is one of the most common nonfermenting aerobic gramnegative microorganisms identified in clinical specimens of hospitalized patients. The emergence of multidrug-resistant (MDR) Pseudomonas aeruginosa
strains is a growing concern in hospitalacquired infections. Typing of strains is important for identifying the sources of infection as well as prevention of cross-infections and monitoring of the efficacy of antimicrobial therapy. The aim of this study was to evaluate the antimicrobial resistance and prevalence of Pseudomonas aeruginosa
serogroups isolated at Kaunas University of Medicine Hospital, Lithuania.
Material and methods
. Minimum inhibitory concentrations of piperacillin, cefoperazone, ceftazidime, cefotaxime, cefepime, imipenem, meropenem, gentamicin, amikacin, tobramycin, and ciprofloxacin for 609 Pseudomonas aeruginosa
strains isolated from various clinical specimens between November 2001 and November 2002 were determined by the microdilution method in Mueller–Hinton agar using interpretative guidelines of National Committee for Clinical Laboratory Standards. Serogroups of Pseudomonas aeruginosa
strains were identified using serums of Seiken Co. Ltd (Tokyo, Japan), containing antibodies against antigens of Pseudomonas aeruginosa
. Pseudomonas aeruginosa
strains were the most sensitive to ceftazidime (78.9%), imipenem (73.6%), meropenem (70.9%) and the most resistant to gentamicin (54.1%) and ciprofloxacin (52.5%). Multidrug-resistant strains made up 9.85% of all Pseudomonas aeruginosa
strains investigated. Multidrug-resistant Pseudomonas aeruginosa
strains were 1.5–3.5 times more resistant to antibiotics compared to non-multidrug-resistant strains, except to amikacin: multidrug-resistant strains were more sensitive (81.7%) than non-multidrug-resistant Pseudomonas aeruginosa
strains (61.0%). Pseudomonas aeruginosa
serogroups O:E and O:B were the most common serogroups (34.7% and 29.0%, respectively) followed by serogroups O:I (11.4%) and O:A (10.1%). Pseudomonas aeruginosa
serogroup O:E strains were the most prevalent among multidrug-resistant strains (48.3%).
. The results of our study show that serogroup O:E was the most prevalent serogroup of Pseudomonas aeruginosa
in our hospital, and its resistance to antibiotics was the highest.