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Home / Equine Research Bank / Appl Environ Microbiol / Epidemiology of Rhodococcus equi strains on Thoroughbred hor...
Applied and environmental microbiology2001; 67(5); 2167-2175; doi: 10.1128/AEM.67.5.2167-2175.2001

Epidemiology of Rhodococcus equi strains on Thoroughbred horse farms.

Abstract: Pulsed-field gel electrophoresis of restriction endonuclease-digested genomic DNA from a large collection of clinical isolates of Rhodococcus equi, an important pathogen of foals, was used to compare strain distribution between farms and over time. Forty-four strains were found among 209 isolates, with 5 of these accounting for over half the isolates and the 22 strains isolated more than once accounting for 90% of the isolates. The average genotypic diversity on each farm and in each year was found to be less than the genotypic diversity of the isolates taken as a whole, with 5.2% of the total diversity being due to differences between farms and 5.5% to differences between years. A small number of strains on each farm were found to have caused at least half the clinical cases of disease, and these varied between farms and, to a lesser extent, years. Most strains were found on more than one farm, and some very similar restriction patterns were found among isolates from different continents, indicating that strains can be very widespread. Multiple strains were isolated in five of the six cases in which more than one isolate from a single foal was examined, indicating that disease may commonly be caused by simultaneous infection with multiple strains. It was concluded that there are a number of different strains of R. equi which carry the vapA gene, and these strains tend to be widespread, but individual farms tend to have particular strains associated with them.
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Publication Date: 2001-04-25 PubMed ID: 11319096PubMed Central: PMC92851DOI: 10.1128/AEM.67.5.2167-2175.2001Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research focused on the distribution and diversity of Rhodococcus equi strains, a significant pathogen affecting foals, across Thoroughbred horse farms and over time. It discovered that while there are many different strains, certain strains are more commonly found on specific farms and multiple strains can infect a single foal simultaneously.

Methodology and Key Findings

  • The researchers used pulsed-field gel electrophoresis, a technique for separating large pieces of DNA by electric fields, to analyze the genomic DNA of 209 clinical isolates of Rhodococcus equi obtained from various Thoroughbred horse farms.
  • They discovered 44 strains among these isolates. Five of these strains accounted for over half of the total isolates. Moreover, 22 strains that were isolated more than once represented 90% of all isolates.
  • While there was genetic diversity present among all isolates, the genotypic diversity on individual farms and in specific years was less. About 5.2% of the total diversity could be attributed to differences between farms, while 5.5% was due to differences across years.
  • A few strains were prevalent on each farm, causing at least 50% of disease cases. These strains varied broadly from farm to farm and also differed to a lesser extent year-over-year.

Spread of Strains

  • Most of the strains were found on more than one farm. Some very similar strains were even noticed among isolates collected from different continents, suggesting that this pathogen can be disseminated extensively.
  • In five out of six cases where multiple isolates were collected from a single foal, different strains were found. This means that Rhodococcus equi infection can frequently be the result of simultaneous exposure to multiple strains.

Conclusions and Implications

  • The researchers concluded that a variety of R. equi strains exist, all of which carry the vapA gene – a gene often associated with virulence in this species.
  • While these strains are widespread, individual farms often have specific strains associated with them. This could have implications for disease control measures, suggesting that these interventions may need to be tailored to the predominant strains present on each farm.
  • The evidence that one foal can be infected by multiple strains simultaneously also underscores the complexity of disease management and the potential need for broad-spectrum treatment approaches.

Cite This Article

APA
Morton AC, Begg AP, Anderson GA, Takai S, Lämmler C, Browning GF. (2001). Epidemiology of Rhodococcus equi strains on Thoroughbred horse farms. Appl Environ Microbiol, 67(5), 2167-2175. https://doi.org/10.1128/AEM.67.5.2167-2175.2001

Publication

Applied and environmental microbiology
ISSN: 0099-2240
NlmUniqueID: 7605801
Country: United States
Language: English
Volume: 67
Issue: 5
Pages: 2167-2175

Researcher Affiliations

Morton, A C
  • Veterinary Preclinical Centre, Faculty of Veterinary Science, University of Melbourne, Victoria 3010, New South Wales, Australia.
Begg, A P
    Anderson, G A
      Takai, S
        Lämmler, C
          Browning, G F

