Microbiology Case Study: A 72 Year Old Woman with Persistent Cough

Clinical History

The patient is a 72 year old female who overall has been fairly healthy. She has struggled with a cough for several years. A CT scan in 2015 showed some tree-in-bud changes in the lungs potentially consistent with an atypical mycobacterial infection. She had a positive methacholine challenge test and was diagnosed with asthma. Her cough has not improved with inhaled asthma treatments. The cough has been persistent and is at times productive of small amounts of whitish sputum. She has not noted any progressive shortness of breath. Over the last several months she has tried trials of both nasal corticosteroids, and treatment with Prilosec for gastroesophageal reflux. Both of these trials had no effect on her cough. At the end of November 2018, a CT scan of the chest was consistent with an atypical mycobacterial infection.

In January 2019, she came back from a skiing trip. She tried to ski but was unable to because of shortness of breath; she came home on the third day prematurely. During this time, she developed increased cough, fevers and chills. An x-ray was obtained by her primary care provider, which showed a right lower lobe infiltrate, and was placed on levofloxacin for 5 days. After completing the antibiotic, she is still very fatigued and still coughing. She presented to her pulmonologist in March 2019. She denied any fevers, chills or chest pain. Her cough has continued with intermittent sputum production. Her appetite and weight have been stable, along with bladder and bowel habits.

The patient’s past medical history is significant for arthritis, cataracts, depression, polymyalgia rheumatica, and sciatic nerve pain. Her past surgical history is only a tonseillectomy in her childhood. Her social and family history is that she runs an educational travel business, is currently divorced, has never been a smoker, and has no family history significant for recurrent infections.

Laboratory Findings

Induced sputum samples were obtained and inoculated on a 7H9 bottle that was incubated and continuously monitored for growth. Eight days later, the 7H9 bottle flagged positive for growth. A gram stain showed branching gram positive bacilli. The Kinyoun acid-fast stain was negative, but a modified Kinyoun showed rare positive staining cells. The bottle was subcultured onto chocolate agar, 7H11 agar, buffered charcoal yeast extract (BCYE) agar, and LJ slants. Two days later, all plates except the 7H11 plate showed growth of white, dry, crinkled colonies as depicted in Image 1. A gram stain of the colonies showed branching gram positive bacilli as shown in Image 2. Again, the Kinyoun stain of the colonies was negative but the modified Kinyoun again highlighted cells as seen in Image 3. A representative colony was sent for identification to Mayo laboratories a day later. MALDI-TOF performed by Mayo Laboratories revealed the bacteria to be Rothia aeria. An attempt was made to set up sensitivities but the organism was not able to grow out on the test medium.

Image 1. Isolated bacteria culture on chocolate agar.
Image 2. Gram stain, 1000x.
Image 3. Modified AFB stain, 1000x.

Discussion

Rothia aeria is a very rare pathogen with a current PubMed search yielding 20 references. It was first isolated from the MIR space station (1) and genomic sequencing was perform on the bacteria (2). It has been shown to be a normal oral flora (3), but also seems to be most associated with endocarditis. A few case reports have discussed sepsis, respiratory infections, and joint infections. Importantly, it has been documented to be confused with Nocardia species (4).

References

  1. Li, Y. et al. Rothia aeria sp. nov., Rhodococcus baikonurensis sp. nov., and Arthrobacter russicus sp. nov., isolated from air in the Russian space laboratory Mir. Int J Syst Evol Microbiol. 2004; 54(pt. 3): 827-835.
  2. Nambu, T. et al. Complete Genome Sequence of Rothia aeria Type strain JCM 11412, Isolated from Air in the Russian Space Laboratory Mir. Genome Announc. 2016 Dec 29; 4(6).
  3. von Graevenitz, A. et al. Coryneform bacteria in throat cultures of healthy individuals. J Clin Microbiol. 1998; 36: 2087-2088.
  4. Saraya, T. et al. Rothia aeria: a great mimicker of the Nocardia species. BMJ Case Rep. Published Online: November 18, 2014.

-Jeff Covington, MD, PhD 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.

