• Giuseppe Celenza, Cristina Pellegrini, Marisa Caccamo, Bernardetta Segatore, Gianfranco Amicosante, and Mariagrazia Perilli.
• Dipartimento di Scienze e Tecnologie Biomediche, Università di L'Aquila, I-67100 L'Aquila, Italy.
• J. Antimicrob. Chemother. 2006 May 1; 57 (5): 975-8.

ObjectivesTo assess the prevalence and types of genes encoding extended-spectrum beta-lactamases (ESBLs) in clinical isolates of Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter spp. from Bolivia.MethodsA total of 642 clinical isolates were collected consecutively during a 4 month period (September to December 2004). Resistance or reduced susceptibility to cefotaxime and/or ceftazidime and/or aztreonam was assessed using double disc synergy tests using clavulanic acid, cefotaxime, ceftazidime and aztreonam to identify putative ESBL-producing isolates. The ESBL determinants were characterized by colony blot hybridization, PCR and DNA sequencing.ResultsOf the 642 isolates, 220 (34.3%) showed resistance or reduced susceptibility to cefotaxime and/or ceftazidime and/or aztreonam, and 150 (23.4%) were putative ESBL producers. A total of 106 ESBL-producing isolates contained the bla(CTX-M-2) gene, and 32 isolates had a novel allele, bla(CTX-M-43). bla(CTX-M) alleles were detected in all P. aeruginosa and Acinetobacter spp. studied. In contrast, only 12 ESBL-producing isolates had bla(PER-2), mainly Enterobacteriaceae, although it was also found in a strain of P. aeruginosa.ConclusionsThis is the first study on ESBL-producing strains in Bolivia and it reveals a high prevalence of bla(CTX-M) genes. The PER-2 enzyme was less prevalent, but its gene was detected in several species, including P. aeruginosa, which is consistent with horizontal transfer.

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