American Pathologists (CAP), p. 214-218.
  2. Pritt BS. 2018. Atlas of Fundamental Infectious Diseases Histopathology. College of American Pathologists (CAP), p. 120-122.
  3. Walsh TJ, Hayden RT, Larone DH. 2018. Larone’s Medically Important Fungi, A Guide to Identification. 6th Ed. ASM Press, p. 53, 178-180.
  4. St-Germain G, Summerbell R. 2011. Identifying Fungi: A Clinical Laboratory Handbook, 2nd Edition, Star Publishing Company Inc., pg. 238-239.
  5. Sellera, FP and Larsson, CE. 2019. Sporothrix schneckii. Etymologica. Emerg. Infect. Dis. 25(9):1631.

John Markantonis, DO is the current Medical Microbiology fellow at UT Southwestern and will be completing his Clinical Pathology residency in 2022. He is also interested in Transfusion Medicine and parasitic diseases.

Samira Peyrovi, M(ASCP)CM is a medical technologist at UT Southwestern Medical Center. She graduated with a degree in biology from Texas Women’s University and has worked in the microbiology section at Clements University Hospital for the past 5 years.

-Andrew Clark, PhD, D(ABMM) is an Assistant Professor at UT Southwestern Medical Center 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.

Microbiology Case Study: A 59 Year Old with History of Rheumatoid Arthritis

A 59 year old male with a history of rheumatoid arthritis, hepatitis C, non-small cell lung carcinoma presents to his rheumatologist. His joint pain has responded well to adalimumab and methotrexate, but over the past month his left elbow has become increasingly painful, despite multiple corticosteroid injections there. He does not report any fevers or chills. On physical exam, his left elbow is warm and swollen. Synovial fluid is aspirated and sent for gram stain and culture.

Image 1. Initial Gram stain findings.
Image 2. Growth on potato flake agar.

The yeast was identified as Candida parapsilosis, a common environmental species of Candida that is becoming increasingly prevalent as a cause of invasive candidal disease. It is easily transmitted by contact and is a source of nosocomial infections. It has the ability to form a biofilm and, thus, has a predilection for indwelling catheters and prosthetic devices. Highest-risk groups include immunocompromised patients, surgical patients, and very low-birth weight neonates.

The microbiology findings exemplify how fungi can be broadly categorized based on how they grow (as a yeast or a mold) in the host and in culture (a cooler environment). In this particular case, the initial gram stain (figure 1), representative of the phenotype in the host, demonstrates neutrophils with intracellular organisms with visible cell walls, suggestive of an active yeast infection with ongoing phagocytosis. The potato flake agar (figure 2) is also growing a yeast. Thus, the pathogen is classified as a yeast. In contrast, molds are characterized by the development of hyphae, which give them their classic “fluffy” appearance in culture (absent in this case). A clinically important subset of this group, the dimorphic fungi, are defined by a yeast phenotype in the host and a mold phenotype in culture.

References

  1. McGinnis, M, and S Tyring. (1996). Medical Microbiology (4th Edition). Galveston, TX: University of Texas Medical Branch at Galveston.
  2. McPherson, R, and M Pincus. (2011). Henry’s Clinical Diagnosis and Management By Laboratory Methods (22nd Edition, pp. 1155-1184). Philadelphia, PA: Elsevier Saunders.
  3. Trofa, D, A Gacser, and J Nosanchuck. “Candida parapsilosis, an Emerging Fungal Pathogen.” Clin Microbiol Rev. 2008 Oct; 21(4): 606-625.

-Frederick Eyerer, MD is a 3rd 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: An 83 Year Old Man with History of Dementia

An 83 year old man presents to an emergency department after an unwitnessed fall and being found down for an undetermined amount of time.  His past medical history includes dementia and type II diabetes mellitus.  A tick is found in his left groin.  Workup reveals mild rhabdomyolysis, mild transaminitis, thrombocytopenia, and multiple infiltrates on chest x-ray, concerning for aspiration pneumonia.  His hospital course is complicated by fever, hypotension, and atrial fibrillation with rapid ventricular response.  Representative images from his peripheral blood smear are shown below.

PCR confirmed the diagnosis of Anaplasma phagocytophilum.  The patient recovered after a 10-day course of doxycycline.

Differentiating Tick-Borne Intracellular Microorganisms

The clinical findings of recent tick exposure, thrombocytopenia, transaminitis, and acute illness are consistent with acute infection with either Ehrlichia or anaplasma.  The images depict morulae (microcolonies of bacteria) within the cytoplasm of neutrophils.  A. phagocytophilum, Ehrlichia chaffeensis, and Babesia microti can all be seen intracellularly on peripheral blood smears.  A. phagocytophilum preferentially infects neutrophils, while E. chaffeensis infects monocytes and B. microti infects erythrocytes.  Unlike A. phagocytophilum and E. chaffeensis, which both appear as intracellular morulae (clusters of bacteria), B. microti is a protozoa whose trophozoite forms are seen in red blood cells as delicate rings or grouped in tetrads (the characteristic “Maltese cross”).

The finding of morulae in granulocytes has a sensitivity of 20-80% for anaplasmosis within the first week of infection.  However, morulae within granulocytes are also found in infection with Ehrlichia ewingii (human granulocytotropic Ehrlichiosis, distinct from human monocytotropic Ehrlichiosis caused by E. chaffeensis), a less common relative of E. chaffeensis that is also transmitted by the Lone Star tick (Amblyomma americanum) and appears to preferentially infect immunocompromised hosts.  For E. chaffeensis, the sensitivity of finding morulae in monocytes is only 7-17% amongst immunocompetent hosts.

