Objective To identify the bacteriological profile of germs causing early onset infection in neonates and their impact on empiric antibiotic prescription.

Methods Retrospective review of charts of all neonates, aged less then 4 days admitted to a tertiary PICU with the diagnosis of early neonatal culture-proven infection between 1998 and 2007. A special emphasis on type of germ and its antibiotic-related sensibility was made.

Results 110 newborns with early onset culture-proven infection were analysed. Mean gestational age (GA) was 34±3 weeks and 60% had GA⩽34 SA. Postnatal age at admission was 13±12 hours. Mean birth weight was 2500±500 grs. Two-thirds of patients had received antibiotics before admission. Overall mortality rate was 16.7%. 61% of isolated bacteria was Gram-negative bacilli. The most frequent species was: group B Streptococcus (38.2%) and Escherichia coli (32%). Multi-drug resistant species was observed in 3.6% and Listeria monocytogenes in one case. Group B Streptococcus was the major germ isolated in term or near term newborn with GA⩾34 weeks (62%) and had a constant sensibility to ampicillin (100%). Escherichia coli species was resistant to ampicillin and to gentamicin in respectively, 37% and 5.7% of cases.

Conclusions Gram-negative bacilli still the major cause of early onset neonatal infection. The most frequent isolated bacteria were group B Streptococcus, constantly ampicillin-sensible, and Escherichia coli. Gram-positive cocci were the major causes in neonates ⩾34 weeks and restriction of empiric third-cephalosporin prescription seems to be useful in such neonates.