Nosocomial gram-positive infections and antimicrobial susceptibility pattern of causative microorganisms at a referral teaching hospital in Tehran, Iran

Research in Pharmaceutical Sciences

Volume 7 - Number 5

Article Type: Original Article
Abstract:
Background and Aims: The aim of this study was to obtain data on the epidemiology of nosocomial Gram-positive infections in a referral teaching hospital, and to determine the susceptibility pattern of causative microorganisms. Methods: Over a 1-year period, Gram-positive microorganisms isolated from specimens of hospitalized patients with documented nosocomial infection underwent antimicrobial susceptibility testing using disk diffusion test. Also, possible risk factors for antibiotic multi-resistance were searched using multivariate logistic regression. Results: During the study period, a total of 137 nosocomial infections were detected. The most frequent infections included bloodstream infection (31.4%), surgical site infection (21.2%), pneumonia (16.8%), and catheter infection (13.9%). Staphylococcus aureus was the most frequently isolated microorganism (56.2%) followed by Enterococcus spp. (21.9%), and Staphylococcus epidermidis (15.3%). All S.aureus strains were sensitive to vancomycin, teicoplanin, linezolid, and chloramphenicol. The most effective agents against Enterococcus spp. were linezolid (100%) and chloramphenicol (95.5%). More than 50% of enterococci strains were resistant to vancomycin and teicoplanin. Resistance rate of these pathogens to other antibiotics was high. Possible risk factors for antibiotic multi-resistance among isolated pathogens were history of antibiotic use within recent 3 months (p < 0.001) and intubation of patient for mechanical ventilation (p < 0.01). Conclusions: This study shows high rate of antimicrobial resistance among nosocomial Gram-positive pathogens complicating antibiotic therapy and its outcomes. This necessitates strict infection control.