Role of body surface cultures in prediction of sepsis in a neonatal intensive care unit

An analysis of surface cultures of 35 preterm infants of less than 33 weeks gestational age hospitalized in a neonatal intensive care unit was made. The babies had received neither antiseptic nor antibiotic therapy prior to collection of specimens. Surface cultures were collected on the 4th or 5th day of life from 16 skin or mucosal sites. At the onset of a febrile episode within 14 days of collection of surface swabs, a blood culture was done on 31 infants (four did not develop fever) and the results were compared with the surface cultures. Sepsis was diagnosed by positive blood culture in twenty neonates (57.1%). With this frequency of sepsis, the optimum sensitivity, specificity and positive predictive values of surface cultures were 60%, 27% and 60%, respectively. These values did not improve substantially for any anatomic site cultured or for any pathogen recovered. We conclude that surface cultures are of limited value in predicting the aetiology of sepsis in neonates.