References

  1. Chapman, AS,  JS Bakken, SM Folk, et al.  “Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichioses, and anaplasmosis–United States: a practical guide for physicians and other health-care and public health professionals.” MMWR Recomm. Rep. 2006; 55(RR-4):1.
  2. McPherson, R, and M Pincus.  (2011).  Henry’s Clinical Diagnosis and Management By Laboratory Methods (22nd Edition, pp. 1073-1074, 1205).  Philadelphia, PA:  Elsevier Saunders.
  3. Paddock, CD, SM Folk, GM Shore, et al.  “Infections with Ehrlichia chaffeensis and Ehrlichia ewingii in persons coinfected with human immunodeficiency virus.” Clin Infect Dis. 2001; 33(9):1586-94.
  4. Schotthoefer, AM, JK Meece, LC Ivacic, et al.  “Comparison of a Real-Time PCR Method with Serology and Blood Smear Analysis for Diagnosis of Human Anaplasmosis: Importance of Infection Time Course for Optimal Test Utilization.” J Clin Microbiol. 2013 Jul; 51(7): 2147-2153.

-Frederick Eyerer, MD is a 3rd 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: Middle Aged Man with Altered Mental Status

Case History

A middle aged male presented to the emergency department with a several day history of altered mental status, insomnia, and lethargy. His family stated that he also had possibly had a seizure. Upon arrival to the emergency department he was febrile to 102°F, hypoxic, but denied shortness of breath, cough, nausea, and vomiting. While in the care of the emergency department he had several witnessed seizures requiring Ativan treatment, so the decision was made to admit the patient for 24-hour EEG monitoring. Past medical history was unremarkable. The patient is a smoker. His hobbies include working as a mechanic and working outdoors in his garden.

Initial brain imaging on MRI demonstrated cortical thickening/gyral swelling with associated signal abnormality within bilateral mesial temporal lobes that is seen with mild associated diffusion abnormality. A lumbar puncture was ordered and his CSF analysis demonstrated normal glucose (73 mg/dL [reference range: 40-80 mg/dL]), normal protein (32 mg/dL [reference range: 15-45 mg/dL]), and normal nucleated cells [reference range: 0-8/mm3]. Bacterial, fungal, and AFB culture as well as PCR for herpes simplex virus and varicella zoster virus were ordered. The CSF bacterial, fungal, and AFB cultures showed no growth of any microorganisms, and PCR results were negative for HSV and VZV. What additional infectious etiologies would you like to test for?

Discussion

Serology studies were ordered which demonstrated positive IgM and IgG antibodies for West Nile virus.

West Nile virus is a member of the Flavivirus genus. It is spread through mosquito bites, and birds are the primary reservoir for this virus. The incubation period for West Nile virus is 4-10 days. Typically, about 80% of those infected with the virus will be asymptomatic. In 20% of cases, the patient will develop a febrile illness, with possible symptoms of headaches, body aches, weakness, joint pain, and fatigue. About 1 in 150 of those infected will develop illness involving the central nervous system. In these cases, symptoms can include high fever, headache, neck stiffness, confusion, seizures, and coma. Death occurs in 10% of those with involvement of the central nervous system. The most important risk factor for death is age with patients over 70 years of age being most at risk.

Diagnosis of West Nile virus generally made by detection of IgM and IgG in the serum and/or CSF. IgM can be detected 3-8 days post symptom onset and remains positive for 2-3 months in the CSF, and occasionally longer in the serum. Diagnosis is made by detection of IgM antibodies or conversion of IgG antibodies, while detection of IgG antibodies in isolation indicates a prior infection. False-positive results can occur in CSF specimens contaminated with blood that is IgM antibody positive. Patients who have been infected with or vaccinated against other flaviviruses can have false-positive serum antibodies. Plaque reduction neutralization test (PRNT) assay can be performed to rule out cross-reactivity with other flaviviruses. RT-PCR testing on CSF is also available for detection of West Nile virus RNA. The sensitivity of CSF RT-PCR is low in immunocompetent patients, but increased in immunocompromised patients due to prolonged viremia.

West Nile virus cases could increase in the future as a consequence of climate change. Currently, most cases of West Nile virus occur between June and September and cases have been reported in all 48 lower states. As climate change progresses, average temperatures are expected to increase around the world. As temperature increases, summers become longer, which means a longer season for mosquitoes. Laboratory studies also demonstrate that the virus replicates faster in warmer temperatures. Precipitation patterns are also expected to change in the future. The effect of precipitation is not as clear as that of temperature, but it can still play a role. In areas with more precipitation, increasing amounts of water could provide new breeding grounds for mosquitoes. On the other hand, extra rain can dilute some of the nutrients that the mosquitoes need. In areas with less precipitation, drought conditions can cause rivers to dry up, creating the pools of standing water that give rise to mosquitoes. In addition, as bodies of water become smaller, birds and mosquitoes will be in closer proximity, facilitating faster spread of the virus. We must be prepared for the possibility that West Nile virus cases may be on the rise in the future.

