Phenotypic and molecular assessment of antimicrobial resistance profile of airborne spp. isolated from flats in Kraków.

Bacteria of the genus were isolated from air sampled from living spaces in Kraków (Poland). In total, 55 strains belonging to the genus were isolated from 45 sites, and 13 species of coagulase-negative staphylococci were identified. The species composition of studied airborne microbiota contains species that are rarely infectious to humans. Most commonly isolated species comprised and . The disk-diffusion tests showed that the collected isolates were most frequently resistant to erythromycin. The PCR technique was employed to search for genes conferring the resistance in staphylococci to antibiotics from the group of macrolides, lincosamides and streptogramins. The analyzed isolates possessed simultaneously 4 different resistance genes. The molecular analysis with the use of specific primers allowed to determine the most prevalent gene which is responsible for the resistance to macrolides and for the enzymatic inactivation of the drug by phosphotransferase. The second most often detected gene was which confers the resistance of staphylococci to macrolides and is responsible for active pumping of antimicrobial particles out of bacterial cells.