Five-year surveillance for Burkholderia pseudomallei in Thailand from 2000 to 2004: prevalence and antimicrobial susceptibility.

OBJECTIVE: To determine the prevalence and antibiotic susceptibility patterns of Burkholderia pseudomallei isolates in Thailand from 2000 to 2004. MATERIAL AND METHOD: the data on WHONET from 28 hospitals participated in the National Antimicrobial Resistance Surveillance Thailand (NARST) surveillance program, was reviewed and analyzed for the prevalence and antimicrobial susceptibility patterns. RESULTS: During the five-year surveillance, the prevalence of B. pseudomallei in clinical isolates was 69% in the Northeast, 14% in the North, 11.8% in the Center, and 5% in the South. Compared to other regions, the prevalence rate in the Northeast had gradually increased from 2000 to 2004. Burirum Hospital had the highest prevalence rate in this area. The majority of isolates were obtained from blood (44.9%), pus (25.6%), respiratory tract (13.3%), and urinary tract (6.3%). The isolates from unusual sites including bone marrow, heart, and placenta were less commonly noted (< 1%). Based on in vitro susceptibility results, all isolates in each region expressed high susceptibility to ceftazidime (> 98.5%), amoxicillin/clavulanic acid (> 95%), cefoperazone/sulbactam (> 98%), imipenem (98.5%), and meropenem (98%), but express less susceptibility to trimethoprim-sulfamethoxazole (< 53%). However, the susceptibility of B. pseudomallei to trimethoprim/ sulfamethoxazole determined by the disk diffusion method is unreliable; it must be performed by the minimal inhibitory concentration method. CONCLUSION: With the exception of the Northeast, the prevalence rate of B. pseudomallei remains stable for all regions in Thailand. The isolates obtained from blood and pus represent more than two-thirds of all clinical isolates. Antimicrobial susceptibility patterns showed no evidence of increased resistance to antimicrobials most commonly prescribed for the treatment of melioidosis.