The patient continued to suffer from seizures and required continuous sedation with phenobarbital. For seizure prophylaxis he was given a combination of Keppra and Vimpat, with the dosage adjusted as needed. Throughout his entire hospital course he was monitored on EEG. For the first week of his stay, his EEG results demonstrated seizure like activity, requiring continued use of anti-seizure medication and sedation. After about one week, his seizure activity began to show improvement, and the process of decreasing his medication had begun.

After several days of improvement, his recover was complicated by abdominal compartment syndrome requiring laparotomy. After this, the patient’s seizure activity began to worsen. Within a few days, the patient became hypotensive, and broad spectrum antibiotics were given to protect against infection. Cultures were taken but no infection was identified. The patient ultimately developed shock and passed away.

References

  1. Paz, S. (2015). Climate change impacts on West Nile virus transmission in a global context. The Royal Society. doi:https://royalsocietypublishing.org/doi/10.1098/rstb.2013.0561
  2. Murray, P. R., Rosenthal, K. S., & Pfaller, M. A. (2021). Togaviruses and Flaviviruses. In Medical microbiology. Edinburgh: Elsevier.
  3. Miller, J. Michael, et al. “A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2018 update by the Infectious Diseases Society of America and the American Society for Microbiology.” Clinical Infectious Diseases 67.6 (2018): e1-e94.

-Robert Toelke, MD is a 1st year clinical and anatomic pathology resident at University of Chicago (NorthShore).

-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 41 Year Old Male with Pneumonia

Case Description

A 41 year old male with a past medical history significant for HIV presented to the emergency department with complaints of a fever, shortness of breath, cough, myalgias, diarrhea, and dark urine for five days. Upon presentation, he was found to meet sepsis criteria for fever of 105° F, white blood cell count of 19 x 109 /L, and tachycardia. Physical exam was unrevealing. Chest x-ray revealed a lobar pneumonia and a CT chest showed ground-glass opacities with superimposed interlobular thickening and intralobular septal thickening, commonly referred to as “crazy-paving” (Image 1). Initial laboratory assessments included CBC, CMP, blood and sputum cultures, and a T-spot. A legionella urine antigen test was ordered a short time later following an infectious disease consult.

CBC and CMP were significant for leukocytosis (19 x 109 /L), hyponatremia (130 mmol/L), and transaminitis (AST: 97, ALT: 91). Blood and sputum cultures were negative as was the T-spot. Ultimately, the diagnosis of Legionnaire’s Disease was made by the positive urine antigen test.

Image 1. Computed tomography images of the chest without contrast demonstrates consolidation and “crazy paving” patterns of radiographic pathology.
Image 2. Representative example of Legionella pneumophila on Buffered Charcoal Yeast Extract (BCYE) media with small wet gray colonies.

Discussion

Legionella is a genus of aerobic, gram negative, intracellular pathogens that are most often found in soil and water.1 There are over 60 known species of Legionella with each consisting of a varied number of serogroups. At least 26 of these species are pathogenic in humans, however only a few are responsible for the vast majority of known cases.2 In North America, upwards of 90% of cases are caused by L. pneumophila, and more specifically its serogroup 1. In Australia and New Zealand, L. longbeachae is the predominant human pathogen.3 Legionella infections most commonly cause community-acquired pneumonia after inhalation of aerosols and can less frequently cause a self-limited febrile syndrome known as Pontiac Fever. Characteristic signs that may cause a treating physician to think of Legionella infection include a constellation of symptoms that include diarrhea, hyponatremia, and elevated liver function tests.4

This case reviews a typical presentation of Legionnaire’s disease and highlights several diagnostic pearls worth remembering. Despite commonly being thought of as an exotic pathogen, Legionella is known to cause between 2%-15% of community-acquired pneumonia cases in the United States and Europe.5 The gold standard for diagnosis is culture of lower respiratory secretions, however it is a fastidious organism that is not easily picked up on gram stain or grown on standard media. When culture is attempted, nutrient enriched BCYE agar is required and the timeframe for growth must be increased to 5 to 7 days for L. pneumophila and 14 days for non-pneumophila strains (Image 2).6 Adding to the difficulty in detection, Legionella is easily treated by empiric therapies, such as macrolides, that cover atypical infections; therefore, delays in testing further reduce sensitivity. The urine antigen test does help to overcome this problem as it can detect infection within 2-3 days of symptom onset and remains positive for at least 1 month following resolution of the illness.6

References

  1. Edelstein PH and Roy CR. Legionnaires’ Disease and Pontiac Fever. In: Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, 8, Bennet JE, Dolin R and Blaser MJ (Eds), Elsevier, Pennsylvania 2015.
  2. National Center for Biotechnology Information Taxonomy Browser. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=444&lvl=3&keep=1&srchmode=1&unlock (Accessed on April 14, 2021).
  3. Yu VL, Plouffe JF, Pastoris MC, et al. Distribution of Legionella species and serogroups isolated by culture in patients with sporadic community-acquired legionellosis: an international collaborative survey. J Infect Dis 2002; 186:127.
  4. Robert R. Muder, L. Yu Victor, Infection Due to Legionella Species Other Than L. pneumophilaClinical Infectious Diseases. 2002; 35(1):990-998. doi.org/10.1086/342884
  5. Chahin A, Opal SM. Severe pneumonia caused by Legionella pneumophila: differential diagnosis and therapeutic considerations. Infect Dis Clin North Am. 2017;31(1):111-121. doi:10.1016/j.idc.2016.10.009
  6. Mercante JW, Winchell JM. Current and emerging Legionella diagnostics for laboratory and outbreak investigations. Clin Microbiol Rev. 2015;28(1):95-133. doi:10.1128/CMR.00029-14

-Allen Green is a first year Clinical Pathology resident at UT Southwestern. He has broad interest in laboratory medicine and Transfusion medicine.

