An analysis of the microbial flora of premature neonates

An analysis of the microbial flora of 10 premature neonates hospitalized in a neonatal intensive care unit (NICU) was made. The babies had received neither antibiotics nor antiseptics and nine out of 10 were born by caesarean section. Samples were collected on the fourth or fifth day of life from 18 skin or mucosal sites. Detailed bacterial counts were obtained by plating out suitable dilutions of the samples on to selective media. Representative samples of each colony type were then subcultured and identified, using standard laboratory methods. Two hundred and fifty-six isolates of staphylococci were obtained and their susceptibility to 23 antibiotics tested. Only 11% of the samples were sterile. Coagulase-negative staphylococci (CNS) were the commonest species isolated and were predominant in every site studied. They were found in 79% of the samples and represented almost 81% of the neonates' flora. Eight species and biotypes of CNS were identified. In decreasing order of frequency, they comprised S. epidermidis (biotypes 1 and 2), S. hominis (biotype 1), S. warneri, S. haemolyticus, S. capitis, S. cohnii and S. hominis (biotype 2). CNS distribution appeared to be highly heterogeneous with no significant specificity of any species for a particular body site. The main quantitative and qualitative variations seemed to relate to the method of delivery, and the intensity and nature of exposure of the neonate to its local environment. A high level of antibiotic resistance was found among the CNS isolates (especially S. epidermidis and S. haemolyticus): penicillin G (96%), oxacillin (31%), erythromycin (52%) and gentamicin (28%). Moreover, multiresistant strains were numerous, supporting the nosocomial origin of CNS.