72 Characteristic and antibiotic resistance of bioaerosols between ambient atmosphere and outdoor night market

The bacterial size, biodiversity, human-associated bacteria (HAB) and antibiotic-resistance of bioaerosols were evaluated and compare at ambient atmosphere and outdoor night market in summer in Taiwan. The air condition in night market is usually very hot and humid in summer night and the night markets are always very crowded. A six-stage viable Andersen cascade impactor was used to collect bioaerosols and to determine their size distributions in both ambient atmosphere and outdoor night market. The sampling time was 10 minutes and the bioaerosol sampling in night market was following the walking tourists. The results showed the average number concentration of bacteria and fungus in the night market was 198 and 267 CFU/m3, respectively. The geometric standard deviation (GSD)and geometric mean diameter (GMD) of bacteria was in the range of 1.86~2.19 and 3.18~5.7 µm, respectively. Moreover, the GSD and GMD of fungus was around 1.83~1.97 and 1.92~4.16 µm, correspondingly. The statistics results revealed that the number of tourists positively affected the concentration of bioaerosol; and the temperature and relative humidity at the time of sampling also associated to the increasing concentration of bioaerosol. The bacterial species identification revealed most of the sampled airborne bacteria were Gram-positive bacteria. Staphylococcus spp. was detected in all sampling size distributions in most of the sampling rounds and their sizes varied widely from 0.65 to >7.0 µm. In the study, the rate of bacteria antibiotic resistance and multidrug resistance in night markets with a larger number of tourists are higher than those in the ambient atmosphere.