Role of Pseudomonas in Nosocomial Infections and Biological Characterization of Local Strains

170 ROLE OF PSEUDOMONAS IN NOSOCOMIAL INFECTIONS AND BIOLOGICAL CHARACTERIZATION OF LOCAL STRAINS Ramprasad Balikaran Pal, Marissa Rodrigues, Suprama Datta Department of Microbiology, Sir. H. N. Medical Research Society, Raja Rammohan Roy Road, Prarthana Samaj, Mumbai-400004, India Email: ramprasad_pal@hnhospital . com; eoslab@ yahoo. com ABSTRACT Background & objectives: Pseudomonas aeruginosa is an important nosocomial pathogen since it can survive in minimal medium. There is a global emergence of multidrug resistant strains of Pseudomonas. These strains are the main causes of nosocomial infections causing morbidity and mortality as these infections are difficult to eradicate. The objective of the present study was to determine the prevalence of strains of P. aeruginosa in hospital environment, its incidence, clinical infections caused and to detect source of nosocomial infection by characterization of the Pseudomonas isolates. Methods: A total of 613 strains of Pseudomonas were isolated from different clinical specimens. 68 strains were isolated from environmental sites like Intensive Care Unit, Operation Theatre and Wards. Strains were identified by standard methods. Antibiogram and Pyocin typing was carried out for further characterization. Genotyping was performed by Pulsed Field Gel Electrophoresis. Results: Highest percentage of P. aeruginosa was from urine samples, followed by pus, tracheal secretions and sputa. Prevalence of the organism was highest in Intensive Care Unit followed by Intensive Care Medical Unit. The antibiogram showed maximum sensitivity to Piperacillin/Tazobactum, followed by Carbenicillin. About 47% of the strains belonged to pyocin type 10, 2.04% belonged to type 33 and 49% could not be typed. Two PFGE patterns were found among the isolates designated as SP and SP1. Out of 47, 44 isolates showing SP pattern were of pyocin type 10 and resistant to Septran, Lomefloxacin, Colistin, PolymyxinB, Ampicillin and Augmentin. The rest 3 isolates showing SP1 pattern were resistant to Gentamycin, Amikacin, Netilmycin, Carbenicillin, Ciprofloxacin and Chloramphenicol in addition to those mentioned earlier. Interpretation & conclusions: Majority of clinical and environmental strains showed a single PFGE pattern and a similar antimicrobial susceptibility pattern. Thus it is presumed that the strains of P. aeruginosa have a common origin. Out of 545 strains, 221 were isolated from post-operative cases. It can be concluded that patients acquired these infections from the hospital.