Microbiology Case Study: A 75 Year Old Female with Breast Erythema and Drainage

Clinical History

A 75 year old female with a past medical history of breast cancer presented to the Emergency Department with chills 3 weeks status-post bilateral breast reconstruction due to ruptured silicone breast implants. Her white blood cell count was 13,440/cmm and her temperature was 39.4ºC. Physical examination revealed erythema of the right breast incision and purulent drainage from the Jackson-Pratt (JP) drain. Two blood cultures were drawn and a specimen was collected from the JP drain fluid and sent for gram smear and culture.

Laboratory Findings

Blood cultures were negative for growth. Gram stain of the drain fluid was significant for many polymophonuclear neutrophils, however no bacteria were seen. Aerobic cultures grew gram positive cocci. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) analysis identified Streptococcus gordonii. The patient was started on doxycycline and amoxicillin-clavulanate. Antibiotic susceptibility testing subsequently showed susceptibility to ceftriaxone and penicillin.

Image 1. Blood agar showing alpha-hemolytic colonies.
Image 2. Gram stain from media showing gram positive cocci.

Discussion

Streptococcus gordonii is a gram positive, non-motile, facultative anaerobic cocci that is part of the Streptococcus sanguinis group of viridans group streptococci (VGS). It is a common oral bacteria that has been implicated in invasive infections such as endocarditis and septic arthritis. It is less frequently a cause of soft-tissue infections such as orbital cellulitis, osteomyelitis, and subcutaneous abscesses. There are case reports of joint prosthesis infections, however breast implant infections have not been reported. Breast implant infections are most commonly caused by Staphylococcus aureus, Pseudomonas aeruginosa, and Staphylococcus epidermidis. There are reports of different VGS species causing breast implant infections. As the bacteria primarily resides in the mouth, infections are usually caused by oral trauma. Although symptoms may often be minor, in cases caused by VGS, systemic symptoms can occur including a toxic shock-like syndrome. In these cases there is a case fatality rate as high as 80%. S. gordonii has been reported as susceptible to clindamycin, ceftriaxone, erythromycin, and levofloxacin. Prompt treatment is important to prevent progression to systemic illness and mortality.

References

  1. Seng P, Bayle, S, Alliez, A, et al. The microbial epidemiology of breast implant infections in a regional referral centre for plastic and reconstructive surgery in the south of France. Int J Infect Dis. June 2015;35:62-66.
  2. Fenelon C, Galbraith JG, Dalton DM, Masterson E. Streptococcus gordonii—a rare cause of prosthetic joint infection in a total hip replacement. J Surg Case Rep. 2017 Jan;1:235.
  3. Liao CY, Su KJ, Lin CH, et al. Planta purpura as the initial presentation of viridans streptococcal shock syndrome secondary to Streptococcus gordonii bacteremia. Can J Infect Dis Med Microbiol. 2016:946385.
  4. Dadon Z, Cohen A, Szterenlicht YM, et al. Spondylodiskitis and endocarditis due to Streptococcus gordonii. Ann Clin Microbiol Antimicrob. 2017:16:68.
  5. Krantz AM, Ratnaraj F, Velagapudi M et al. Streptococcus gordonii empyema: a case report and review of empyema. Cureus. 2017 Apr;9(4):e1159.

-Jonathan Wilcock, 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 49 Year Old Man with Chest Pain and Shortness of Breath

Case History

A 49 year old male presented to the emergency department (ED) with complaints of chest pain, shortness of breath, and chills for the past two weeks. He describes the pain as sharp and located on the left side of his chest. Past medical history is non-contributory, except for current IV drug use. His temperature was 97.7°F, blood pressure 141/63, heart rate 87, respirations 18 with an oxygen saturation of 91-93% on room air. On physical exam, a regular rate & rhythm with no murmur or regurgitation was noted and lungs showed fine bilateral crackles. His white blood cell count was increased at 22.1 TH/cm2 and troponin I was also elevated at 0.19 ng/ml. Blood cultures were collected and the patient was started on ceftaroline and piperacillin tazobactam for presumed infective endocarditis. He was transferred to the medical intensive care unit and intubated due to respiratory distress. An echocardiogram revealed a large mobile vegetation on the aortic valve with severe insufficiency and a vegetation & thickening of the mitral valve with severe regurgitation.

