Prevalence and molecular characterization of extended-spectrum β-lactamase-producing Klebsiella pneumoniae in Riyadh, Saudi Arabia

BACKGROUND AND OBJECTIVES:Reports on extended-spectrum β-lactamases (ESBL) production by Enterobacteriaceae, and especially in Klebsiella pneumoniae, are few in Saudi Arabia. Therefore, we determined the prevalence of ESBL in K pneumoniae from Riyadh and characterized the predominant β-lactamase gene in these isolates.METHODS:A total of 400 K pneumoniae samples were isolated from two hospitals in Riyadh during 2007 and screened for production of ESBL using ESBL-E-strips and combined disk methods. PCR assay was used to detect blaTEM, blaSHV, and blaCTX-M genes.RESULTS:Phenotypic characterization identified a high ESBL rate of 55% of K pneumoniae isolates. ESBL-producing K pneumoniae were PCR positive for SHV, TEM and CTX-M β-lactamase genes with prevalences 97.3%, 84.1% and 34.1%, respectively. Within the CTX-M family, two groups of enzymes, CTX-M-1 and CTX-M-9-like genes were found with prevalences of 60% and 40%, respectively.CONCLUSIONS:This study confirms the high rate of ESBL in K pneumoniae clinical isolates in hospitals in Riyadh. This study demonstrates the worldwide spread of blaCTX-M genes. This first report of the presence of the blaCTX-M gene in clincial isolates in Saudi Arabia is evidence of the continuing worldwide spread of this gene