Aim The focus of the present study was to evaluate the copper ions treatment on the viability of Mycobacterium avium subsp. paratuberculosis (MAP) and other bacterial communities in cow’s milk. Methods and Results A copper ions treatment was evaluated in naturally contaminated cow’s milk to assay MAP load and/or viability, and relative abundance of other bacterial communities. In addition, physical–chemical analyses of the milk were also performed. All analyses were carried out before and after a copper ions treatment. After copper ions treatment, pH and copper concentration markedly increased in milk; the numbers of viable MAP significantly decreased. The relative abundance of the four target phyla decreased, with the phyla Bacteroidetes and Firmicutes surviving treatment in higher proportions (4 and 2·1% of original populations, respectively). A progressively higher percentage of dead bacterial cells after 5 and 20 min copper ions treatments was found (12 and 35%, respectively). Conclusion With the exception of some MAP‐tolerant strains, we have once again demonstrated that copper ions have a significant inactivating effect on MAP as well as certain other bacterial communities found in naturally contaminated cow’s milk. Significance and Impact of the Study This study showed a significant inactivation of both MAP and other bacteria by copper ions in raw cow’s milk, information that could be useful as a tool for MAP control.

No abstract

Aims A major drawback of using dairy slurry as fertilizer is that it may contains pathogens such as Mycobacterium avium subsp. paratuberculosis (MAP), and it could represent a risk to animal and public health. Thus, the aim of this study was to evaluate the fate of MAP and bacterial communities in dairy slurry after chemical treatments. Methods and Results Cattle slurry, naturally contaminated with MAP, was collected from a dairy herd and divided into 32 glass bottles which were assigned to eight different treatments (control, 3·0% CaO, 0·5% NaOH; 0·087%, 0·11% and 0·14% H2SO4; and 1·0 and 2·5% KMnO4). Treated dairy slurry samples were evaluated at 0, 1, 3, 7, 15, 30 and 60‐days following treatment application for viable MAP and dairy slurry pH, and in addition temperature in this material was monitored continuously. Bacterial counts were estimated at each sampling time. A Bayesian zero‐inflated Poisson mixed model was fitted to assess the effect of each treatment on the count of MAP cells. Model results indicated that only the 3·0% CaO treatment had a statistically important negative effect on MAP counts during the study period. For most treatments, MAP was undetectable immediately after chemical treatment but re‐appeared over time, in some replicates at low concentrations. However, in those cases MAP counts were not statistically different than the control treatment. Regarding the fate of the other bacterial populations, the Firmicutes phylum was the dominant population in the un‐treated slurry while Clostridia class members were among the most prevalent bacteria after the application of most chemical treatments. Conclusion Only 3% CaO treatment had a statistically important negative effect on MAP viability in cattle slurry. Significance and Impact of the Study This study provides evidence of MAP partial control in dairy slurry. This information should be considered as a best management practice to reduce MAP and other pathogens for slurry management on dairy farms.

RESUMENEl diagnóstico de la infección por Mycobacterium avium subsp. paratuberculosis (MAP) al utilizar un sistema de cultivo líquido resulta en una mayor sensibilidad, rapidez y automatización. Sin embargo, tiene como desventajas una mayor tasa de contaminación en relación con los sistemas convencionales y también es menos específico. El presente estudio identificó algunas bacterias contaminantes del sistema de cultivo BACTEC-MGIT 960 al procesar muestras clínicas de ganado bovino del sur de Chile. No se detectaron micobacterias en las muestras falsas positivas a MAP mediante la técnica Reacción en Cadena de la Polimerasa-Análisis con Enzimas de Restricción (PRA)-hsp65. Por otra parte, el Análisis de los Espaciadores Intergénicos Ribosomales (RISA) seguido de un análisis de secuenciación, reveló la presencia de Paenibacillus sp., Enterobacterias y Pseudomonas aeruginosa como contaminantes comunes. Los protocolos de eliminación de contaminantes deberían considerar esta información para mejorar los resultados diagnósticos de los sistemas de cultivo líquido. Además se requieren estudios adicionales que consideran un mayor número de muestras para establecer conclusiones más representativas de la población bovina.Key words: Mycobacterium avium subsp. paratuberculosis, liquid culture, contaminant bacteria, RISA, PRA-hps65. SUMMARYDiagnosis of Mycobacterium avium subsp. paratuberculosis infection by liquid culture is sensitive, faster than conventional solid culture and automated. However, a disadvantage of these culture systems is the potential for high frequency of culture contamination. Contaminant bacteria were identified as a step toward better contaminant control. No mycobacteria were detected by mycobacterial Polymerase Chain Reaction-Restriction Enzyme Analysis (PRA)-hsp65. Ribosomal Intergenic Spacer Analysis (RISA) followed by sequence analysis identified Paenibacillus sp., Enterobacteriaceae and Pseudomonas aeruginosa as common contaminants. The present study aimed to identify a representative sample of contaminants encountered when culturing clinical faecal samples from Chilean cattle. Further studies involving a larger and more representative sample of animals are required to extrapolate the results to a broader population.Palabras clave: Mycobacterium avium subsp. paratuberculosis, cultivo líquido, RISA, PRA-hps65.

No abstract