Laboratory Identification

Image 1. Gram stain showed gram positive cocci arranged in pairs and chains (1000x oil immersion).
Image 2. Small, gray, non-hemolytic colonies grew on blood and chocolate agar after 48 hours of incubation at 35°C in 5% CO2. There was no growth on MacConkey agar.
Image 3. Portions of valve leaflets showing acute neutrophilic fibrinous exudate (H&E, 300x).
Image 4. Special stain highlighting numerous bacterial cocci (GMS, 300x).

Blood cultures were positive within 24 hours of collection and gram positive cocci arranged in pairs and chains were noted (Image 1). Enterococcus spp., vancomycin resistance not detected was reported by polymerase chain reaction (PCR). Small, gray, non-hemolytic colonies grew after 2 days of incubation (Image 2). MALDI-TOF mass spectrometry identified the isolate as Enterococcus faecalis.

Discussion

Enterococcus spp. are gram positive, catalase negative cocci that are arranged in pairs & chains and are facultative anaerobes. Enterococcus spp. are widespread in nature and a component of the normal flora of the gastrointestinal tract and less commonly found in the oral cavity and on the skin. Commonly, Enterococcus spp. are opportunistic pathogens and cause infections of the urinary tract, intraabdominal cavity, surgical sites, bacteremia, and infective endocarditis.   

In the microbiology laboratory, Enterococcus spp. grow readily on non-selective media and are usually alpha-hemolytic or non-hemolytic on blood agar. The two main species, E. faecalis and E. faecium, will grow in 6.5% NaCl, hydrolyze esculin in the presence of bile salts, and are positive for both leucine aminopeptidase (LAP) and L-pyrrolidonyl-beta-naphthylamide (PYR). Biochemically, arabinose utilization serves as a useful indicator to distinguish E. faecalis (negative) and E. faecium (positive). A variety of identification systems are able to identify the great majority of Enterococcus spp. to a species level.

Ampicillin or vancomycin are acceptable treatment options for Enterococcal infections if found to be susceptible by antibiotic testing. It is important to note, Enterococcus spp. are intrinsically resistant to cephalosporins, aminoglycosides, trimethoprim-sulfamethoxazole, and clindamycin. For serious infections, including infective endocarditis, it is recommended to treat with a cell wall active agent such as ampicillin and an aminoglycoside (gentamicin or streptomycin) to create a synergistic bactericidal effect. Emergence of E. faecium acquired vancomycin resistance (VanA/VanB) is increasing and more board spectrum agents such as daptomycin and linezolid are necessary to effectively treat these infections.     In the case of our patient, upon identification of E. faecalis from multiple blood cultures, his antibiotics were switched to IV ampicillin and gentamicin. He underwent valve replacement surgery and both the aortic and mitral valves grew E.faecalis as well and showed numerous bacterial cocci on histology (Images 3 & 4). He completed a six week course of ampicillin and gentamicin and was discharged home in good condition.

-Hansini Laharwani, MD is a first year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center. 

-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the Director of Clinical Pathology as well as the Microbiology and Serology Laboratories. Her interests include infectious disease histology, process and quality improvement, and resident education.

Microbiology Case Study: A 70 Year Old Male with a Decubitus Ulcer

Clinical History

A 70 year old male with a history of multiple system atrophy and left hip fracture presented to his primary care physician after being found by his home health nurse to have a sacral decubitus ulcer. Physical examination revealed an afebrile immobile patient with a 3.0 cm stage III ulcer over the sacrum with purulent exudate. Tissue was obtained and sent to our laboratory for Gram stain and culture.

Laboratory Findings

Gram stain was significant for many polymorphonuclear neutrophils and mixed gram positive and gram negative organisms. Blood and chocolate plates grew mixed organisms with a predominant gram positive coccobacillus. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) identified this organism as Trueperella bernardiae.

Image 1. Gram stain from tissue showing mixed gram positive and gram negative organisms.
Image 2. Blood agar showing non-hemolytic white colonies.

