Background & objectives: Nosocomial infections increase patient’s mortality and are considered as a health problem. The aim of this study was to assess the risk factors for nosocomial infections and antimicrobial resistance pattern of isolated bacteria in NICU and PICU, in Bahrami and Children’s Medical Center hospitals, Tehran .

  Methods: In a prospective cross-sectional study from October 2008 to September 2009, risk factors and etiology of nosocomial infections were evaluated in all patients who showed infectious signs upon 48h admission. Infectious agents were diagnosed by the standard microbiological tests and antibiotic sensitivity of isolates was determined using dick diffusion method. The data for location of the hospital, admission history, presence of immunodeficiency, fever and using venous and urine catheters, suction, venous injection as well as cerebral shunt and surgery have been collected by a questionnaire and analyzed, statistically .

  Results: About 9.3% (70 individuals) of cases encountered with nosocomial infections. From whom, 24.3% were infected by Pseudomonas aeroginosa and 18.6% and 3.14% by Klebsiella pneumonia and Enterobacter spp, respectively. The location of the hospital, using of suction and surgery were the most common risk factors related to nosocomial infections (p<0.05).

  Conclusion: Our findings showed that the hospital location, suction and surgery were the most common risk factors and Pseudomonas aeroginosa, Klebsiella pneumonia and Enterobacter spp were the common infectious threats. So, we need to design the special program to improve nosocomial infection control in hospitals .