Microbiology Case Study: 41 Year Old Male with Complaints of Abdominal Pain for One Month

Case History

A 41 year old African male presented to the ED with complaints of abdominal pain, weight loss, and decreased appetite over one month. He immigrated from Zimbabwe 10 years prior, and most recently visited 4 months ago. His past medical history is non-contributory. He was found to have microcytic anemia (Hgb 9.3 g/dL, MCV 77.0 fL), pneumonia, and focal small bowel dilation with thickening and inflammatory changes on abdominal CT.

Endoscopy revealed a large, villous, infiltrative mass in the third portion of the duodenum. On histologic examination of the duodenum biopsy, viable Schistosoma eggs were seen within the vessels in the lamina propria and associated with adenocarcinoma (Images 1 and 2). Schistosoma mansoni eggs were identified on stool ova and parasite exam (Image 3), and serology was positive for Schistosoma IgG antibody.

Image 1. 10x objective magnification of a hematoxylin and eosin stained histology slide of the duodenal biopsy with associated adenocarcinoma and multiple eggs can be visualized.
Image 2. 40x objective magnification of a hematoxylin and eosin stained slide from the duodenal biopsy of a man from Africa who presents with abdominal pain who is found to have a mass on endoscopy. Seen is a viable egg with intact miracidium and no evidence of calcification.
Image 3. 100x oil immersion objective magnification of an iodine prep from a concentrated formalin-fixed stool specimen demonstrating a Schistosoma mansoni egg with its characteristic large lateral spine.

Discussion

Although this is not a common infection to encounter in the US, prevalence in endemic areas ranges from 30-100%. Infection occurs through contact with water contaminated with human feces; common circumstances are irrigation ditches as well as bathing and washing water.1

Schistosomiasis may be an indolent infection in many immunocompetent hosts. Chronic infection requires a shift from inflammatory TH1 response to a modulatory TH2 response.2 There is also evidence that Schistosoma infection may downregulate the immune response by inducing M2 differentiation of macrophages.3 These anti-inflammatory macrophages have been associated with a microenvironment favorable to malignancy. It has also been shown that S. mansoni is a risk factor for hepatocellular carcinoma (HCC) and colonic adenocarcinoma, possibly by altering p53 activation, initiation of chronic granulomatous response that blocks venules, increasing cell turnover, and promotion of ROS and RNOS production.4 Anti-idiotype antibodies produced in chronic infection may also down-regulate both specific and non-specific immune responses.5

This case is an unusual presentation in the US in that viable ova are typically not seen, and S. mansoni is more likely to involve the distal colon and liver rather than the small bowel. There is a known association between S. mansoni infection and HCC, and there are sporadic reports of association with tumors of the prostate, ovary, uterus, and cervix.5,6 To our knowledge however, there are no other reported cases of duodenal adenocarcinoma with concurrent schistosomiasis.

References

  1. Chai J and Jung B. Epidemiology of Trematode Infections: An Update. 2019. Adv Exp Med Biol. 1154:359-409.
  2. Barsoum RS, et al. Human Schistosomiasis: Clinical Perspective: Review. 2013. Journal of Advanced Research. 4:433-44.
  3. Hussaarts L, et al. Chronic helminth infection and helminth-derived antigens promote adipose tissue M2 macrophages and improve insulin sensitivity in obese mice. 2015. FASEB J. 29(7):3027-39.
  4. El-Tonsy MM, et al. Schistosoma mansoni infection: Is it a risk factor for development of hepatocellular carcinoma? 2013. Acta Trop. 128(3):542-7.
  5. Palumbo E. Association Between Schistosomiasis and Cancer. 2007. Infectious Diseases in Clinical Practice. 15(3):145-8.
  6. Peterson MR and Weidner N. Gastrointestinal neoplasia associated with bowel parasitosis: real or imaginary? 2011. J Trop Med. 2011:234254.

-Daniel Welder, MD is a second year Clinical Pathology resident at UT Southwestern Medical Center in Dallas, Texas. He has interests in Hematopathology, Transfusion Medicine and dabbles in Microbiology.

-Dominick Cavuoti, DO is a Professor at UT Southwestern in the Department of Pathology. He is multifaceted and splits his time as the Medical Director of the Parkland Hospital Clinical Microbiology Laboratory and Parkland Cytology attending among other administrative and educational activities.

-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 52 Year Old with a Liver Abscess

Clinical history

A 52 year old patient with a history of recent travel to India presented to interventional radiology from an outside hospital for aspiration of a liver abscess, and was subsequently returned to the outside hospital. The patient had spent 2 months in India before returning to the US, and about 1 month later developed right upper quadrant pain. Abdominal CT showed 2 cystic masses measuring 2-4cm. Aspiration of the cysts yielded 0.5mL of bloody fluid, which was sent for bacterial culture and smear. Infectious disease prescribed antimicrobial treatment consisted of ceftriaxone and metronidazole, followed by paromomycin and levofloxacin.

Laboratory findings

A gram smear of the patient’s liver mass aspirate showed few neutrophils and no bacteria. Culture of the aspirate showed no growth at 5 days. Multiple sets of blood cultures collected at the outside hospital all showed no growth at 5 days.

Image 1. Entamoeba coli trophozoite seen in the patient’s stool ova and parasite exam, demonstrating an eccentric karyosome and coarse, irregular peripheral chromatin.

A single ova and parasite exam of the patient’s stool was sent and showed few Entamoeba coli trophozoites. A sample of the patient’s blood was sent to the Mayo reference lab for serum Entamoeba histolytica antibody testing, which came back positive. Stool was sent for Entamoeba histolytica antigen testing which was negative.

