Identification of virulence-associated antigens and plasmids in Rhodococcus equi from patients with acquired immune deficiency syndrome and prevalence of virulent R. equi in soil collected from domestic animal farms in Chiang Mai, Thailand.

Abstract

Abstract. The prevalence of virulent Rhodococcus equi in soil collected from 17 domestic animal farms (from 12 cattle, 1 pig, and 4 horse farms) and in 6 clinical specimens from patients with acquired immune deficiency syndrome (AIDS) in Chiang Mai, Thailand, was investigated. The isolates were tested for the presence of 15-17-kDa antigens (VapA) and a 20-kDa antigen (VapB) by immunoblotting and for the presence of virulence plasmid DNA. Rhodococcus equi was isolated from most soil samples (68 of 80) obtained from the 17 farms, with 2.0 ϫ 10 2 to 6.0 ϫ 10 5 colony-forming units per gram of soil. We detected VapA in none of the 537 isolates from the soil samples. In one isolate from a pig farm, both VapB and virulence plasmid DNA were detected. Of the 6 clinical isolates from patients with AIDS, however, 4 isolates contained both VapB and virulence plasmid DNA. The remaining 2 isolates were avirulent.

Intermediately virulent Rhodococcus equi isolates from pigs in Slovenia: discovery of new plasmid types and assessment of genetic diversity by pulsed-field gel electrophoresis

“…It has been demonstrated that R. equi strains from pigs may express VapA or VapB, which are characteristic for strains from AIDS patients (Takai et al, 1996;Makrai et al, 2002;Takai et al, 2002). This raised questions about the zoonotic potential of R. equi and increased interest in further research.…”

Plasmid Profiles and Prevalence of Intermediately VirulentRhodococcus equifrom Pigs in Nakhonpathom Province, Thailand: Identification of a New Variant of the 70-kb Virulence Plasmid, Type 18

“…Some of the protein profiles, plasmid characteristics, and virulence levels of these strains have been described previously [5, 7, 10, 11]. …”

“…In Thailand, infection by R. equi has been reported in patients with and without HIV infection in Chiang Mai, and 52 isolates from 69 sporadic cases collected between 1993 and 2001 were VapB-positive R. equi [10, 11]. Isolates of VapB-positive R. equi collected from healthy pigs at an abattoir and from immunodeficient patients in Chiang Mai contained the same plasmid types [11], so the pig was thought to be a source of VapB-positive R. equi infections in immunocompromised patients [5, 10, 11].…”

“…Isolates of VapB-positive R. equi collected from healthy pigs at an abattoir and from immunodeficient patients in Chiang Mai contained the same plasmid types [11], so the pig was thought to be a source of VapB-positive R. equi infections in immunocompromised patients [5, 10, 11]. A study to examine the plasmid pattern of VapB-positive R. equi to evaluate any correlation between human infection and pig infection in each area was necessary to prove the source of infection.…”

Isolation of virulent Rhodococcus equi from Arabian horses in Şanlıurfa, Turkey

“…R. equi has been isolated from feces and soil at various isolation rates (4,(14)(15)(16). R. equi culture positivity rates were reported as 68%-86% (16), 86% (17), and 95% (15) from soil samples. On the other hand, Takai et al reported 72%-92% culture positivity for R. equi in equine feces (9).…”