69 Association of aerodynamic size of bioaerosols with biodiversity and antibiotic-resistance in kindergartens

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Abstract The bacterial size, biodiversity, human-associated bacteria (HAB) and antibiotic-resistance of bioaerosols were evaluated at three kindergartens in Taiwan in winter and spring. Kindergartens A, B, and C were in urban, semi-urban, and rural areas, respectively. A six-stage viable Andersen cascade impactor was used to collect bioaerosols and to determine their size distributions. A BD Phoenix-100 automated interpretation system was used to identify the airborne bacteria species and their antibiotic resistance. The results revealed that 1,425 colonies (97.6%) of the sampled airborne bacteria contained 63 species in 29 genera, and 56.6-86.4 % were HABs. About 84.8 % of selected airborne bacteria revealed antibiotic-resistance to at least one antibiotic agent. Staphylococcus spp. was detected in all sampling rounds in the three kindergartens, with a range of abundance between 2.0 and 70.0%. They resisted to 16.9-25.0% of tested antibiotic agents and their sizes varied widely from 1.1 to >7.0 µm. The urban-area kindergarten yielded higher bacteria antibiotic-resistant rate and multidrug resistance than did the lower urbanization level kindergartens. The statistical results revealed that the kindergarten in the rural area, with a higher temperature, a lower relative humidity, and a lower CO2 concentration than the others, tended to have the largest biodiversities (P < 0.05). Moreover, bioaerosol aerodynamic size was statistically correlated with Shannon (P = 0.001) and inverse Simpson (P = 0.002) diversities. Airborne HAB, especially belonged to Firmicute, that coagulated with human flakes and had high multidrug resistance rate might increase indoor transmission under poor ventilation in kindergarten.

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