[In vitro activity of 18 antimicrobial agents against clinical isolates of Acinetobacter spp.: multicenter national study GEIH-REIPI-Ab 2010]

Abstract

Objectives: To determine the prevalence of resistance to antimicrobials in Acinetobacter baumannii (A. baumannii) from Spain and to compare it with those obtained in the first national study (GEIH-Ab project 2000).

Methods: A total of 446 isolates of A. baumannii obtained from 43 Spanish hospitals during February-March 2010 were studied. Identification of A. baumannii was confirmed by ARDRA and MALDI-TOF. Susceptibility to 18 antimicrobial agents was determined by microdilution (Clinical and Laboratory Standards Institute, CLSI). The CLSI break-points were used, except for doripenem, rifampin, sulbactam (Societé Française de Microbiologie [SFM] break-points) and tigecycline (European Committee on Antimicrobial Susceptibility Testing [EUCAST] break-points for Enterobacteriaceae).

Results: The percentage of resistant isolates (intermediate susceptible plus resistant) was: > 94% (ceftazidime, piperacillin and ciprofloxacin), 82-86% (carbapenems, tetracycline), 60-70% (tobramycin, sulbactam, gentamicin, doxycycline), 49% (amikacin), 30% (minocycline, rifampin), 24% (tigecycline), and 3% (colistin). These isolates were, in comparison with those of the first study, more resistant (P < .01) to ceftazidime (99% vs 83%), carbapenems (82-86% vs 43-48%), sulbactam (65% vs 53%) and colistin (3% vs 0%), but more susceptible to aminoglycosides (particularly gentamicin: 70% vs 96% of resistant isolates), tetracycline (83% vs 91%) and rifampicin (30% vs 51%).

Conclusion: There is a high prevalence of A. baumannii resistant to antimicrobials, particularly to carbapenems. The resistance to carbapenems, ceftazidime and sulbactam was significantly higher than that observed for isolates from the GEIH-Ab project 2000. The resistance to aminoglycosides, tetracycline and rifampin, however, was significantly decreased.