Rare finding of Corynebacterium bovis in a facial surgical wound

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Dear Editor, A man in his 50s developed atypical operative site skin changes 2 weeks after Mohs surgery for an invasive squamous cell carcinoma on his right cheek [American Joint Committee on Cancer (AJCC) stage T1, Brigham and Women’s Hospital (BWH) stage T1]. The growth was cleared in a single stage and closed in a layered fashion with polyglactin 910 and polypropylene sutures. His medical history included a liver transplant for which he was taking long-term tacrolimus for immunosuppression; and a deep venous thrombosis for which he was taking apixaban. Initially, the wound healed well without signs of infection. However, 2 weeks postsurgery the patient experienced progressive redness, dull pain and swelling near the suture line. Oral doxycycline provided slight improvement, but symptoms worsened, prompting re-evaluation. Physical examination revealed a violaceous, erythematous plaque with induration and patterned purpuric plaques at the suture positions (Figure 1). Punch biopsy showed a granulomatous and neutrophilic infiltrate, while Gram stain highlighted clusters of Gram-positive cocci and coccobacilli (Figure 2). Wound swab was deferred in the absence of purulent drainage or fluctuance. An additional punch biopsy for culture grew Corynebacterium bovis as identified using matrix-assisted laser desorption–­ionization time-of-flight mass spectrometry. Susceptibility testing revealed sensitivities to erythromycin, gentamicin, penicillin and vancomycin. Our institution’s infectious disease department chose a 7-day course of amoxicillin 500 mg three times daily, based on the results of the sensitivity testing, in respect of the ‘antibiotic ladder’ and in accordance with the literature.^1–3^ The patient subsequently experienced complete symptom resolution. The infection resolved with antibiotic treatment alone, avoiding suture removal and surgical revision.

Corynebacterium bovis is a facultatively anaerobic, catalase-positive, Gram-positive bacterium, commonly associated with bovine mastitis and dermatitis in immunocompromised mice. Human infections are rare, with only 18 reported cases, primarily at ocular, prosthetic joint or neurosurgical sites.^1,2^ In this case, the source of infection was unclear as the patient denied contact with farm animals or rodents. Corynebacterium bovis has been isolated from Merino sheep in Argentina, and following surgery the patient wore a new Merino sweater.^3^ There are no established guidelines for C. bovis infections in humans, although penicillin has shown effectiveness.^1–3^ However, the literature notes increasing instances of biofilm-forming and multidrug-resistant strains of Corynebacterium, including C. bovis, emphasizing the need for targeted antimicrobial treatment.^4^ Unlike other Corynebacterium species, C. bovis is not among normal human flora, and its presence in deeper tissue cultures should not be dismissed as contamination.^5^ Additionally, polyglactin 910 sutures often induce granulomatous reactions and are more susceptible to biofilm formation compared with non-braided sutures, suggesting avoidance of these suture types in patients at increased risk of infection, such as those on long-term immunosuppression.^6,7^ Evidence supporting antibiotic prophylaxis for immunosuppressed patients undergoing dermatological procedures is mixed and it is therefore not routinely performed at our institution.^8^

Funding sources: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Data availability: The data underlying this article will be shared on reasonable request to the corresponding author.

Ethics statement: Not applicable.

Patient consent: Written patient consent for publication was obtained.