[Presence of integrons and their relationships with the resistance to third generation cephalosporins among nosocomial isolates of Acinetobacter baumannii].

BACKGROUND

Acinetobacter baumannii is an important etiological agent causing nosocomial infections. High level of resistance for different kind of antimicrobials has been observed, including beta-lactam antibiotics. This feature, chromosomal or plasmid encoded, has been associated to integrons harbouring antibiotic resistance gene cassettes.

AIMS: To investigate the presence of integrons among clinical isolates resistant to third generation cephalosporins (3GC).

MATERIAL AND

METHODS

One hundred A. baumannii strains isolated from several Chilean hospitals were included in this study. Minimal inhibitory concentrations (MIC) of 3GC by an agar dilution method were carried out. Integrons class 1, 2 and 3 were investigated by colony blot hybridisation and confirmed by PCR.

RESULTS

High level of resistance to all assayed 3GC was observed. On the other hand, integrón class 2 was the most prevalent (77% of isolates) followed by integron class 1 (52%). Forty six percent of isolates hybridised with probes for both of them. However, no positive hybridisation was detected for integron class 3.

CONCLUSIONS

Nevertheless, most isolates harboured one or both class of integron; there was no direct relationship between the presence of these genetic structures and the resistance to this kind of beta-lactam antibiotics.