Reduction in antimicrobial resistance prevalence in Escherichia coli from a pig farm following withdrawal of group antimicrobial treatment.

An important element in the control of antimicrobial resistance (AMR) is reduction in antimicrobial usage. In the veterinary sector individual antimicrobial treatment of livestock, rather than the use of group treatment, can help achieve this goal. The aim of this study was to investigate how cessation of group antimicrobial treatment impacted the prevalence of AMR in commensal Escherichia coli in pigs at one farm over an 11-month period. Minimum inhibitory concentrations of eight antimicrobials were determined for 259 E. coli isolates collected during the study. A significant reduction in the prevalence of multidrug resistance and a significant increase in the proportion of full susceptibility to the panel of nine antimicrobials tested was seen after 11 months. Whole genome sequencing of 48 multidrug resistant isolates revealed E. coli clones that persisted across multiple visits and provided evidence for the presence of plasmids harbouring AMR genes shared across multiple E. coli lineages. E. coli were also isolated from on-farm environmental samples. Whole genome sequencing of one multidrug resistant isolate obtained from cleaning tools showed it was clonal to pig-derived E. coli that persisted on the farm for 11 months. In this study we provide evidence that withdrawal of group antimicrobial use leads to significant reductions in key indicators for AMR prevalence and the importance of the farm environment as a reservoir of resistant bacteria. These findings support policy makers and producers in the implementation of measures to control AMR and reduce antimicrobial use.

A sensitive method for the recovery of Escherichia coli serogroup O55 including Shiga toxin-producing variants for potential use in outbreaks.

AIM: Shiga toxin-producing Escherichia coli (STEC) cause bloody diarrhoea, kidney failure and occasionally death. However, identifying the source of infection caused by STEC other than serogroup O157 is hampered by the availability of sensitive methods for detecting these pathogens. In this study, we developed novel tools for detecting E. coli O55 that is potentially associated with human outbreaks. METHODS AND RESULTS: Overall specificity of immuno-magnetic separation (IMS) beads coated with anti-O55 serum was good with exception of cross-reactivity with E. coli O22 and O23, which was eliminated using an O55-specific PCR. Limit of detection for E. coli O55 using O55-IMS beads in spiked cattle faeces was on average 50 CFU per ml (range 1-90), and improved to <10 CFU per ml using the O55-specific PCR, following IMS on samples enriched for 2 h with E. coli O55. Application of these tools to test cattle faeces collected on-farm allowed the isolation of O55:H19, which through whole genome sequencing was compared to STEC O55:H7 human outbreak strains. CONCLUSION: These tools provide a sensitive method which could be used to screen samples for STEC O55, whether environmental or human clinical. SIGNIFICANCE AND IMPACT OF THE STUDY: Several human outbreaks reported in England were caused by STEC O55:H7. Tools developed here could assist in identification of the environmental source for these isolates, which has not yet been established.

Detection of extended-spectrum ß-lactam, AmpC and carbapenem resistance in Enterobacteriaceae in beef cattle in Great Britain in 2015.

AIMS: This study investigated the occurrence and genetic diversity of Enterobacteriaceae with extended-spectrum ß-lactamase (ESBL)-, AmpC- and carbapenemase-mediated resistance in British beef cattle, and related risk factors. METHODS AND RESULTS: Faecal samples (n = 776) were obtained from farms in England and Wales (n = 20) and Scotland (n = 20) in 2015. Isolates from selective agars were identified by MALDI ToF mass spectrometry. Selected isolates were characterized by multiplex PCR (blaCTX -M, blaOXA , blaSHV and blaTEM genes), whole-genome sequencing (WGS), minimum inhibitory concentrations and pulsed-field gel electrophoresis. None of the faecal samples yielded carbapenem-resistant Escherichia coli. Ten (25%) of the farms tested positive for ESBL-producing CTX-M Enterobacteriaceae, 15 (37·5%) of the farms were positive for AmpC phenotype E. coli and none were positive for carbapenem-resistant E. coli. WGS showed a total of 30 different resistance genes associated with E. coli, Citrobacter and Serratia from ESBL agars, and colocation of resistance genes with blaCTX -M1 . Buying bulls and bringing in fattening cattle from another farm were identified as significant risk factors for positive samples harbouring CTX-M Enterobacteriaceae or AmpC phenotype E. coli respectively. CONCLUSIONS: Beef cattle on a proportion of farms in GB carry ESBL-producing Enterobacteriaceae. Factors, such as operating as a closed herd, may have an important role in reducing introduction and transmission of resistant Enterobacteriaceae. The results indicate management factors may play an important role in impacting ESBL prevalence. In particular, further study would be valuable to understand the impact of maintaining a closed herd on reducing the introduction of resistant Enterobacteriaceae. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study showing the presence of ESBL-producing Enterobacteriaceae in British beef cattle.

