Prevalence of adhesin and toxin genes in E. coli strains isolated from diarrheic and non-diarrheic pigs from smallholder herds in northern and eastern Uganda

Abstract

BackgroundEnterotoxigenic E. coli (ETEC) significantly contribute to diarrhea in piglets and weaners. The smallholder pig producers in Uganda identified diarrhea as one of the major problems especially in piglets. The aim of this study was to; i) characterize the virulence factors of E. coli strains isolated from diarrheic and non-diarrheic suckling piglets and weaners from smallholder herds in northern and eastern Uganda and ii) identify and describe the post-mortem picture of ETEC infection in severely diarrheic piglets. Rectal swab samples were collected from 83 piglets and weaners in 20 herds and isolated E. coli were characterized by PCR, serotyping and hemolysis.ResultsThe E. coli strains carried genes for the heat stable toxins STa, STb and EAST1 and adhesins F4 and AIDA-I. The genes for the heat labile toxin LT and adhesins F5, F6, F18 and F41 were not detected in any of the E. coli isolates. Where the serogroup could be identified, E. coli isolates from the same diarrheic pig belonged to the same serogroup. The prevalence of EAST1, STb, Stx2e, STa, AIDA-I, and F4 in the E. coli isolates from suckling piglets and weaners (diarrheic and non-diarrheic combined) was 29, 26.5, 2.4, 1.2, 16, and 8.4 %, respectively. However the prevalence of F4 and AIDA-I in E. coli from diarrheic suckling piglets alone was 22.2 and 20 %, respectively. There was no significant difference in the prevalence of the individual virulence factors in E. coli from the diarrheic and non-diarrheic pigs (p > 0.05). The main ETEC strains isolated from diarrheic and non-diarrheic pigs included F4/STb/EAST1 (7.2 %), F4/STb (1.2 %), AIDA/STb/EAST1 (8 %) and AIDA/STb (8 %). At post-mortem, two diarrheic suckling piglets carrying ETEC showed intact intestinal villi, enterocytes and brush border but with a layer of cells attached to the brush border, suggestive of ETEC infections.ConclusionThis study has shown that the F4 fimbriae is the most predominant in E. coli from diarrheic piglets in the study area and therefore an F4-based vaccine should be considered one of the preventive measures for controlling ETEC infections in the piglets in northern and eastern Uganda.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0796-2) contains supplementary material, which is available to authorized users.

Prevalence and characterization of virulence genes in Escherichia coli isolated from piglets suffering post‐weaning diarrhoea in Shandong Province, China

“…Bacterial cultivation for E. coli was conducted based on previously published procedures (Ikwap et al, ). Briefly, each sample was directly cultured onto sterile MacConkey agar (Hopebiol, Qingdao, China) and incubated at 37°C overnight under aerobic condition.…”

Profiles of virulence genes in enterotoxigenic Escherichia coli isolates from suckling piglets in Serbia

“…Studies on the incidence of STb and LT enterotoxins reveal significant differences between countries. In Switzerland, the prevalence of STb toxin was 90% (23), in Vietnam 83% (5), in Slovakia 50% (25), in Uganda 39% (9) and in China 20% (13). Our results show a prevalence of 35% and 30% for LT and STb toxins, respectively.…”

“…Contrary to the above findings, a number of studies report low incidence (4.3%, 4.7%, and 5.6%) for LT toxin (5,12,24). The results of Ikwap et al (9) are interesting, as they show absence of both LT and STa toxins in 18 isolates from suckling piglets with diarrhoea. Among enterotoxins, the least common in the present study was STa toxin, whose genes were determined in 10 isolates, that is 8.3%, which was somewhat more than 3.4% reported from China (13) for E. coli isolates from suckling piglets with diarrhoea.…”

“…Original paper DOI: dx.doi.org /10.21521/mw.6326 Diarrhoea in the neonatal period is a major health issue and a permanent challenge to the veterinary profession. At the same time, diarrhoea causes serious economic losses in pig production due to increased morbidity, mortality, treatment costs and poor growth (9,12,18). Escherichia coli (E. coli) live in the intestines and are part of the commensal microbiota that plays an important role in the protection of the intestinal tract of animals (21,26).…”

“…Some authors note a varying connection between the astA gene and F4 adhesin. For example, in Slovakia 100% of astA gene-positive strains were also positive for F4 adhesin (25), in Japan 88.2% (26), in the Czech Republic 64.6% (27), and in Uganda 3 out of 4 F4-positive strains carried the EAST1 gene (9). Our results are in agreement with the above, as 38 out of 43 EAST1-positive strains (88.4%) carried genes for F4, which indicates a close relationship between EAST1 and F4 genes in isolates from suckling piglets with diarrhoea in Serbia.…”