High Fecal Prevalence of mcr-Positive Escherichia coli in Veal Calves at Slaughter in France

International audienceThe aim of this study was to determine the percentage of healthy veal calves carrying mcr-positive E. coli strains at the time of slaughter in France. Fecal samples were selectively screened for mcr-positive E. coli isolates using media supplemented with colistin. Screening for mcr genes was also carried out in E. coli isolates resistant to critically important antimicrobials used in human medicine recovered from the same fecal samples. Overall, 28 (16.5%) out of the 170 veal calves tested carried mcr-positive E. coli. As some calves carried several non-redundant mcr-positive strains, 41 mcr-positive E. coli were recovered. Thirty-one and seven strains were positive for mcr-1 and mcr-3 genes, respectively, while no strain was positive for the mcr-2 gene. Co-carriage of mcr-1 and mcr-3 was identified in three strains. All mcr-positive E. coli isolates, except one, were multidrug-resistant, with 56.1% being ciprofloxacin-resistant and 31.7% harboring blaCTX-M genes. All mcr-3-positive E. coli carried blaCTX-M genes, mainly blaCTX-M-55. This study highlights the high prevalence of mcr-positive E. coli strains in feces of veal calves at the time of slaughter. It also points out the multidrug (including ciprofloxacin) resistance of such strains and the co-occurrence of mcr-3 genes with blaCTX-M-55 genes

Comparison of the incidence of pathogenic and antibiotic-resistant <em>Escherichia coli</em> strains in adult cattle and veal calf slaughterhouse effluents highlighted different risks for public health

International audienceThe goal of this study was to investigate the involvement of bovine slaughterhouse effluents and bio-solids in the risk of environmental dissemination of pathogenic and antibiotic-resistant Escherichia coli. Several samples were collected from one adult cattle and one veal calf slaughterhouse wastewater treatment plant (WWTP). The treatment process had no impact on the percentage of Shiga toxin-producing E. coli (STEC) and on the percentage of atypical enteropathogenic E. coli (aEPEC). A STEC O157:H7 was isolated from the thickened sludge of the adult cattle slaughterhouse. As thickened sludge is intended to be spread on agricultural lands, the detection of this pathogenic strain is a public health issue. The percentage of antibiotic-resistant E. coli was 5.0% and 87.5% in wastewater from the adult cattle and the veal calf slaughterhouse, respectively. These percentages were not significantly different after treatment. Integron-bearing E. coli isolates were only detected in the veal calf slaughterhouse WWTP with percentages above 50.0% for all sampling points whatever the step of the treatment process. Taken together, these findings highlighted the fact that different public health risks might be associated with adult cattle or veal calf slaughterhouses regarding the dissemination of pathogenic and antibioticresistant E. coli isolates into the environment

Diagnosing Intramammary Infection: Meta-Analysis and Mapping Review on Frequency and Udder Health Relevance of Microorganism Species Isolated from Bovine Milk Samples

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry provides accurate species-level identification of many, microorganisms retrieved from bovine milk samples. However, not all those microorganisms are pathogenic. Our study aimed to: (1) determine the species-specific prevalence of microorganisms identified in bovine milk of apparently healthy lactating quarters vs. quarters with clinical mastitis (CM); and (2) map current information and knowledge gaps on udder health relevance of microorganisms retrieved from bovine milk samples. A mixed study design (meta-analysis and mapping review) was chosen. We gathered several large Canadian, US and Brazilian data sets of MALDI-TOF results for organisms cultured from quarter milk samples. For meta-analysis, two datasets (apparently healthy quarters vs. CM samples) were organized. A series of meta-analyses was conducted to determine microorganisms’ prevalence. Then, each species reported was searched through PubMed to investigate whether inflammation (increased somatic cell count (SCC) or signs of CM) was associated with microorganism’s recovery from milk. A total of 294 different species of microorganisms recovered from milk samples were identified. Among 50,429 quarter-milk samples from apparently healthy quarters, the 5 most frequent species were Staphylococcus chromogenes (6.7%, 95% CI 4.5–9.2%), Aerococcus viridans (1.6%, 95% CI 0.4–3.5%), Staphylococcus aureus (1.5%, 95% CI 0.5–2.8%), Staphylococcus haemolyticus (0.9%, 95% CI 0.4–1.5%), and Staphylococcus epidermidis (0.7%, 95% CI 0.2–1.6%). Among the 43,924 quarter-milk CM samples, the 5 most frequent species were Escherichia coli (11%, 95% CI 8.1–14.3%), Streptococcus uberis (8.5%, 95% CI 5.3–12.2%), Streptococcus dysgalactiae (7.8%, 95% CI 4.9–11.5%), Staphylococcus aureus (7.8%, 95% CI 4.4–11.9%), and Klebsiella pneumoniae (5.6%, 95% CI 3.4–8.2%). When conducting the PubMed literature search, there were 206 species identified by MALDI-TOF for which we were not able to find any information regarding their association with CM or SCC. Some of them, however, were frequently isolated in our multi-country dataset from the milk of quarters with CM (e.g., Citrobacter koseri, Enterococcus saccharolyticus, Streptococcus gallolyticus). Our study provides guidance to veterinarians for interpretation of milk bacteriology results obtained using MALDI-TOF and identifies knowledge gaps for future research