Novel bovine-associated pVAPN plasmid type in Rhodococcus equi identified from lymph nodes of slaughtered cattle and lungs of people living with HIV/AIDS.

Rhodococcus equi is a well-recognized Gram-positive intracellular facultative bacterium that is opportunistic in nature, which causes pyogranulomatous infections in humans and multiple host animals. The pathogenicity of the microorganism has been attributed to the presence of plasmid-encoded virulence-associated proteins (Vap). To date, three host-associated virulence plasmid types of R. equi have been identified as follows: the circular pVAPA and pVAPB, related, respectively, to equine and porcine isolates, and a recently described linear pVAPN plasmid associated with bovine strains, although these three types are found in human isolates. Recent phylogenomic studies support the evidence that human R. equi infection is zoonotically acquired. Nevertheless, data regarding distribution and prevalence of the host-adapted virulence plasmid types of R. equi isolated from meat animals are scarce or unnoticed. Here, the three host-associated virulence plasmid types (pVAPA, pVAPB, and pVAPN) were investigated in 154 R. equi isolates recovered from lymph nodes of cattle with lymphadenitis (n = 31), faeces of cattle without enteric signs (n = 49), as well as different clinical specimens from human patients (n = 74). The analysis of virulence profile of 74 R. equi from humans revealed six (8.1%) isolates pVAPB (type 8), two (2.7%) pVAPN, and one (1.3%) pVAPB (type 11), all of which were from lung samples from people living with HIV/AIDS. From the lymph node samples of cattle, 41.9% (13 of 31) isolates revealed pVAPN type, whereas all isolates from faecal samples were negative for three host-associated types. Here, recently described bovine-associated pVAPN type was detected in R. equi isolates recovered from the lungs of people living with HIV/AIDS and lymph nodes from slaughtered cattle intended for human consumption; a finding that represents a public health concern, mainly in countries where undercooked or raw meat are traditionally consumed.

Virulence markers associated with Trueperella pyogenes infections in livestock and companion animals.

Trueperella pyogenes is an opportunistic pathogen that causes diverse pyogenic infections in livestock. The genes that encode the exotoxin pyolysin (plo) and other putative factors that promote adhesion of pathogen to host cells (fimbriae fimA, fimC, fimE, fimG, neuraminidases nanH, nanP, and collagen-binding protein cbpA) have been associated with virulence, particularly in mastitis and uterus infections of dairy cows. However, the role of these virulence markers in the pathogenicity of the agent in domestic animals infections still is incompletely understood. The genes plo, fimA, fimC, fimE, fimG, nanH, nanP, and cbpA were investigated in 71 T. pyogenes strains recovered from cattle, sheep, goats, dogs, equines, and a pig, recovered from mastitis (n = 35), and non-mastitis (n = 36) cases (abscesses, reproductive tract diseases, pneumonia, lymphadenitis, encephalitis). The most common genes harboured by the isolates were: plo (71/71 = 100·0%), fimA (70/71 = 98·6%), nanP (56/71 = 78·9%), fimE (53/71 = 74·6%), fimC (46/71 = 64·8%) and nanH (45/71 = 63·4%), whereas cbpA (6/71 = 8·4%) and fimG (4/71 = 5·6%) were uncommon. The most frequent genotypes were plo/fimA/fimE/fimC/nanH/nanP (17/71 = 23·9%), plo/fimA/fimE/nanH/nanP (13/71 = 18·3%), and plo/fimA/fimE/fimC/nanP (11/71 = 15·5%). No association was observed between the presence of genes vs clinical signs or host species. To the best of our knowledge, this is the first report on aforementioned virulence factors of pathogen detected in diseased horses and dogs. SIGNIFICANCE AND IMPACT OF THE STUDY: The role of particular virulence factors of Trueperella pyogenes that determine different pyogenic infections among domestic animals is poorly understood. Eight putative virulence genes and genotype profiles of 71 isolates were investigated among different clinical manifestations in domestic animals. The most common genes were plo (71/71 = 100·0%), fimA (70/71 = 98·6%), nanP (56/71 = 78·9%), fimE (53/71 = 74·6%), fimC (46/71 = 64·8%) and nanH (45/71 = 63·4%), whereas plo/fimA/fimE/fimC/nanH/nanP (17/71 = 23·9%), plo/fimA/fimE/nanH/nanP (13/71 = 18·3%), and plo/fimA/fimE/fimC/nanP (11/71 = 15·5%) were the most frequent genotypes. Studies involving virulence factors are critical in the investigation of molecular epidemiology, pathogenicity, and hypothetical differences in the virulence among T. pyogenes strains from different geographical areas.