Shewanella

Background

• Genus of Gram-negative bacilli within the family Vibrionaceae
• Saprophytic bacteria that cause spoilage of fish and dairy; rarely causes disease in humans
• The only two species that cause disease in humans are:
  • Shewanella putrefaciens
  • Shewanella algae
• Live in warm saltwater, usually in warm countries or in temperate countries during the summer

Clinical Manifestations

• Usually found in polymicrobial infection
• Most commonly associated with cellulitis or bacteremia
• Cellulitis typically occurs after saltwater exposure to broken skin (or occasionally freshwater exposure)
  • Can complicated chronic leg ulcers, burns, wounds
• Can also be found in abdominal or biliary tract infections, respiratory infections, ear infections
• Rarely found in bone, urianry tract, eye infections
• Single case reports of endocarditis, meningitis, aneurysm infection

Management

• Generally resistant to penicillin, amoxicillin, and first-generation cephalosporins
• Generally susceptible to third-generation cephalosporins, piperacillin, carbapenems, aminoglycosides, and fluoroquinolones
• Variable susceptibility to amoxicillin/clavulanic acid, colistin, TMP-SMX

Further Reading

• Shewanella algae and Shewanella putrefaciens: clinical and microbiological characteristics. Clin Microbiol Infect. 2005;11(5):347-352. doi: 10.1111/j.1469-0691.2005.01108.x
• Human Infection with Shewanella putrefaciens and S. algae: Report of 16 Cases in Martinique and Review of the Literature. Am J Trop Med Hyg. 2013;89(1):151-156. doi: 10.4269/ajtmh.13-0055