Molecular detection of GES-2 extended spectrum β-lactamase producing Pseudomonas aeruginosa in Pretoria, South Africa

Screening for and detection of the novel extended spectrum β-lactamase (ESBL), GES-2 produced by Pseudomonas aeruginosa remains a problem in the clinical microbiology laboratory. This study aimed to compare the normally used ESBL screening agent ceftazidime, with molecular detection, to demonstrate the presence of GES-2 ESBL production in clinical isolates of P. aeruginosa. Ceftazidime was found unreliable as an ESBL screening agent, with a specificity of 34.4%, when National Committee for Clinical Laboratory Standards resistance criteria for P. aeruginosa were employed. An improved PCR detection method was devised, that amplified a 371 bp segment of bla GES-2. This should lead to more cost-effective DNA sequencing and sequence interpretation in the laboratory.