Plesiomonas shigelloides--associated diarrhea.

Although Plesiomonas shigelloides is considered to be a cause of diarrhea in the Orient, it has infrequently been noted to be associated with diarrhea in Taiwan. Six cases of various extent of diarrhea were found to be associated with P. shigelloides in stool culture in this department between January 1987 and December 1988. Only two of them had history of chronic diarrhea and the others had mild or even no symptom. All six strains of this organism were susceptible to most commonly used antibiotics, but resistant to ampicillin, carbenicillin, clindamycin, oxacillin, penicillin, and vancomycin. Those which required least minimal inhibitory concentration (MIC) were cefazolin, ceftazidime, cefuroxime, ciprofloxacin, and trimethoprim/sulfamethoxazole. Our experiences showed that P. shigelloides may cause mild diarrhea in normal hosts. It sometimes is an incidental finding. An oxidase test for this organism should be included as routine culture of the stool specimen, but treatment is not always necessary.