An Unusual Case of Polymicrobial Bacteremia From Methicillin-Resistant Staphylococcus Aureus and Shigella

Bloodstream infections (BSIs) are a significant cause of morbidity and mortality worldwide. Patients with polymicrobial BSI have a two-fold risk of hospital mortality as compared with patients with monomicrobial BSI. We present a case of a 53-year-old African American male with a medical history significant for hyperlipidemia, coronary artery disease, hypertension, anxiety, depression, and human immunodeficiency virus non-adherent to antiretroviral therapy who presented to the hospital with complaints of shoulder pain and diarrhea. The physical exam was significant for multiple skin abscesses, the largest being 5x6 cm. Blood culture grew Shigella and methicillin-resistant Staphylococcus aureus (MRSA), stool culture grew Shigella, and wound culture after incision and drainage grew MRSA. Transthoracic echocardiogram showed no vegetations. He was treated with vancomycin and ceftriaxone. The patient's clinical condition improved, and diarrhea resolved. Patient repeat cultures showed no growth. As polymicrobial bacteremia is associated with higher morbidity and mortality, early initiation of antibiotics and appropriate antibiotic therapy are pivotal.