Neonatal sepsis is the most serious problem in the neonatal intensive care (NICU) with highly significant morbidity and mortality among infants. The study was to determine the causative organisms in neonatal sepsis at NICU of HRH Princess Maha Chakri Sirindhorn Medical Center (MSMC), Ongkharak, Nakhon-Nayok. A retrospective chart review for 5 years during January 1, 2007 to December 31, 2011 in neonates with clinical suspicious signs and symptoms of sepsis and positive blood culture admitted to MSMC was investigated. The results showed that a total of 2,087 neonates admitted to NICU over a period of 5 years with 124 episodes of sepsis from 102 neonates (males: females = 1.2:1) who had clinical suspicious signs and symptoms of sepsis and positive blood culture. The incidence rate of septicemia was 11.9 per 1,000 patients admitted year. Forty percents were classified as early neonatal sepsis (EOS) and sixty percents were classified as late neonatal sepsis (LOS). There were 2 cases developed meningitis and the mortality was seen in 6 cases which mainly associated with gram negative organisms. The most common organisms in EOS were Coagulase negative Staphylococcus (CONS) followed by Enterobacter spp and A. baumannii. That of LOS were CONS followed by Enterobacter spp and K. pneumoniae. Sensitivity of gram positive organisms to vancomycin, fosfomycin, chloramphenicol and ciprofloxacin was 100%, 90.4%, 84.2% and 69.6% respectively whereas that of gram negative organisms to meropenem, ciprofloxacin and amikacin was 94%, 81.6% and 81.2% respectively. For gram negative organisms and third generation cephalosporins, sensitivity to cefoperazone, ceftazidime, ceftriaxone and cefotaxime was 71.4%, 36.7%, 22.4% and 14.2% respectively. Identification of the causative organisms and antimicrobial susceptibility helps the physician to choose the most appropriate empirical treatment.
