Colonization by gentamicin-resistant Staphylococcus epidermidis in a special care baby unit

Babies entering a special care baby unit during a 3-month period were studied prospectively for colonization by gentamicin-sensitive and -resistant coagulase-negative staphylococci (CNS). Gentamicin-resistant isolates were characterized by biotyping, antibiotic sensitivity pattern and phage-typing. All the babies studied became colonized with gentamicin-resistant CNS and often with multiple strains. Gentamicin-sensitive CNS usually appeared first and predominated, but gentamicin-resistant staphylococci could be detected by enrichment culture at a median time of 1 day, and, by direct culture at a median time of 4 days. Similar strains were found in the environment and nasal carriage was detected in 60% of the staff of the unit by enrichment culture. The gentamicin-resistant strains were all resistant to benzylpenicillin and other antibiotics. No particular pathogenic strain could be identified, but clusters of colonizations by distinguishable strains were noted. Biotype SVI was frequently encountered, particularly among clinically significant isolates.