-Dominick Cavuoti is a full professor at UT Southwestern and practices both Medical Microbiology, Infectious Disease Pathology and Cytology.

-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 Patient, A Toilet, and a Worm

Case History

A patient presents with a worm they found in the toilet.

Image 1. The offender.
Image 2. Mouth parts of the worm.

Discussion

This is Ascaris lumbricoides, a roundworm. Distinctive morphologic features include tapered ends, mouthparts consisting of three prominent lips (pictured in image 2), and a length of up to 35cm for females. The adults live in the duodenum and proximal jejunum. The eggs have an irregular external mamillated outer shell that gives them a roughened outer surface. Clinically, infection can range from asymptomatic to severe disease, in which the larvae, hatched from ingested eggs, migrate from the small bowel through the circulatory system to the lungs, where they mature in the alveolar capillary bed and cause Ascariasis pneumonitis (Löffler syndrome).

Other diagnostic considerations include Enterobius vermicularis (pinworm), Lumbricus terrestris (earthworm), Trichuris trichiura (whipworm), and the hook worms, Necator americanus and Ancylostoma duodenale.

Enterobius vermicularis, the pinworm, is the most common helminth infection in the United States. Clinically, the classic presentation is a child with pruritus ani. Females measure up to 1.3 cm in length and have a pointed posterior end, and both sexes have lateral alae and a prominent esophageal bulb. The worm in this case is far too large to be a pinworm.

The earthworm, Lumbricus terrestris, is soil-dwelling and non-pathogenic but occasionally encountered in the laboratory for identification purposes. Key morphologic features include a segmented body with no distinctive mouthparts and a clitellum (a mating organ that is a non-segmented portion of the body and often a different color from the rest of the body).

Trichuris trichiura, the whipworm, have a classic whip-like appearance with long, narrow anterior ends that anchor the worm to the large intestine, where they can remain for up to 10 years. Both males and females measure up to 5.0 cm in length, and diagnosis is often made by identification of the eggs, which are football-shaped and have polar plugs at both ends. Clinically, trichuriasis can cause dysentery-type symptoms and, in heavily infected children, can lead to rectal prolapse.

Necator americanus and Ancylostoma duodenale are the hookworms. Adult females measure up to 1.2 cm, and these two species are differentiated by examination of the mouthparts: Necator americanus has cutting plates, while Ancylostoma duodenale has cutting teeth. In addition to the large size difference between hookworms and roundworms, the lamprey-like appearance of these mouthparts is notably different from the “fleshy lips” of Ascaris. Hookworms and roundworms, however, are similar in that their larvae have the ability to migrate through tissue to the blood stream then the lungs, where they can cause Löffler syndrome and are expectorated then swallowed before reaching the small bowel. Unlike Ascaris, the larvae of which hatch from ingested eggs and penetrate the host through the bowel wall to get to the lung capillary beds where they can mature, hookworm larvae hatch outside the body and, on contact with a host (once again, lamprey-style), directly penetrate the skin, enter the circulation, travel to the lungs, then migrate up the bronchial tree to be swallowed. If ingested, Ancylostoma larvae can mature into adults in bowel without needing to migrate through the lungs.

References

  1. Centers for Disease Control and Prevention. “Stool Specimens – Intestinal Parasites: Comparative Morphology Tables.” https://www.cdc.gov/dpdx/diagnosticProcedures/stool/morphcomp.html. Last reviewed May 3, 2016. Accessed April 2, 2021.
  2. “Earthworms.” University of Pennsylvania. https://www.sas.upenn.edu/~rlenet/Earthworms.html. Accessed April 2, 2021.
  3. McPherson, R, and M Pincus. (2011). Henry’s Clinical Diagnosis and Management By Laboratory Methods (22nd Edition, pp. 1218-1220). Philadelphia, PA: Elsevier Saunders.

-Frederick Eyerer, MD is a 3rd 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 55 Year Old Man with New Onset Neurologic Deficits

Clinical History

A 55 year old male with a 43-pack-year smoking history was transferred to our hospital for evaluation of new onset neurologic deficits including slurred speech, aphasia, and right upper extremity diminished dexterity and neglect. CT chest was remarkable for a mass in the superior segment of the left lower lobe. Needle core biopsy of the lung mass revealed poorly differentiated non-small cell carcinoma. Head MRI demonstrated an enhancing mass in the left frontoparietal junction that was concerning for metastasis from a lung primary. The patient was started on chemotherapy as an outpatient. Follow-up imaging showed growth of the brain mass. A biopsy of the brain mass showed no evidence of metastasis, only “reactive brain with foci of dense mixed inflammation and filamentous bacteria consistent with abscess.”

Image 1. Head MRI demonstrating left frontoparietal mass.

Laboratory Findings

A portion of the brain biopsy was submitted for bacterial smear and culture. The aerobic culture grew chalky white colonies that, when stained with modified acid-fast stain, showed modified acid-fast positive filamentous bacteria, suspicious for Nocardia spp. Bacteria of similar morphology were also seen in the surgical pathology specimen when stained for modified AFB and with GMS.