Discussion

Trueperella bernardiae is a nonspore-forming, facultatively anaerobic, gram-positive coccobacillus. It was previously categorized within the Actinomyces and Arcanobacterium genera. It is classically associated with pig farming. It is often considered to be a contaminant or normal flora, however, it has been reported as a cause of bone and soft tissue infections. Highly invasive diseases are rare. The incidence of infection may have been underreported previously due to the difficulty to culture and identify it from normal flora prior to the advent of MALDI-TOF. Antibiotic sensitivity data is limited, however, there are reports of susceptibility to beta-lactams, clindamycin, tetracycline, and vancomycin. Minimum inhibitory concentration interpretation is often based on data from bacteria of the Corynebacterium.

References

  1. Rattes ALR, Araujo MR, Federico MP, et al. Trueperella bernardiae: first report of wound infection post laparoscopic surgery. Clin Case Rep. 2016 Aug;4(8):812-815.
  2. Lawrence CHD, Waseem S, Newsholme W, Klein JL. Trueperella bernardiae: an unusual cause of septic thrombophlebitis in an injection drug user. New Microbes New Infect. 2018 Nov;26:89-91.
  3. Cobo F, Rodriquez-Granger J, Sampedro A, et al. Two Rare Cases of Wound Infections Caused by Trueperella bernardiae. Jpn J Infect Dis. 2017;70:682-684.
  4. Gowe I, Parsons C, Best M, et al. Successful treatment of olecranon bursitis caused by Trueperella bernardiae: importance of environmental exposure and pathogen identification. Case Reports in Infectious Diseases. 2018;5353085.

-Jonathan Wilcock, 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 90 Year Old Male with Acute Appendicitis

Case History

A 90 year old male is transferred from his nursing care facility to the hospital for management of acute appendicitis. He had acute onset of right lower quadrant abdominal pain the morning prior to admission with fevers, rigors and drenching sweats. Imaging showed ruptured appendicitis with a fecalith surrounded by small pockets of fluid. His past medical history included dementia, heart disease, hyperlipidemia, hypertension, and glucose intolerance. He denied having any prosthetic joints or valves. Blood was obtained for microbiological analysis.

Laboratory Identification

Blood culture bottles flagged positive. Gram stain of the blood culture bottles showed medium to long gram negative bacilli (Image 1). The blood culture media was plated on blood, chocolate, and MacConkey agar. Aerobically, yellow colonies grew on the blood and chocolate agar. The yellow colonies turned red when exposed to 10% KOH (Image 2). Definitive diagnosis of Chryseobacterium gleum was obtained by MALDI-TOF.

Image 1. Gram stain from the blood culture bottle shows gram negative bacilli.
Image 2. Growth of the organism on chocolate agar with addition of 10% KOH solution (circled in black).

Discussion

Chryseobacterium gleum is a gram negative bacillus. They form yellow colonies that grow on blood and chocolate agar. They rarely grow on MacConkey agar and are non-fermenters when they do grow. Species of Chryseobacterium will turn red with addition of 20% KOH due to a pigment protein called flexirubin. Interestingly, our lab had only 10% KOH and the colonies turned red with this as well. Other key biochemical and physiologic characteristics of Chryseobacterium include being indole and oxidase positive and they are non-motile.

Chryseobacterium species are found in the environment and are usually not part of normal flora, therefore infection requires exposure of the bug to a debilitated patient in order to colonize the respiratory tract. However, infection of other body sites that may or may not have preceded respiratory tract colonization have been reported. These organisms can survive in chlorinated tap water. They are an emerging cause of hospital associated infections. No virulence factors have been studied. Risk factors for infection include immunosuppression, trauma, surgery, burns, foreign body implants and infused fluids. Of note, the patient was thought to obtain his Chryseobacterium bacteremia from his ruptured appendicitis.

For therapy, there are no definitive guidelines due to lack of understanding of resistance mechanisms. These antibiotics have been reported to have potential activity: Ciprofloxacin, rifampin, clindamycin, trimethoprim/sulfamethoxazole and vancomycin (reportedly for C. indologenes). Our patient was given Piperacillin/tazobactam, Ceftriaxone and metronidazole for two days, Cefepime for one day, Vancomycin for a day. Infectious disease recommended continuing piperacillin/tazobactam and starting trimethoprim/sulfamethoxazole and discontinuing vancomycin.

