Resumo

TORRES, Luis; GAGLIOTTA, Vanesa; TORRES, Orlando  e  BENITEZ, Minerva. β-Lactamasas de Espectro Expandido en Enterobacterias aisladas en Centros de Salud de Caracas. Rev. Soc. Ven. Microbiol. [online]. 2006, vol.26, n.2, pp.80-88. ISSN 1315-2556.

The extended-spectrum ß-lactamases (ESBLs) are ß-lactamases produced by a variety of gram-negative bacteria that confers resistance to cephalosporins of third and quarter generation and aztreonam. They are most commonly produced by isolates of K. pneumoniae and E. coli, although the plasmidic nature of the genes that encode them has allowed a wide dissemination to other bacterial genera. A phenotypical and molecular detection of ESBLs were carried out to 224 Enterobacteria isolates from eight Health Centers of Caracas . A 91.1% of stumps analyzed by double disk method and the NCCLS 2004, were ESBLs' producers. The MIC analysis for ceftazidime, cefotaxime, cefepime and aztreonam showed a bigger proportion of stumps ESBL with ceftazidimase activity compatible to the SHV families and/or TEM, and in a smaller proportion to the CTX-M family. The PCR results based on genes bla_SHV, bla_TEM and bla_CTX-M, amplification confirmed a predominance of SHV-ESBL (72%) and CTX-M-ESBL (21.1%). Therefore, carbapenems with 100% of sensibility constitute the best therapeutic option. This investigation has allowed the detection of circulating ESBLs type in eight hospitals, and is also the first report that determines the CTX-M type ESBLs in our country.

Palavras-chave : -lactamases; bacterial resistance; SHV-ESBL; CTX-M-ESBL.