The incidence of methicillin-resistant Strains is increasing in these last years. This increase is particularly evident in Strains isolated from hospital environments. In this work we evaluated the methicillin-resistance of 58 Staphylococcus Strains, isolated from a surgical intensive care ward, in various experimental conditions, which changing in: culture medium, inoculum, incubation period and antibiotic concentration. Besides this we took in consideration various factors which can influence the frequency of methicillin-resistance and can also lead to errors in the evaluation itself. From our study we can conclude that the factors are: survey "in vitro" of the resistance or of the sensitivity, exclusion or inclusion of staphylococci different from Staphylococcus aureus, double count of the same Strains isolated in different times.
Bacteriological Techniques Culture Media