Discussion

Entamoeba coli is a non-pathogenic protozoan that can exist as a commensal organism in the human gastrointestinal tract. This organism has not been established to have any disease causing effect per se, but its presence may indicate exposure to water sources that could contain parasitic organisms. (3)

Entamoeba histolytica, by contrast, is a parasitic protozoal pathogen. Most infections are asymptomatic, but they can manifest as amebic dysentery or extraintestinal disease. The most common extraintestinal manifestation is amebic liver abscesses.1

Intestinal amebiasis occurs via ingestion of amebic cysts, typically through contaminated food or water, but also through other forms of fecal-oral contact. Infections are seen most commonly in areas with poor sanitation, but can be found in developed countries in patients who have migrated from or traveled to endemic areas.2

Once the amebic cysts pass into the small intestine, they form trophozoites, which are able to penetrate the mucous barrier of the gut and destroy intestinal epithelial cells. This leads to blood and mucus in the stool. (2) Once the amebae penetrate the gut wall, they are able to reach the blood and ascend through the portal system to the liver and form amebic liver abscesses.3

Clinical presentation of these abscesses typically includes right upper quadrant pain and fever in a patient with a history of travel to an endemic area. Serologic testing is used for confirmation if clinical presentation and imaging are suggestive, but this cannot distinguish between current infection and prior exposure, and up to 35 percent of uninfected inhabitants of endemic areas show positive serology.3 Stool microscopy may be the initial, and indeed only test available in some areas, but cannot differentiate E. histolytica from non-pathogenic E. dispar and E. moshkovskii strains.2

Image 2. E. histolytica trophozoite with ingested red blood cell, visible as a dark inclusion, as well as demonstrating a central karysome and fine, uniformly distributed chromatin. (CDC: https://www.cdc.gov/dpdx/amebiasis/index.html) Erythrophagocytosis is suggestive of E. histolytica.

Empiric treatment in the setting of consistent epidemiology, clinical picture, and radiology consists of metronidazole or tinidazole for tissue clearance followed by paromomycin, diiodohydroxyquin, or diloxanide furoate for intraluminal clearance.

Infectious diseases was taking care of this patient and decided her clinical syndrome is probably extraintestinal Entamoeba histolytica amoebiasis based on the results of the CT findings and the antibody in the right clinical setting.  Although her stool ova and parasite only showed Entamoeba coli, she clearly has been exposed to contaminated food or water.  In addition, the Entamoeba histolytica stool antigen was negative, but this can be an insensitive test.

References

  1. Leder, Karin, and Peter F. Weller. “Extraintestinal Entamoeba histolytica amebiasis.” UpToDate, Wolters Kluwer, 27 Jan. 2020, http://www.uptodate.com/contents/extraintestinal-entamoeba-histolytica-amebiasis?search=entamoeba%20histolyticatreatment&topicRef=5727&source=see_link. Accessed 4 Feb. 2020.  
  2. Leder, Karin, and Peter F. Weller. “Intestinal Entamoeba histolytica amebiasis.” UpToDate, Wolters Kluwer, 27 Jan. 2020, http://www.uptodate.com/contents/intestinal-entamoeba-histolytica-amebiasis?search=entamoeba%20histolyticatreatment&source=search_result&selectedTitle=1~46&usage_type=default&display_rank. Accessed 4 Feb. 2020.
  3. Weller, Peter F. “Nonpathogenic enteric protozoa.” UpToDate, Wolters Kluwer, 25 July 2019, http://www.uptodate.com/contents/nonpathogenic-enteric-protozoa?search=entamoeba%20coli%20treatment&source=search_result&selectedTitle=1~6&usage_type=default&display_rank=1. Accessed 4 Feb. 2020.

-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.

Microbiology Case Study: A Teenager with an Infected Wound

Case History

A male teenager presented to the emergency department following a 4 wheeler accident. He sustained extensive trauma to his right lower leg with a large, dirty laceration and grossly exposed muscle. His pulses were intact and motor & sensory nerve function were preserved. The wound was irrigated at the bedside and the patient was admitted with a plastic surgery consult for wound coverage. Cefepime was empirically started. After 10 days in the hospital and multiple surgeries to care for the wound, the patient developed a fever and increased pain, erythema, and swelling at surrounding the wound. The trauma service ordered blood and wound cultures.

Laboratory Identification

Image 1. The wound culture grew lavender-green colonies on blood agar (48 hours of incubation in CO2).
Image 2. Clear, lactose-negative colonies on MacConkey agar (48 hours of incubation in CO2).
Image 3. Gram stain from the blood agar plate showed gram negative rods (100x, oil immersion).

The oxidase reaction was negative. MALDI-TOF mass spectrometry identified the isolate as Stenotrophomonas maltophilia from the wound culture. Blood cultures were negative.

Discussion

Stenotrophomonas maltophilia is a common non-fermenting gram negative rod that is ubiquitous in moist environments but is not commonly a member of human flora. S. maltophilia can readily be isolated from hospital surfaces and those with traumatic injuries, prolonged hospitalizations, on mechanical ventilation, and with in-dwelling devices are more susceptible to nosocomial infections by this organism. Those who are immunocompromised or have cystic fibrosis are also at an increased risk.  

In the laboratory, S. maltophilia is characterized as an aerobic, Gram-negative rod that grows as lavender-green colonies on blood agar (Image 1) and has an ammonia-like odor. This organism is catalase and oxidase negative and DNase positive. S. maltophilia is motile and is able to utilize glucose and maltose by oxidative fermentation. Current automated identification systems and MALDI-TOF mass spectrometry are able to accurately identify S. maltophilia.  

S. maltophilia is intrinsically resistant to many broad-spectrum antibiotics, including carbapenems and aminoglycosides. Beta-lactam resistance is due to two beta-lactamases and renders beta-lactam inhibitors ineffective. Trimethoprim-sulfamethoxazole (TMP-SMX) is the antibiotic of choice to treat S. maltophilia infections; however, resistance can develop. In the case TMP-SMX resistance, ceftazidime, minocycline, ticarcillin-clavulanate, ciprofloxacin, and levofloxacin can be tested. 

In the case of our patient, susceptibility testing was performed on the Vitek2 instrument and the isolate was susceptible to TMP-SMX. He was switched to TMP-SMX and underwent additional surgical procedures to wash out the infected area.

-Karla Perrizo, MD, is a Clinical Pathology resident at the University of Mississippi Medical Center.

-Lisa Stempak, MD is the System Director of Clinical Pathology at University Hospitals Cleveland Medical Center in Cleveland, Ohio. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. Her interests include infectious disease histology, process and quality improvement, and resident education.

