Antimicrobial susceptibility and body site distribution of community isolates of coagulase-negative staphylococci.

The primary aim of this study was to determine antimicrobial resistance in coagulase-negative staphylococci (CoNS) from healthy adults in the community. Healthy adults (n = 114) were swabbed on six body sites; both armpits, both knee pits and both sides of the groin. Species determination was performed using Matrix Assisted Laser Desorption Ionization - Time of Flight (MALDI-TOF) and susceptibility testing for 11 relevant antimicrobials was performed by the disc diffusion method and minimal inhibitory concentration gradient test. In total, 693 CoNS isolates were identified. Susceptibility testing was done on 386 isolates; one CoNS from each species found on each participant from the different body sites. The prevalence of antimicrobial resistance in the CoNS isolates were; erythromycin (24.6%), fusidic acid (19.9%), tetracycline (11.4%), clindamycin (7.8%), gentamicin (6.2%) and cefoxitin (4.1%). Multidrug resistance was observed in 5.2% of the isolates. Staphylococcus epidermidis and S. hominis were the first and second most prevalent species on all three body sites. We conclude that CoNS isolates from healthy adults in the community have a much lower prevalence of antimicrobial resistance than reported in nosocomial CoNS isolates. Still, we believe that levels of resistance in community CoNS should be monitored as the consumption of antimicrobials in primary care in Norway is increasing.