Abstract
BackgroundRhodococcus equi is an emerging zoonotic presumably foodborne pathogen. Since the data on the worldwide prevalence of R. equi in meat animals are scarce, the present study aimed to investigate the molecular epidemiology of R. equi in swine, cattle and horse carcasses intended for human consumption in Poland.ResultsTotally 1028 lymph node samples were examined. R. equi was isolated from 26.6 % (105/395) swine and 1.3 % (3/234) bovine healthy submaxillary lymph nodes. In horses, R. equi was isolated only from 0.5 % (1/198) samples of middle tracheo-branchiales lymph node while no lymphocentrum retropharyngeum sample was positive (0/198). The purulent lesions were observed only in 0.8 % swine submaxillary lymph nodes samples (3/398) and in two of them R. equi was detected.All bovine and most of swine isolates (98.1 %) were vapB-positive. 87.9 % of swine isolates carried 95-kb type 5 plasmid, 3.7 % type 1 and plasmid types: 4, 7, 10, 11, 21, 31 were carried by a single isolate (0.9 %). All bovine isolates carried VAPB type 26. Single horse isolate was vapA-positive and carried plasmid VAPA 85-kb type I.ConclusionsThe prevalence of vapB-positive R. equi in investigated healthy swine intended for human consumption was very high.Not only swine, but also even apparently healthy cattle or horse carcasses should be considered as a potential source of R. equi for humans, especially in countries where undercooked or raw beef or horsemeat is traditionally consumed.
Highlights
Rhodococcus equi is an emerging zoonotic presumably foodborne pathogen
Ten distinct VapB plasmid types were found in 10 traA-positive isolates: 9 in swine and 1 in cattle (Table 2)
Our results revealed the presence of 95-kb type 5 plasmid in most of vapB-positive swine isolates
Summary
Rhodococcus equi is an emerging zoonotic presumably foodborne pathogen. Since the data on the worldwide prevalence of R. equi in meat animals are scarce, the present study aimed to investigate the molecular epidemiology of R. equi in swine, cattle and horse carcasses intended for human consumption in Poland. Rhodococcus equi is a Gram-positive bacterium widespread in the environment of grazing farms. It is common in the feces of wildlife and farm animals including swine, cattle, horses and others [1,2,3,4,5]. The virulence of R. equi is determined by the virulence-associated plasmids (VAPs) which harbor the pathogenicity islands that contain vap genes encoding the virulence-associated proteins (Vaps) [6, 7]. In virulent strains isolated from horses the vapA gene encoding virulence-associated 15– 17-kDa protein (VapA) is predominant, whereas in swine isolates the vapB gene of the virulence-associated 20-. The aforementioned three genes are located on plasmids VAPA, VAPB, and VAPN, respectively. Analysis of restriction enzyme digestion patterns revealed several distinct VAPA plasmid types and over 20 types of VAPB plasmid but the digestion patterns of VAPN have not been so far recognized [3, 11, 12]
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