143 Association of bioaerosol specie, concentration and size distribution during and after work shifting and after guest-visiting in intensive care units

The association of bacteria specie, concentration and size distribution during, after work shifting and after guest-visiting were evaluated in intensive care units (ICUs). Two six-stage viable Andersen cascade impactors were used to collect airborne bacteria and fungi separately in ICUs. Their concentrations and size distributions were determined after culturing. A BD Phoenix-100 automated interpretation system was used to identify the sampled bacteria species. The fungi species were identified by trained medical laboratory technologist. The results showed that during the work shifting, 33.33% of the sampled bacteria was Pantoea agglomerans. Tatumella ptyseos was about 25%, Rodentibacter pneumotropicus was 16.66%, and Pasteurella multocida was 4.166%. However, after work shifting, 28.57% of the sampled bacteria was Tatumella ptyseos. Yersinia pseudotuberculosis was 28.57%, and Actinobacillus lignieresii was 14.29%. After guest-visiting, 75% of the sampled bacteria was Bacillus licheniformis and Pseudomonas fluorescens was about 25%. The total airborne bacteria concentrations in the three periods were 56.77, 16.49, and 9.42 CFU/m3, respectively. The taxonomic results of the airborne fungi in the three periods were Penicillium oxalicum, Trichophuton spp., Aspergillus niger, and Microsporum (all accounting for 16.66%); Penicillium oxalicum (50%), and Scopulariovsis brevicaulis (50%); and Aspergillus niger (33.33%) and Penicillium oxalicum (33.33%), respectively. The total concentrations of airborne fungi in the three periods were 14.13, 4.71, and 7.07 CFU/m3, correspondingly. The population of medical workers during the work shifting was much higher than those at other periods. Increasing the air change rate per hour during work shifting is recommended to decrease the risk of patient infection.