Longitudinal study on the occurrence in pigs of colistin-resistant Escherichia coli carrying mcr-1 following the cessation of use of colistin.

AIMS: In 2015, colistin-resistant Escherichia coli and Salmonella with the mcr-1 gene were isolated from a pig farm in Great Britain. Pigs were subsequently monitored over a ~20-month period for the occurrence of mcr-1-mediated colistin resistance and the risk of mcr-1 E. coli entering the food chain was assessed. METHODS AND RESULTS: Pig faeces and slurry were cultured for colistin-resistant E. coli and Salmonella, tested for the mcr-1 gene by PCR and selected isolates were further analysed. Seventy-eight per cent of faecal samples (n = 275) from pigs yielded mcr-1 E. coli after selective culture, but in positive samples only 0·2-1·3% of the total E. coli carried mcr-1. Twenty months after the initial sampling, faecal samples (n = 59) were negative for E. coli carrying mcr-1. CONCLUSIONS: The risk to public health from porcine E. coli carrying mcr-1 was assessed as very low. Twenty months after cessation of colistin use, E. coli carrying mcr-1 was not detected in pig faeces on a farm where it was previously present. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that cessation of colistin use may help over time to reduce or possibly eliminate mcr-1 E. coli on pig farms where it occurs.

Non-invasive infra-red therapy (1072 nm) reduces ß-amyloid protein levels in the brain of an Alzheimer's disease mouse model, TASTPM.

BACKGROUND: Alzheimer's disease (AD) is the most prevalent neurodegenerative disease and common cause of dementias in the Western world. This study investigated the expression profile of heat-shock proteins (HSPs) involved in maintaining healthy neurons in the TASTPM AD mouse model, and whether chronic treatment with 1072 nm infra-red (IR1072) modified the expression profiles of HSPs and amyloidopathy in female TASTPM mice. METHODOLOGY/PRINCIPAL FINDINGS: Quantitative immunoblotting and immunohistochemistry were used to examine the expression of proteins such as HSPs, phosphorylated tau (tau-P), amyloid precursor protein (APP), ß-amyloid1-40 (Aß), and Aß1-42. TASTPM mice at 3, 7 and 12 months were investigated as well as female TASTPM mice which had undergone a chronic, 5 month, IR1072 treatment. During the first 12 months of age, a critical period of AD progression, reduced HSP40 and HSP105 were observed. αB-crystallin, Aß1-42 and tau-P increased over this period, particularly between 3 and 7 months. Chronic IR1072 treatment of female TASTPM mice elicited significant increases in HSP60, 70 and 105 and phosphorylated-HSP27 (P-HSP27) (50-139%), together with a concomitant profound decrease in αB-crystallin, APP, tau-P, Aß1-40 and Aß1-42 (43-81%) protein levels at 7 months of age. Furthermore, IR1072 treatment elicited a modest, but significant, reduction in Aß1-42 plaques in the cerebral cortex. CONCLUSIONS/SIGNIFICANT FINDINGS: IR1072 treatment provides a novel non-invasive and safe way to upregulate a panel of stress response proteins in the brain, known to both reduce protein aggregation and neuronal apoptosis. This approach recently entered clinical trials for AD in the USA, and may provide a novel disease modifying therapy for a range of neuropathologies.