Surveillance of antimicrobial susceptibility of Pseudomonas aeruginosa isolates from a central hospital in central Portugal: 7 years of evolution or involution?

Abstract number: P574

Pereira S.G., Oliveira H., Albuquerque L., Leitão R., Cardoso O.

Objectives:Pseudomonas aeruginosa (PA) is an important nosocomial pathogen causing a wide variety of infections, being at present the fourth most common nosocomial pathogen. In order to apply optimal therapeutic guidelines, physicians must be aware of recent resistance surveillance and epidemiological data. The aim of this study was to determine antimicrobial susceptibility of PA isolates in order to assist the guidelines for empirical antibiotic prescription regimens and to evaluate the infection control measures implemented in the hospital surveyed.

Methods: From April 2003 to April 2010, 2719 PA isolates were collected in Centro Hospitalar de Coimbra: 1719 were nosocomial isolates and 1000 from ambulatory. Isolates were obtained from sputum (40.9%), urine (25.3%), exudates (12.4%), blood (4.7%) and other sources (16.6%). Identification and susceptibility patterns of the isolates were performed with API32GN (BioMérieux) and MicroScan WalkAway (Dadebehring). Susceptibilities to Piperacillin (PIP), Piperacillin plus Tazobactam (TZP), Aztreonam (AZT), Ceftazidime (CAZ), Imipenem (IP), Meropenem (MP), Amikacin (AMK), Gentamicin (GN), and Ciprofloxacin (CIP) were guideline by CLSI.

Results: Considering all isolates, AMK was the best agent (86.5%), and CIP was the worst (61.0%). The same result was observed in nosocomial isolates, with AMK as the best agent (82.8%) and CIP the worst (54.4%). In ambulatory isolates, MEM was the best agent (95.3%). Since the beginning of the study, susceptibility rates have progressively diminished in nosocomial and ambulatory isolates. In the year 2007–2008, it was observed a small increase in the susceptibility rate of several antimicrobials in all isolates (AZT, CAZ, GN, IP, MP, AMK, CIP), but in the following years, it has decreased, being at present in the lowest level since the beginning of the study. Susceptibility rates of the most important b-lactams IP, MP and CAZ have diminished in 16.5%, 21% and 13.8%, respectively, in nosocomial isolates, and 10.9%, 8.9% and 9.9%, respectively, in ambulatory ones. Contrarily, the susceptibility rate of TZP has increased (9.8%) since 2007–2008.

Conclusion: Appropriate empirical treatments based on knowledge of particular resistance patterns are important determinants to the success of therapeutics. Studies of surveillance can be helpful in fighting the development and spread of resistance among pathogenic agents.

Session Details

Date: 07/05/2011
Time: 00:00-00:00
Session name: Abstracts of 21st ECCMID / 27th ICC
Location: Milan, Italy, 7 - 10 May 2011
Presentation type:
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