Resumo

MUNOZ M, Liliana et al. Detection of gene aac(6')-aph(2") in associated with aminoglucosides resistance in Staphylococcus coagulase-negative strains isolates from one neonatal unit in Bogota. rev.fac.med. [online]. 2009, vol.57, n.4, pp.326-333. ISSN 0120-0011.

Background. The most common cause of resistance to aminoglucosides is the acetilation and phosphorilation of the antibiotic by the enzyme AAC(6')APH(2"). Objetive. To determine the presence of the gene aac(6')-aph(2") in strains of coagulase-negative Staphylococci isolated from infected neonates and to investigate the concordance with the susceptibility tests in-vitro. Materials and methods. the aac(6')-aph(2") gene was determined in 63 coagulase-negative Staphylococci strains isolated from blood cultures and catheter tips obtained from the neonatal care unit at the Instituto Materno Infantil in Bogotá, Colombia. Results. Staphylococcus epidermidis was the most frequently identified microorganism. The aac(6')-aph(2") gene was detected in 55 out of 63 strains (73,43%), 42 strains (87,5%) isolated from blood cultures, and 13 strains (23,6%) isolated from catheter tips. Susceptibility to gentamycin was determined by minimum inhibitory concentration, and susceptibility to amikacin by the disk diffusion antibiotic sensitivity test. There was no a significant statistical association between the presence of the gene and the microbial susceptibility to either gentamycin or amikacin. Conclusion. The presence of the aac(6')-aph(2") gene in strains of Staphylococcus epidermidis is very high. Differences in the expression of the gene might explain some cases of inconsistency with the susceptibility tests.

Palavras-chave : enzymes; staphylococcal infections; Staphylococcus epidermidis; infant; newborn; drug resistance; bacterial.

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