Image 2. Blood agar plate growing chalky white colonies.
Image 3. Modified acid-fast positive filamentous bacteria at 1000x.

Disscussion

Nocardia is a genus of aerobic, catalase positive, saprophytic bacteria often found in the environment, but that can also be considered as normal flora on skin and in the respiratory tract. Nocardia species are variably acid-fast; for proper identification they must be stained with a modified acid-fast procedure (Fite, Kinyuon), using a weaker decolorizing acid. Nocardia will be negative by traditional acid-fast staining procedures (Ziehl–Neelsen). When Gram stained, Nocardia will appear as branching filamentous gram-positive bacilli with a “beaded” staining pattern (as if a string of beads). 

Multiple species are considered human pathogens, including N. asteroides, N. brasiliensis, N. cyriacigeorgica, N. farcinica, and N. nova. These organisms can cause disease in immunocompromised patients if inhaled or inoculated via trauma. If there is an established pulmonary infection, Nocardia may spread hematogenously, often infecting the brain. 

Central nervous system nocardiosis may occur in any region in the brain and can present with mass effect symptoms without typical infectious symptoms, as in our patient. Prognosis varies based on the extent of disease and the cause of a patient’s immunosuppression. Treatment of CNS nocardiosis usually begins with an induction phase of intravenous TMP-SMX and imipenem for 3-6 weeks or until there is clinical improvement. Once the patient improves, they can be switched to oral therapy with a sulfonamide and/or minocycline and/or amoxicillin-clavulanate.  

References

  • Beaman BL. Nocardia Species : Host-Parasite Relationships. 1994;7(2):213-264.
  • Spelman D. Clinical manifestations and diagnosis of nocardiosis. In: Sexton DJ, Mitty J, eds. UpToDate. UpToDate, Inc.
  • Spelman D. Microbiology, epidemiology and pathogenesis of nocardiosis. In: Sexton DJ, Mitty J, eds. UpToDate. UpToDate, Inc.
  • Spelman D. Treatment of Nocardiosis. In: Sexton DJ, Mitty J, eds. UpToDate. UpToDate, Inc.
  • Tille, Patricia M., PhD, BS, MT(ASCP) Facs. Bailey & Scott’s Diagnostic Microbiology. 14th ed. Elsevier; 2017.

-Michael Madrid, 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 53 Year Old Man with Confusion, Auditory Hallucinations, and Hearing Loss

Clinical History

A 53 year old male with a past medical history significant for dermatomyositis, antisynthetase syndrome, and atrial fibrillation with rapid ventricular response presented with a chief complaint of worsening confusion, auditory hallucinations, and hearing loss. Pertinent medications included prednisone and mycophenolate. Head MRI demonstrated leptomeningeal enhancement and hydrocephalus. A lumbar puncture was performed, with CSF results as follows:

Laboratory Findings

CSF was sent to the microbiology lab for bacterial and fungal smears and cultures. No organisms were seen on the Gram stain.

Within 3 days, however, rare colonies of yeast were growing on both the bacterial and fungal media. The yeast was identified as Cryptococcus neoformans using the in-house MALDI-TOF mass spectrometry instrument.

Image 1. Budding C. neoformans at 1000x.
Image 2. Colonies of C. neoformans on potato flake agar.

Discussion

Cryptococcus neoformans is an environmental saprophytic yeast that can be found around the world, although it is often associated with avian droppings.1 The cell is surrounded by a polysaccharide capsule that protects it from environmental hazards and, once within the host, from phagocytosis.2 Additionally, the cell wall of C. neoformans contains melanin due to the presence of the phenol oxidase enzyme, which assists in the formation of melanin from various phenolic substrates.1 Both the polysaccharide capsule and the melanin-containing cell wall can be helpful in the laboratory identification of C. neoformans.

If inhaled, Cryptococcus neoformans can cause disease (cryptococcosis) in immunocompromised patients. The most significant risk factor is AIDS, however any cause of immunodeficiency can be a risk factor, including long-term steroid therapy, organ transplantation, malignancy, and liver disease.1 Once inhaled, the organism spreads hematogenously and tends to favor the central nervous system, causing cryptococcal meningoencephalitis.1

Prognosis for patients with cryptococcosis can vary widely. In AIDS-associated CNS cryptococcosis, predictors of mortality include abnormal mental status, cerebrospinal fluid antigen titer >1:1024 by latex agglutination or >1:4000 by lateral flow assay, and CSF white blood cell count <20/µL.1 The prognosis for patients who are immunocompromised for other reasons depends on the cause of their immunosuppression.1

Treatment of patients with cryptococcal meningoencephalitis consists of an induction phase with amphotericin B and flucytosine followed by a consolidation phase with fluconazole then a long-term maintenance phase with a smaller dose of fluconazole.3

References

  1. Jobson M. Microbiology and epidemiology of Cryptococcus neoformans infection. In: Post T, ed. UpToDate. UpToDate, Inc. Accessed March 13, 2021. https://www.uptodate.com
  2. Tille, Patricia M., PhD, BS, MT(ASCP) Facs. Bailey & Scott’s Diagnostic Microbiology. 14th ed. Elsevier; 2017.
  3. Perfect JR, Dismukes WE, Dromer F, et al. Clinical practice guidelines for the management of cryptococcal disease: 2010 update by the infectious diseases society of America. Clin Infect Dis. 2010;50(3):291-322. doi:10.1086/649858

