Epidemiology of extended-spectrum beta-lactamase producing gram-negative bacilli at Siriraj Hospital, Thailand, 2003

A cross-sectional study was conducted from August to September, 2003 to determine the prevalence and risk factors in acquiring extended-spectrum beta-lactamase (ESBL) producing gram-negative bacilli (GNB) in patients admitted to Siriraj Hospital and the outcomes of these infections. Of 346 isolates of gram-negative bacteria in 249 patients, 102 isolates from 87 patients were colonization only, but 244 isolates from 162 patients were infections. The common GNB were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacter cloacae. The overall prevalence of ESBL producers was 30.1%. K. pneumoniae had a very high prevalence of ESBL producers (56.9%). The urinary tract was the most common site for ESBL- producing GNB infections. Nosocomial infections, duration from admission to infection, peripheral line, urinary catheterization, nasogastric tube insertion and previous use of beta-lactams, cephalosporins and fluoroquinolones were associated with acquiring ESBL-producing GNB infections. ESBL-producing GNB were significantly more resistant to antimicrobial agents. More than 80% of ESBL-producing GNB were susceptible to carbapenems. Mortality in patients infected with ESBL-producing GNB (41.3%) was significantly higher than those infected with non- ESBL-producing GNB (19.8%).