Rapid and specific differentiation of enterotoxin-producing Escherichia coli strains from other Gram-negative enteric bacteria using multiplex PCR

Enterotoxigenic Eschcrichia coli (ETEC) may produce heat-labile (LT) and he at-stable (STI or STII) enterotoxins. Differentiation between ETEC and othe r pathogenic and non-pathogenic E. coli as well as other Gram-negative bact eria responsible for induction of diarrhoea, requires isolation, biochemica l identification and determination of toxins (or their genes - elt, estI, e stII). A multiplex polymerase chain reaction (PCR) system for the rapid and specific detection of enterotoxin-gene-positive E. coli was developed, The primers described by other authors, specific for the universal stress prot ein A (UspA) of E. coli and enterotoxin genes were used and allowed a simul taneous amplification of the E. coli-specific uspA and the respective toxin genes. The specificity of this multiplex PCR system was confirmed by testi ng ETEC, non-ETEC and other non-E. coil bacteria. The specific 884 bp uspA gene and 280 bp (eltI). 166 bp (estI) or 278 bp (estII) amplification produ cts were generated with the respective ETEC strains whereas no amplificatio n was detected with non-E. coil bacteria. The multiplex PCR developed allow ed the rapid and specific identification of enterotoxin-producing E. coil c olonies directly grown from faecal samples of pigs with diarrhoea. The test may be used as a method for the determination of ETEC among other pathogen ic groups of E. coil and other Gram-negative enteric isolates.