In order to determine the epidemiological features of cholera in Lao PDR, the presence of mobile genetic elements such as plasmid, class I integron and SXT element in V. cholerae isolated from surface water were examined. Among the 22 strains isolated from 13 distantly separated sampling sites, no mobile genetic elements associated with drug resistance were found reflecting the antibiogram of the strains. Nevertheless, cholera epidemics due to multiple drug resistant V. cholerae occurred repeatedly in those areas until 2000.

The detection rate of rotaviruses from diarrheal stools in Lao People's Democratic Republic (Lao PDR) was studied in the period from 1994 to 2003. Rotavirus antigen was detected using latex agglutination kit. The average detection rate was 2.4%, or 18 of 738 cases examined in total. Rotavirus was not detected from 175 cases examined in 1995, 1998, 2000 and 2003, but 8 of 85 cases (9.4%) examined in 1997 were positive for rotavirus. The detection rate was 6.0% in the age group younger than 2 years and 0.6% in the age group older than 2 years. These detection rates were markedly lower than those in neighboring countries such as Vietnam and Thailand.

Drug susceptibility of Neisseria gonorrhoeae in the past 3 years in Lao People's Democratic Republic (Lao PDR) was examined. The organisms were collected from the patients visiting Center for Laboratory and Epidemiology, Ministry of Health, Vientiane, Lao PDR. A total of 131 isolates of N. gonorrhoeae (45 in 2000. 27 in 2001, and 59 in 2002) were collected, and the drug susceptibilities of the isolates were examined by disc method using 5 anti-microbial agents (ciprofloxacin, ceftriaxone, penicillin, spectinomycin, and tetracycline). The susceptibility was expressed as sensitive (S), intermediate (M) and resistant (R) depending on the Zone Diameter Interpretive Chart attached to the disc preparation. As the results, almost all isolates were resistant to penicillin and tetracycline, but sensitive to ceftriaxone and spectinomycin. Most of the penicillin resistant isolates were regarded as penicillinase producing N. gonorrhoeae (PPNG) depending on the effect of clavulanic acid. N. gonorrhoeae is getting resistant to ciprofloxacin in the 3-year examination period. About 10% of the isolates were resistant to ciprofloxacin in 2000, but the rate of resistant strains went up to 70% in 2002. There were very few isolates showing intermediate susceptibility.

Drug susceptibility of Staphylococcus aureus has been examined in the past 9 years to monitor the appearance of drug resistant strains especially methicillin resistant S. aureus (MRSA). The pattern of drug susceptibility has been relatively constant, but S. aureus is gradually becoming resistant to ampicillin. One MRSA was isolated in 1996 from the nasal vestibulum of a non-infected patient at Mahosot Hospital but not isolated thereafter. In 2001, 2 strains of MRSA which belonged to different clones were first isolated from the infection foci of patients. One was isolated from Setthathirath Hospital, where many Japanese staff have been dispatched since 2000. Careful monitoring and epidemiological studies of MRSA are recommended.