Treatment of infection caused by animal commensal pathogen Staphylococcus simulans

Staphylococcus simulans is an animal pathogen belonging to the coagulase-negative staphylococci (CoNS) group that was occasionally identified in the skin of healthy people. Although it was suggested that S. simulans share some virulence factors with S. aureus, little is known about human infections, and clinical relevance is limited to a few reports. Herein, we report a case of bacteremia caused by S. simulans.

A 39-year-old man was brought to the hospital due to heart attack. During the course of admission, his procalcitonin, C-reactive protein, and erythrocyte sedimentation rate were elevated. He was empirically started on vancomycin and meropenem. However, meropenem was discontinued after the identification of the fact that S. simulans was susceptible to oxacillin, as well as the identification of Streptococcus mitis in blood culture. Repeat blood culture a day after antibiotic initiation was persistently positive for S. simulans only, while the second repeat blood culture 3 days after antibiotic initiation was negative. The patient remained hemodynamically stable, and the laboratory values were back to normal. He continued the antibiotic course for a total of 14 days and was discharged in stable condition.

CoNS should not be easily discarded as a sample contaminant and pathogen identification to species level is crucial. Clinicians should be aware of the virulence potential of S. simulans.