-Michael Madrid, 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 38 Year Old Female with Vaginal Bleeding and Diarrhea

A 38 year old female with history of endometriosis presented to emergency department complaining of heavy vaginal bleeding for 2 weeks duration. She also reported recent diarrhea, abdominal pain, nausea, fatigue, shortness of breath, fever, and chills. On physical exam, the patient had fever, tachycardia, tachypnea, and abdominal distention with a large, 32-week size uterine mass. She was found to have microcytic anemia (Hgb 9.2 g/dL, MCV 77.1 pg), diabetic ketoacidosis (glucose 522 mg/dL, ketones and glucose in urine, A1c 9.1%), and based on the above vital signs and leukocytosis (WBC 31.75/L)met sepsis criteria.

Abdominal CT revealed multiple uterine leiomyomas (fibroids), with the largest measuring up to 13.2 cm and demonstrating characteristics concerning for pyomyoma (abscess arising in  leiomyoma). The patient underwent exploratory laparotomy and myomectomy. Gross images of the resected uterine mass demonstrated  a circumscribed whorled nodular lesion with patchy necrosis (Image 1). Histologic examination of the resected lesion demonstrated a bland smooth muscle tumor, devoid of cytologic atypia and mitotic activity, with area of abscess formation showing necrosis and abundant neutrophils leading to a diagnosis of  “Leiomyoma with severe acute inflammation, areas of necrosis and abscess formation, consistent with pyomyoma (14 cm)” (Image 2).  A tissue Gram stain demonstrates multiple morphotypes of bacteria (image 3). Blood cultures, drawn on admission, flagged positive and the Gram stain revealed gram negative rods and blood, chocolate and Maconkey agars grew creamy gray non-hemolytic colonies that did not ferment lactose.  MALDI-TOF mass spectrometry was performed and identified the isolate as Salmonella species. A triple sugar iron agar slant was set up to confirm the phenotype of a non-typhoidal serovar of Salmonella. Growth of the organism demonstrated abundant hydrogen sulfide production, an acidic butt, and an alkaline slant, confirming the nontyphoidal phenotype.

Image 1. Gross image of the resected leiomyoma (fibroid). Formalin fixed, serially sectioned, encapsulated smooth muscle mass with patchy areas of abscess formation and necrosis. Mass measures 14 cm in greatest dimension.
Image 2. Histopathologic micrograph of hematoxylin and eosin stained leiomyoma (10x objective). A) shows spindle-shaped smooth muscle cells with admixed neutrophils. Central area of necrosis with abscess formation. B) shows edematous and necrotic smooth muscle with intermixed acute inflammation.
Image 3. Tissue Gram stain showing multiple morphotypes of bacilli with poorly staining gram characteristics (40x objective).

Discussion

Pyomyoma, also referred to as suppurative leiomyoma, is an exceedingly rare complication of uterine leiomyoma, which involves infarction of the benign tumor followed by introduction and growth of bacteria.1 Microbes can be introduced by way of ascending genitourinary infection, spread from adjacent structures, or hematogenous or lymphatic spread.2 These infections may be polymicrobial or caused by a single microorganism, and the reported causative agents vary widely, with the most common being Escherichia coli, Staphylococcus species, streptococcal species, enterococcal species, Bacterioides species, Clostridium perfringens, and Candida.3 However, there have been no reported cases of Salmonella species isolated from pyomyoma to date.

Salmonella is a gram negative bacillus belonging to the Enterobacteriacae family.4,5 Salmonella enterica, the species responsible for causing disease in humans, is sub-divided into numerous serovars, which can be broadly grouped into typhoid and nontyphoid.4,5 While the typhoid serovars cause enteric fever, the nontyphoid serovars can cause gastroenteritis and bacteremia.5 Most nontyphoid Salmonella infections are foodborne, and approximately 5% of nontyphoid Salmonella infections progress to bacteremia.4 The bacteria gain access to the bloodstream by utilizing multiple virulence factors to invade the epithelial cells of the gut.4 Salmonella can be identified in the laboratory from blood culture based on several characteristic biochemical results, including Gram stain, absence of lactose fermentation, motility, hydrogen sulfide and gas production, utilization of citrate, and decarboxylation of lysine and ornithine.

This case presents Salmonella species as the cause of sepsis in the setting of pyomyoma, a very rare entity. It is postulated that gastroenteritis caused by nontyphoid Salmonella may have been the cause of the patient’s recent diarrhea, and uncontrolled blood glucose levels in the setting of diabetes may have contributed to the progression to sepsis. We could hypothesize whether the Salmonella seeded the fibroid precipitating the abscess formation since Salmonella is known to cause abscess formation in unusual sites including having a proclivity for vascular sites (e.g., aortitis). The patient unfortunately experienced complications from her sepsis with concomitant surgery. She became unresponsive despite numerous attempts at resuscitation and died.

