Antimicrobial resistance of Acinetobacter baumannii: six years of National Antimicrobial Resistance Surveillance Thailand (NARST) surveillance.

OBJECTIVE

To determine the prevalence, clinical epidemiology, and antimicrobial susceptibilities of Acinetobacter baumannii in Thailand from 2000 to 2005.

MATERIAL AND METHOD

Twenty-eight hospitals participated in the National Antimicrobial Resistance Surveillance Thailand program. All data were reviewed and analyzed for the prevalence, clinical epidemiology, and antimicrobial susceptibilities of the clinical isolates of A. baumannii from 2000 to 2005.

RESULTS

The number of clinical isolates of Acinetobacter spp. increased from 8,699 isolates in 2000 to 14,071 isolates in 2005. The most common species, identified by biochemical and growth characteristics, was A. baumannii. More than 50% of all isolates were from the respiratory tract specimens. The percentage of resistance has been increasing, particularly multi-drug-resistant (MDR) or carbapenem-resistant phenotypes. Of carbapenem-resistant strains, the prevalence was 2.1% and 46.7% in 2000 and 2005, respectively. Most carbapenem-resistant strains were also MDR. The prevalence of MDR strains was highest in the Central region and Bangkok. Cefoperazone/sulbactam was the antimicrobial against largest proportion Acinetobacter spp., although the prevalence of resistance to this agent is on the upward trend.

CONCLUSION

A standardized technique to identify the organisms to the species level should be determined to be used in the surveillance system. Because the prevalence of Acinetobacter spp. resistant to multiple classes of antimicrobials including carbapenems and cefoperazone/sulbactam are increasing, there is an urgent need for a more active surveillance system, more stringent infection control efforts, and powerful antimicrobial stewardship programs in all healthcare sectors to minimize the further spread of this MDR strain.