Poor Effect of Empiric Antibiotic Treatment of Gram-Negative Bacteria on Myroides spp.: A Case Report and Literature Review.

Background: Myroides spp. are a group of Gram-negative bacteria which may cause opportunistic infections in humans. They are widely resistant to clinically relevant empiric antibiotics. Importantly, the focus of infection, regional susceptibility data, and patient's medical history dictate the choice of an empiric antibiotic treatment. Unfortunately, the empiric treatment is not always optimal. Especially immunocompromised patients are at risk of having opportunistic infections, which are not necessarily common causes of typical infections. Case Presentation: We report here a case of a patient with several comorbidities, including chronic kidney failure, heart failure, and leg ulcers, who developed fever and infection of his chronic leg ulcers. Cefuroxime was initiated as an empiric treatment of suspected sepsis with unknown origin. Two days later, the initial blood culture sample indicated Gram-negative rods which VITEK MS mass spectrometry identified as Myroides spp. The patient's antibiotics were first changed to meropenem, and the next day, ciprofloxacin was added. After susceptibility testing, ciprofloxacin was changed to levofloxacin. Fortunately, the patient recovered with the treatment and was discharged from hospital. Conclusions: Myroides spp. are widely resistant opportunistic pathogens to acknowledge to be out of reach for first-line empiric antibiotic treatment. Myroides cases reported earlier have suggested soil exposure or pig bite as potential sources of infection. In the case described here, one possible source of Myroides might be cat scratches or cat licks.