Short communication: Mycolicibacterium smegmatis, basonym Mycobacterium smegmatis, causing pyogranulomatous mastitis and its cross-reactivity in bovine (para)tuberculosis testing

Abstract

Different mycobacterial species are encountered in bovine medicine. The fastidiously growing mycobacteria (Mycobacterium bovis as the cause of bovine tuberculosis, and Mycobacterium avium ssp. paratuberculosis, MAP, as the cause of paratuberculosis) are well known and targeted in eradication/control or monitoring programs in different countries, whereas the rapidly growing species is only rarely identified from bovine disease. The latter have occasionally been reported as the cause of bovine clinical mastitis, but recent reports are scarce. In this study, Mycolicibacterium smegmatis (basonym Mycobacterium smegmatis) was identified as cause of granulomatous, relapsing clinical mastitis in 2 cows from one Belgian dairy herd. Milk, blood, and fecal samples were collected, as well as tissue samples after the cows were culled. Serological analysis conducted on milk and serum samples resulted in positive reactions for MAP, but negative for Mycobacterium bovis. Production of IFN-γ showed sensitization with mycobacteria or similar organisms, other than M. bovis, in one cow. Detection of MAP by bacteriological culture and IS900-based quantitative PCR on milk and feces remained negative. In conclusion, this paper describes M. smegmatis as a cause of bovine clinical mastitis in Belgium and suggests cross-reactivity of the intramammary M. smegmatis infection with routinely used serological tests for MAP.

Rescue ofMycobacterium bovisDNA obtained from cultured strains during official surveillance of animal TB: key steps for robust whole genome sequence data generation

“…The bacterial genera that appear in these samples, all of which have been associated with animal infections or the animal's regular microbiota [37][38][39][40][41][42][43][44][45], suggest that the contamination source is related with the sampled animals and not with posterior contamination introduced by handling of the samples. Of course, if such organisms are present in a high amount in the sampled tissues, and since the decontamination procedure does not eliminate the DNA (as discussed above), they will generate WGS reads.…”

“…Looking to each sample individually (Figure 3D), it becomes evident the presence of reads classified as belonging to other organisms and high percentages of reads that could not be classified in the most recent samples. The genus of the most frequent contaminants in all samples were Homo (human DNA), most likely from cross-contamination in sample manipulation, and other known animal pathogens or regular members of animal's microbiota (i.e., Clostridium, Serratia, Bacillus, Paenibacillus, Rhodococcus, Staphylococcus, Rummeliibacillus, and Mycolicibacter) [37][38][39][40][41][42][43][44][45]. One aspect that stands out is that the percentage of contamination with Gram-negative pathogens is higher in the WGA samples (average of 6.0%) than in the original (non-amplified) samples (average of 0.3%) from 2019 to 2021.…”

Rescue of Mycobacterium bovis DNA Obtained from Cultured Samples during Official Surveillance of Animal TB: Key Steps for Robust Whole Genome Sequence Data Generation

“…The bacterial genera that appear in these samples, all of which have been associated with animal infections or the animal's regular microbiota [23][24][25][26][27][28][29], suggest that the contamination source is related to the sampled animals and not to posterior contamination introduced by handling the samples. Of course, if such organisms are present in a high amount in the sampled tissues, and since the decontamination procedure does not eliminate the DNA (as discussed above), they will generate WGS reads.…”

“…Looking at each sample individually (Figure 3D), it becomes evident that there are reads classified as belonging to other organisms and high percentages of reads that could not be classified in the most recent samples. The genus of the most frequent contaminants in all samples was Homo (human DNA), most likely from cross-contamination in sample manipulation, and other known animal pathogens or regular members of the animal's microbiota (i.e., Clostridium, Serratia, Bacillus, Paenibacillus, Rhodococcus, Staphylococcus, Rummeliibacillus, and Mycolicibacter) [23][24][25][26][27][28][29]. One aspect that stands out is that the percentage of contamination with Gram-negative pathogens is higher in the WGA samples (average of 6.0%) than in the original (non-amplified) samples (average of 0.3%) from 2019 to 2021.…”

Insights into the genomic features, lifestyle and therapeutic potential of B1 sub-cluster mycobacteriophages

“…The lipid-rich, waxy cell wall of mycobacteria spp is hard to penetrate, rendering them naturally immune to a wide range of drugs and also linked to opportunistic infections in humans and animals (66). M. smegmatis, although are considered non-pathogenic, they can cause opportunistic infections.…”