An evaluation of the pooling method for detecting enterotoxigenic escherichia coli

Abstract

The effectiveness of the common practice of using a mixture (pool) of bacterial colonies for detecting enterotoxigenic Escherichia coli (ETEC) was evaluated. Pools were constructed with E. coli whose phage lysotypes were known. After pooling and storage of isolates in the normal manner, attempts were made to recover and' identify the original lysotypes in the pool. It was observed that bacteria from one or two colonies {lysotypes) almost always overgrew in the pool, thus reducing the number of recoverable individual strains. In general, enterotoxigenic E. coS (ETEC) did not show a survival advantage in the pools over non-ETEC strains. Therefore, the use of the pooling technique to enhance the likelihood of recovery of ETEC from faecal specimens is of doubtful value.