Colonização por Staphylococcus aureus resistentes à oxacilina e à vancomicina

Goud et al 1 , in their very interesting article regarding the prevalence of Staphylococcus aureus in their community, state that “the anterior nares are the most common site for colonization”. Recent data suggest that the oropharynx could be more frequently colonized by S. aureus than the anterior nares 2-4 . Furthermore, even in some populations where nasal colonization is more common than oropharyngeal colonization, the use of a throat swab would increase significantly the rate of detection of the carriers 5 . In addition, another matter of discussion would be the chosen screening method for vancomycin resistance. The authors used disk-diffusion, which is not considered accurate and reliable enough for the detection of decreased susceptibility of S. aureus to this antimicrobial agent. It is of paramount importance to remember that, according to the current guidelines issued by the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS), minimum inhibitory concentration (MIC) tests should be performed to determine the susceptibility of all isolates of staphylococci to vancomycin. The disk test, although detecting accurately S. aureus containing vanA (vancomycin resistant isolates), does not differentiate vancomycin-susceptible from vancomycin-intermediate isolates 6 .