References

  1. Azimi-Ghomi O and Gradon J. Pyomyoma: Case Report and Comprehensive Literature Review of 75 Cases Since 1945. 2017. SM Journal of Case Reports. 3(4):1054.
  2. Obele, CC, et al. A Case of Pyomyoma following Uterine Fibroid Embolization and a Review of the Literature. 2016. Case Reports in Obstetrics and Gynecology. 2016:9835412.
  3. Iwahashi N, et al. Large Uterine Pyomyoma in a Perimenopausal Female: A Case Report and Review of 50 Reported Cases in the Literature. 2016. Molecular and Clinical Oncology. 5(5):527-531.
  4. Eng SK, et al. Salmonella: A Review on Pathogenesis, Epidemiology, and Antibiotic Resistance. 2014. Frontiers in Life Science. 8(3):284-293.
  5. Coburn B, et al. Salmonella, the Host and Disease: A Brief Review. 2006. Immunology & Cell Biology. 85(2):112-118.

-Heather Jones is a first year AP/CP resident at UT Southwestern.

-Katja Gwin is an Assistant Professor at UT Southwestern in the Department of Pathology and specializes in gynecologic pathology.

-Dominick Cavuoti is a Professor at UT Southwestern in the Department of Pathology and specializes in cytopathology, infectious disease pathology 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: Blood stream infection in a 77 year old patient – is it Really from Mosquitoes?

A 77 year old male with a past medical history of end stage renal disease (ESRD) on hemodialysis, type 2 diabetes, coronary and peripheral artery disease, and squamous cell carcinoma of the lung on current chemotherapy/radiation was admitted to our hospital from his outpatient hematology oncology clinic for acute hypoxia. Due to an episode of decreased responsiveness and a potential stroke, Head computed tomography (CT) and computed tomography angiography (CTA) were performed. Electroencephalography showed diffuse slowing, suggestive of encephalopathy. Three days after admission, he became hypotensive and febrile. Pulmonology/critical care was consulted; blood and respiratory samples collected for cultures. The blood culture grew gram negative rods in the aerobic bottles (Images 1-3) after overnight incubation. The patient was initially on cefepime and switched to meropenem 500 mg IV daily.

The following day, the blood culture isolate was identified as Elizabethkingia anophelis. The isolate was resistant to both of the patient’s prior inpatient antibiotics, cefepime and meropenem. Additionally, the isolate was resistant to first, second, and third generations of cephalosporins, aztreonam, tetracyclines and tobramycin. However, it was susceptible to amikacin, ciprofloxacin, gentamicin, and trimethoprim/sulfamethoxazole. Meropenem was discontinued and replaced with ciprofloxacin 400 mg IV daily. Infectious disease was consulted; at this time the patient was displaying nuchal rigidity and extreme encephalopathy. Increased dosing of Ciprofloxacin for better central nervous system penetration, in combination with trimethoprim/sulfamethoxazole 2.5mg/kg IV q8h, rifampin 600 mg IV daily was recommended and a lumbar puncture to be performed once the patient was stable. Sadly, due to underlying severe comorbidities, along with worsening CNS responses, the patient expired on day 9.

Image 1. Small gram negative rods of E. anophelis from positive aerobic blood cultures.
Image 2. Blood Agar Plate growing E. anophelis after overnight incubation at 35 degrees C
Image 3: Chocolate plate growing smooth creamy gram negative E. anophelis after overnight incubation at 35 degrees C

Discussion

The genus Elizabethkingia was named after Elizabeth O. King, a microbiologist at the Center for Disease Control (CDC) and Prevention, who discovered many medically important bacteria in the late 1940s to early 1960s. This included describing Elizabethkingia meningoseptica (formerly Chryseobacterium meningosepticum) in 1959. Elizabethkingia and Kingella genera, and the species Kingella kingae are also named in her honor.1 Elizabethkingia is a gram negative, obligate aerobic bacillus. It was classified under the families Flavobacteriaceae and Chryseobacterium, but was reclassified as Elizabethkingia in 2005.2 E. meningoseptica, the most frequently isolated Elizabethkingia species, has been implicated in cases of neonatal sepsis, meningitis, and nosocomial pneumonia.3

On the other hand, E. anophelis was recently characterized in 2011 and was initially thought to be underrepresented likely due to the genotypic and phenotypic similarity to E. meningoseptica.4,5,6 The species name Elizabethkingia anophelis originated from the anopheles mosquito as it has been isolated from the midgut of Anopheles gambiae mosquitoes.4 The role of mosquitos in maintenance and transmission of Elizabethkingia anophelis is unclear.4,6 Oxidase and catalase positive E. anophelis, (Fig 1) grows well on blood and chocolate agar plates (Fig 2 and 3) as smooth and slight-yellowish colonies although it does not grow on MacConkey agar.7

Beginning late 2015, an increased number of Elizabethkingia infections were identified in Southeastern Wisconsin. Between November 2015 to May 2016, 63 cases of E. anophelis were reported to the Wisconsin Division of Public Health. Cases spread across Illinois and Michigan as well, making it the largest E. anophelis outbreak described to date. A case series published from Froedtert Health System hospitals described their experience with E. anopheles.8 This was a retrospective case series of all consecutive patients admitted to Froedtert Health System hospitals with positive cultures of any site for Elizabethkingia, Flavobacterium, and Chryseobacterium from November 2015 to June 2016. In this time period, 11 patients were identified with cultures positive for E. anophelis. All patients had positive blood cultures at the time of hospital admission. E. anophelis was identified in both sterile and nonsterile body fluids. All 11 patients had at least one major comorbidity, including cancer, COPD, diabetes, ESRD requiring hemodialysis, and alcohol abuse. Two patients died within 30 days of a positive E. anopheles culture (attributable mortality rate, 2/11 = 18.2%).5, 8, 9

Interestingly, vertical transmission of E. anopheles causing neonatal meningitis has been reported.6 Molecular evidence suggested vertical transmission from a mother with chorioamnionitis, but a mechanism of colonization for the mother could not be found and environmental contamination was not also found.6,7 On the other hand, taps and aerators contaminated with E. anophelis in an intensive care unit has been reported.10 E. anophelis should be treated as a true pathogen, particularly in patients with multiple comorbidities.8 Isolation in sterile fluid should never be considered a contaminant.

