The egg yolk reaction ofStaphylococcus aureusisolated from burns

Abstract

Staph. aureus from burns of in-patients were tested for egg yolk reaction during three periods; in 1958 and in 1960 approximately 80 % of the strains gave a negative reaction (EY-), but in 1962 only 36 % of the strains were egg yolk negative.Staphylococci of phage group III were more commonly EY- than those of other groups isolated from burns. Within each of groups I and III, however, there were patterns predominantly EY- and others predominantly egg yolk positive (EY+); in group I the majority of strains isolated in 1960 were of phage type 52 and EY-, while those isolated in 1962 were predominantly of phage type 80 or related patterns which were always EY+.Most of the staphylococci in burns were resistant to penicillin, tetracycline and erythromycin; within groups I and III, the staphylococci which were EY- were also more commonly resistant than EY+ strains to these three antibiotics.Most of the staphylococci from burns were mercuric chloride resistant (presumptive epidemic strains); of the mercuric chloride sensitive staphylococci, the proportion of EY+ strains was greater than that of EY- strains.