Polymicrobial soft tissue infection including Shewanella putrefaciens

Excerpt

A 53-year-old man with end-stage kidney disease presented to our emergency department with a rapidly progressing soft tissue infection of the left foot. The patient had a history of diabetes mellitus, heart transplant, pacemaker implantation and CMV colitis under immunosuppressive therapy. Physical examination showed tachycardia of 106 bpm, fever of 39.1 °C. The patient reported an erythema of the left forefoot for 5 days and a painful ulcer on the lateral edge of the foot now accompanied by a foul smell, a sudden black discoloration of Dig. V and a whitish blister (Fig. 1a, b). Wound swab cultures and blood cultures were obtained and treatment with meropenem and vancomycin was initiated. Blood tests revealed a CRP of 280 mg/l, PCT of 7.7 ng/ml and WBC of 13.15/nl. Surgical debridement including amputation of Dig. V was performed the same evening. Blood cultures were negative. Gram stain of the wound swab showed Gram-negative rods and Gram-positive cocci (Fig. 1c, d). Both swabs and tissue biopsies showed a polymicrobial infection including Enterococcus faecalis, Staphylococcus aureus, and Shewanella putrefaciens. S. putrefaciens was tested susceptible to ceftriaxone (MIC <1 µg/ml), ciprofloxacin (MIC <0.5 µg/ml), piperacillin/tazobactam (MIC <4/4 µg/ml), and meropenem (MIC <1 µg/ml), but not to cefazolin. The patient was followed-up with a second-look resection of os metatarsale V and finally recovered under i.v. therapy with meropenem. He had to be readmitted, however, with osteomyelitis of os metatarsale III and IV (caused by Streptococcus dysgalactiae) 8 weeks later.

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