The laboratory interpretation of coagulase-negative staphylococcal bacteraemia in neonates.

In an attempt to detect markers of significance of coagulase-negative staphylococci (CNS) isolated from neonatal blood cultures, epidemiological data and the rate of appearance of positive blood cultures were examined. The main epidemiological factor studied was the relative abundance of the different biotypes of CNS in blood cultures, on neonatal skin and the hands of neonatal unit staff. Our results showed that the relative recovery rates of biotypes found from these sources showed no significant differences. The number of positive blood culture bottles in each set and the number of days taken for growth to appear showed wide variations. A higher proportion of aminoglycoside-resistant strains were found in the group showing both blood culture bottles positive and in the group where isolates were obtained by 24 h of incubation. We conclude that there is no advantage in biotyping CNS in assessing clinical significance, but the association of aminoglycoside resistance with the isolation pattern of CNS in neonatal blood cultures requires further examination.