Biology subjects

Mounsey, O.

Publications and source records attributed to Mounsey, O..

3 recordsLinked to original sources

bioRxiv2019

Molecular epidemiology of cefotaxime-resistant Escherichia coli from dairy farms in South West England identifies a dominant plasmid encoding CTX-M-32

Third-generation cephalosporin resistance (3GC-R) in Escherichia coli is a rising problem in human and farmed animal populations. We conducted whole genome sequencing analysis of 138 representative 3GC-R isolates previously collected from dairy farms in South West England and confirmed by PCR to carry acquired 3GC-R genes. This analysis identified blaCTX-M (131 isolates: encoding CTX-M-1, -14, -15, -32 and the novel variant, CTX-M-214), blaCMY-2 (6 isolates) and blaDHA-1 (one isolate). A highly conserved plasmid was identified in 73 isolates, representing 27 E. coli sequence types. This novel ~220 kb IncHI2 plasmid carrying blaCTX-M-32 was sequenced to closure and designated pMOO-32. It was found experimentally to be stable in cattle and human transconjugant E. coli even in the absence of selective pressure and was found by multiplex PCR to be present on 26 study farms representing a remarkable range of transmission over 1500 square kilometres. However, the plasmid was not found amongst human urinary E. coli we have recently characterised from people living in the same geographical location, collected in parallel with farm sampling. There were close relatives of two blaCTX-M plasmids circulating amongst eight human and two cattle isolates, and a closely related blaCMY-2 plasmid found in one cattle and one human isolate. However, phylogenetic evidence of recent sharing of 3GC-R strains between farms and humans in the same region was not found. ImportanceThird-generation cephalosporins (3GCs) are critically important antibacterials and 3GC-resistance (3GC-R) threatens human health, particularly in the context of opportunistic pathogens such as Escherichia coli. There is some evidence for zoonotic transmission of 3GC-R E. coli through food, but little work has been done examining possible transmission (e.g. via interaction of people with the local near-farm environment). We characterised acquired 3GC-R E. coli found on dairy farms in a geographically restricted region of the United Kingdom and compared these with E. coli from people living in the same region, collected in parallel. Whilst there is strong evidence for recent farm-to-farm transmission of 3GC-R strains and plasmids - including one epidemic plasmid that has a remarkable capacity to transmit - there was no evidence that 3GC-R found on study farms had a significant impact on circulating 3GC-R E. coli strains or plasmids in the local human population.

microbiology↗

bioRxiv2019

Characterisation of AmpC Hyper-Producing Escherichia coli from Humans and Dairy Farms Collected in Parallel in the Same Geographical Region

ObjectivesTo characterise putative AmpC hyper-producing 3rd generation cephalosporin-resistant E. coli from dairy farms and their phylogenetic relationships as well as to identify risk factors for their presence; to assess evidence for their zoonotic transmission into the local human population\n\nMethodsProteomics was used to explain differences in antimicrobial susceptibility. Whole genome sequencing allowed phylogenetic analysis. Multilevel, multivariable logistic regression modelling was used to identify risk factors.\n\nResultsIncreased use of amoxicillin-clavulanate was associated with an increased risk of finding AmpC hyper-producers on farms. Expansion of cephalosporin resistance in AmpC hyper-producers was seen in farm isolates with marR mutations (conferring cefoperazone resistance) or when AmpC was mutated (conferring 4th generation cephalosporin and cefoperazone resistance). Phylogenetic analysis confirmed the dominance of ST88 amongst farm AmpC hyper-producers but there was no evidence for acquisition of farm isolates by members of the local human population.\n\nConclusionsIn this two-year surveillance study of 53 dairy farms, AmpC hyper-production was the cause of cefotaxime resistance in 46.2% of E. coli. There was evidence of recent farm-to-farm transmission and of adaptive mutations to expand resistance. Whilst there was no evidence of isolates entering the local human population, efforts to reduce 3rd generation cephalosporin resistance on dairy farms must address the high prevalence of AmpC hyper-producers. The finding that amoxicillin-clavulanate use was associated with increased risk of finding AmpC hyper-producers is important because this is not currently categorised as a highest-priority critically important antimicrobial and so is not currently targeted for specific usage restrictions in the UK.

microbiology↗

bioRxiv2019

Evidence for reduced CTX-M carriage in cattle-associated Escherichia coli at low temperatures and on publicly accessible farmland: implications for surveillance and potential for farm-to-human transmission

Little is known about the drivers of critically important antibacterial resistance in species with zoonotic potential present on farms (e.g. CTX-M {square}-lactamase-positive Escherichia coli). Here, we collected samples, monthly over a two-year period, on 53 dairy farms in the South West of England, and data for 610 variables concerning antimicrobial usage, management practices and meteorological factors. We detected E. coli resistant to amoxicillin, ciprofloxacin streptomycin and tetracycline, respectively, in 2754/4145 (66%), 263/4145 (6%), 1475/4145 (36%) and 2874/4145 (69%) of all samples from faecally contaminated sites. E. coli positive for blaCTX-M were detected in 224/4145 (5.4%) of samples. Multilevel, multivariable logistic regression showed antibiotic dry cow therapeutic choice (including use of cefquinome or framycetin) to be associated with increased odds of blaCTX-M positivity. Low temperature was associated with reduced odds of blaCTX-M E. coli positivity in samples and to reduced odds of finding E. coli resistant to each of the four test antibacterials. This was additional to the effect of temperature on total E. coli density. Furthermore, samples collected close to calves had increased odds of having E. coli resistance to each antibacterial or positive for blaCTX-M. Samples collected on pastureland had reduced odds of having E. coli resistant to amoxicillin or tetracycline, and being positive for blaCTX-M. ImportanceAntibacterial resistance poses a significant threat to human and animal health and global food security. Surveillance for resistance on farms is important for many reasons, including to track the impacts of interventions aimed at reducing the prevalence of resistance. In this epidemiological survey of dairy farm antibacterial resistance, we show that local temperature, as it changes over the course of a year, is associated with the prevalence of antibacterial resistant E. coli. Also, that prevalence of resistant E. coli is higher in indoor environments and in environments inhabited by young animals. These findings have profound implications for routine surveillance and for surveys carried out for research. They provide important evidence that sampling at a single time-point and/or single location on a farm is unlikely to be adequate to accurately determine the status of the farm with regard to the presence or number of resistant E. coli.

microbiology↗