Detection and hazard assessment of pathogenic microorganisms in medical wastes

This study was undertaken to investigate the types and concentrations of microbial agents in various medical wastes as well as to characterize their survivals in these wastes at different temperatures for microbial risk assessment. Medical wastes collected from 5 major hospitals in South Korea were classified and stored at three different temperatures (-20, 6, and 30 degrees C). Presence of various microorganisms such as pathogenic viruses and bacteria were investigated by both cultivation and by (RT)-PCR assays. A number of (opportunistic) pathogenic bacteria, including Pseudomonas spp., Lactobacillus spp., Staphylococcus spp., Micrococcus spp., Kocuria spp., Brevibacillus spp., Microbacterium oxydans, and Propionibacterium acnes, were identified from the various medical wastes. In addition, pathogenic viruses such as noroviruses and hepatitis B virus were also detected in one of the human tissue wastes. Commonly identified bacterial and viral pathogens such as Pseudomonas spp., Corynebacterium diphtheriae, Escherichia coli, Staphylococcus spp., and respiratory synctial virus (RSV) were inoculated into either gauzes or diapers, and their survivals were characterized. Viral agents such as RSV showed poor survival in most environmental conditions, and demonstrated that various pathogens could be present in medical wastes but that the associated health risk appeared to be low. However, medical waste should be carefully controlled and monitored to prevent nosocomial infection associated with the exposure to these wastes.