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.


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.   


  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.

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