The fecal presence of enterotoxin and F4 genes as an indicator of efficacy of treatment with colistin sulfate in pigs

Abstract

BackgroundEnterotoxigenic Escherichia coli (ETEC) strains producing multiple enterotoxins are important causes of post-weaning diarrhea (PWD) in pigs. The aim of the present study was to investigate the fecal presence of ETEC enterotoxin as well as F4 and F18 genes as an indicator of colistin sulfate (CS) efficacy for treatment of PWD in pigs. Forty-eight piglets were weaned at the age of 21 days, and were divided into four groups: challenged treated, challenged untreated, unchallenged treated, and unchallenged untreated. Challenge was performed using 109 CFU of an ETEC: F4 strain, and treatment was conducted using oral CS at the dose of 50,000 IU/kg. The fecal presence of genes encoding for STa, STb, LT, F4 and F18 was detected using PCR.ResultsThe PCR amplification of ETEC virulence genes showed that nearly 100% of pigs excreted genes encoding for STa and STb toxins in the feces before the challenge. These genes, in the absence of the gene encoding F4, were considered as a marker for F4-negative ETEC. One day after ETEC: F4 oral challenge pigs in the two challenged groups excreted the genes encoding LT and F4 in the feces. These genes were considered as a marker for F4-positive ETEC. However, the gene encoding F18 was not detected in any fecal samples of the 4 groups throughout the experiment. After only 3 days of successive oral treatment with CS, a significant reduction in both the F4-positive and negative ETEC populations was observed in the challenged treated group compared to the challenged untreated group (p < 0.0001).ConclusionsOur study is among the first to report that under controlled farming conditions, oral CS treatment had a significant effect on both fecal F4-positive and F4-negative ETEC in pigs. However, CS clinical efficiency was correlated with non-detection of F4-positive ETEC in the feces. Furthermore the fecal presence of F4-negative ETEC was not associated with clinical symptoms of post-weaning diarrhea in pigs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0915-0) contains supplementary material, which is available to authorized users.

Evolution of Pig Fecal Microbiota Composition and Diversity in Response to Enterotoxigenic Escherichia coli Infection and Colistin Treatment in Weaned Piglets

“…Challenged piglets were housed in the same room (in two different pens), while unchallenged piglets were housed in two separate rooms. After the one week period of acclimatization (at 28 days old), pigs in the challenged groups were orally gavaged with a single dose of 10 9 CFU of ETEC: F4 strain ECL8559A (O149: LT: STa: STb: F4: Nal R ) kindly provided by the OIE Reference Laboratory for Escherichia coli (EcL, FVM from the Université de Montréal) as previously described [ 17 , 30 ]. Colistin sulfate (Bond & Beaulac Inc., Acton Vale, QC, Canada) was administered orally in 5 mL of water using a polyethylene tube attached to a syringe, at a dose of 50,000 IU/kg twice a day for 5 successive days as previously described [ 17 ].…”

Post weaning diarrhea in pigs: risk factors and non-colistin-based control strategies

“…ETEC bacteria adhere to pig's small intestinal epithelium, causes an increase of water and electrolytes secretion into the intestinal lumen generated by the release of enterotoxins, and alter the functions of enterocytes by increasing secretion and reducing absorption [7]. Excessive secretion of electrolytes and water leads to dehydration, metabolic acidosis, osmotic diarrhea and possible death [28,[58][59][60] (Fig. 2).…”

“…The laboratory diagnosis is particularly important in PWD to avoid the inappropriate use of antimicrobials. DNA-based molecular detection methods such multiplex PCR based on the detection of ETEC virulence genes are rapidly becoming part of the routine laboratory diagnosis of PWD, and these genes are used as a biomarkers of ETEC strain [ 7 , 58 ].…”

Effects of a Four-Week High-Dosage Zinc Oxide Supplemented Diet on Commensal Escherichia coli of Weaned Pigs

“…Enterotoxigenic Escherichia coli (ETEC) are commonly associated with post-weaning diarrhea (PWD) in piglets, a disease causing serious losses in the pig industry worldwide (Fairbrother et al, 2005; Rhouma et al, 2017a). Currently, different strategies are utilized to reduce ETEC-associated economic costs in pig farming, including oral colistin sulfate treatment in some regions of the world (Rhouma et al, 2017b), vaccination (Moon and Bunn, 1993; Blázquez et al, 2018) and probiotics (Li et al, 2018; Yan et al, 2018). In addition, high-level dietary zinc oxide supplementation is used against PWD in the pig production sector (Fairbrother et al, 2005; Vahjen et al, 2011; Bednorz et al, 2013; Starke et al, 2014; Pieper et al, 2015; Kloubert et al, 2018).…”