Detection of Escherichia coli O157:H7 in soil and water using multiplex PCR

Abstract

Aims: To evaluate the suitability of a multiplex PCR‐based assay for sensitive and rapid detection of Escherichia coli O157:H7 in soil and water. Methods and Results: Soil and water samples were spiked with E. coli O157:H7 and subjected to two stages of enrichment prior to multiplex PCR. Detection sensitivities were as high as 1 cfu ml^–1 drinking water and 2 cfu g^–1 soil. Starvation of E. coli O157:H7 for 35 d prior to addition to soil did not affect the ability of the assay to detect initial cell numbers as low as 10 cfu g^–1 soil. Use of an 8‐h primary enrichment enabled detection of as few as 6 cfu g^–1 soil, and 10⁴ cfu g^–1 soil with a 6‐h primary enrichment. When soil was inoculated with 10⁵ cfu g^–1, the PCR assay indicated persistence of E. coli O157:H7 during a 35 d incubation. However, when soil was inoculated with lower numbers of pathogen, PCR amplification signals indicated survival to be dependent on cell concentration. Conclusions: A multiplex PCR‐based assay, in combination with an enrichment strategy enabled sensitive and rapid detection of E. coli O157:H7 in soil and water. Significance and Impact of the Study: The ability to sensitively detect E.coli O157:H7 in environmental material within one working day represents a considerable advancement over alternative more time‐consuming methods for detection of this pathogen.