Microbiology Case Study: A 60 Year Old with Non-Healing Wound

Clinical history

A 60 year old patient with a past medical history of type II diabetes mellitus, right Charcot foot, and cirrhosis presented to the emergency department with altered mental status and several days of subjective fevers, as well as a 2 month history of right lateral malleolar non-healing ulcer which had subacutely increased in size and volume of drainage.

The patient’s spouse reported the wound had been showing purulent discharge for 3 weeks. Nine days before presentation, the patient had seen a foot and ankle specialist for evaluation of his Charcot foot and the ulcer. Radiographs were taken at this time, but no treatment was initiated. Worsening of the wound was associated with an episode of long travel, after which the patient reported being able to see bone.

Infectious disease noted that the patient had a pet corgi.

On exam, the patient was febrile with dry mucous membranes and oriented only to person. MRI showed evidence of possible osteomyelitis. The patient subsequently underwent a right below the knee amputation.

Laboratory findings

Gram smear of a sample taken from the patient’s ankle wound in the emergency department showed many neutrophils, moderate gram positive cocci and moderate gram negative bacilli, with intraleukocytic organisms seen. Growth was observed on blood and chocolate agar plates, but there was no growth on the MacConkey plate. The organisms were identified as few Pasteurella multocida, few vancomycin resistant Enterococcus faecalis, and few usual skin flora.

Image 1. Gram stain of the sample taken from the patient’s ankle wound.

Blood cultures drawn in the emergency department were positive at 10 hours in both bottles, and again on planting showed growth on blood and chocolate agar, but no growth on MacConkey. The organism was identified as P. multocida, consistent with that which grew from the ankle wound culture.

The patient underwent a right below the knee amputation, and anaerobic cultures taken from the right foot again grew P. multocida.

Discussion

Pasteurella multocida is a nonmotile gram negative bacillus which is part of the normal oropharyngeal flora in domestic dogs and cats. It is a facultative anaerobe, positive for oxidase, catalase, and indole. It grows on chocolate and blood agar, forming small, gray, non-hemolytic colonies. It does not typically grow on MacConkey agar.

P. multocida is classically associated with a zoonotic soft tissue infection in humans who suffer bite wounds from a pet, as well as licking of any broken skin by a pet. These infections have a characteristic rapid onset and intense inflammatory response, and can progress to necrotizing fasciitis. Cases of Pasteurella osteomyelitis can be associated with significant wound infections. Conditions such as diabetes, liver dysfunction, and organ transplantation can predispose patients to Pasteurella bacteremia.

Pasteurella spp. are susceptible to beta-lactam antibiotics in most cases, and since Pasteurella wound infections are usually polymicrobial, recommended treatment is broad-spectrum such as amoxicillin-clavulanate. In isolated Pasteurella infections, first line treatment is penicillin, although there are some that favor testing isolates from sterile sites for the presence of beta-lactamase production, and treating those infections with ampicillin-sulbactam, pipercillin-tazobactam, or ceftriaxone. (Weber)

References

  1. Weber, David J., and Sheldon L. Kaplan. “Pasteurella infections.” UpToDate, Wolters Kluwer, 15 June 2018, http://www.uptodate.com/contents/pasteurella-infections?search=pasteurella%20treatment&source=search_result&selectedTitle=1~25&usage_type=default&display_rank=1#H14. Accessed 4 Feb. 2020.

-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.

Microbiology Case study: A 42 Year Old Male with Bacteremia

Case History

A 42 year old male with past medical history of diabetes mellitus and essential hypertension presented to the emergency department with high fever and chills which developed two days prior. His examination revealed a painful ulcer on the planter aspect of his right toe with surrounding erythema. According to patient, the exact duration of the ulcer is unclear as it was on planter aspect of his foot and he does not inspect his feet regularly. However, the ulcer grew in size and symptoms over the past week. He denies any cough, diarrhea or abdominal pain. He is on oral anti-diabetics with well-controlled blood sugar. Complete blood count revealed leukocytosis. Blood was collected and sent to microbiology laboratory for gram stain and culture.

Laboratory identification

Cultures signaled positive after 32 hours of incubation and gram negative rods were identified on Gram stain (Image 1). The organism grew after 24 hours of incubation on 5% sheep blood, chocolate, and MacConkey agars (Images 2 & 3). MALDI-TOF mass spectrometry identified the isolate as Salmonella spp. The isolate was sent to the public health department for additional testing by molecular typing where it was identified as Salmonella enterica subsp. enterica serovar Brandenburg (Salmonella Brandenburg). Later, MRI revealed osteomyelitis of right third toe which was considered as the likely source of patient’s bacteremia.

Image 1. Gram stain of positive blood culture broth showing gram negative rods
Image 2. Non-lactose fermenting colonies growing on MacConkey agar
Image 3. Colonies producing hydrogen sulfide making them appear black on Hektoen enteric agar

Discussion

Salmonella is a genus of the family Enterobacteriaceae in the order Enterobacterales. They are non-spore forming gram negative facultative anaerobes. Salmonella spp. are lactose non-fermenters and usually produce H2S on triple sugar iron and Hektoen enteric agar.

The genus has only two species: Salmonella enterica, divided into 6 subspecies and containing over 2500 serovars, and Salmonella bongori. Subspecies and serotype determination is necessary for epidemiological investigations. Serotyping is used to classify Salmonella based on bacterial surface antigens; the thermostable polysaccharide cell wall or somatic (“O”) antigens and the thermo-labile flagella proteins or “H” antigens. It is also possible to identify Salmonella serotypes on the basis of phage typing, plasmid profiling, ribotyping and pulsed field gel electrophoresis (PFGE) of DNA fragments generated from restriction enzyme digestion.

Salmonella are zoonotic bacteria that can cause abortion, metritis, and systemic illness in ewes and does. Natural reservoirs of Salmonella are domestic and wild animals, including poultry, swine, cattle, birds, dogs, rodents, tortoises, turtles and cats. Humans also serve as a natural host. The most common source of transmission of Salmonella is the consumption of contaminated poultry and meat products. Person-to-person, fecal–oral transmission does occur and has been a problem in health care facilities traced to inadequate hand washing.

