Association of farm-related factors with characteristics profiles of extended-spectrum ß-lactamase- / plasmid-mediated AmpC ß-lactamase-producing Escherichia coli isolates from German livestock farms.

Resistance to ß-lactam antibiotics, including third-generation cephalosporins, is of major concern for animal and human health. In this study, extended-spectrum ß-lactamase (ESBL) / plasmid-mediated AmpC (pAmpC) ß-lactamase -producing Escherichia coli isolates from German livestock farms were characterised and associations of these isolate characteristics with farm-related factors were investigated across different types of livestock. A total of 469 isolates originating from 150 farms (34 broiler farms, 38 fattening pig farms, 43 dairy cattle farms, 35 beef cattle farms) was included in the analyses. ESBL-gene family, phylogroup and phenotypic antimicrobial susceptibility for several antimicrobial agents were determined. This data was used to define different profiles characterising the isolates. Multivariate analyses using a distance-based non-parametric approach were performed to investigate associations between the profiles of the isolates and farm-related factors (e.g. management, husbandry, and environment of the farms). Co-occurrence of ESBL-gene families were not found in any of the isolates analysed. Sixty-eight percent of the isolates carried blaCTX-M variant genes. The frequency of phylogroups was as follows: A (55%), B1 (35%), D (17%) and B2 (3%). The most frequent phenotypic non-wildtype profile was non-wildtype status of solely cefepime (27%). Profiles of isolates from broilers differed substantially from those of other isolates. Associations between farm-related factors and characteristics profiles differed, depending on the isolate characteristics included in the analyses. Some factors describing the farm environment, like waterfowl in the surrounding of the farm, were associated with all tested profiles. The epidemiological method applied defines distances between isolates on basis of isolate characteristics data and is capable of analysing associations between isolate characteristics and epidemiological factors. As additional data, such as plasmid characteristics, gene type, or sequence information could be included in future studies, the method is suitable to identify points of action to reduce the occurrence of antimicrobial resistant bacteria.

Investigation of potential risk factors for the occurrence of Escherichia coli isolates from German fattening pig farms harbouring the mcr-1 colistin-resistance gene.

Within the scope of a cross-sectional investigation on fattening pig farms conducted in 2011 and 2012, 48 fattening farms in different agricultural regions of Germany were sampled. Primary cultures of boot swabs and collective faecal samples were stored at -80 °C and screened for the presence of the mcr-1 colistin-resistance gene. The laboratory results were linked to farm-related data collected via questionnaire. Logistic regression models were used to investigate the association between occurrence of mcr-1 and farm-related data. Escherichia coli carrying the mcr-1 gene were isolated from 26 of 216 (12.0%) mixed bacterial cultures originating from 12 of 48 (25.0%) farms. Results of the logistic regression analyses indicate that the transmission between pigs or their direct environment is crucial for the occurrence of these resistant bacteria. However, there was no statistically significant association between antimicrobial use and the occurrence of the mcr-1 gene.