[In vitro activity of 9 antibiotics and 3 beta-lactamase inhibitors against 107 clinical isolates of Acinetobacter baumanii].

BACKGROUND

Acinetobacter sp. is an important cause of nosocomial infections and it is often resistant to many antibiotics. In our hospital it often causes infections in patients on the intensive care unit. The aim of this study was to know the susceptibility of Acinetobacter sp. strains isolated in our hospital.

METHODS

The in vitro activities of nine antimicrobial agents (ticarcillin, piperacillin, ceftazidime, imipenem, meropenem, gentamicin, tobramycin, amikacin and colistin) and three beta-lactamase inhibitors (sulbactam, clavulanate and tazobactam) against 107 clinical isolates of Acinetobacter baumannii were studied. MICs were determined by a dilution agar method, except for colistin, which we used the disk-diffusion agar method.

RESULTS

Of the antimicrobial agents tested imipenem and colistin were highly active against all isolates (100% susceptibility), meropenem presented good activity (96.3% susceptibility), ticarcillin presented moderated activity (84.1% susceptibility). Most of the strains were resistant to ceftazidime (4.7% susceptibility), piperacillin (3.7% susceptibility) and the aminoglycosides (amikacin 21.5% susceptibility, gentamicin 2.8% susceptibility and tobramycin 4.7% susceptibility). Sulbactam was the most active agent among the beta-lactamase inhibitors studied (CMI90 = 4 micrograms/ml).

CONCLUSIONS

Recent trends indicate increasing antimicrobial resistance of Acinetobacter baumannii, posing a serious threat to hospitalized patients. An strict attention to maintain a good housekeeping and control of the environment and of the antimicrobial usage, appears the measures most likely to control the spread of Acinetobacter baumannii in hospitals.