Abstract
The present study is aimed at evaluating microbiological air pollution in libraries, cafeterias and selected classrooms of two schools in Bydgoszcz city, northern Poland and determining the antibiotic resistance of Staphylococcal strains isolated from the indoor air. One of the investigated schools (School A) is located in the very center of the city, in the vicinity of a park, among old houses and stone-lined streets, while the other (School B), among modern residential buildings, close to a street with heavy traffic. In each school, air samples were collected in the morning, always from all three sampling sites, using the MAS-100 sampler. Selective growth media were used for bacteria and mold isolation and quantifying analysis. The antibiotic resistance of the isolated mannitol-positive staphylococci was assessed using the disc diffusion method in accordance with EUCAST recommendations. The highest mean concentration of heterotrophic bacteria was recorded in the cafeterias: 884 CFU m−3 in School A and 1906 CFU m−3 in School B. Molds were the most abundant in the library and cafeteria in School B, where their average concentration exceeded 300 CFU m−3. Cladosporium and Penicillium species prevailed, while Fusarium, Acremonium and Aspergillus were less abundant. Airborne mannitol-positive staphylococci were recorded at low concentrations, ranging from 6 to 11 CFU m−3 on average. According to the taxonomic analysis, Staphylococcus aureus isolates were the most abundant in both schools, followed by S. xylosus, S. haemolyticus and S. saprophyticus. The antibiograms indicated that resistance to erythromycin was common in 62.5% of the isolated staphylococcal strains. Levofloxacin and gentamicin were the most effective antibiotics. No multidrug-resistant strains were identified.
Highlights
Air quality in public facilities, including schools, is of growing concern
The concentration of heterotrophic bacteria was correlated with the size of the studied rooms (Figure 1a,b)
The results presented in the previous section (Section 3.1) indicated that heterotrophic bacteria were the most numerous microorganisms and that their concentrations were similar to those reported by other authors
Summary
Air quality in public facilities, including schools, is of growing concern. Numerous reports indicate that indoor air pollution is worse than outdoor air pollution and that the composition of indoor air microflora is more stable [1,2]. The concentrations of the majority of indoor air pollutants are so low that they cannot be considered harmful, long-term exposure may have negative effects on human health [3]. Indoor air contaminants come from different sources. Some of them, such as building materials, furnishings, ventilation systems and household products (e.g., air fresheners) can release pollutants. According to Andualem et al [5] overcrowded classrooms, inadequate fresh air supply, poor construction and maintenance of school buildings negatively affect air quality in schools. Since students and teachers spend most of their day inside school buildings, the concentration of airborne microorganisms is an important parameter with a large impact on their performance, mental health and even physical condition [6]. The absence of a student due to health issues may affect their academic achievements [7,8]
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