Abstract

Five hundred and fifty-two strains of Staphylococcus aureus of hospital origin were resistant to penicillin, streptomycin, and tetracycline. Of these, 298 were also resistant to neomycin and kanamycin, and this resistance was related to pigment production on glycerol monoacetate agar, the production of β-lysin, the absence of fibrinolytic and proteolytic activity, and to phage susceptibility. The use of physiological markers, the inadequacy of phage typing, and the possible reasons for the emergence of neomycin-resistant staphylococci are discussed.