            MeSH Terms

            • Actinomycetales Infections / epidemiology
            • Actinomycetales Infections / microbiology
            • Actinomycetales Infections / veterinary
            • Analysis of Variance
            • Animal Husbandry
            • Animals
            • Bacterial Proteins / genetics
            • Blotting, Southern
            • DNA, Bacterial / analysis
            • Electrophoresis, Gel, Pulsed-Field
            • Genes, rRNA
            • Horse Diseases / epidemiology
            • Horse Diseases / microbiology
            • Horses
            • Membrane Glycoproteins / genetics
            • Multivariate Analysis
            • RNA, Ribosomal, 16S / genetics
            • Rhodococcus equi / classification
            • Rhodococcus equi / genetics
            • Rhodococcus equi / isolation & purification
            • Ribotyping
            • Virulence Factors

            References

            This article includes 19 references
            1. Fuhrmann C, Lämmler C. [Characterization of Rhodococcus equi isolates from horse and man].. Berl Munch Tierarztl Wochenschr 1997 Feb;110(2):54-9.
              pubmed: 9139629
            2. Gordon DM. The genetic structure of Escherichia coli populations in feral house mice.. Microbiology (Reading) 1997 Jun;143 ( Pt 6):2039-2046.
              pubmed: 9202479doi: 10.1099/00221287-143-6-2039google scholar: lookup
            3. Haites RE, Muscatello G, Begg AP, Browning GF. Prevalence of the virulence-associated gene of Rhodococcus equi in isolates from infected foals.. J Clin Microbiol 1997 Jun;35(6):1642-4.
              pmc: PMC229812pubmed: 9163507doi: 10.1128/jcm.35.6.1642-1644.1997google scholar: lookup
            4. Hosmer DW, Lemeshow S. Applied logistic regression. New York, N.Y: John Wiley & Sons, Inc.; 1989.
            5. Kanno T, Asawa T, Ito H, Takai S, Tsubaki S, Sekizaki T. Restriction map of a virulence-associated plasmid of Rhodococcus equi.. Plasmid 1993 Nov;30(3):309-11.
              pubmed: 8302941doi: 10.1006/plas.1993.1065google scholar: lookup
            6. Lasker BA, Brown JM, McNeil MM. Identification and epidemiological typing of clinical and environmental isolates of the genus Rhodococcus with use of a digoxigenin-labeled rDNA gene probe.. Clin Infect Dis 1992 Aug;15(2):223-33.
              pubmed: 1381620doi: 10.1093/clinids/15.2.223google scholar: lookup
            7. Nei M. Estimation of average heterozygosity and genetic distance from a small number of individuals.. Genetics 1978 Jul;89(3):583-90.
              pmc: PMC1213855pubmed: 17248844doi: 10.1093/genetics/89.3.583google scholar: lookup
            8. Rainey FA, Burghardt J, Kroppenstedt RM, Klatte S, Stackebrandt E. Phylogenetic analysis of the genera Rhodococcus and Nocardia and evidence for the evolutionary origin of the genus Nocardia from within the radiation of Rhodococcus species. Microbiology 1995;141:523–528.
            9. Sambrook J, Fritsch EF, Maniatis T. Molecular cloning—a laboratory manual. 2nd ed. Vol. 2. Cold Spring Harbor, N.Y: Cold Spring Harbor Laboratory Press; 1989.
