Shewanella spp

• S. algae
• S. halioti
• S. putrefaciens
• S. upenei
• S. xiamenensis

Gram Stain

• Gram negative bacilli short, long or filamentous - nonfermenter

Clinical Significance

These organisms are found in a variety of environmental and food sources. Marine environments are often implicated as a source of infection (S. algae – salt water sources, S. putrefaciens- fish, poultry, meats, fresh and salt water sources).

Although of low pathogenicity, they have been associated primarily with skin/soft tissue infections, cellulitis, and necrotizing fasciitis.

They have also been implicated in bacteremia, endocarditis, septicemia, otitis media, ophthalmic infections, septic arthritis, abscesses, osteomyelitis, and peritonitis.

Hepatobiliary disease is a predisposing condition for infection with these organisms.

S. algae appears to be more pathogenic than S putrefaciens.

Usual Susceptibility Pattern

These organisms are usually susceptible to aminoglycosides and carbapenems (some resistance described).

They are resistant to narrow spectrum penicillins and cephalosporins.

Susceptibility to piperacillin-tazobactam, 3rd/4th generation cephalosporins, TMP/SMX, quinolones (levofloxacin/moxifloxacin more active than ciprofloxacin), and tetracycline is variable.