Evaluation of the lysostaphin-susceptibility test for the classification of staphylococci.

A collection of 39 staphylococcal strains of known peptidoglycan structure was cultivated on media supplemented with different peptones or with glycine or inosine. The susceptibility to lysostaphin 50 mg/litre was then checked by a plate-dilution method. The results of the test were dependent on the conditions of growth. Another collection of 403 staphylococcal strains from international collections, clinical material and healthy human skin was also tested for susceptibility to lysostaphin. No uniform pattern of the lysostaphin sensitivity in individual staphylococcal species was found. The lysostaphin-susceptibility test thus seems to be of little value in the classification of staphylococci for the purposes of medical microbiology.