Since Elizabethkingia is a non-glucose, non-lactose-fermenter, the MIC breakpoint of E. anophelis is reported based on those of non-Enterobacterales Table 2B-5 of CLSI (Clinical Laboratory Standard Institute) M100 guidelines. Elizabethkingia species, including E. anophelis, are intrinsically resistant to several antibiotics and produce elevated MIC on in vitro susceptibility tests. A number of species also harbor beta-lactamase/metallo beta-lactamase (MBL) genes. Empirical treatment should include piperacillin/tazobactam plus quinolone, rifampin, or minocycline. Vancomycin has been used in severe infections, especially meningitis. The best duration of therapy has not been evaluated by clinical trials8.

In summary, our patient acquired this infection in the setting of multiple chronic comorbidities and was immunocompromised due to active malignancy and recent chemotherapy. He has a similar clinical profile to the other patients in the above-mentioned study. One notable difference is that our patient’s isolate was resistant to cefepime, where the isolates from this outbreak were susceptible. After discussion with our infectious disease colleagues regarding this case, we agreed his cause of death was likely multifactorial, though this infection may have been a significant contributing factor.

References

  1. KING EO. Studies on a group of previously unclassified bacteria associated with meningitis in infants. Am J Clin Pathol. 1959 Mar;31(3):241-7. doi: 10.1093/ajcp/31.3.241. PMID: 13637033.
  2. Kim KK, Kim MK, Lim JH, Park HY, Lee ST. Transfer of Chryseobacterium meningosepticum and Chryseobacterium miricola to Elizabethkingia gen. nov. as Elizabethkingia meningoseptica comb. nov. and Elizabethkingia miricola comb. nov. Int J Syst Evol Microbiol. 2005 May;55(Pt 3):1287-1293. doi: 10.1099/ijs.0.63541-0. PMID: 15879269.
  3. Jean SS, Lee WS, Chen FL, et al. Elizabethkingia meningoseptica: an important emerging pathogen causing healthcare-associated infections. J Hosp Infect 2014; 86:244–9.
  4. Kämpfer P, Matthews H, Glaeser SP et al. . Elizabethkingia anophelis sp. nov., isolated from the midgut of the mosquito Anopheles gambiae. Int J Syst Evol Microbiol 2011; 61(Pt 11):2670–5. [PubMed] [Google Scholar]
  5. Perrin A, Larsonneur E, Nicholson AC, et al. Evolutionary dynamics and genomic features of the Elizabethkingia anophelis 2015 to 2016 Wisconsin outbreak strain. Nat Commun 2017; 8:15483.
  6. Lau, Susanna K.P.; Wu, Alan K.L.; Teng, Jade L.L.; Tse, Herman; Curreem, Shirly O.T.; Tsui, Stephen K.W.; et al. (February 2015). “Evidence for Elizabethkingia anophelis Transmission from Mother to Infant, Hong Kong”. Emerging Infectious Diseases. 21 (2): 232–241. doi:10.3201/eid2102.140623. PMC4313635. PMID25625669
  7. Koneman’s Color Atlas and Textbook of Diagnostic Microbiology. 7th Edition. 2016.
  8. Castro, C. E., Johnson, C., Williams, M., Vanderslik, A., Graham, M. B., Letzer, D., . . . Munoz-Price, L. S. (2017). Elizabethkingia anophelis: Clinical Experience of an Academic Health System in Southeastern Wisconsin. Open Forum Infectious Diseases, 4(4). doi:10.1093/ofid/ofx251
  9. Wisconsin Department of Health Services; Elizabethkingia 2017. Available at: https://www.dhs.wisconsin.gov/disease/elizabethkingia.htm. Accessed 9 January 2017. [Google Scholar]
  10. Balm MN, Salmon S, Jureen R, Teo C, Mahdi R, Seetoh T, Teo JT, Lin RT, Fisher DA. Bad design, bad practices, bad bugs: frustrations in controlling an outbreak of Elizabethkingia meningoseptica in intensive care units. J Hosp Infect. 2013 Oct;85(2):134-40. doi: 10.1016/j.jhin.2013.05.012. Epub 2013 Aug 17. PMID: 23958153.

-J. Stephen Stalls, MD is a PGY-II pathology resident at the East Carolina University Department of Pathology and Laboratory Medicine. He plans to pursue hematopathology and molecular pathology fellowships, but also greatly enjoys his time in the microbiology lab. Outside of work, he enjoys playing the drums and going to concerts.

-Phyu Thwe, Ph.D., D(ABMM), MLS (ASCP)CM is a Technical Director at Vidant Medical Center Clinical Microbiology Laboratory. She completed a Clinical and Public Health Microbiology Fellowship through a CPEP-accredited program at the University of Texas Medical Branch (UTMB) in Galveston, Texas. She is interested in extrapulmonary tuberculosis and developing diagnostic algorithms.