Salmonella brandenburg ranked 16th among the serovars responsible for human infections. It causes acute diarrhea and severe illness in a variety of animals and was first isolated in New Zealand in 1986. Since 1996 Salmonella Brandenburg has been associated with an emerging epidemic of abortions and deaths in sheep in the southern regions of the South Island. Subsequently, the same strain was reported to cause disease in horses, goats, deer, pigs and humans. The disease is known to have high morbidity and mortality within a flock or herd, rapid local spread and an occupational, health and safety risk to farm workers and their families.

There are three clinically distinguishable forms of salmonellosis in humans. These include gastroenteritis, enteric fever and septicemia. Established Salmonella bacteremia requires aggressive antimicrobial treatment with ciprofloxacin, ceftriaxone, or less frequently trimethoprim-sulfamethoxazole. A careful search for focal metastatic disease should be undertaken, especially when relapse follows cessation of treatment. Surgical drainage of metastatic abscesses may be required, with surgical intervention. Resistance to any of the drugs used to treat invasive infection may occur, so treatment should be supported by susceptibility testing.

In the case of our patient, he was treated with ceftriaxone and underwent toe amputation. The patient had an uncomplicated hospital course and made a complete recovery.

References[EMT1] 

  1. Alvseike O., Skjerve E. (2000). Probability of detection of Salmonella using different analytical procedures, with emphasis on subspecies diarizonae serovar 61:k:1,5,(7) [S. IIIb 61:k:1,5,(7)]. International Journal of Food Microbiology, 58, 49-58.
  2. Clark G, Swanney S, Nicol C, and and Fenwick S. Salmonella Brandenburg – the 1999 Season. Proceedings of the Sheep and Beef Cattle Society of the New Zealand Veterinary Association, 151-156, 2000
  3. Bailey K.M. (1997). Sheep abortion outbreak associated with Salmonella Brandenburg. Surveillance, 24(4), 10-11
  4. Baumler A.J., Tsolis R.M., Heffron F. (2000). Virulence Mechanisms of Salmonella and their Genetic Basis. In “Salmonella in Domestic Animals” (Ed. C. Wray and A. Wray). CAB International 2000, pp. 57-72

-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 55 Year Old with Fever, Chills, and a Cough

Clinical History

A 55 year old patient with past medical history of stage IV non-Hodgkin’s lymphoma on rituximab and Campylobacter jejuni bacteremia 1 year prior presented to the Emergency Department on the orders of their primary care provider, after outpatient blood cultures grew gram negative bacilli resembling Campylobacter species. Their symptoms included a 1-2 month history of fatigue and weakness and a 3 week history of intermittent fevers and chills with developing productive cough, sinus pressure, sore throat, progressive dyspnea on exertion, nausea, and decreased appetite.

Laboratory Findings

Initial (outpatient) blood culture was positive in the aerobic bottle at 60.1 hours, with the initial gram stain showing no organisms. The bottle was placed back in the analyzer and flagged positive again, at which point a second gram stain was performed, which again showed no organisms. An acridine orange stain was performed (Image 1), revealing multiple spiral/”gull shaped” rods. A third gram stain (Image 2) with more time allowed for safranin staining revealed faint gram negative rods. MALDI-TOF MS was attempted with no identification. The culture growth was sent to a reference laboratory and was identified via sequencing as Helicobacter species. The organism was not viable for susceptibility testing.

Image 1. Acridine orange stain of blood culture sample: this stain causes the nucleic acids to fluoresce orange, highlighting the bacteria against the background of blood.
Image 2. Gram stain after allowing extra time for safranin staining, showing few gram negative rods.
Image 3. A replating on blood agar showed difficult to discern, thin spreading colonies.

Two sets of subsequent blood cultures also grew gram negative bacilli at 65 and 67 hours. The blood culture broth from one of these cultures was also sent to the reference lab, but again did not have viable growth for susceptibility testing.

Discussion

The genus Helicobacter includes 35 species, consisting of gram negative spiral bacilli, previously considered to be part of the Campylobacter genus. Pathogenic species are classically associated with the gastrointestinal tract as they are able to survive in the harsh acidic conditions of the human stomach. The most common clinically relevant species is H. pylori, which is associated with gastric ulcers as well as other inflammatory processes in the stomach and duodenum. In prior reports, bacteremia caused by Helicobacter species is typically associated with some other underlying disease process, such as malignancy, immunocompromised state, or disruption of the GI mucosal barrier (1, 2, 3, 4, 5, 6).

Helicobacter spp. are similar in morphology to Campylobacter spp. on a gram stain; given the patient’s prior history of C. jejuni bacteremia, it was not unreasonable for the gram smear to initially be called consistent with Campylobacter spp. However, the clinical course and antibiotic susceptibility profiles of Helicobacter and Campylobacter bacteremia cases can differ in important ways. Further, susceptibilities can differ between different species of Helicobacter. There are no established guidelines for the treatment of Helicobacter spp. bacteremia and breakpoints for antibiotic susceptibility testing for some Helicobacter species have not been established. (7)

The patient in this case was discharged on a course of azithromycin with clinical improvement: at that time, the sequencing result revealing Helicobacter had not yet been received, and the clinical team was acting on the belief that the organism in the patient’s blood was a recurrence of the previous Campylobacter infection. On a follow up outpatient appointment with Infectious Disease, wherein sequencing results were available, tetracycline was prescribed due to concern about the possibility of resistance or relapsing infection.

