Detection of extended-spectrum b-lactamases in members of the family enterobacteriaceae at a teaching hospital, Riyadh, Kingdom of Saudi Arabia.
OBJECTIVE
To determine the prevalence of extended spectrum b-lactamase at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia and to compare the ability of the disc diffusion, double disc potentiation methods and the extended-spectrum b-lactamase E test to detect exended-spectrum b-lactamase among enterobacteriaceae.


METHODS
This study was undertaken during the time period period January 1 through to September 30 1999, at King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia. A total of 187 multiresistant isolates of enterobacteriacae from different clinical specimens were tested for the extended-spectrum b-lactamases. The performance of disc diffusion, double disc potentiation methods using cefotaxime, ceftazidime, ceftriaxone and aztreonamand the extended-spectrum b-lactamase E based on the reduction of the minimum inhibitory concentration of ceftazidime in the presence of clavulanic acid were compared for the detection of extended-spectrum b-lactamase production.


RESULTS
Thirty six percent of our isolates produced extended-spectrum b-lactamases. Among these 42% were Klebsiella pneumoniae and 20% were Escherichia coli. Other species of Enterobacteriaceae produced extended-spectrum b-lactamase in low numbers. Disc diffusion method was not suitable for detecting extended-spectrum b-lactamases among the isolates. Double disc potentiation performed comparably well with the extended-spectrum b-lactamases E test.


CONCLUSIONS
Extended-spectrum b-lactamases occurs in Klebsiella pneumoniae and Escherichia coli at a significant number. The use of double disc potentiation method for screening is practical and the extended-spectrum b-lactamase E test with ceftazidime is a useful confirmatory test for extended-spectrum b-lactamase production.
Babay
Hanan A
HA
Department of Pathology/Microbiology, King Khalid University Hospital, PO Box 2925, Riyadh 11461, Kingdom of Saudi Arabia. hahabib@ksu.edu.sa
D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology*; D004755:Enterobacteriaceae / Q000187:drug effects*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000453:epidemiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012529:Saudi Arabia / Q000453:epidemiology; D018440:beta-Lactam Resistance