Prevalence of multi-drug-resistant (MDR) bacteria in air samples from indoor and outdoor environments

The prevalence of multi-drug-resistant (MDR) bacteria in 48 air samples from indoor environments, surgical rooms, dental surgery and waste management plants has been investigated. A total of 280 bacterial strains belonging to different genera were isolated, and the operating rooms were the most contaminated ones (107 isolates), with all the isolates belonging to Gram-positive cocci (51.5 % Micrococcus spp., 48.5 % Staphylococcus spp.). Only 5 % of the isolates was sensitive to all the antibiotics tested, while the remaining strains resulted resistant to three (13 %), four (14 %), five (9 %) and six (10 %) antibiotics. Correlation between the resistance patterns and the environmental source of MDR bacteria isolates also emerged from the present investigation. This study confirms the high presence of antibiotic-resistant bacteria in air samples, finding that represents a threat for the possible transfer of resistance genes to pathogenic bacteria.