Utilisation d’huiles végétales ou minérales : un outil potentiel dans la lutte contre Varroa jacobsoni

Dans un contexte de lutte intégrée contre Varroa jacobsoni, la mise au point d’outils complémentaires, chimiques, biotechniques et biologiques, est devenue nécessaire compte tenu de l’évolution de la parasitose face aux moyens classiques de lutte. Parmi ces outils, les huiles pulvérisées sur les abeilles représentent une piste que nous avons développée depuis plusieurs années sur la base d’observations faites en testant l’effet de kairomones ou d’huiles essentielles émulsifiées dans l’eau sur des abeilles parasitées, et sur la base de données bibliographiques existantes

Table_2_Spread of the mcr-1 colistin-resistance gene in Escherichia coli through plasmid transmission and chromosomal transposition in French goats.XLSX

IntroductionColistin-resistance widely disseminated in food-producing animals due to decades of colistin use to treat diarrhea. The plasmid-borne mcr-1 gene has been extensively reported from bovine, swine and chicken worldwide, but smaller productions such as the goat farming sector were much less surveyed.MethodsWe looked for colistin-resistant isolates presenting plasmid-borne genes of the mcr family in both breeding (n=80) and fattening farms (n=5). Localization of the mcr-1 gene was performed using Southern blot analysis coupled to short-read and long-read sequencing.ResultsOnly the mcr-1 gene was identified in 10% (8/80) of the breeding farms and four over the five fattening farms. In total, 4.2% (65/1561) of the animals tested in breeding farms and 60.0% (84/140) of those tested in fattening farms presented a mcr-1-positive E. coli. The mcr-1 gene was located either on the chromosome (32.2%) or on IncX4 (38.9%) and IncHI2 (26.8%) plasmids. As expected, both clonal expansion and plasmidic transfers were observed in farms where the mcr-1 gene was carried by plasmids. Tn6330 transposition was observed in the chromosome of diverse E. coli sequence types within the same farm.DiscussionOur results show that the mcr-1 gene is circulating in goat production and is located either on plasmids or on the chromosome. Evidence of Tn6330 transposition highlighted the fact that chromosomal insertion does not impair the transmission capability of the mcr-1 gene. Only strict hygiene and biosecurity procedures in breeding farms, as well as a prudent use of antibiotics in fattening farms, can avoid such complex contamination pathways.</p

Table_1_Spread of the mcr-1 colistin-resistance gene in Escherichia coli through plasmid transmission and chromosomal transposition in French goats.XLSX

IntroductionColistin-resistance widely disseminated in food-producing animals due to decades of colistin use to treat diarrhea. The plasmid-borne mcr-1 gene has been extensively reported from bovine, swine and chicken worldwide, but smaller productions such as the goat farming sector were much less surveyed.MethodsWe looked for colistin-resistant isolates presenting plasmid-borne genes of the mcr family in both breeding (n=80) and fattening farms (n=5). Localization of the mcr-1 gene was performed using Southern blot analysis coupled to short-read and long-read sequencing.ResultsOnly the mcr-1 gene was identified in 10% (8/80) of the breeding farms and four over the five fattening farms. In total, 4.2% (65/1561) of the animals tested in breeding farms and 60.0% (84/140) of those tested in fattening farms presented a mcr-1-positive E. coli. The mcr-1 gene was located either on the chromosome (32.2%) or on IncX4 (38.9%) and IncHI2 (26.8%) plasmids. As expected, both clonal expansion and plasmidic transfers were observed in farms where the mcr-1 gene was carried by plasmids. Tn6330 transposition was observed in the chromosome of diverse E. coli sequence types within the same farm.DiscussionOur results show that the mcr-1 gene is circulating in goat production and is located either on plasmids or on the chromosome. Evidence of Tn6330 transposition highlighted the fact that chromosomal insertion does not impair the transmission capability of the mcr-1 gene. Only strict hygiene and biosecurity procedures in breeding farms, as well as a prudent use of antibiotics in fattening farms, can avoid such complex contamination pathways.</p

Staphylococcus aureus from 152 cases of bovine, ovine and caprine mastitis investigated by Multiple-locus variable number of tandem repeat analysis (MLVA)

Staphylococcus aureus is one of the main etiological agents of mastitis in ruminants. In the present retrospective study, we evaluated the potential interest of a previously described automated multiple loci Variable Number of Tandem Repeats (VNTR) Assay (MLVA) comprising 16 loci as a first line tool to investigate the population structure of S. aureus from mastitis. We determined the genetic diversity of S. aureus strains from cases of clinical and subclinical mastitis in dairy cattle (n = 118, of which 16 were methicillin-resistant), sheep (n = 18) and goats (n = 16). The 152 strains could be subdivided into 115 MLVA genotypes (including 14 genotypes for the ovine strains and 15 genotypes for the caprine strains). This corresponds to a discriminatory index (D) value of 0.9936. Comparison with published MLVA data obtained using the same protocol applied to strains from diverse human and animal origins revealed a low number (8.5%) of human-related MLVA genotypes among the present collection. Eighteen percent of the S. aureus mastitis collection belonged to clonal complexes apparently not associated with other pathological conditions. Some of them displayed a relatively low level of diversity in agreement with a restricted ecological niche. These findings provide arguments suggesting that specific S. aureus lineages particularly adapted to ruminant mammary glands have emerged and that MLVA is a convenient tool to provide a broad overview of the population, owing to the availability via internet of databases compiling published MLVA genotypes

Fièvre Q : état d'avancement du projet EXPAIRCOX sur les risques de transmission et la perception de ces risques

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Origin of the animal and food isolates.

a<p>the number of MRSA isolates is indicated in brackets.</p>b<p>the origin of one of the 13 food poisoning associated isolates is unknown.</p>c<p>NA : not applicable.</p

Minimum spanning tree of the 251 <i>S. aureus</i> isolates using MLVA-16_Orsay.

<p>Minimum spanning tree of the 251 <i>S. aureus</i> isolates (106 human-associated isolates, 98 animal-associated isolates and 47 isolates from food products among which 13 were related with food-poisoning) using MLVA-16_Orsay. Each circle represents a MLVA genotype. The size of each circle indicates the number of isolates within this MLVA genotype. The different clusters are annotated. The host origin is indicated with a specific color. Isolates involved in food poisoning events are represented by black circles. Human and food isolates are highlighted with two different hatch patterns.</p

Dendrogram of the HARMONY collection using MLVA-16_Orsay.

<p>Color coding is according to MLST clonal complex assignment whereas clustering is done according to the displayed MLVA data. Strain Id, clonal complex, sequence type, spa type, spa code and geographic origin are indicated. MLVA cluster bootstrap values are shown for the main clusters.</p