Lectin typing of methicillin-resistant Staphylococcus aureus from Singapore, England and Wales, and Denmark.

Methicillin-resistant Staphylococcus aureus (MRSA) isolates from a possible outbreak in Singapore (84) were examined together with all MRSA isolated in Denmark in 1986-1990 (58) and 14 distinct epidemic and 10 distinct single hospital strains from England and Wales. All 84 Singapore isolates were phage typed routinely and 52 isolates were further analysed together with the Danish isolates with an additional set of experimental phages and by lectin typing. The British strains, previously phage typed in the same way, were lectin typed. The following lectins were used: wheat-term agglutinin, soy-bean agglutinin, tomato lectin and Concanavalin-A. Routine phage typing of the Danish isolates showed that 41 isolates belonged to 19 different types; 17 isolates were non-typable (NT). Addition of experimental phage typing and lectin typing enhanced discrimination to 47 types. The 24 British strains could be divided into eight [corrected] "lectin types". Sixty-one of the isolates from Singapore were non-typable by phage typing; the remaining 23 strains belonged to five types. Further examination of 52 isolates with the experimental set of phages and by lectin typing gave 14 closely related types; 48% of these isolates belonged to only two types.