Plesiomonas shigelloides

Gram Stain

• Gram negative bacilli - fermenter

Clinical Significance

This organism is found in a variety of environmental sources including soil and water.

It is associated with both intestinal and extraintestinal infections.

Intestinal infections are more common in summer months and typically self-limited. They may be more severe in immunocompromised individuals. A history of travel to tropical areas or consumption of seafood is common.

Extraintestinal infections are rare and include septicemia, meningitis, skin/soft tissue (cellulitis) and bone/joint infections (septic arthritis/osteomyelitis), endophthalmitis, and cholecystitis.

Infections in immunocompromised individuals may have a fulminant course.

Usual Susceptibility Pattern

This organism produces a variety of beta-lactamases and is typically resistant to ampicillin, 1st/2nd generation cephalosporins, and beta-lactamase inhibitor combinations.

Aminoglycosides have low intrinsic activity and should be considered resistant.

Resistance to tetracyclines is common.

Most strains are susceptible to TMP/SMX and quinolones.