Diversity of ß-lactamases in Pseudomonas aeruginosa isolates producing metallo-ß-lactamase in two Tunisian hospitals.

This study was conducted to identify the ß-lactamase content of 30 metallo-ß-lactamase-producing Pseudomonas aeruginosa isolated in 2007 from two Tunisian hospitals and to investigate their genetic relatedness. All these isolates produced VIM-2. bla(PER-1), bla(PSE-1), bla(OXA-2), and bla(OXA-10) were identified in 17, 5, 21, and 1 isolates, respectively. These enzymes were often associated in the same isolate: 26 isolates had at least two ß-lactamases. The predominant serotype was O12. Pulsed-field gel electrophoresis revealed genetic diversity among the metallo-ß-lactamase-producing P. aeruginosa isolates. This is the first report on the existence of bla(PER-1), bla(PSE-1), bla(OXA-2), and bla(OXA-10) in Tunisia.

Molecular epidemiology and genetic environment of acquired bla ACC-1 in Salmonella enterica serotype Livingstone causing a large nosocomial outbreak in Tunisia.

Eighty-four isolates of Salmonella enterica serovar Livingstone were collected from patients hospitalized in a pediatric ward in Sfax Hospital (South Tunisia). These isolates were responsible for two nosocomial outbreaks in 2000 and 2002. Twenty-eight clinical isolates of S. enterica serovar Livingstone were also obtained in two other Tunisian hospitals in Monastir (Central Tunisia) and Tunis (North Tunisia), respectively, in 2002 and 2003. Pulsed-field gel electrophoresis yielded that these isolates were closely related. Antimicrobial susceptibility testing showed a particular beta-lactam resistance phenotype, suggestive of the presence of an AmpC-type enzyme in 111 of the 112 clinical isolates. bla(ACC-1) was characterized by polymerase chain reaction (PCR) and sequence analysis in the 111 isolates. TEM-1 was characterized in all strains and SHV-2a in only two strains. The genetic organization of bla(ACC-1) was determined by PCR mapping and sequencing. The plasmid-borne bla(ACC-1) gene mapped immediately downstream from ISEcp1. This ISEcp1 insertion sequence was itself disrupted by IS26 insertion sequences. A supplementary deletion of 13 bp was observed in ISEcp1 upstream IS26, in all isolates from Tunis, except one. PCR analysis and sequencing also revealed the presence of tnpR, bla(SCO-1), gdha, IS1353, and TniB Delta 1.