Indoor Air Quality and Potential Health Risk Impacts of Exposure to Antibiotic Resistant Bacteria in an Office Rooms in Southern Poland

Abstract

The aims of this article are to characterize: the quantity of culturable bacterial aerosol (QCBA) and the quality of culturable bacterial aerosol (QlCBA) in an office building in Southern Poland during the spring. The average concentration of culturable bacterial aerosol (CCBA) in this building ranged from 424 CFU m^-3 to 821 CFU m^-3, below Polish proposals for threshold limit values. Size distributions were unimodal, with a peak of particle bacterial aerodynamic diameters less than 3.3 μm, increasing potentially adverse health effects due to their inhalation. The spring office exposure dose (SPED) of bacterial aerosol was estimated. The highest value of SPED was in April (218 CFU kg^-1), whereas the lowest was in June (113 CFU kg^-1). Analysis was undertaken to determine the antibiotic resistance of isolated strains and their ability to form biofilms, which may facilitate the spread of antibiotic resistance genes. In the course of the study, it was found that Staphylococcus xylosus had the greatest ability to form biofilms, while the strains with the highest antibiotic resistance were Micrococcus luteus D and Macrococcus equipercicus. Given that mainly antibiotic-sensitive bacteria from bioaerosol were isolated, which transfers resistance genes to their plasmids, this shows the need for increased monitoring of indoor air quality in workplaces.

Keywords: antibiotic resistance; bioaerosol; health risk assessment; indoor air quality; size distribution.

Figure 1

Sampling site location (Map data: 2017© Google, ORION-ME; https://commons.wikimedia.org).

Figure 2

Size distribution of the bacterial aerosol in the offices indoor air. D_ae—aerodynamic diameter; ΔC—concentration of bacterial aerosol on particular stage of 6-stage Andersen impactor; C_total—total concentration of bacterial aerosol; Δ log D_ae—logarithm of differences of cut-off diameters for particular stage of 6-stage Andersen Impactor.

Figure 3

Biofilm formation by the isolated strains. Bars represent the standard deviation.

Figure 4

Multiplex PCR of plasmid DNA: Lane I–VII strains (I—Gemella haemolysans; II—Macrococcus equipercicus; III—Macrococcus brunensis; IV—Bacillus cereus; V—Micrococcus luteus D; VI—Staphylococcus xylosus; VII—Enterococcus faecium), lane C: negative control - without template DNA; lane M: 100bp DNA ladder. Line 1–5 indicate the size of the amplification products:1-vatB (136bp), 2-ermA (190bp), 3-aacA-aphD (227bp), 4-tekK (360bp), 5-mecA (532bp).