MICROBIOLOGY

• P. shigelloides is a facultative, anaerobic, Gram-negative rod [Fig] weakly related to the species of Enterobacteriaceae and Vibrionaceae.
  • Previously known as Aeromonas shigelloides
  • Distinguish from Shigella spp. by oxidase test; distinguished from Aeromonas by negative DNAse testing.
  • Non-lactose fermenting, oxidase-positive
• Ubiquitous environmentally, it can be isolated from soil, usually freshwater, fish, shellfish, and a wide range of animal species.
• The mechanism of diarrhea due to Plesiomonas shigelloides is unknown. It can produce a cholera-like enterotoxin, thermostable enterotoxin, and thermolabile enterotoxin.
• Many isolates produce beta-lactamases.
  • Usually susceptible to fluoroquinolones and carbapenems.