Microbiology Case Study: A 57 Year Old Man with Fever

Case History

A 57 year old male with a recent history of a left above the knee amputation developed a fever during the same admission of 101.1°F. His amputation had been complicated by poor wound healing, and he had a simultaneous right leg abscess that grew methicillin-sensitive Staphylococcus aureus. Examination of his wound showed serosanguinous drainage with no erythema or purulence. Blood cultures and a wound swab were sent for microbiological analysis.

Laboratory Findings Wound cultures grew methicillin-resistant Staphyloccocus aureus thought to represent colonization rather than true infection. Blood cultures flagged positive in one anaerobic bottle only at 30 hours. A gram smear showed gram-negative cocci (Image 1). Anaerobic blood plates grew pinpoint colonies (Image 2). MALDI-TOF identified the bacteria as a Veillonella species.

Image 1. Gram stain from anaerobic culture showing gram negative cocci.
Image 2. Growth on anaerobic blood plate.


Veillonella species are gram negative cocci. They are lactate fermenting, obligate anaerobes and are considered normal flora of the intestines and oral mucosa. As such, they are usually regarded as a contaminant. They have, however, been implicated in osteomyelitis, prosthesis infections, and endocarditis. They are particularly associated with poor oral hygiene, chronic periodontitis, and smoking. They have important implications in dental disease due to their ability to form biofilms. They are frequently resistant to ampicillin and have also been noted to be resistant to tetracyclines in periodontal patients. Identification is done by molecular methods, typically MALDI-TOF. PCR has also been developed, but is not routinely used.

This was considered a contamination due the absence of symptoms and isolation in one bottle only. A follow up blood culture was negative. Routine wound care was resumed.


  1. Rovery C, Etienne A, Foucault C, Berger P, Brouqui P. Veillonella montpellierensis endocarditis. Emerg Infect Dis. 2005;11(7):1112–1114.
  2. Mashima I, Theodorea CF, Thaweboon B, Thaweboon S, Nakazawa F. Identification of Veillonella Species in the Tongue Biofilm by Using a Novel One-Step Polymerase Chain Reaction Method. PLoS One. 2016;11(6):e0157516. Published 2016 Jun 21.

-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.

2 thoughts on “Microbiology Case Study: A 57 Year Old Man with Fever”

  1. I don’t believe there is a clear distinction between colonization and carriage. However, in general, carriage denotes the presence of a pathogenic organism in an asymptomatic individual. If this organism were not considered normal flora or there were non-pathogenic and pathogenic strains, carriage may be an appropriate term. However, it is known to be part of the human microbiota and generally does not cause illness unless it gains access to an unusual site. Therefore, I believe colonization is a more appropriate descriptor for it when it is isolated.

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