            10. Selander RK, Caugant DA, Ochman H, Musser JM, Gilmour MN, Whittam TS. Methods of multilocus enzyme electrophoresis for bacterial population genetics and systematics.. Appl Environ Microbiol 1986 May;51(5):873-84.
              pmc: PMC238981pubmed: 2425735doi: 10.1128/aem.51.5.873-884.1986google scholar: lookup
            11. Soedarmanto I, Oliveira R, Lämmler C, Dürrling H. Further studies on Rhodococcus equi isolated from bovine lymphadenitis. Med Sci Res 1998;26:835–837.
            12. Soedarmanto I, Oliveira R, Lämmler C, Dürrling H. Identification and epidemiological relationship of Rhodococcus equi isolated from cases of lymphadenitis in cattle.. Zentralbl Bakteriol 1997 Nov;286(4):457-67.
              pubmed: 9440194doi: 10.1016/s0934-8840(97)80047-3google scholar: lookup
            13. Soedarmanto I, Zhicai W, Setyamahanani A, Lämmler C. Pheno- and genotyping of Rhodococcus equi isolated from faeces of healthy horses and cattle.. Res Vet Sci 1998 May-Jun;64(3):181-5.
              pubmed: 9690599doi: 10.1016/s0034-5288(98)90121-7google scholar: lookup
            14. Takai S. Epidemiology of Rhodococcus equi infections: a review.. Vet Microbiol 1997 Jun 16;56(3-4):167-76.
              pubmed: 9226831doi: 10.1016/s0378-1135(97)00085-0google scholar: lookup
            15. Takai S, Fortiner G, Pronost S, Rahal K, Becu T, Begg A, Browning G, Prescott J F. Genetic analysis of virulent Rhodococcus equi based on restriction fragment length polymorphism of virulence plasmids: a molecular approach for epidemiology of virulent R. equi worldwide. In: Werney U, Wade J F, Mumford J A, Kaaden O-R, editors. Equine infectious diseases VIII: Proceedings of the Eighth International Conference. R &W Publications. 1998. pp. 587–588. Newmarket, United Kingdom.
            16. Takai S, Koike K, Ohbushi S, Izumi C, Tsubaki S. Identification of 15- to 17-kilodalton antigens associated with virulent Rhodococcus equi.. J Clin Microbiol 1991 Mar;29(3):439-43.
              pmc: PMC269796pubmed: 2037660doi: 10.1128/jcm.29.3.439-443.1991google scholar: lookup
            17. Takai S, Sekizaki T, Ozawa T, Sugawara T, Watanabe Y, Tsubaki S. Association between a large plasmid and 15- to 17-kilodalton antigens in virulent Rhodococcus equi.. Infect Immun 1991 Nov;59(11):4056-60.
              pmc: PMC258996pubmed: 1937765doi: 10.1128/iai.59.11.4056-4060.1991google scholar: lookup
            18. Takai S, Takeda K, Nakano Y, Karasawa T, Furugoori J, Sasaki Y, Tsubaki S, Higuchi T, Anzai T, Wada R, Kamada M. Emergence of rifampin-resistant Rhodococcus equi in an infected foal.. J Clin Microbiol 1997 Jul;35(7):1904-8.
              pmc: PMC229871pubmed: 9196223doi: 10.1128/jcm.35.7.1904-1908.1997google scholar: lookup
            19. Tenover FC, Arbeit RD, Goering RV, Mickelsen PA, Murray BE, Persing DH, Swaminathan B. Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing.. J Clin Microbiol 1995 Sep;33(9):2233-9.
              pmc: PMC228385pubmed: 7494007doi: 10.1128/jcm.33.9.2233-2239.1995google scholar: lookup

