Pathotypes and serogroups of enterotoxigenic Escherichia coli isolated from pre-weaning pigs in north Vietnam

Abstract

The contribution of enterotoxigenic Escherichia coli (ETEC) to pre-weaning diarrhoea was investigated over a 6 month period at five selected commercial piggeries (CPs) in north Vietnam with at least 100 sows each. Diarrhoea was found to affect 71?5 % of the litters born during the period of study. Of 406 faecal specimens submitted for bacteriological culture, 200 (49?3 %) yielded a heavy pure culture of E. coli and 126 (31 %) were confirmed by PCR to carry at least one of eight porcine ETEC virulence genes. ETEC was responsible for 43 % of cases of diarrhoea in neonatal pigs during the first 4 days of life and 23?9 % of the remaining cases up until the age of weaning. Pathotypes were determined by PCR for the 126 ETEC isolates together with 44 ETEC isolates obtained from village pigs (VPs) raised by smallholder farmers. The CP isolates belonged to five pathotypes, four of which were also identified in VP isolates. Haemolytic serogroup O149 : K91 isolates that belonged to F4/STa/STb/LT were most commonly identified in both CPs (33 % of isolates) and VPs (45?5 %). Other combinations identified in both production systems included O64 (F5/STa), O101 (F4/STa/STb) and O-nontypable (F"/STb). A high proportion of CP isolates (22?3 %) possessed all three enterotoxins (STa/STb/LT), lacked the genes for all five tested fimbriae (F4, F5, F6, F41 and F18) and belonged to serogroup O8. These unusual O8 F" isolates were haemolytic and were isolated from all ages of diarrhoeic piglets at each CP, suggesting that they have pathogenic potential.

Prevalence of virulence genes in Escherichia coli strains isolated from piglets in the suckling and weaning period in Mexico

“…Our observation agreed with other studies in which 9 and 11 % of isolates were positive for STa toxin in suckling and weaned piglets, respectively (Lee et al, 2008). Do et al (2006) reported the presence of STa in 92.1 % of isolates from weaning piglets with diarrhoea; Parma et al (2000) reported the presence of this gene in 24.5 % of isolates, it being the predominant gene in isolates from piglets from 1 week to 3 months of age.…”

“…These fimbriae are highly associated with ETEC diarrhoea in piglets in experimental animals and in the field (Vu-Khac et al, 2006). The F41 adhesin gene is not as prevalent in countries such as Slovakia, Korea, USA and Vietnam (VuKhac et al, 2006;Do et al, 2006;Zhang et al, 2007;Lee et al, 2008). In our study, the F41 adhesin gene was strongly associated with the population of piglets, since on average 36 % of the isolates from piglets with diarrhoea were positive, regardless of the suckling or weaning stage.…”

Prevalence of Escherichia Coli from Pigs and Cattle

“…Martins et al, (2000) reported prevalence of E.coli from three states of Brazil which was found to be 65.7% in diarrhoeic and 42.8% in non-diarrhoeic piglets. Do et al, (2006) from North Vietnam reported that diarrhoea was found to affect 71.5% of the litter born during that period. Ngeleka et al, (2003) reported the prevalence of E.coli pathotypes from diarrhoeic (40%) and non-diarrhoeic piglets (22.9%).…”

Pathogenicity of Vietnamese Enterotoxigenic Escherichia coli Strains in Colostrum-deprived One-day-old Piglets

“…The pathotypes of the F-strains (NVP608, NVP613, NVP1268, NVP1390, NVP1452) together with fimbriated strains (NVP1402, NVP1271, NVP2081, NVP1372) were confirmed by agglutination with F4, F5, F6, and F41 antisera and by polymerase chain reaction (PCR; with primers specific for F4, F5, F6, F41, F18, STa, STb, and LT). 11,12 The reference E. coli strains FV847a (F4-positive), 1547 (F5-positive), 1500 (F6-positive), and 1520 (F41-positive) were used as positive controls, and strain C600 (E. coli K12) was used as a fimbria-negative control in the in vitro assays.…”

“…A relatively high frequency of ETEC isolates (22.2%) belonged to serogroup O8, produced enterotoxins (STa/STb/ LT), but did not possess any of the recognized fimbriae (designated F-ETEC). 11 The objectives of this study were to examine the adherence capability and pathogenicity of the most common ETEC serotypes and pathotypes in Vietnam, including the F-strains. The F-strains were compared with representative conventional ETEC pathotypes in assays to measure in vitro attachment.…”