[Epidemiology of S. aureus cross-infections in dermatological wards]

Over a three-year period, 196 of 3115 patients admitted in a dermatological department became infected with S. aureus (6,2 %). 205 strains of S. aureus were isolated. Serologic typing, phage-typing and antibiotic sensitivity tests revealed 3 epidemic and 2 endemic strains. The 3 epidemic strains infected 24 patients: 12 from july to november 1972 were infected with a serotype 66438 S. aureus resistant to fusidic acid. 6 patients (male) were infected with a serotype III in february and march 1972; 8 patients were contaminated with a serotype 18 S. aureus from december 1973 to february 1974, after staying in a surgical department. Of the 2 endemic strains 1, phage-pattern 53/79, is non-typable by serologic-typing; this strain has been observed only in the dermatological department and 20 patients were infected with, from january to october 1974. The second endemic strain, phage-pattern 81/+ serotype I, cross-infected 16 patients during this three-year survey; 12 of them were admitted repeatedly. During this three-year survey, it could be proved that, at least, 1 out of 3 patients is infected with an epidemic or an endemic strain. We can suggest that the factors enhancing cross-infection in dermatological department are: the sex of patients (80 % were male); presence of a tween splitting enzyme by S. aureus promotes growth of Staphylococci on the skin; patients transfered from a department to another or repeatedly admitted are more often infected. But, as they are source of some outbreaks, they need special measures (asepsis and hygiene); corticoïds or immunodepressors enhance cross-infection; antibiotics must not be only limited but varied too.