New Protocol for the Enumeration of Salmonella and Shigella from Wastewater

Abstract

Development of stringent standards for the microbiological quality of the wastewater has necessitated a sensitive and efficient method for the enumeration of pathogens present in wastewaters. Standard methods are used all over the world for the identification of microbes by the public health engineers. However, this conventional method has serious problems, which are related to the long detection time required for turbid wastewaters and corresponding reduced isolation of the microbes. The Conventional method has been modified by omitting the concentration and blending steps, and named as the The Direct method should be able to provide maximum possible recovery specifically for the turbid wastewaters. An existing sewage treatment plant was selected to carry out the study over a period of six months. Samples were collected from the various stages of treatment and analyzed for the isolation of Salmonella and Shigella using the Conventional method and the proposed direct method. The direct method required less time compared to the Conven- tional method. More importantly, the recovery of Salmonella and Shigella has improved by 105% and 276%, respectively, over the Conventional method. The consistent improvement in the recovery of the pathogens has been seen at various stages of the sewage treatment.