Antimicrobial susceptibility testing was performed and showed resistance to meropenem, aztreonam, gentamicin, and tobramycin. The organism was susceptible to piperacillin/tazobactam and trimethoprim/sulfamethoxazole.

References

  1. Tille P. Bailey & Scott’s Diagnostic Microbiology. Fourteenth Edition. Elsevier; 2017.
  2. Murray P. Medical Microbiology. Seventh Edition. Elsevier; 2013.
  3. Jain V, Hussain NAFA, Siddiqui T, Sahu C, Ghar M, Prasad KN. Simultaneous isolation of Chryseobacterium gleum from bloodstream and respiratory tract: first case report from India. JMM Case Rep. 2017;4(10):e005122. Published 2017 Oct 16. doi:10.1099/jmmcr.0.005122

-Angela Theiss, 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 81 Year Old Female with Persistent Fevers

Case History

The infectious disease service was consulted on an 81 year old female for persistent fevers. She initially presented a few weeks prior with cough & shortness of breath which was diagnosed as an acute chronic obstructive pulmonary disease (COPD) exacerbation for which she received levofloxacin and steroids. The patient continued to have a persistent cough and dysphagia after discharge. Her respiratory status and cough worsened and she was readmitted and intubated. Vancomycin, piperacillin/tazobactam and levofloxacin were started as well as fluconazole for suspected esophageal candidiasis. Her past medical history was significant for breast cancer, atrial fibrillation, and diabetes mellitus. Of note, patient was originally from Puerto Rico but moved to the United States 40 years ago and denied recent travel and any known tuberculosis exposures. She formerly worked in a deli packing cheeses. A bronchoscopy was performed and a brochoalveolar lavage (BAL) specimen as well as blood and stool specimens were submitted for bacterial culture and ova and parasite exam.

Laboratory Identification

Image 1. Multiple larval forms in the stood specimen from an ova and parasite exam. (Iodine stain, 100X).
Image 2. High power of the larvae with a short buccal cavity (red arrow) and prominent genital primordium (blue arrow), (Iodine stain, 1000x).

The bronchoscopy revealed a bloody fluid admixed with clots which was clinically consistent with diffuse alveolar hemorrhage. The roundworms depicted above were identified in both the BAL and stool O&P exam. Based on the presence of the short buccal cavity and the prominent genital primordium and the absence of eggs, the identification of Strongyloides stercoralis was made. Given the large amount of larvae present in both the lungs and gastrointestinal tract, the patient was diagnosed with a strongyloidiasis hyperinfection.  

Discussion

Strongyloides stercoralis is classified as a nematode (roundworm) and is the cause of strongyloidiasis in humans. The helminth is found worldwide, especially in warm climates and underdeveloped countries, and is the cause of 30-100 million infections. Infection is due to fecal contamination of soil, where free-living forms are found, or water. Infective filariform larvae penetrate intact skin, particularly bare feet, resulting in infection. The free living cycle begins with the rhabditiform larvae passed through the stool develops into the infective filariform larvae or when the  rhabditiform larvae mature into free living adult male & female forms that mate and produce eggs which then hatch and become infective filariform larvae that can infect humans. The parasitic life cycle begins with the infective filariform larvae penetrates human skin. The worm is then either coughed up from the lungs and swallowed or migrates to the small intestine where eggs are laid and hatch.

Patients may present with gastrointestinal symptoms such as abdominal pain, bloating, and diarrhea, pulmonary symptoms like dry cough and throat irritation, or skin rashes along points of entry (feet, ankles). When the larvae are in the lung, Loeffler’s syndrome, characterized by pneumonia symptoms with coughing and wheezing, may develop due to an accumulation of eosinophils in response to the parasitic infection. In patients who are immunocompromised, the rhabditiform larvae can develop into the filariform larvae in the host and can directly penetrate the bowel mucosa or perianal skin resulting in autoinfection, dissemination throughout the body, and high parasite burden. Symptoms of hyperinfection include bloody diarrhea, bowel perforation, destruction of lung parenchyma with bloody sputum, meningitis, and septicemia. Hyperinfection most commonly occurs after steroid administration for asthma or COPD exacerbation, but can also be seen in those receiving chemotherapy or who have had organ transplants.  

