Research Article ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF PSEUDOMONAS AERUGINOSA CLINICAL ISOLATES AT A TERTIARY CARE HOSPITAL IN KATHMANDU, NEPAL CHANDER ANIL*, RAZA MOHAMMAD SHAHID Department of Microbiology, Kathmandu Medical College Teaching Hospital, Sinamangal / Duwakot, Kathmandu, Nepal, Email: drchandera@gmail.com Received: 23 June 2013, Revised and Accepted: 16 July 2013 ABSTRACT Objective: Increasing number of reports had documented the continued emergence of resistance among P. aeruginosa strains to common antimicrobial drugs, world-wide. This study investigated the antimicrobial resistance patterns of P. aeruginosa clinical isolates obtained from hospitalized patients. Methods: Between January 2012 and June 2012, one hundred and forty-five strains of P.aeruginosa were isolated from different clinical specimens and fully characterized by standard bacteriological procedures. Antimicrobial susceptibility patterns of each isolate was carried out by the Kirby- Bauer disk diffusion method as per guidelines of CLSI. Results: Majority of isolates of P.aeruginosa (120, 83.75%) were obtained from specimens of pus, sputum, urine and tracheal aspirates. The isolated pathogens showed resistance to amikacin (17.25%), ciprofloxacin (27.59%) and cefoperazone -sulbactum (34.48%). Resistance rates to Co- trimoxazole, piperacillin, ceftriaxone and chloramphenicol varied from 51.00% to 73.00%. All the isolates were susceptible to imipenem. 30 (20.69%) of P.aeruginosa isolates were multi-drug resistant. Conclusion: The results confirmed the occurrence of drug resistant strains of P.aeruginosa. Imipenem, amikacin, and ciprofloxacin were found to be the most effective antimicrobial drugs. It therefore calls for a very judicious, rational treatment regimens prescription by the physicians to limit the further spread of antimicrobial resistance among the P.aeruginosa strains. Keywords: antimicrobial resistance, clinical isolates, Nepal, Pseudomonas aeruginosa INTRODUCTION Antimicrobial agents have been the only easily and widely used therapeutic option available to counter the infections caused by diverse microbial agents. However, microbial populations have developed various strategies to overcome these antimicrobial agents - a major contributing factor in the development of anti-microbial resistance world-wide. Pseudomonas aeruginosa is an ubiquitous and versatile human opportunistic pathogen and has implications on morbidity, mortality and healthcare costs both in hospitals and in the community 1 . The development of resistance to all available antibiotics in some organisms may preclude the effectiveness of any antibiotic regimen 2,3 . Infections caused by P.aeruginosa are frequently life-threatening and difficult to treat as it exhibits intrinsically high resistance to many antimicrobials 4 and the development of increased, particularly multi-drug resistance in health care settings 4,5 . Mechanisms that cause antimicrobial drug resistance and multi-drug resistance in P.aeruginosa are due to acquisition of resistance genes (e.g those encoding beta-lactamase 6 and amino-glycoside modifying enzymes 7 via horizontal gene transfer and mutation of chromosomal genes (target site, efflux mutations) are the target of the fluoroquinolones particularly ciprofloxacin 8 . Biofilm formation in P.aeruginosa, particularly in the case of pulmonary infections in patients with cystic fibrosis, contribute to its resistance to antimicrobial agents 9 . Hypermutable (or mutator) strains of P.aeruginosa exhibiting increased mutation rates are common in chronic infecions such as those that occur in the lungs of cystic fibrosis patients 10 . Increase in the frequency of multi- drug resistant (MDR) strains of P.aeruginosa has severely limited the availability of therapeutic options. Ongoing studies on current antimicrobial resistance profiles of P.aeruginosa are essential to find out the susceptibilities of this pathogen against commonly prescribed antibiotics in any health care facility. This would help the physicians to optimize the current therapeutic treatment options. Data on antimicrobial susceptibility profiles of P. aeruginosa is limited in Nepal 11,12 . This study was therefore designed to find out the current antimicrobial susceptibility patterns of P.aeruginosa strains in a centrally located urban tertiary care hospital in Kathmandu, Nepal. MATERIALS AND METHODS Setting This investigation was carried out in the Department of Microbiology, Kathmandu Medical College Teaching Hospital, a centrally located urban tertiary care medical center in the Kathmandu valley, Nepal between the period January 2012 and June 2012. Specimens Specimens were collected from patients who were hospitalized for more than one week duration. A total of 850 clinical specimens were investigated for bacterial culture and identification. Only one isolate from each patient was considered in the study. Laboratory Identification of Isolates The specimens were collected from the hospitalized patients admitted in different wards of the hospital. These were processed for bacterial species identification by standard microbiological procedures. Specimens were taken from various sources like pus/wound, sputum, urine, tracheal aspirates, central venous (CV) catheter tip, broncho-alveolar lavage (BAL) fluid, catheters and high vaginal swabs and were inoculated on routine culture media like Mac-Conkey agar, blood agar and eosin-methylene blue agar. A battery of tests were performed that included gram's staining, colony morphology, motility tests, sugar fermentation tests and biochemical tests such as oxidase test, urease test and IMViC (indole, methyl red, Voges-Proskauer and citrate) tests for the confirmation of the isolates as Pseudomonas aeruginosa 13 . Susceptibility tests Anti-microbial susceptibility tests were done by the Kirby-Bauer disk diffusion method as per the recommendations of National Vol 6, Suppl 3, 2013 ISSN - 0974-2441