Study of prevalence of gram- negative bacteria caused nosocomial infections in ICU in Besat hospital in Tehran and detection of their antibiotic resistance pattern-year 2007

Nosocomial infections are an important public health problem in many developing countries, particularly in the intensive care unit (ICU). These infections are accompanied with longer hospitalization, higher therapy expenses and emerging drug resistance among bacterial causative agents. The aim of this study was to determine the prevalence of gram negative bacteria caused nosocomial infection in ICU of Besat hospital and detection of their antibiotic resistance pattern.This project was a descriptive cross- sectional study conducted during a period of 12 months in 2007 at ICU of Besat hospital. Bacterial strains were isolated from various clinical samples of the patients and were identified at the species level by using conventional methods. The susceptibility testing was performed on the isolated bacteria by disc diffusion method. Chi square test was used for data analysis. In this study, nosocomial infections by gram negative bacteria were identified in 65 out of 165 patients. So the incidence rate of nosocomial infection in this ward was 39.39%. The most prevalent isolated organism was Klebsiella pneumoniae (46.2%) followed by Escherichia coli (23.1%). Pneumonia (78.5%) was the most common infection in patients. The most effective antibiotics were cefotaxime clavonic acid,ceftazidime clavonic acid, amikacin and imipenem. All the isolates showed 80 to 100% resistance to ampicillin. The history of surgery and antibiotic therapy showed significant correlation with nosocomial infection (P<0.05). the most prevalent isolated bacteria was Klebsiella pneumoniae and the most common infection was pneumonia. High antibiotic resistance was seen in isolated bacteria in present study. Nosocomial infection showed significant correlation with a history of surgery and antibiotic therapy.