In the laboratory, the diagnosis of S. stercoralis is most often made by an ova and parasite exam of the stool, duodenal fluid, sputum or BAL specimens (Image 1). Most commonly the rhabditiform larvae are present and are identified by the presence of a short buccal cavity and prominent genital primordium (Image 2). These two features are helpful in distinguishing S. stercoralis from hookworms (Ancylostoma spp. and Necator americanus) which have a longer buccal cavity and indistinct genital primordium. The eggs of these two nematodes are also very similar, although typically S. stercoralis eggs hatch before they are passed in stool specimens. S. stercoralis can also be visualized on H&E histology sections in the crypts of intestinal biopsies where the adult female measures up to 2.2 mm in length. Finally, serologic testing can be helpful when there is a high suspicion of disease in the face of multiple negative stool exams, but cannot distinguish between a current or past infection. Most patients do not remember a specific exposure and prevention includes wearing gloves and shoes when handling or walking on soil that may contain contaminated fecal material. Treatment options for an acute or chronic S. stercoralis include a short course of ivermectin or albendazole. In the case of disseminated infection, ivermectin should be given until stool and sputum exams are negative for 2 weeks. In the case of our patient, she was started on ivermectin, but succumbed to the disease due to extensive pulmonary hemorrhage.   

-Jaswinder Kaur, MD, is a fourth year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center. 

-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the Director of Clinical Pathology as well as the Microbiology and Serology Laboratories. Her interests include infectious disease histology, process and quality improvement, and resident education.

Microbiology Case Study: A 54 Year Old Male with Right Upper Quadrant Pain

Case History

A 54 year old male with a past medical history of Type II diabetes mellitus and obesity was admitted for a few days history of severe pain over right upper quadrant accompanied by fevers, chills, nausea, vomiting and diarrhea. Physical exam revealed a palpable gallbladder. Ultrasound imaging showed a distended gallbladder with a thickened, edematous and hyperemic wall that was interpreted as acalculus cholecystitis. The patient underwent percutaneous drainage of the gallbladder with plans to undergo a cholecystectomy once the acute phase of his illness stopped. The gallbladder fluid was sent to microbiology for analysis.

Laboratory Findings

Anaerobic plates obtained from organisms growing in thioglycollate broth grew low, convex opaque white colonies. The organisms did not produce the classic double zone of beta hemolysis (Image 1).  Gram stain of the culture showed gram positive bacilli that were “boxcar” shaped (Image 2). Aerobic plates had no growth. The organisms were catalase negative and non-motile. MALDI-TOF identified the organism as Clostridium perfringens.

Image 1. Growth on CNA plate in anaerobic environment
Image 2. Gram stain from the anaerobic culture shows boxcar-shaped gram positive bacilli.

The patient was also placed on piperacillin-tazobactam while in the hospital.  His condition improved and he was discharged home with a seven day course of cefpodoxime and metronidazole with a general surgery follow up appointment.

Discussion

Clostridium perfringens is a gram positive bacilli with blunt ends (boxcar shaped). These obligate anaerobes are spore formers, however these are rarely seen. When seen, they produce subterminal spores. These organisms cause of crepitant myonecrosis (gas gangrene), gangrenous cholecystitis, septicemia, and food poisoning.  They are present in large numbers as normal microbiota in the gastro-intestinal tract of humans and animals, the female genital tract and oral mucosa. Typically, infections are caused by endogenous strains gaining access to normal sterile sites due to a predisposing factor that compromise normal anatomy: surgery, trauma, or altered host defense mechanisms (diabetes, burns, immunosuppression, and aspiration).

Penicillin is recommended in most infections, however resistance has been reported. Optimal management of intra-abdominal infection is to achieve appropriate source control and drainage is important.   

References

  1. Tille P. Bailey & Scott’s Diagnostic Microbiology. Fourteenth Edition. Elsevier; 2017.
  2. Murray P. Medical Microbiology. Seventh Edition. Elsevier; 2013.

-Angela Theiss, 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.