            Citations

            This article has been cited 15 times.
            1. Xu Z, Hao X, Li M, Luo H. Rhodococcus equi-Derived Extracellular Vesicles Promoting Inflammatory Response in Macrophage through TLR2-NF-κB/MAPK Pathways. Int J Mol Sci 2022 Aug 28;23(17).
              doi: 10.3390/ijms23179742pubmed: 36077142google scholar: lookup
            2. Cohen ND, Kahn SK, Bordin AI, Gonzales GM, da Silveira BP, Bray JM, Legere RM, Ramirez-Cortez SC. Association of pneumonia with concentrations of virulent Rhodococcus equi in fecal swabs of foals before and after intrabronchial infection with virulent R. equi. J Vet Intern Med 2022 May;36(3):1139-1145.
              doi: 10.1111/jvim.16409pubmed: 35322902google scholar: lookup
            3. Álvarez-Narváez S, Giguère S, Cohen N, Slovis N, Vázquez-Boland JA. Spread of Multidrug-Resistant Rhodococcus equi, United States. Emerg Infect Dis 2021 Feb;27(2):529-537.
              doi: 10.3201/eid2702.203030pubmed: 33496218google scholar: lookup
            4. Álvarez-Narváez S, Giguère S, Anastasi E, Hearn J, Scortti M, Vázquez-Boland JA. Clonal Confinement of a Highly Mobile Resistance Element Driven by Combination Therapy in Rhodococcus equi. mBio 2019 Oct 15;10(5).
              doi: 10.1128/mBio.02260-19pubmed: 31615959google scholar: lookup
            5. Nakagawa R, Moki H, Hayashi K, Ooniwa K, Tokuyama K, Kakuda T, Yoshioka K, Takai S. A case report on disseminated Rhodococcus equi infection in a Japanese black heifer. J Vet Med Sci 2018 May 18;80(5):819-822.
              doi: 10.1292/jvms.18-0064pubmed: 29593168google scholar: lookup
            6. Javed R, Taku AK, Sharma RK, Badroo GA. Molecular characterization of Rhodococcus equi isolates in equines. Vet World 2017 Jan;10(1):6-10.
              doi: 10.14202/vetworld.2017.6-10pubmed: 28246441google scholar: lookup
            7. Witkowski L, Rzewuska M, Takai S, Chrobak-Chmiel D, Kizerwetter-Świda M, Feret M, Gawryś M, Witkowski M, Kita J. Molecular characterization of Rhodococcus equi isolates from horses in Poland: pVapA characteristics and plasmid new variant, 85-kb type V. BMC Vet Res 2017 Jan 26;13(1):35.
              doi: 10.1186/s12917-017-0954-2pubmed: 28122544google scholar: lookup
            8. McQueen CM, Dindot SV, Foster MJ, Cohen ND. Genetic Susceptibility to Rhodococcus equi. J Vet Intern Med 2015 Nov-Dec;29(6):1648-59.
              doi: 10.1111/jvim.13616pubmed: 26340305google scholar: lookup
            9. Whitfield-Cargile CM, Cohen ND, Suchodolski J, Chaffin MK, McQueen CM, Arnold CE, Dowd SE, Blodgett GP. Composition and Diversity of the Fecal Microbiome and Inferred Fecal Metagenome Does Not Predict Subsequent Pneumonia Caused by Rhodococcus equi in Foals. PLoS One 2015;10(8):e0136586.
              doi: 10.1371/journal.pone.0136586pubmed: 26305682google scholar: lookup
            10. Witkowski L, Rzewuska M, Cisek AA, Chrobak-Chmiel D, Kizerwetter-Świda M, Czopowicz M, Welz M, Kita J. Prevalence and genetic diversity of Rhodococcus equi in wild boars (Sus scrofa), roe deer (Capreolus capreolus) and red deer (Cervus elaphus) in Poland. BMC Microbiol 2015 May 22;15:110.
              doi: 10.1186/s12866-015-0445-1pubmed: 25997952google scholar: lookup
            11. Flaminio MJ, Nydam DV, Marquis H, Matychak MB, Giguère S. Foal monocyte-derived dendritic cells become activated upon Rhodococcus equi infection. Clin Vaccine Immunol 2009 Feb;16(2):176-83.
              doi: 10.1128/CVI.00336-08pubmed: 19109450google scholar: lookup
            12. Rodríguez-Lázaro D, Lewis DA, Ocampo-Sosa AA, Fogarty U, Makrai L, Navas J, Scortti M, Hernández M, Vázquez-Boland JA. Internally controlled real-time PCR method for quantitative species-specific detection and vapA genotyping of Rhodococcus equi. Appl Environ Microbiol 2006 Jun;72(6):4256-63.
              doi: 10.1128/AEM.02706-05pubmed: 16751540google scholar: lookup
            13. Asoh N, Watanabe H, Fines-Guyon M, Watanabe K, Oishi K, Kositsakulchai W, Sanchai T, Kunsuikmengrai K, Kahintapong S, Khantawa B, Tharavichitkul P, Sirisanthana T, Nagatake T. Emergence of rifampin-resistant Rhodococcus equi with several types of mutations in the rpoB gene among AIDS patients in northern Thailand. J Clin Microbiol 2003 Jun;41(6):2337-40.
              doi: 10.1128/JCM.41.6.2337-2340.2003pubmed: 12791846google scholar: lookup
            14. Yerlikaya Z, Karagülle B, Otlu B, Muz A. From Paddock to Foal: Prevalence and Genotypic Diversity of Rhodococcus equi on Stud Farms in Türkiye. Vet Sci 2026 Jan 10;13(1).
              doi: 10.3390/vetsci13010072pubmed: 41600728google scholar: lookup
            15. Saeed S, Fawzy G, Shah A, John M. A Silent Invader: Asymptomatic Rhodococcus Infection Unmasked in A Patient with Ectopic ACTH-Dependent Cushing's Syndrome. Eur J Case Rep Intern Med 2025;12(9):005711.
              doi: 10.12890/2025_005711pubmed: 40927801google scholar: lookup
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