Emergence of class 1 integron-associated GES-5 and GES-5-like extended- spectrum b-lactamases in clinical isolates of Pseudomonas aeruginosa in South Africa

Several different Guiana extended-spectrum (GES) enzymes have been described occurring in Enterobacteriaceae and Pseudomonas aeruginosa worldwide. Polymerase chain reaction and gene sequencing analysis confirmed bla sub(GES) genes identified in three P. aeruginosa clinical isolates from South Africa as bla sub(GES-5) and bla sub(GES-5)-like, respectively. Compared with GES-1, the GES-5-like protein exhibited an A21E amino acid change, a novel mutation not previously described in this family. Integron structures identified upstream from the bla sub(GES-5) and bla sub(GES-5)-like genes were found to be identical to bla sub(GES-2)- carrying integrons described previously from the same geographical region. These findings confirm the establishment and persistence of integron- associated GES-type extended-spectrum b-lactamases (ESBLs) in the South African nosocomial environment. This study describes the first isolation of class 1 integron-associated bla sub(GES-5) and the emergence of a novel GES-5-like ESBL in South Africa.