Simplified lyogroup system, a new method for routine identification of staphylococci: description and comparison with three other methods.

A simplified system for routine identification of the six lyogroups of human staphylococci is described. The method is based on the determination of the lytic activity on five different test media and of the phosphatase activity of each isolate. A total of 689 staphylococci isolated from clinical material over a 6-month period were identified according to this simplified system. The same strains were identified in parallel using three other methods designed for routine identification of staphylococci: the Kloos and Schleifer abbreviated scheme (J Clin. Microbiol. 1:82-88, 1975) the scheme proposed by the Subcommittee on the Taxonomy of Staphylococci and Micrococci (Int. J. Syst. Bacteriol. 26:332-334, 1976), and the API STAPH micromethod. Isolated whose identification was in disagreement were identified on a taxonomic level according to the extensive classification scheme of Schleifer and Kloos. In addition, 42 reference staphylococci of known identity were reidentified using the simplified lyogroup system as well as the three other routine methods. The results of this comparative study was detailed and discussed. A primary advantage of the simplified lyogroup system is that it also provides separation of staphylococci from micrococci, which must be performed separately when the other methods are used. Other significant advantages concerned with reliability, speed, and practicality are shown.