Risk assessment of bacterial infection from underground pit sludge of UOEH hospital

In order to evaluate the risk of bacterial infection to workers from the sludge in a sewage pit of UOEH Hospital, a bacterial flora analysis based on the molecular-technique using the 16S rRNA gene was performed. Sludge samples taken from five different points in the pit were used. Bacterial numbers of each sludge sample were detected in the range of 1.9 × 10⁷ cells/g to 4.4 × 10⁸ cells/g. The results of bacterial flora analysis showed that the proportion of known bacteria (similarities of 16S rDNA sequences to that of type strain being 97% or more) and that of unclassified bacteria in the sludge samples were about 20 and 80%, respectively. Regarding the pathogenic bacteria, two Legionella species were detected in two samples, and one Mycobacterium species was detected in one sample. Since the frequency of pathogenic bacteria was equivalent to normal soil, it was concluded that the risk of bacterial infection from the sludge was low.