Prevalence of virulent Rhodococcus equi in isolates from soil and feces of horses from horse-breeding farms with and without endemic infections

Takaı̈, Shinji; Ohbushi, S; Koike, K; Tsubaki, Shiro; Oishi, Hideo; Kamada, Masanobu

doi:10.1128/jcm.29.12.2887-2889.1991

Cited by 112 publications

(68 citation statements)

References 7 publications

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“…Although all horse farms are likely to be infected with R. equi, clinical disease ranges from enzootic and devastating on some farms, to sporadic or undiagnosed on others. This may reflect differences in environment (temperature, irritant dust, soil pH) and management conditions, as well as differences in the virulence of isolates (Takai et al 1991). Rhodococcus equi may be found in areas never inhabited by horses, although greater concentrations occur where horses are present.…”

Section: Discussionmentioning

confidence: 99%

Rhodococcus equi pneumonia in an adult horse

Waldridge

Morresey

Loynachan

et al. 2008

Equine Veterinary Education

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Summary A 20‐year‐old, Thoroughbred mare in the fifth month of gestation was examined for weight loss, pyrexia and lethargy. Physical examination, ultrasonography and radiography revealed a severe abscessing pneumonia and a dead fetus. The mare did not respond to symptomatic treatment and died suddenly. Necropsy revealed multifocal pulmonary abscessation. Rhodococcus equi was isolated from the lungs, liver and kidneys. Specific immune function of the mare and presence of the virulence associated protein A (VapA) of the R. equi isolated was not determined. It is likely that immunosuppression is required for systemic R. equi infections in adult horses; however, it is unknown if VapA is necessary to produce disease in adult horses.

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Section: Discussionmentioning

confidence: 99%

Rhodococcus equi pneumonia in an adult horse

Waldridge

Morresey

Loynachan

et al. 2008

Equine Veterinary Education

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“…It has been shown that PCR rapidly and accurately identifies and distinguishes between virulent and avirulent strains of R. equi by detection of the VapA gene (Anzai et al, 1997;Sellon et al, 2001). However, PCR may result in false-positives due to detection of very small numbers of R. equi that are present as environmental contaminants because the organism is ubiquitous and present in the soil and horse dung of most horse farms (Takai et al, 1991b). Moreover, decrease in sensitivity of PCR amplification has been experienced due to the presence in clinical samples of substances (e.g.…”

Section: Discussionmentioning

confidence: 99%

Clinical Evaluation of a Peptide‐ELISA based upon N‐terminal B‐cell Epitope of the VapA Protein for Diagnosis ofRhodococcus equiPneumonia in Foals

Phumoonna

Muscatello

Chicken

et al. 2006

Journal of Veterinary Medicine, Series B

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A total of 227 field samples from naturally exposed foals aged between 3 weeks and 6 months were used in an evaluation of a peptide-based enzyme-linked immunosorbent assay (ELISA) for diagnosis of Rhodococcus equi infection. A biotinylated peptide derived from the virulence-associated protein A (VapA) of R. equi, a horse pathogen, was synthesized and designated as PN11-14. The peptide corresponds to the N-terminal B-cell epitope TSLNLQKDEPNGRASDTAGQ of the VapA protein. Based upon a serum immunoglobulin (Ig)G titre of 512 as a positive cut-off value for the R. equi infection, the ELISA provided the overall sensitivity of 47.62%, specificity of 69.67% and an accuracy of 59.47% with a positive predictive value of 57.47% for true R. equi pneumonia. The assay was improved by detecting VapA-specific IgGb antibodies against N-terminal B-cell epitope of the VapA protein rather than IgG antibodies. The VapA-IgGb ELISA showed the overall sensitivity of 70.47%, specificity of 72.13% and accuracy of 71.36% with a positive predictive value of 68.52%. Diagnosis of R. equi disease in 6-week-old foals showed that the VapA-IgGb ELISA provided an increasing trend (P=0.0572) in sensitivity of 82.4% in comparison with the VapA-IgG ELISA which showed the sensitivity of 58.8%. However, differences in specificity of both tests were statistically insignificant (P=0.357) as analysed by the McNemar test. These results indicated that detection of VapA-specific IgGb antibodies may be a better predictor of R. equi disease in foals.

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“…Farms with endemic R. equi pneumonia are heavily contaminated with virulent R. equi, while the others are not, although avirulent R. equi are frequently found in environment and feces on every farm (Takai, 1997). This implies that foals on farms with endemic R. equi pneumonia are frequently exposed to high numbers of virulent bacteria (Takai et al, 1991b;Takai, 1997). Yet, the actual proportion of virulent strains in the environment is no indication for the prevalence of R. equi pneumonia (Martens et al, 2000;Takai et al, 2001a;Muscatello et al, 2006a;Cohen et al, 2008).…”

Section: Epidemology Of R Equi In Horse Infectionsmentioning

confidence: 99%

Molecular and infection biology of the horse pathogenRhodococcus equi

Bargen

Haas

2009

FEMS Microbiol Rev

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The soil actinomycete Rhodococcus equi is a pulmonary pathogen of young horses and AIDS patients. As a facultative intracellular bacterium, R. equi survives and multiplies in macrophages and establishes its specific niche inside the host cell. Recent research into chromosomal virulence factors and into the role of virulence plasmids in infection and host tropism has presented novel aspects of R. equi infection biology and pathogenicity. This review will focus on new findings in R. equi biology, the trafficking of R. equi-containing vacuoles inside host cells, factors involved in virulence and host resistance and on host-pathogen interaction on organismal and cellular levels.

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Prevalence of virulent Rhodococcus equi in isolates from soil and feces of horses from horse-breeding farms with and without endemic infections

Cited by 112 publications

References 7 publications

Rhodococcus equi pneumonia in an adult horse

Rhodococcus equi pneumonia in an adult horse

Clinical Evaluation of a Peptide‐ELISA based upon N‐terminal B‐cell Epitope of the VapA Protein for Diagnosis ofRhodococcus equiPneumonia in Foals

Molecular and infection biology of the horse pathogenRhodococcus equi

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