References

  1. Abidi, Maheen Z., et al. “Helicobacter Canis Bacteremia in a Patient with Fever of Unknown Origin.” Journal of Clinical Microbiology, vol. 51, no. 3, 2013, pp. 1046–1048.
  2. Araoka, Hideki, et al. “Clinical Characteristics of Bacteremia Caused by Helicobacter Cinaedi and Time Required for Blood Cultures To Become Positive.” Journal of Clinical Microbiology, vol. 52, no. 7, 2014, pp. 2745–2745.
  3. De Luca, et al. “Helicobacter Pylori Bacteremia: An Unusual Finding.” Infectious Disease Reports, vol. 8, no. 3, 2016, pp. 74–75.
  4. Han, Xiang Y., et al. “Helicobacter Pylori Bacteremia with Sepsis Syndrome.” Journal of Clinical Microbiology, vol. 48, no. 12, 2010, pp. 4661–4663.
  5. Imataki, Osamu, et al. “Enteral Malakoplakia Prior to Helicobacter Cinaedi Bacteremia.” American Journal of Gastroenterology, vol. 112, no. 1, 2017, pp. 187–188.
  6. Saito, Sho, et al. “Helicobacter Fennelliae Bacteremia: Three Case Reports and Literature Review.” Medicine, vol. 95, no. 18, 2016, p. e3556.
  7. Yamamoto, Kei, et al. “Comparison of the Clinical and Microbiological Characteristics of Campylobacter and Helicobacter Bacteremia: the Importance of Time to Blood Culture Positivity Using the BACTEC Blood Culture Systems.” BMC Research Notes, vol. 10, no. 1, 2017, pp. 1–6.

-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.

Microbiology Case Study: A 60 Year Old Male Status-Post Orthotopic Liver Transplant with Headache and Word-Finding Difficulty

Case History

A 60 year old male with a past medical history of ulcerative colitis requiring total proctocolectomy and immunomodulatory therapy followed by an anti-Tumor Necrosis Factor α blocker for the last two years and primary sclerosing cholangitis with subsequent decompensated cirrhosis that ultimately required an orthotopic liver transplant on tacrolimus and prednisone for immunosuppression presents 17 days post-transplant with worsening headache for two weeks with associated word finding difficulty and expressive aphasia.

Laboratory and Diagnostic Findings

Brain magnetic resonance imaging demonstrated, a “Heterogeneous, partially hemorrhagic and centrally necrotic mass within the posterior left temporal lobe…infectious etiologies such as pyogenic/non-pyogenic abscesses to include fungal organisms, are highest on the differential” (Image 1). At the time of admission, his complete blood count demonstrated a leukocytosis (16.48×109 cells/L), anemia (hemoglobin of 7.8 g/dL, hematocrit of 24.8%) and a normal platelet count (367×109 cells/L). The automated differential showed 82% neutrophils, 10% lymphocytes, 6% monocytes, 1% eosinophils, and 1% basophils. A lumbar puncture was performed to obtain cerebral spinal fluid (CSF) and the analysis showed a glucose of 60 mg/dL, protein of 34 mg/dL, nucleated cell count of <1, and 6 red blood cells (completely normal CSF indices). Broad spectrum antimicrobials (Vancomycin, Piperacillin/Tazobactam, Metronidazole and Micafungin) were initiated. A 1,3-β-D-glucan test had a result of >500 pg/mL in both serum and CSF. Galactomannan, Histoplasma urine antigen, Cryptococcus antigen and other fungal testing were negative. Antifungal therapy was changed to voriconazole. Craniotomy was determined to be the best course of action and the patient was taken to surgery for debridement and pathologic evaluation.

Frozen section evaluation during the time of surgery showed granulomatous inflammation. Septate hyphae were observed on the fungal smear. Following surgery, amphotericin was added. Histologic evaluation of the tissue submitted from surgery showed pyogranulomatous inflammation with pigmented, spore-like structures present in multinucleated giant cells on hematoxylin and eosin (H&E) stain (Image 2). Grocott’s methenamine silver (GMS) stain also highlighted short segments of septate hyphae (Image 3).

Cultures from the surgical debridement grew a mould with central pigmentation (Image 4). Direct microscopic examination of the mould revealed thick-walled, oblong conidia with 3-5 cells, and uniformly pigmented hyphae (Image 5). A germ tube test showed germ tubes originating from both ends of the conidia consistent with Bipolaris species.

Image 1. T1-weighted (left) and T2-weighted (right) magnetic resonance imaging of the brain demonstrating a left temporal lobe mass.
Image 2. Hematoxylin and Eosin stained photomicrographs showing pyogranulomatous inflammation with giant cell formation and circular structures within them (left) (40x objective magnification). The right shows gold-brown pigmented structures within granulomatous inflammation (40x objective magnification).
Image 3. Grocott’s methenamine silver stain highlighting short segments of irregular septate hyphae in the brain debridement specimen (10x objective magnification).
Image 4. Mature wooly brown-black colony on potato dextrose agar.
Image 5. Photomicrograph of a lactophenol blue tape prep of the mature fungal colony. Pigmented hyphae and short 3-4 cell conidia are readily identified (40x objective magnification). This specimen also tested germ tube positive (not shown), indicating that this dematiaceous fungus is Bipolaris spp.

The patient’s mental status significantly improved following surgical debridement, 2 weeks of liposomal Amphotericin B, as well as long term treatment with voriconazole. The voriconazole was later switched to posaconazole due to concerns for fluoride toxicity. He completed a year of posaconazole with significant improvement of the abscess observed on imaging and resolution of headaches with no other visual problems. He continued to recover cognitive function with some residual difficulty with reading, comprehension and speech that eventually resolved.

Discussion

Phaeohyphomycosis refers to infections caused by dematiaceous fungi that exist in a variety of forms when seen in tissues and commonly involves skin, soft tissue and nasal sinuses.1 In rare cases, central nervous system (CNS) involvement has been reported. CNS phaeohyphomycosis is predominantly seen in immunosuppressed patients; however, cases involving immunocompetent individuals do exist.2 In one case series from Houston, Texas, five of seven cases of cerebral mycosis were caused by a dematiaceous mould.3 Interestingly, the patient presented in this case came to medical attention around the Dallas-Fort Worth area of Texas.

Cladophialophora bantiana is the most common dematiaceous fungus associated with CNS phaeohyphomycosis, but rare cases of Bipolaris species have been reported previously in literature.4-6

We report a case of CNS phaeohyphomycosis by Bipolaris species following orthotopic liver transplant with an excellent patient outcome. This case is unusual, in part, because the typical hospital course of a patient with phaeohyphomycosis is generally dismal.7 The stories of successful treatment often involve complete debridement of discrete lesions.7-8 In our case, the patient underwent surgical debridement and treatment initially with liposomal Amphotericin B and later transitioned to long term therapy with newer azole antifungals.

