Species identification, antibiotic sensitivity and slime production of coagulase-negative staphylococci isolated from clinical specimens

Two hundred and seventy-five consecutive clinical isolates of coagulase-negative staphylococci, including strains associated with disease, contaminants and skin colonizers, were speciated, tested for slime production and for their sensitivity to a range of antibiotics. Staphylococcus epidermidis was the most commonly identified species, comprising 63% of all isolates. Slime production was detected in half the strains of Staph. epidermidis, Staph. haemolyticus and Staph. saprophyticus but was rare in other species. Most Staph. haemolyticus strains and approximately half of the Staph. epidermidis strains were resistant to five or more antibiotics. A significant association was found between slime production and multiple antibiotic resistance. For catheter-associated strains, clinical relevance was predictable by species i.e. Staph. epidermidis. Multi-resistant slime-positive Staph. haemolyticus strains, although infrequently associated with disease, were common skin colonizers, presumably acquired from the hospital environment. We describe a practical and inexpensive scheme for the speciation of human coagulase-negative staphylococcal isolates.