The immunological response of foals to Rhodococcus equi: A review

Woolcock, J. B.; Mutimer, M. D.; Bowles, Pamela M.

doi:10.1016/0378-1135(87)90108-8

Cited by 27 publications

(14 citation statements)

References 12 publications

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“…Currently available diagnostic methods for R. equi pneumonia include culture and serology (1,11,21,26,27). However, the perceived lack of sensitivity of TW fluid culture (5,7,10,14,21) and the lack of specificity of serological techniques (6,8,9) have been problematic in the clinical setting.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Nucleic Acid Amplification, Serology, and Microbiologic Culture for Diagnosis ofRhodococcus equiPneumonia in Foals

Sellon¹,

Besser

Vivrette

et al. 2001

J Clin Microbiol

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Recently, a technique was described for amplification of Rhodococcus equi-specific chromosomal and vapA DNA from blood and tracheal wash fluids. It was hypothesized that this technique would be more sensitive than standard culture techniques or serology for diagnosis of R. equi pneumonia in foals. Tracheal wash fluid, nasal swabs, whole blood samples, and serum samples from 56 foals with pneumonia were analyzed. Final clinical diagnosis was determined by the attending clinician on the basis of final interpretation of all available information about each foal, including clinical presentation, diagnostic test results, response to therapy, and outcome. Clinical diagnosis was used as a final reference standard for calculation of sensitivity, specificity, and predictive values for PCR, serology using an agar gel immunodiffusion test, and tracheal wash fluid culture. PCR of tracheal wash fluid using primers that recognized the vapA virulence plasmid of R. equi had a diagnostic sensitivity of 100% and specificity of 90.6%. Sensitivity and specificity were 57.1 and 93.8%, respectively, for standard microbiologic culture of tracheal wash fluid and 62.5 and 75.9%, respectively, for serology. PCR of tracheal wash fluid is more sensitive and specific for diagnosis of R. equi pneumonia than are other available diagnostic tests.Rhodococcus equi is a gram-positive, pleomorphic coccobacillus that causes pneumonia and enteritis in foals less than 6 months of age and has been associated with a variety of suppurative processes in immune-suppressed humans (19). The organism is worldwide in distribution and commonly isolated from soil and environmental samples (2,4,23). Strains of R. equi isolated from sick foals uniformly contain an 85-to 90-kb plasmid that carries the gene responsible for expression of a 15-to 17-kDa antigen of undetermined function (vapA) (24,25). Environmental strains of R. equi not associated with equine disease do not contain this plasmid.The onset of clinical signs of R. equi pneumonia in foals is often insidious, and the infection is not recognized until severe abscessation has occurred and prognosis is poor. Culture of the organism from tracheal wash (TW) fluid is currently considered the "gold standard" for diagnosis (7). However, it can be difficult to reliably grow R. equi from a single TW sample, possibly because of prior antibiotic administration (12,14) or the presence of multiple pathogenic bacterial species (5, 21). Hillidge reported that only 7 of 11 foals (62%) with positive R. equi cultures at necropsy, and 57 of 89 foals (64%) with radiographic evidence of lung abscessation, yielded R. equi on culture of TW (10). Other studies reported a 100% positive result on cultures of TW fluid from foals later confirmed to have R. equi pneumonia at necropsy (14,17).Recently, a technique was described for amplification of R. equi-specific chromosomal and vapA DNA from blood and TW fluids (20). It was hypothesized that this technique would be more sensitive than standard culture techniques or serology for dia...

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Section: Discussionmentioning

confidence: 99%

Comparison of Nucleic Acid Amplification, Serology, and Microbiologic Culture for Diagnosis ofRhodococcus equiPneumonia in Foals

Sellon¹,

Besser

Vivrette

et al. 2001

J Clin Microbiol

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“…The basis of immunity in horses, particularly that relating to cell-mediated immune mechanisms, is largely unknown. Current understanding of immunity of horses to R. equi has recently been reviewed (187).…”