References

  1. Revankar SG, Sutton DA, & Rinaldi MG, (2004). Primary Central Nervous System Phaeohyphomycosis: A Review of 101 cases. CID, 38, 206-2016
  2. Filizzola MJ, Martinez F, & Rauf SJ, (2003). Phaeohyphomycosis of the central nervous system in immunocompetent hosts: report of a case and review of the literature. Int J Infec Dis, 7, 282-286
  3. Raparia K, Powell SZ, Cernoch P, Takei H, (2010). Cerebral mycosis: 7-year retrospective series in a tertiary center. Neuropathology, Jun; 30(3): 218-223.
  4. Frank T, Esquenazi Y, Nigo M, Wanger A, Portnoy B, & Shepard S, (2016). Disseminated Phaeohyphomycosis with Brain Abscess and Biliary Invasion Due to Bipolaris spp. In an Immunocompetent Patient. Annals of Clinical & Laboratory Science, 46(4). 
  5. McGinnis MR, Campbell G, Gourley WK, & Lucia HL, (1992). Phaeohyphomycosis Caused by Bipolaris spicifera, An Informative Case. Eur. J. Epidemiol, 8(3), 383-386
  6. Rosow L, Jiang JX, Deuel T, Lechpammer M, Zamani AA, Milner DA, Folkerth R, Marty FM, & Kesari S, (2011). Cerebral phaeohyphomycosis caused by Bipolaris spicifera after heart transplantation. Transpl Infect Dis, 13, 419-423.
  7. Dixon DM, Walsh TJ, Merz WG, McGinnis MR, (1989). Infections due to Xylohypha bantiana (Cladosporium trichoides). Rev Infect Dis, 11: 515-525.
  8. Gadgil N, Kupfermen M, Smitherman S, Fuller GN, Rao G, (2013). Curvularia brain abscess. J Clin Neurosci, Jan;20(1): 172-175.

-John Markantonis, DO is a second year Clinical Pathology resident at UT Southwestern in Dallas. He has interests in Medical Microbiology and Transfusion Medicine.

-Dominick Cavuoti, DO is a Professor at UT Southwestern in the Department of Pathology. He is multifaceted and splits his time as the Medical Director of the Parkland Hospital Clinical Microbiology Laboratory and Parkland Cytology attending among other administrative and educational activities.

-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: 18 Year Old Male with Shortness of Breath

Case History

A 18 year old male with no significant past medical history presented with 2-3 month cough, hemoptysis, fevers, night sweats and 15 pound unintentional weight loss. He originally started to feel mild shortness of breath with activity following his return from the Pacific Northwest. He was diagnosed with pneumonia and given antibiotics. He denied vaping, hookah use or any smoking. Of note, his maternal grandmother had pulmonary tuberculosis two years ago, but at that time he had a negative interferon-gamma release assay (IGRA). Since that time he had traveled extensively including Europe and Asia.

Upon admission, physical examination showed decreased breath sounds and coarse crackles in the right lower lung field. His blood test results were unremarkable. Chest X-ray and CT scan showed diffuse reticular pattern and a 4 cm cavitary lesion in his right lower lobe (Image 1). Brochoalveolar lavage fluid, sputum as well as blood were submitted to microbiology lab for bacterial, fungal and mycobacterial culture.

Image1. Chest X-ray and CT showed diffuse reticular pattern with a 4cm cavitary lesion in his right lower lobe.

Laboratory results and management

The patient’s Quanti FERON®-TB Gold test (an IGRA) was positive.Laboratory studies including fungal culture to look for endemic fungi and HIV were negative. Auramine-rhodamine (acid fast) staining of sputum smear showed 4+ acid fast bacilli (AFB). Mycobacterium tuberculosis was confirmed by both our laboratory developed TB-PCR assay and a commercial TB-PCR assay (Xpert MTB/RIF). DNA sequencing was performed by the Centers for Disease Control and Prevention (CDC) in order to predict antibiotic susceptibility profiles for first-line anti-tuberculosis drugs including Ethambutol, Isoniazid, Pyrazinamide, and Rifampin. Because the result showed drug-susceptible tuberculosis, the patient started the first-line anti-tuberculosis drugs. Four days after admission, the patient discharged home with follow up with the department of health. After six weeks incubation, the sputum culture grew Mycobacterium tuberculosis with a pan-susceptible antibiotic profile.

Image 2. Ziehl-Neelsen stain of acid fast bacilli (AFB) on sputum smear. Image from the CDC website.

Discussion

Mycobacterium tuberculosis (MTB) remains a global health problem. The continuing spread of drug-resistant tuberculosis is one of the most difficult challenges for MTB control. The CDC recommends rapid laboratory confirmation of MTB with using a nucleic acid amplification test (NAAT), followed early drug susceptibility testing. Our case is consistent with the previous reports that NAAT can identify MTB and DNA sequencing can determine the drug susceptibility within a few days. Our case can be summarized into two points.

First, early NAAT provided diagnosis MTB within 2 days after patient admission, enabling the timely initialization of infection control measures. Although culture remains the gold standard for laboratory confirmation of active TB infection, it can take 6-8 weeks to grow in a culture media since MTB is slow growing pathogen. Early laboratory confirmation of MTB with NAAT led rapid initiation of the patient treatment and transmission interruption.

Second, DNA sequencing guided us to start an optimal anti-tuberculosis treatment within 3 days because of the accurate prediction of susceptibility profiles for first-line anti-tuberculosis drugs. In comparison, the conventional susceptibility testing with the drug-containing medium requires 1 month to complete beyond initial growth and identification of the organism. Recent studies demonstrated high accuracy of genotypic predictions (>91.3 % sensitivity; >93.6% specificity). Our case supports a theory that DNA sequencing can help to determine which anti-tuberculosis drugs should be used for treatment.

Despite the notable advantage, NAAT has limitations. There is a relatively low positive predictive value in smear-negative pulmonary MTB. Recent meta-analysis found that overall sensitivity of NAAT to be 90.4% for diagnosis of pulmonary MTB. The sensitivity of the NAAT further defined to be lower in smear negative (75%) compared to smear positive (98%) pulmonary MTB. Additionally, cost effectiveness of NAAT and DNA sequencing is another concern. Further assessments of the benefit of NAAT and DNA sequencing utilization for smear negative MTB are needed.

