Bacillus mycoides bacteremia after dog bite trauma in a patient on chronic suppressive antibiotics

Bacillus mycoides (B. mycoides) is a Gram-positive bacillus belonging to the Bacillaceae family, found in soil and plant rhizospheres. Infection of humans by B. mycoides is exceedingly rare, previously reported only twice in the literature. Here, we present a third case of B. mycoides infection, specifically a bloodstream infection in a patient following a dog bite to the hand. The patient, who had a chronic Left Ventricular Assist Device (LVAD) in place and was on a chronic suppressive regimen of doxycycline and cefadroxil for a preexisting driveline infection, developed B. mycoides bacteremia despite ongoing antibiotic therapy. She was successfully treated with intravenous ampicillin-sulbactam plus vancomycin, followed by oral ciprofloxacin upon discharge. The patient's recovery was uncomplicated and the final susceptibility testing confirmed pan-susceptibility to all tested agents. This case highlights the potential pathogenicity of B. mycoides in humans and raises questions on the risk factors for infection and optimal management of B. mycoides infections in the setting of relatively limited clinical data.