TYPING OF STAPHYLOCOCCUS-AUREUS ISOLATED FROM NASAL CARRIERS

Eighteen Staphylococcus aureus strains (9 pairs) were isolated from 9 apparently healthy persons (including 5 persons from medical staff) re garded as persistent nasal carriers in a 5-7-day or 3-5-month period, respectively. The 18 S. aureus strains were characterized phenotypical ly and by genotypic methods. Biochemical properties determined with a commercial identification system, production of haemolysins as well as most of the antibiotic resistance date revealed an identity between b oth strains of each pair. This putative identity was confirmed for mos t of the paired strains by phage typing and plasmid profiling for all 9 pairs by determination of the number of repeats in the X region of t he sed gene and by macrorestriction analysis of the chromosomal DNA of the isolates. The present results indicate that a single clone of S. aureus might colonize continuously persistent nasal carriers over a 5- 7 day period, even for a period of 3-5 months.