The incidence of penicillin-resistant staphylococci in a semi-closed community.

Barber and Rozwadowska-Dowzenko (1948) recorded that naturally resistant penicillinase-producing staphylococci found within hospital communities had increased in the previous successive three years from 14% to 38% and then to 59%. Forbes (1949) isolated resistant staphylococci from 23 out of 50 nurses. Martin and Whitehead (1949) examined the nose, throat, saliva, and skin of 50 medical students and laboratory workers and found the carrier rate of resistant staphylococci to be 19.4% in this semi-closed community. In view of the increasing incidence of resistant staphylococci in closed communities, it was decided to investigate the carrier state in another type of semiclosed community. The community chosen was a boys' grammar school. A constant set of 30 16-year-old boys occupying the same classroom had both anterior nares swabbed for the isolation of staphylococci. They were swabbed monthly over a period of 12 months. The tube coagulase test was used to recognize Staph. pyogenes; strains were regarded as penicillin-resistant if their growth was inhibited by 0.25 to 0.5 units penicillin per ml. All resistant strains produced sufficient penicillinase after 18 hours' incubation to neutralize 30 units penicillin per ml.