Section: Immunity To Infectionmentioning

confidence: 99%

Rhodococcus equi: an animal and human pathogen

1991

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Recent isolations of Rhodococcus equi from cavitatory pulmonary disease in patients with AIDS have aroused interest among medical microbiologists in this unusual organism. Earlier isolations from humans had also been in immunosuppressed patients following hemolymphatic tumors or renal transplantation. This organism has been recognized for many years as a cause of a serious pyogranulomatous pneumonia of young foals and is occasionally isolated from granulomatous lesions in several other species, in some cases following immunosuppression. The last decade has seen many advances in understanding of the epidemiology, pathogenesis, diagnosis, treatment, and immunity to infection in foals. The particular susceptibility of the foal is not understood but can be explained in part by a combination of heavy challenge through the respiratory route coinciding with declining maternally derived antibody in the absence of fully competent foal cellular immune mechanisms. R. equi is largely a soil organism but is widespread in the feces of herbivores. Its growth in soil is considerably improved by simple nutrients it obtains from herbivore manure. About one-third of human patients who have developed R. equi infections had contact in some way with herbivores or their manure. Others may have acquired infection from contact with soil or wild bird manure. R. equi is an intracellular parasite, which explains the typical pyogranulomatous nature of R. equi infections, the predisposition to infection in human patients with defective cell-mediated immune mechanisms, and the efficacy of antimicrobial drugs that penetrate phagocytic cells.

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“…Esta diferença, no entanto, não foi significativa. Woolcock et al (1987) constataram em seu trabalho, que animais pertencentes a propriedades com registros desta enfermidade, possuiam títulos muito maiores ao fator equi quando comparados com propriedades sem problema. Apesar do menor percentual de soropositividade ser encontrado justamente no Haras 2, o maior título médio geométrico de anticorpos foi detectado nesta propriedade, confirmando a constatação do pesquisador acima citado (Fig.…”

Section: Discussionunclassified

“…Rhodococcus equi é um cocobacilo gram positivo capsulado (Bisping & Amtsberg 1988, Carter & Cole 1990, Quinn et al 1994) que pode ser encontrado no trato gastrointestinal de equinos (Takai et al 1987, Woolcock et al 1987. Pode causar em potros de até 6 meses de idade uma broncopneumonia piogranulomatosa, enterite ulcerativa e linfoadenite mesentérica (Prescott & Hoffman 1993, Takai et al 1995.…”

Section: Introductionunclassified

Soroepidemiologia de Rhodococcus equi em equinos da região de Bagé, RS, pelo teste de inibição da hemólise sinérgica

et al. 1997

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Com o objetivo de avaliar a situação soroepidemiológica da infecção por Rhodococcus equi na região de Bagé, RS, foram testadas 290 amostras de soro sanguíneo de éguas e potros aparentemente sadios, obtidos de 6 haras com diferentes histórias de rodococose. Para relacionar o resultado sorológico com a presença deste agente bacteriano no trato intestinal destes animais, foram coletadas 123 amostras de fezes. O teste sorológico utilizado foi a inibição da hemólise sinérgica (IHS) que detecta anticorpos neutralizantes contra o "fator equi". Um percentual de 87,93% (255/290) dos animais amostrados apresentaram estes anticorpos. O título médio geométrico (GMT) destes anticorpos foi mais elevado nos potros do que nas éguas. A soropositividade destes equinos ao teste sorológico teve correlação com o isolamento do R. equi nas fezes dos respectivos animais. A maior taxa de isolamento de R. equi das fezes dos equinos e o maior GMT, ocorreu no único haras com casos clínicos recentes de enfermidade causada por esta bactéria. No entanto, todos os animais deste e dos demais haras, encontravam-se aparentemente sadios, sendo necessário, estabelecer em trabalho futuro, a possível relação entre títulos de anticorpos e sua importância na detecção da enfermidade.

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The immunological response of foals to Rhodococcus equi: A review

Cited by 27 publications

References 12 publications

Comparison of Nucleic Acid Amplification, Serology, and Microbiologic Culture for Diagnosis ofRhodococcus equiPneumonia in Foals

Comparison of Nucleic Acid Amplification, Serology, and Microbiologic Culture for Diagnosis ofRhodococcus equiPneumonia in Foals

Rhodococcus equi: an animal and human pathogen

Soroepidemiologia de Rhodococcus equi em equinos da região de Bagé, RS, pelo teste de inibição da hemólise sinérgica

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