BackgroundBloodstream infection (BSI) is one of the most common causes of nosocomial infection in neonatal intensive care units (NICU). The aim of the present study was to determine bacterial agents and their susceptibility patterns to antibiotics and to investigate the risk factors associated with BSI.MethodsThis was a nested case–control study carried out from September 2009 to June 2010 in the NICU wards in Sanandaj hospitals western Iran. Cases were patients with BSI and controls were other patients who had negative blood culture. Bacteriologic diagnosis and antibiotic susceptibility pattern was performed based on the Edward & Ewings and the National Committee of Clinical Laboratory (NCCL) Standards.ResultsOf 472 patients who hospitalized in NICU, 6.4% had BSI (n = 30) including 17girls (56.7%) and 13 boys (43.3%). Enterobacter SPP was the predominant isolated bacteria from blood culture (36.7%). The maximum antibiotic resistance and sensitivity were observed by Tetracycline and Ciprofloxacin respectively. Risk factors associated with BSI were age ≤ 7 days (p = 0.001), previous antibiotic consumption (p = 0.013), and low birth weight (LBW), (p = 0.001).ConclusionsGram negative bacteria and Entrobacter in particular are the most common pathogens. Improving prenatal health care, standards of infection control and choosing accurate antibiotics are recommended to avoid BSI in neonatal intensive care units.