In conclusion, our case demonstrated that NAAT and DNA sequencing was beneficial to reduce the time to initiation of an optimal MTB management.

References

  1. Prediction of Susceptibility to First-Line Tuberculosis Drugs by DNA Sequencing. N Engl J Med 2018; 379: 1403-15.
  2. Use of Nucleic Acid Amplification Tests in Tuberculosis Patients in California, 2010-2013. Open Forum Infect Dis. 2016 Oct; 3(4): ofw230.
  3. Assessment by Meta-Analysis of PCR for Diagnosis of Smear-Negative Pulmonary Tuberculosis. J Clin Microbiol. 2003 Jul; 41(7): 3233-3240.

-Sachie Ikegami MD, PhD is a 1st year anatomic and clinical pathology resident at University of Chicago (NorthShore). Sachie’s academic interests include neuropathology and molecular pathology. She is passionate about understanding how pathology informatics improving clinical practice. Outside of the lab, she enjoys jogging.

-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 Child with Acute Abdominal Pain

Clinical presentation

An elementary school age child presented to the pediatric emergency department with an acute onset of abdominal pain. According to the parents, the patient recently had an ear infection and completed a course of amoxicillin. They noted the patient was more tired than usual, but did not have a fever. They reported no recent sick contacts or travel. Past medical history was significant for constipation, but normal bowel movements were noted over the past few days. On physical exam, the abdomen was soft and non-distended with diffuse mild tenderness noted on the right side. No masses were noted.  Laboratory testing was unremarkable and the WBC count, liver & pancreas enzymes, and alpha fetal protein were within normal limits. An abdominal CT scan revealed a mass with central necrosis in the liver concerning for an abscess. The patient was started on ceftriaxone & metronidazole and underwent a surgical procedure to drain the lesion.   

Laboratory Identification

Image 1. Gram stain of the direct liver aspirate showed many gram positive cocci in pairs & chains and numerous white blood cells (oil immersion).
Image 2. Rare small, white non-hemolytic colonies grew on CDC agar after 42 hours of incubation at 35°C under anaerobic conditions.

No bacterial growth was observed on blood or chocolate agars incubated at 35°C in CO2. MALDI-TOF mass spectrometry identified the isolate as a viridans groups streptococci, Streptococcus intermedius. The organism was susceptible to penicillin, ceftriaxone, and vancomycin by broth microdilution. Blood cultures were not collected for this patient.

Discussion

Streptococcus intermedius is a viridans group streptococci that belongs to the S. anginosus group. The S. anginosus group also includes S. anginosus and S. constellatus. This group of viridans streptococci composes the normal flora of the oropharynx, urogenital, and gastrointestinal tracts. These organisms are known for causing peritonitis and abscesses, particularly in the brain, breast, liver, and oral cavity.

Similar to other streptococci, S. intermedius is a gram positive cocci that grows in chains and is catalase negative. The anginosus group are facultative anaerobes and grow as pinpoint colonies (<0.5 mm) on blood agar. This is in contrast to pyogenic, beta-hemolytic streptococci which are greater than 0.5 mm in size after the same incubation period. The anginosus group streptococci can exhibit a variety of hemolysis patterns, including alpha, beta, or gamma hemolysis. A distinct butterscotch or caramel odor is noted on examination. The anginosus group can possess Lancefield antigens A, C, F, G, or be non-groupable, so it is important not to misidentify them as other streptococci that also have these antigens.

Historically, further identification of viridans group streptococci was challenging; however, the advent of automated systems and MALDI-TOF mass spectrometry has been useful in providing species level identifications for more common isolates. Molecular sequencing methods using sodA gene can be helpful as well for the most reliable results. While penicillin resistance is becoming more frequent in viridians group streptococci, it is still rare in the S. anginosus group.  

In the case of our patient, an echocardiogram was performed and found to be negative for endocarditis. The patient’s symptoms improved and they were discharged home on ceftriaxone and metronidazole. A follow up CT scan to confirm resolution of the abscess was scheduled.  

-Lisa Stempak, MD is the System Director of Clinical Pathology at University Hospitals Cleveland Medical Center in Cleveland, Ohio. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. Her interests include infectious disease histology, process and quality improvement, and resident education.

Microbiology Case Study: A 73 Year Old with Bacteremia Caused by an Unusual Pathogen

Case History

A 73 year old patient with a medical history significant for diabetes and diabetic foot ulcers presented to an outpatient orthopedic clinic complaining of right foot pain and fevers. Physical exam findings were significant for a right metatarsal ulceration that extended to the bone which prompted admission to a local hospital. Tissue from debridement of this ulcer was sent for routine bacterial culture and blood cultures were also collected. The patient was started on empiric antibiotics.

Laboratory Findings

The tissue culture gram stain showed mixed gram negative and gram positive bacteria. Two days after admission, an anaerobic blood culture bottle flagged positive with gram negative rods which could not be identified by Verigene nucleic acid detection test. It was plated on routine anaerobic and aerobic culture plates for further identification. Four days after admission, another blood culture set flagged positive with staphylococci which was identified on the Verigene as methicillin susceptible Staphylococcus aureus in the aerobic bottle. Seven days after admission, the gram negative organism grew and was identified by MALDI-TOF mass spectrometry as Campylobacter ureolyticus. The tissue culture grew mixed gram positive and negative bacteria including Staphylococcus aureus, Bacterodies fragilis group, and Trueperella bernardiae. The patient’s antibiotic therapy was tailored to cover the MSSA and Campylobacter and they were successfully discharged.

Image 1. Colony gram stain of Campylobacter ureolyticus isolated from the patient’s blood culture. The bacteria appear as thin S-shaped gram negative rods.

