Serotypes, virulence genes, and PFGE profiles of Escherichia coliisolated from pigs with postweaning diarrhoea in Slovakia

Hung Vu Khac,Miguel Blanco,Jorge Blanco,Cecilia López,Enrique A González,Emil Pilipcinec,Azucena Mora,Jesús E Blanco,Ghizlane Dahbi,Emil Holoda

doi:10.1186/1746-6148-2-10

Abstract

BackgroundPostweaning diarrhoea (PWD) in pigs is usually the main infectious problem of large-scale farms and is responsible for significant losses worldwide. The disease is caused mainly by enterotoxigenic E. coli (ETEC) and Shiga-toxin producing E. coli (STEC). In this study a total of 101 E. coli isolated from pigs with PWD in Slovakia were characterized using phenotypic and genotypic methods.ResultsThese 101 isolates belonged to 40 O:H serotypes. However, 57% of the isolates belonged to only six serotypes (O9:H51, O147:H-, O149:H10, O163:H-, ONT:H-, and ONT:H4), including two new serotypes (O163:H- and ONT:H4) not previously found among porcine ETEC and STEC isolated in other countries. Genes for EAST1, STb, STa, LT and Stx2e toxins were identified in 64%, 46%, 26%, 20%, and 5% of isolates, respectively. PCR showed that 35% of isolates carried genes for F18 colonization factor, and further analyzed by restriction endonuclease revealed that all of them were F18ac. Genes for F4 (K88), F6 (P987), F17, F5 (K99), F41, and intimin (eae gene) adhesins were detected in 19 %, 5%, 3%, 0.9%, 0.9%, and 0.9% of the isolates, respectively. The study of genetic diversity, carried out by PFGE of 46 representative ETEC and STEC isolates, revealed 36 distinct restriction profiles clustered in eight groups. Isolates of the same serotype were placed together in the dendrogram, but high degree of polymorphism among certain serotypes was detected.ConclusionSeropathotype O149:H10 LT/STb/EAST1/F4 (14 isolates) was the most commonly detected followed by O163:H- EAST1/F18 (six isolates), and ONT:H4 STa/STb/Stx2e/F18 (five isolates). Interestingly, this study shows that two new serotypes (O163:H- and ONT:H4) have emerged as pig pathogens in Slovakia. Furthermore, our results show that there is a high genetic variation mainly among ETEC of O149:H10 serotype.

Highlights

Postweaning diarrhoea (PWD) in pigs is usually the main infectious problem of large-scale farms and is responsible for significant losses worldwide
54% were of one of these eight serogroups (O8, O9, O45, O54, O141, O147, O149, and O163) and 57% of the isolates belonged to only six serotypes, including two new (O163:H- and ONT:H4) serotypes not previously found among porcine pathogenic E. coli
Toxin genes Amplification of the toxin genes by polymerase chain reaction (PCR) showed that 77% of isolates possessed genes for production of five types of toxins: labile enterotoxin (LT), STa, STb, Shiga toxin 2e (Stx2e), and EAST1

Summary

Introduction

Postweaning diarrhoea (PWD) in pigs is usually the main infectious problem of large-scale farms and is responsible for significant losses worldwide. The disease is caused mainly by enterotoxigenic E. coli (ETEC) and Shiga-toxin producing E. coli (STEC). Postweaning diarrhoea (PWD) is usually the main infectious problem of large-scale farms and is responsible for significant losses worldwide [1,2]. The disease is caused mainly by enterotoxigenic E. coli (ETEC), and Shiga-toxin producing E. coli (STEC), called verotoxin-producing E. coli (VTEC) [2,3,4,5,6,7]. ETEC can cause severe diarrhoea in newborn and weaned piglets by the production of heat-labile enterotoxin (LT) and/or heat-stable enterotoxins (STa or STb). In addition to F4 (K88) and F18, other fimbrial colonization antigens such as F5 (K99), F6 (P987), and F41 have been associated with postweaning diarrhoea, but less frequently [4,13,14,15]

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