Antimicrobial resistance patterns of Acinetobacter baumannii in clinical isolates

Abstract number: p1778

Tsilika  G.T., Pliatsika  V.P., Tsivitanidou  M.T., Sofianou  D.S.

Objectives: 

A. baumannii is a nosocomial pathogen, commonly isolated from critically ill and immunocompromised patients. The aim of the present study was to evaluate the antimicrobial resistance of A. baumannii strains isolated in a tertiary care hospital througout a three-year period.

Methods: 

A total of 1311 A. baumannii strains were selected from January 2002 to December 2004.The specimens were obtained from inpatients hospitalized in intensive care unit (ICU) and pediatric intensive care unit (PICU) and other departments of our hospital.The identification and the antimicrobial susceptibility testing were performed using the Vitek 2 automated system(bioMerieux,France).

Results: 

The isolates included in the study originated from haemocultures (28.5 %), central venous catheters (10.4 %), urine (10.2 %), bronchial aspirates (25.4 %), wounds (25.5 %). Out of 1311 strains 45.2 % isolated from ICU and PICU and the remaining 54.8 % from the other departments. We determined the occurrence of resistance to 20 common used antimicrobial agents during a three-year period. The majority of isolates were resistant to 17 or more antibiotics tested.Some strains were defined by resistance to all antimicrobial agents exept colistin.The resistance to imipenem rose dramatically from 18.4% in 2002 to 45.9% in 2004.Notable increase detected also to: Trimethoprim/Sulfamethoxazole: from 80.9% in 2002 to 97% in 2004, Amikacin: from 80.5% in 2002 to 96.5% in 2004, Netilmicin: from 79.8% in 2002 to 91% in 2004, Ticarcillin/clavulanic acid: from 76.8% in 2002 to 97.4% in 2004, Piperacillin/tazobactam: from 30.3% in 2002 to 47.5% in 2004. Resistance rates to other antibiotics tested were as following:amikacin 71%, ampicillin 100%, cephalothin 100%, cefotaxime 97.7%, cefoxitin 100%, ceftazidime 93.4%,ciprofloxacine 96.2%, nalidic acid 6.6%, norfloxacin 96.4%,ofloxacin 95.1%, ticarcillin 97%, tobramycin 42.8%. Noteworthy is the decreasing of gentamycin resistance from 38.8% 2002 to 17.2% in 2004.Colistin was the only antimicrobial agent active to all clinical isolates.

Conclusions: 

The emergance and rapid spread of multidrug resistant A. baumannii isolates are of a great concern worldwide.Imipenem was one of the most potent agents for treatment of those infections caused by multiresistant strains.The increasing prevalence of imipenem resistance limits therapeutic options and leads to outbreaks of carbapenems resistant strains.