Discussion

The Campylobacter genus has 24 species of bacteria including C. jejuni and C. coli which are the most frequent cases of campylobacteriosis, a diarrheal illness which is described below. Other less frequent pathogenic species include C. fetus, C. upsaliensis, C. lari, and C. ureolyticus. Campylobacter species appear as a curved S-shaped spiral rods and are gram negative on gram stain, are nonspore forming, and motile, with the exception of C. ureolyticus, which is aflagellate. Because Campylobacter is difficult to culture, rapid detection tests have been developed including antigen detection tests, however, these lack specificity. Several FDA approved nucleic acid  amplification tests for Campylobacter exist, such as the BD MAX enteric bacterial panel that can detect C jejuni/C coli (speciation requires a reference lab).

Campylobacter grows best under microaerophilic conditions and at 42o C (closer to the body temperature of chickens). C. ureolyticus is unique as it grow anaerobically. Media that is selective and differential for Campylobacter, including charcoal cefoperazone deoxycholate agar (CCD) and charcoal based selective medium (CSM), is often used for stool specimens. Campylobacter appears as flat grey colonies that tend to spread along streak lines. Identification of Campylobacter includes a characteristic gram morphology, growth microaerophilically (expect for C. ureolyticus), and oxidase positivity.  C. jejuni are hippurate hydrolysis positive. C. coli are hippurate hydrolysis negative, however, there are C. jejuni that are hippurate hydrolysis negative, making this test non-specific.

Clinical and Laboratory Standards Institute (CLSI) recommends antibiotic susceptibility testing for C. jejuni and C. coli and includes testing for ciprofloxacin, erythromycin, and tetracycline resistance which requires microaerophilic conditions.

Campylobacter is mainly a zoonotic disease acquired from poultry, cattle, sheep, pigs, and domestic pets. C. ureolyticus, is thought to be transmitted most frequently form cattle, however, more research is needed in this area. A common cause of Campylobacter is consumption of undercooked meat, especially poultry due to the high prevalence of Campylobacter in US retail poultry. In 2015, 5,000 US retail poultry samples were tested for Campylobacter with 12% of samples testing positive; 24% of chicken breast samples tested positive and 0.2 % of ground turkey samples tested positive. The majority of isolates were C. jejuni and C. coli (65% and 34% respectively). In 2004, 60% of chicken samples tested positive in the US (1). Campylobacter most frequently infects young children ages 1-5 as well as adolescents and young adults and is most frequently seen between the months on June and August (1).

C. ureolyticus is a less studied species of Campylobacter, however there is evidence that this species can cause diarrheal disease and extra –intestinal infections. Some studies of fecal specimens from patients presenting with diarrhea illness in Ireland revealed 24% of Campylobacter positive stools were C. ureolyticus species (4). C. ureolyticus has also been isolated skin and soft tissue abscesses, however, C. ureolyticus is rarely the sole bacteria isolated, raising the questions of whether it a true soft tissue pathogen. The most frequent soft tissue site of infection is the perianal region (4).   

Campylobacter usually presents as a diarrheal illness, causing fever, diarrhea (can be bloody or non-bloody), and abdominal cramping with symptoms lasting days to weeks. The disease is usually self- limited, but in 10-15% of cases patients are admitted to hospitals (1). Generally, patients will clear campylobacter enteritis without the need for antibiotics. Indications for antibiotics include severe bloody diarrhea, relapsed cases, high fever, greater than 1 week course, and extraintestinal infections or immunocompromised status. Interestingly, presentations of C. jejuni/C. coli can mimic appendicitis and lead to unnecessary appendectomies. Extra-intestinal infections include bacteremia, septic arthritis, abscess formation, meningitis, peritonitis, prostatitis, urinary tract infections, and neonatal sepsis. Guilian-barre syndrome can be seen after C. jejuni infections, especially the heat stable serotypes HS19 and HS41, which is medicated by antibodies that develop against ganglioside-like epitopes in the bacterial cell wall LPS region which cross react with peripheral nerve gangliosides. C. jejuni/C. coli can also induce reactive arthritis and rarely have been implicated in inciting inflammatory bowel disease exacerbations and celiac disease (1-2).

In severe infections or extraintestinal infections, azithromycin is the preferred antibiotic as fluoroquinolone resistance is rising in the US. In 2014, 27% of C. jejuni and 36% of C. coli isolates were resistant to ciprofloxacin, and 2% of C. jejuni and 10% of C. coli isolates were resistant to azithromycin (1-2). In an Italian cohort of patients, greater than 60% of Campylobacter strains were ciprofloxacin or tetracycline resistant, while 29% of C. coli isolates were resistant to tetracycline, fluoroquinolones, and macrolides (3). Interestingly, use of these antibiotics in animal feed has been directly associated with the occurrence of antibiotic resistant Campylobacter stains (1-3). Antibiotic resistance and guidelines for the management of C. ureolyticus infections is largely unknown.

Overall, Campylobacter usually presents as a self-limiting diarrheal illness, however, less frequently extra-intestinal infections can occur such as in this patient’s case. The most common pathogenic species include C. jejuni and C. coli, while other Campylobacter species are seen less frequently. In this patient’s case, C. ureolyticus was isolated from the blood after the patient developed a right metatarsal ulcer. While we were unable to culture Campylobacter from the patient’s wound culture, this is the most likely source of their blood stream infection. 

References

  1. Whitehouse CA, Young S, Li C, Hsu CH, Martin G, Zhao S. Use of whole-genome sequencing for Campylobacter surveillance from NARMS retail poultry in the United States in 2015. Food Microbiol. 2018;73:122-128.
  2. Tack DM, Marder EP, Griffin PM, et al. Preliminary incidence and trends of infections with pathogens transmitted commonly through food – Foodborne Diseases Active Surveillance Network, 10 U.S. sites, 2015-2018. Am J Transplant. 2019;19(6):1859-1863.
  3. Garcia-Fernandez A, Dilonisi AM, Arena S, Iglesias-Torrens Y, et al. Human Campylobacteriosis in Italy: Emergence of Multi-Drug Resistance to Ciprofloxacin, Tetracycline, and Erythromycin. Front Microbiol. 2018 Aug 22;9:1906. doi: 10.3389/fmicb.2018.01906. eCollection 2018.
  4. O’donovan D, Corcoran GD, Lucey B, Sleator RD. Campylobacter ureolyticus: a portrait of the pathogen. Virulence. 2014;5(4):498-506.

-Liam Donnelly, MD is a 2nd 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.