Corynebacterium equi infection complicating neoplastic disease

Area of Science:

• Veterinary Medicine
• Human Infectious Diseases
• Microbiology

Background:

• Corynebacterium equi (C. equi) is a soil-dwelling bacterium primarily known as a pathogen in animals like horses, swine, and cows.
• Human infections with C. equi are rare but can be severe, particularly in individuals with compromised immune systems.
• Immunosuppressive therapy, often used for conditions like lymphoma, increases the risk of opportunistic infections.

Observation:

• Two human cases of pulmonary infection and bacteremia caused by C. equi are presented.
• Both patients had underlying lymphoma and were undergoing immunosuppressive treatment.
• Previously reported human cases also involved patients on immunosuppressive therapy.

Findings:

• C. equi infections can manifest as pulmonary disease with bloodstream invasion (bacteremia).
• Misidentification of C. equi as normal flora or other gram-positive rods (e.g., Bacillus, Listeria) is possible if its characteristics are not recognized.
• C. equi isolates typically show sensitivity to erythromycin, tetracycline, gentamicin, and carbenicillin.

Implications:

• Clinicians should be aware of C. equi as a potential pathogen in immunocompromised patients, especially those with lymphoma.
• Accurate identification of C. equi is essential to avoid misdiagnosis and ensure appropriate treatment.
• Prompt treatment with antibiotics such as erythromycin, combined with surgical intervention if necessary, can lead to successful outcomes.