Observations on coagulase-negative staphylococci in a neonatal unit in India

Fifty neonates were included in a prospective study which determined the frequency of colonization and infection with coagulase-negative staphylococci (CNS) in a neonatal unit. The isolates were characterised by species, antibiotic resistance and ability to produce slime. Twenty-four epidemiologically related isolates (including four isolates from the hands of staff) were also phage typed and had plasmid analysis performed. On the first day of birth, 18% of infants were colonized with CNS, 40% and 30% by days 3-5 and day 7 respectively, and 25% by the 14th day and beyond. Staphylococcus haemolyticus and S. epidermidis were the most frequent CNS species encountered, accounting for 36% and 35% of isolates. Resistance to four or more antibiotics was present in 37% of strains isolated on the first day and this increased to 100% of isolates from infants who stayed for more than 14 days. Forty-five percent of CNS were slime producers; no significant difference was observed in slime producing ability between the species or isolates at different days after birth. Five infants developed septicaemia due to CNS. Staphylococcus haemolyticus and S. epidermidis were recovered as the only pathogens from three and two cases respectively. Detailed typing revealed that one case of infection with S. haemolyticus was preceded by surface colonization with an identical strain. Evidence was also obtained for the transmission of CNS between babies on the hands of staff.