Genotypes and prevalence of carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa in a hospital in Saudi Arabia.

BACKGROUND The molecular epidemiology of resistance of carbapenem-resistant Enterobacteriaceae (CRE) and Pseudomonas aeruginosa are important in the study of multidrug-resistant bacteria. We evaluate the prevalence of the different mechanisms of CRE in a hospital in Saudi Arabia. METHODS Carbapenem non-susceptible isolates of Enterobacteriaceae and Pseudomonas aeruginosa were tested by real-time PCR for the detection of genes responsible for beta-lactam resistance. RESULTS There were a total of 200 isolates with carbapenem non-susceptibility and these were Klebsiella pneumoniae (n=96, 48%), Escherichia coli (n=51, 25.5%) and Pseudomonas aeruginosa (n=45, 22.5%). The detected carbapenemases were oxacillinase-48 (OXA-48) (n=83, 41.5%), New Delhi metallo-β-lactamase (NDM) (n=19, 2.5%) and both NDM and OXA-48 (n=5, 2.5%). The other carbapenemases were imipenemase (n=1, 0.5%), Verona integrin encoded metallo-β-lactamase (n=6, 3%) and Klebsiella pneumoniae carbapenemase (n=1, 0.5%), but none were detected in 86 isolates (43%). CONCLUSION The most common carbapenemases were OXA-48 and a significant percentage had no detectable genes. These data will help in the selection of new antimicrobial therapies.