Microbiological assessment of sheep lymph nodes with lymphadenitis found during post-mortem examination of slaughtered sheep: implications for veterinary-sanitary meat control

Abstract

Background: Microbiological examination of lesions found in slaughtered animals during meat inspection is an important part of public health protection as such lesions may be due to zoonotic agents that can be transmitted by meat. Examination of inflamed lymph nodes also plays a particular important role, as lymphadenitis may reflect a more widespread infection. Such lesions in sheep are mainly caused by pyogenic bacteria but also mycobacteria are occasionally found. Meat inspection data from 2017 to 2018 from southern Poland, especially from the Małopolska region, indicate that purulent or caseous lymphadenitis involving the mediastinal and tracheobronchial lymph nodes (MTLNs) is a common finding. The primary aim of the current study was to determine the aetiology of these lesions. Furthermore, it was investigated how presence of lesions was correlated with age and grazing strategy of affected sheep. Results: Post-mortem examination revealed purulent or caseous lymphadenitis in the MTLNs of 49 out of 284 animals (17.3%). Subsequent microbiological examination revealed the presence of Corynebacterium pseudotuberculosis (34.7%), Streptococcus dysgalactiae subsp. equisimilis (34.7%), Staphylococcus aureus (8.2%), Enterococcus spp. (2.0%), Trueperella pyogenes (2.0%), and β-haemolytic strains of Escherichia coli (2.0%). Mycobacterium spp. and Rhodococcus equi were not detected. In older sheep, the probability of the presence of purulent or caseous lymphadenitis was higher than in younger, and the risk was increasing by 1.5% with each month of life. Sheep grazing locally had 4.5times greater risk of having purulent or caseous lymphadenitis than individuals summer grazing in the mountains. Conclusion: The most common aetiological agents of purulent or caseous lymphadenitis in the MTLNs of sheep in the Małopolska region were C. pseudotuberculosis and S. dysgalactiae subsp. equisimilis. Particular attention during post-mortem examination should be paid to the carcasses of older sheep and sheep grazing on permanent pastures, as they seem more prone to develop purulent or caseous lymphadenitis.

First study on molecular epidemiology of caseous lymphadenitis in slaughtered sheep and goats in Duhok Province, Iraq

“…In terms of age, CLA was only found in both sheep and goats of older than 1 year. These findings are consistent with what has been published by Kaba et al (2011) and Didkowska et al (2020) . The higher rates in older sheep and goats compared to younger animals are most likely owing to the older animals’ increased risk of bacterial infection, which increases CLA infection rates ( Ali et al , 2016 ).…”

Rhodococcus equi—Occurrence in Goats and Clinical Case Report

“…In addition, isolation of the ruminant-specific (pVAPN-carrying) R. equi aligns with previous studies. It confirms that the goat’s environment or goat meat might be a potential source of infection for humans [ 23 , 46 , 54 ].…”

Antibiotic Susceptibility Profiles of Bacterial Isolates Recovered from Abscesses in Cattle and Sheep at a Slaughterhouse in Algeria

“…The analysis of bacterial isolates from pus showed the predominance of Enterobacterales isolates, particularly E. coli , followed by Staphylococcus spp. Enterobacterales, and E. coli especially have been found to be major players in the formation of abscesses in animals [ 5 , 26 , 27 ], although several studies have isolated S. aureus from abscesses as the quintessential suppurative pathogen in large proportions [ 13 , 14 , 28 , 29 ]. These bacterial species isolated are zoonotic pathogens, which places public health at risk.…”