Staphylococcus epidermidis isolation and antibiotic resistance in a neonatal intensive care unit

Bacterial ecology was studied in 1114 newborns (355 at term, 759 preterm) admitted to a neonatal intensive care unit (NICU) during a three year period. Bacterial samples were taken in each newborn from external ear canal, pharynx and eyes in all patients, and from endotracheal tube, umbilical catheter and blood in selected patients. The predominant flora was characterized by gram-positive microorganisms (63.53%), Staphylococcus epidermidis representing 34.68% of all isolated strains. S. epidermidis isolation increased significantly with time (p < 0.002) and was highest in summer. The percentage of S. epidermidis resistant strains to oxacillin (63.8%) and to amikacin (17.8%) was high. This is the antimicrobial combination we commonly employ as empirical treatment of suspected bacterial infection in our NICU. Knowledge of characteristics of local microbial flora seems important in order to optimize preventive and therapeutic policies for neonatal infections.