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Shiga toxin (Stx2e)-producing Escherichia coli (STEC) is one of the most important E coli pathotypes in animals and is the etiologic agent of edema disease (ED) in pigs. ED has been reported to have a mortality rate from 50- 90% in herds and can often reoccur. A review of historical diagnostic data from a veterinary diagnostic laboratory, revealed that approximately 19% of E coli isolates originating from US swine herds genotyped from 2009 to 2019 were positive for the Stx2e gene. Isolates were further characterized by colony morphology on blood agar (BA) plates and antimicrobial susceptibility.

52nd Annual Meeting of the American Association of Swine Veterinarians (February 27 - March 2, 2021)

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Enterovirulent Escherichia coli infections cause significant losses in the pig industry. In a current study whole-genome sequencing was used to analyse the molecular features of a multidrug-resistant (MDR) ETEC strain and a multidrug-resistant hybrid Shiga toxin-producing/enterotoxigenic Escherichia coli (STEC/ETEC) strain isolated from diarrheic pigs in Switzerland.

The ETEC strain possessed three virulence plasmids, while the STEC/ETEC hybrid strain harboured a multivirulence plasmid that co-carried virulence genes of both ETEC and STEC pathotypes, confirming the key role of plasmids in the emergence of hybrid pathotypes. All resistance genes of the ETEC strain were identified on a single plasmid. The STEC/ETEC hybrid strain carried two antimicrobial resistance plasmids. It was shown that all plasmids were conjugative at room temperature and 37 °C.

The co-localization of multiple resistance genes on MDR conjugative plasmids poses the risk of simultaneous selection of several resistance traits during empirical treatment. Thus, preventive strategies and targeted therapy following antibiotic susceptibility testing should be encouraged to avoid further dissemination of such plasmids.

Read the full study on www.sciencedirect.com

Colistin is an antimicrobial polypeptide. It is often used to treat neonatal diarrhea and post-weaning diarrhea - caused by enterotoxigenic and Shiga toxin producing Escherichia coli (ETEC and STEC).

However, the spread of colistin-resistant E.coli is alarming. Resistance was first associated with mutations on chromosomes until Liu et al. 2015 identified the plasmid-mediated resistance gene mcr-1. Since then, five different mcr genes have been localised and a global spread of the resistance genes observed and documented by several studies.

The aim of the study "Co-occurrence of mcr-1, mcr-4 and mcr-5 genes in multidrug-resistant ST10 Enterotoxigenic and Shiga toxin-producing Escherichia coli in Spain" from 2006 to 2017 was the characterization of clonal groups of colistin-resistant E. coli in pigs affected by PWD in conventional husbandry.

76.9% of the 186 ETEC and STEC isolated in Spain showed resistance to colistin. Within the resistant groups 102 were identified as mcr-4 carriers, 37 as mcr-1 carriers and 5 as mcr-5 carriers, with mcr-1/mcr-4, mcr-1/mcr-5 and mcr-4/mcr-5 occurring simultaneously in five isolates. Three different mcr-4 variants were also discovered and the clonal group ST10-A (CH11-24) was described as mainly responsible for the spread of the mcr-4 gene.

The study shows the great importance of intensive pig farming as a reservoir for colistin-resistant ETEC and STEC. This can become a serious threat to human health.

Shiga toxin producing Escherichia (E.) coli (STEC) are important foodborne pathogens. They can cause severe diseases such as haemorrhagic Colitis or haemolytic uremic syndrome. A longitudinal cohort study in three finishing sites was conducted to study the epidemiology of STEC in final fattening pigs and examine the risks they may pose for human infections with STEC.

Consistent with our prior studies, Stx2e was the most frequently observed Stx variant in final fattening pigs (93,9%).

The results confirm that pigs raised for pork production are a reservoir for human STEC infections. Circulating serotypes within the cohorts as well as factors for site management have a significant influence on the prevalence of STEC.

Source: International Journal of Food Microbiology

Read the full study on www.sciencedirect.com

Last July, the European Commission adpoted an Implementing Decision regarding the authorisation of all the veterinary drugs containing 'colistin' in combination with other oral antimicrobial drugs.

Read the full article on pig333.com

The Committee therefore recommended the refusal of the granting of the marketing authorisations and the withdrawal of the existing marketing authorisations for veterinary medicinal products containing zinc oxide.

Read the full article on pig333.com

402 MCR-1 isolates identified

Thursday, 11. August 2016

German researchers found more than 400 Escherichia coli isolates, which tested positive for the MCR-1 gene. This gene can make bacteria resistant to colistin, a powerful antibiotic. MCR-1 was found in 79,8% of colistin-resistant E.coli isolates. The study screened over 10.000 E.coli isolates, which have been gathered from German food and livestock from 2010 to 2015. The gene was most prevalent in poultry production and food chains. Overall, the scientists claim, that the prevalence of the MCR-1 gene is twice as high in Germany as it is in France. The colistin resistance in Germany is also higher than the average among European countries, which may be caused by higher use of polymixin antibiotics. More studies need to be conducted to better assess the findings.

Read the full article on www.cidrap.umn.edu

First results from resistance monitoring conducted at the Federal Institute for Risk Assessment (BfR) show that colistin resistant bacteria are wide spread among farm animals in Germany. The resistances were most frequently found in Escherichia coli of broilers. “The current results underline that the strategy of a responsible use of antibiotics must be consistently pursued in future", says the President of the BfR, Professor Dr. Dr. Andreas Hensel. Further biomolecular studies will be conducted to assess potential risks to consumers. It is recommended to follow careful kitchen hygiene, so germs are not transferred from meat to other food. Also, meat should be heated thoroughly before eating, so that it reaches a temperature of 70°C for 2 minutes at its core.

Read the full article on www.bfr.bund.de

PVS moved Colistin to class 3 antimicrobials

Wednesday, 16. December 2015

To match the latest scientific literature regarding antimicrobial use in human and veterinary fields, the Pig Veterinary Society (PVS) has updated their prescribing principles for antimicrobials. These principles divide antimicrobials into 3 classes. Class 1 antimicrobials can be subscribed within responsible use guidelines, class 2 antimicrobials are not to be used unless sensitivity tests or clinical experience has proven that the first choice antimicrobials are not effective. Colistin has now been moved into Class 3, which are products of last resort. Those are only to be used when no other option is available and has to be supported by laboratory sensitivity tests. This step was necessary, because the importance of Colistin as a critically important antimicrobial in human medicine is increasingly evident. PVS advices their members to download the new version of the principles and follow the guidance within the document.

Read the full article on www.pigvetsoc.org.uk

Danish agricultural fields are increasingly contaminated with zinc. This is due to the high content of zinc in pig manure which is used as fertilizer on said fields.The Danish Ministry of Environment and Food called the presented data “worrying” and that alternatives have to be considered. In pigs zinc and copper are used after weaning, especially for the prophylaxis of diarrhea and edema disease. An alternative for the latter could be the one shot vaccination against Shiga toxin.

Read the full article on www.animal-health-online.de