Extended-spectrum beta-lactamases in urinary isolates of Escherichia coli, Klebsiella pneumoniae and other gram-negative bacteria in a hospital in Eastern Province, Saudi Arabia

OBJECTIVE: To evaluate the prevalence and antimicrobial susceptibility of extended spectrum beta-lactamase (ESBL) producing gram-negative organisms isolated from patients with urinary tract infection (UTI).

METHODS: We carried out this study at Almana General Hospital, Eastern Province, Kingdom of Saudi Arabia, during the period August 2003 to October 2004. We studied urinary isolates of Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), Enterobacter spp and Pseudomonas aeruginosa (P. aeruginosa) for ESBL production and antimicrobial susceptibility.

RESULTS: We studied a total of 2302 urinary gram-negative isolates for the presence of ceftazidime resistance and ESBL. The isolates included E. coli (1238), K. pneumoniae (522), Enterobacter spp (138) and P. aeruginosa (404). Of the 2302 isolates, 232 (10%) were ceftazidime resistant and 204 (8.9%) were ESBL producers. We detected ESBL in 119 (9.6%) E. coli, 59 (11.3%) K. pneumoniae, 14 (10.14%) Enterobacter species and 12 (2.97%) P. aeruginosa isolates. The ESBL-producing strains were most commonly isolated from patients with indwelling Foley s catheter [131 (64.2%)] and those in the long-term care ward [90 (44.2%)]. Only 26 (12.7%) ESBL-producing isolates were from outpatients. More than 89% of the ESBL producers were susceptible to imipenem and meropenem. Amikacin and piperacillin/tazobactam were active against 68% and 45% of the isolates. Susceptibility to gentamicin and ciprofloxacin was 22.5% and 14%. The least active antibiotic was cefepime (11.8%).

CONCLUSION: This study shows the presence of ESBL producers in uropathogens from both inpatients and outpatients and demonstrates their high resistance to various classes of antimicrobial agents.