Abstract | May 3, 2021
The Grass is Gangrene-r on the Other Side: Shewanella Bacteremia Rooted in the Subtropical Soil
Learning Objectives
- Know more about emergingly relevant human pathogens, how to recognize them clinically, and how to appropriately treat them;
- Identify preventive measures included in proper diabetic foot care and identify potential advanced complications.
Introduction:
Shewanella putrefaciens is a bacterium notorious for producing the well-known putrid smell from rotting fish. Typically thriving in marine environments and contaminated foods, it can also be found in coastal soils, and more recently has emerged as a potential source of nosocomial pneumonia given its ability to create biofilms. Shewanella is rarely pathogenic in humans, with less than 300 cases ever reported, with the majority of them being in tropical environments, and only a fraction being isolated in blood specimens. This case highlights the importance of proper diabetic foot care and an instance of a rare pathogen unique to living in a subtropical region.
Case: A 62-year-old Caucasian male with history of type 2 diabetes (A1c 7.0%), hypertension, and morbid obesity (BMI 51) presented after being found down at home by a friend who had last seen him 3 days ago. Patient stated he generally had not felt well for the past several days. Initial vitals were 99/65mmHg, 163bpm, 98.1F, respiratory rate 12, pulse oximetry 96% on room air. Exam revealed necrotic wounds to bilateral feet consistent with dry gangrene as well as nonpurulent cellulitis of the pannus and scrotum. Labwork was notable for leukocytosis of 26.8K/uL with 16% bands, lactate 7.0mmol/L, and creatinine 3.02mg/dL. The patient was admitted to the intensive care unit with severe sepsis, borderline septic shock, and provided aggressive fluid resuscitation and broad-spectrum antibiotics. Clinically, the soft tissue infections were consistent with streptococcus, however blood cultures grew gram negative rods in 2/2 sets, raising concern for prevotella. Speciation revealed shewanella putrefaciens, resistant to imipenem and aztreonam. Patient denied recent saltwater exposure or seafood consumption, however stated he rarely wears shoes and frequently walks outdoors barefoot.
Diagnosis:
Shewanella putrefaciens bacteremia secondary to contaminated soil exposure of bilateral feet dry gangrene.
Management:
Antibiotic coverage was narrowed to cefepime per sensitivities (14-day course) and surgical debridement of gangrenous toes performed. Repeat blood cultures were negative at 5 days. The patient’s hospital course was complicated by development of gastrointestinal bleed and acute systolic heart failure requiring a 55-day hospitalization, and was ultimately discharged home with self-care.
