Astra Vitkauskiene
Lithuanian University of Health Science, Lithuania
Title: Nosocomial dissemination of Multidrug resistant Pseudomonas aeruginosa in Lithuania
Biography
Biography: Astra Vitkauskiene
Abstract
Despite the advances in hospital care and the introduction of a wide variety of antimicrobial agents, Pseudomonas aeruginosa (P. aeruginosa) continues to be a common cause of nosocomial infections and are important pathogens which causes problems clinically as a result of its high resistance to antimicrobial agents. Treatment of P. aeruginosa infections is usually difficult and mortality is high. In our study we found that 53.7% of clinical P. aeruginosa strains were resistant to carbapenems. Carbapenem-resistant strains more frequently were resistant to majority of tested antibiotics (to ceftazidim, piperacillin, ciprofloxacin, gentamicin, amikacin), comparing to carbapenem-sensitive strains (P<0,001). 41 (56.0%) of carbapenem resistant strains had MIC value higher than 16 µg/ml; 6 (14.6%) stains out of these have shown to be high-level ceftazidime resistance with MIC >64 µg/ml. Cephalosporin with β-lactamase inhibitor combination inhibited 53 out of 73 carbapenem-resistant P. aeruginosa at concentration less than 2 µg/ml. We found 9 (13.4%) fully resistant strains with MIC >32 µg/ml and 58 (86.6%) intermediately resistant strains with MICs range between 2 and 16 µg/ml to aztreonam. Our study has shown that more than 50% (n=28) of ciprofloxacin resistant isolates exhibited MIC values above 16 µg/ml. Tobramycin had activity against 56% (n=41) of tested isolates which twenty four were inhibited at MIC below 1µg/ml. However more than 65% (n=21) of tobramycin resistant strains had MICs above 16 µg/ml. β-lactam resistance was caused by chromosomal mechanisms (AmpC +/- OprD) in 54 isolates out of 73 (74%). In 16 (22%) of P. aeruginosa strains the presence of a carbapenemase was found and three isolates were ESBL produces.