Transition of drug susceptibilities of Vibrio cholerae O1 in Lao People's Democratic Republic.

The changes of drug susceptibilities of Vibrio cholerae O1 isolated during the past 7 years (1993-1999) in Lao PDR were investigated. The most noteworthy finding was the appearance of polymyxin B sensitive El Tor vibrios. Until 1996, the susceptibilities were almost as expected and cholera disappeared in 1997. When a cholera outbreak resurfaced in 1998, the susceptibilities of isolated V. cholerae O1 against tetracycline, sulfamethoxazol-trimethoprim, chloramphenicol and polymyxin B were quite different from those of previously isolated organisms. Minimum inhibitory concentrations (MICs) of tetracycline and chloramphenicol against the isolates in 1998 were about 16 times higher than those against the previous isolates, and the MICs of sulfamethoxazol-trimethoprim were about 256 times higher than those against the previous isolates, (trimethoprim 32 microg/ml: sulfamethoxazol 608 microg/ml). Eleven percent of the isolates (11/99) were as sensitive to polymyxin B as the classic cholera vibrios (MIC < 2 microg/ml). In 1999, the susceptibility pattern was almost the same as that in 1998 except for polymyxin B to which 58% of the isolates (21/36) became sensitive.

Bacterial diarrhea in Laos, a region where cholera was endemic.

There were cholera outbreaks in Lao PDR since 1993. Two provinces were epidemic areas of cholera in 1993. However the area of cholera occurrence increased to 7 provinces through 1994. Then a bacterial survey had done for the purpose of public health improvement. EPEC was markedly isolated from the hospital in Vientiane. In apparent infection of Salmonella and non-01 Vibrio cholerae with soldiers stationed in the island in Mekong River belong to Vientiane were pointed out. The outbreak of diarrhea in suburban village of Vientiane, the diarrhea was not due to cholera but due to Shigella dysenteriae and Aeromonas sobria. As far as results in the capital city Vientiane and the Vientiane province go, it could say that there was no record and isolation of V. cholerae or non-01 V. cholerae 0139 in this study. On the contrary, Vibrio cholerae 01 serotype Eltor Ogawa was isolated although the community declared the end of the cholera outbreak. This study pointed out the importance of establishing sanitary conditions and health education systems in Lao PDR.