Porcine mycobacteriosis caused by Mycobacterium avium subspecies hominissuis

More than 150 species of mycobacteria are described, most being opportunistic pathogens and all representing a risk for human and animal health. Human infections derived from environmental mycobacteria are increasing in both industrialized and developing countries. The most susceptible groups are children, the elderly and those, including animals, with immunocompressive conditions. Drug therapy for mycobacteriosis is difficult and not always successful. Infections caused by drug-resistant mycobacteria can be life threatening also for healthy adults and thus represent a real risk for humans. Environmental mycobacterial infections of pigs are usually without clinical signs and the lesions are mainly detected at slaughter. Mycobacterium-infected pork can pass for human consumption due to the poor sensitivity of visual meat control at slaughterhouses, and mycobacteria in pigs also cause economic losses due to condemnation of carcasses. The main challenge is represented by evaluation of the hygiene risk associated with using mycobacteria-contaminated pork. Most environmental mycobacteria species have been isolated from sources such as water, swimming pools, soil, plants and bedding material. In our study mycobacterial growth in piggeries was identified in all bedding materials, sawdust, straw, peat and wood chips in most cases, and water and food samples in many cases, and only occasionally in dust and on wall surfaces. The maximum number of mycobacteria was almost 1 billion (109) per gram of bedding, which is close to the maximum concentration in any growth media. Mycobacteria can multiply in piggeries and contaminate feed and water. Isolation of mycobacteria from pig faeces can be considered an indicator for risk of human infection. Environmental mycobacteriosis in humans and pigs is mainly caused by M. avium subsp. hominissuis. There is little evidence of direct transmission from animals to humans, but particular strains can be recovered from both humans and pigs. In our studies, identical mycobacteria RFLP and MIRU-VNTR fingerprints of porcine and human origins were evident. Interspecies clusters were more common than intraspecies clusters using both methods. Therefore, we concluded that pigs act as a reservoir for virulent M. avium strains and the vector for transmission of infections in humans to pigs, and vice versa, may have an identical source of infection. Culturing mycobacteria is the gold standard for diagnosis, but detection of environmental mycobacteria based on cultivation and biochemical methods can take several weeks. Culture-independent, rapid and accurate techniques for detecting mycobacteria in food and feed chains are urgently needed. In this work we developed a rapid and accurate real-time quantitative PCR for detecting environmental mycobacteria in bedding materials and pig organs. Conclusion: Mycobacteria can multiply in bedding materials and the consequent heavy contamination can cause simultaneous infections in pigs. Mycobacterial DNA was found in pig organ samples, including those without lesions, and similar strains were found from humans and pig organ samples, which suggests that mycobacteria can be transmitted between humans and pigs

Antimicrobial use and susceptibility of indicator Escherichia coli in Finnish integrated pork production

In pigs, antimicrobial use (AMU) practices vary at different production phases between herds and between countries. Antimicrobial resistance (AMR) development is linked to AMU but recognized as a multi-factorial issue, and thus, any information increasing knowledge of AMU and AMR relationships is valuable. We described AMU and screened the carriage of different AMR phenotypes of indicator Escherichia coli in 25 selected Finnish piglet-producing and finishing herds that formed nine birth-to-slaughter production lines. Moreover, we studied associations between AMU and AMR in both herd types and throughout the production line. Treatment records were obtained from the national Sikava register for 1year, and AMU was quantified as mg/PCU (population correction unit) and TIs (treatment incidences). For phenotypic antimicrobial susceptibility testing, ten pen-level pooled feces samples (n=250) in each herd were collected from one room representing the oldest weaned piglets or the oldest finishing pigs. Majority of the medications (96.8%) was administered parenterally, and penicillin was the predominant antimicrobial in every herd. More different antimicrobial substances were used in piglet-producing than in finishing herds (median 5 and 1, respectively, pPeer reviewe

Effect of a live attenuated vaccine against Lawsonia intracellularis in weaned and finishing pig settings in Finland

Background: The intracellular bacterium Lawsonia intracellularis is an important pathogen in modern swine production. The aim of this study was to investigate the effect of a live attenuated L. intracellularis vaccine (Enterisol-Ileitis (R)) on the health and production parameters of weaned and finishing pigs in a commercial Finnish 850-sow farm with diagnosed L. intracellularis infection. The herd was free from enzootic pneumonia, swine dysentery, progressive atrophic rhinitis, sarcoptic mange and salmonellosis. Four weekly groups of approximately 500 piglets were included in the study for a total of approximately 2000 piglets. Half of these piglets were vaccinated at 3 weeks of age and the other half served as controls. The study piglets were ear-tagged with individual numbers and colour-coded and were individually weighed at weaning (4 weeks), delivery to the finishing farm (12-14 weeks) and at slaughter. Mortality, symptoms of diseases and medications of the study piglets were registered in the nursery and finishing unit. Feed conversion rate was calculated for the finishing period and lean meat percentage was measured at slaughter. Results: Vaccinated piglets had a higher live weight than unvaccinated piglets at delivery to the finishing unit (+ 1.18 kg, P = 0.002) and at slaughter (+ 3.57 kg, P <0.001). The daily weight gain of vaccinated piglets was better than unvaccinated piglets in the nursery (+ 14.8 g/d, P = 0.013) and in the finishing unit (+ 30.9 g/d, P <0.001). Vaccination had no effect on feed conversion rate or lean meat percentage (P = 0.102). Altogether, 3.9 and 4.6% of the pigs were medicated for different reasons in the vaccinated and control groups, respectively. The return on investment for the vaccination was calculated to be 0.41. Conclusions: Immunisation of piglets with a live attenuated L. intracellularis vaccine resulted in higher meat yield in pig production via significantly higher live weight and average daily weight gain in a Finnish specific pathogen-free setting.Peer reviewe

Comparison of Variable-Number Tandem-Repeat Markers typing and IS1245 Restriction Fragment Length Polymorphism fingerprinting of Mycobacterium avium subsp hominissuis from human and porcine origins

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