Species distribution of coagulase-negative staphylococci isolated from clinical sources

Abstract

The distribution of coagulase-negative staphylococcal species from clinical material was investigated in order to detect possible tropisms. 398 strains of staphylococci (336 coagulase-negative and 62 coagulase-positive strains) and 3 micrococcus strains were isolated. Differentiation between the two genera was achieved by testing sensitivity to lysostaphin and anaerobic growth in thioglycolate. Four S. hominis strains reacted like micrococci in these tests. Staphylococci were classified according to the Kloos and Schleifer biotyping scheme in a modified way on microtitre plates. Additionally coagulation and reduction of methylene blue milk were determined and the test proved to be useful. Identified coagulase-negative species included S. epidermidis (205 strains), S. hominis (64), S. haemolyticus (35), S. warneri (15), S. capitis (5), S. simulans (6), S. saprophyticus (5), and S. species (1). A high predominance of S. epidermidis was found among isolates from nasopharyngeal (91%) and tracheobronchial (80%) tracts and most other localizations. A different distribution of species was observed in urine and vaginal swabs where non-S. epidermidis species accounted for over 50% of identified strains. The majority of S. hominis and S. haemolyticus strains was isolated from these sources. S. simulans, like S. saprophyticus was found in urine specimens only and occurred predominantly in women of the sexually active age.