Indagine epidemiologica locale sulle infezioni sostenute da Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Burkholderia cepacia e sensibilità agli antibiotici di questi microrganismi.

Background: The aim of this local surveillance study was to determine the distribution of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Burkholderia cepacia in our geographic area, their impact in the hospital and community acquired infections and their resistance to antimicrobial agents currently used in the treatment of infections due to these microrganisms. Materials and Methods: During the period January 2001 - June 2003, 14.200 clinical isolates were collected from urine,wounds, catheters, body fluids, blood, respiratory tract specimens. Bacterial identifications were performed according to the standard methods (Murray, 2003) and antibiotic susceptibility tests were carry out in microassay by the automated system MicroScan (Dade Behring, Milano, Italy).The following antimicrobial agents were tested: piperacillin (PIP), ticarcillin (TIC), piperacillin-tazobactam (TZP), ticarcillin-clavulanic acid (TTC), ceftazidime (CAZ), ceftriaxone (CRO), aztreonam (ATM), imipenem (IPM), trimethoprim-sulfamethoxazole (SXT), gentamicin (CN), amikacin (AK), tobramycin (TOB), ciprofloxacin (CIP). Results: A total of 994 Pseudomonadaceae were isolated from in- (67%) and out-patients (33%).They were P.aeruginosa (81%), other Pseudomonas species as P.fluorescens and P.putida (8%), S.maltophilia (9%) and B.cepacia (2%).The great majority of the strains were collected from respiratory tract specimens (70%) and urine (15%).The divisions from which derived the greater quantity of isolates were pediatric (33.8%), intensive care (22.7%) and pneumology (10%) units.Antibiotics more active against P. aeruginosa were IPM, CAZ,AK and TZP. IPM was effective against B. cepacia also.The other drugs, except SXT, displayed against this microrganism high rates of resistance. Even S. maltophilia was not susceptible to much antimicrobial agents, whereas SXT was the drug more active against this germ. Conclusion: P. aeruginosa was the microrganism more frequently isolated among non-fermenting Gram-negative bacteria (81%). In serious infections sustained by this pathogen (often multidrug resistant), combination therapy with b-lactam–aminoglycoside antibiotics is recommended. With the exception of P. aeruginosa, the other pathogens resulted very susceptible to SXT, the role of this antibiotic against infection due to S. maltophilia and B.cepacia may be revalued.