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Home / Equine Research Bank / J Clin Microbiol / Emergence of rifampin-resistant Rhodococcus equi in an infec...
Journal of clinical microbiology1997; 35(7); 1904-1908; doi: 10.1128/jcm.35.7.1904-1908.1997

Emergence of rifampin-resistant Rhodococcus equi in an infected foal.

Abstract: To investigate the emergence of rifampin resistance in Rhodococcus equi strains isolated from foals and their environment in Japan, we compared the in vitro antimicrobial susceptibilities to rifampin of 640 isolates from 64 infected foals and 98 soil isolates from their horse-breeding farms. As a control, 39 human isolates from patients with and without AIDS were also tested for susceptibility to rifampin. All of the isolates showed rifampin sensitivity, except isolates from one infected foal and two patients with AIDS that showed rifampin resistance. To investigate the emergence of rifampin-resistant R. equi in the infected foal, which had received rifampin monotherapy for a month before euthanasia, 99 isolates of R. equi from the lesions and 20 isolates from the intestinal contents of the one foal with rifampin-resistant organisms were analyzed for rifampin susceptibilities, pathogenicities, and ribotypes. Of the 99 isolates from the lesions, all of which were virulent R. equi strains containing a virulence plasmid with a size of 85 or 90 kb, 90 (91%) isolates were rifampin resistant (MIC, > or = 12.5 microg/ml). On the other hand, of the 20 isolates from the intestinal contents, 11 (55%) isolates showed rifampin resistance (MIC, > or = 25 microg/ml), and 5 of them were avirulent R. equi strains. Among these 101 rifampin-resistant R. equi isolates with and without virulence plasmids characterized by ribotyping, 58 were type I, 20 were type II, 11 were type III, and 12 were type IV. These results demonstrated that at least eight different rifampin-resistant R. equi strains emerged concurrently and respectively from the different lesions and intestinal contents of the infected foal.
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Publication Date: 1997-07-01 PubMed ID: 9196223PubMed Central: PMC229871DOI: 10.1128/jcm.35.7.1904-1908.1997Google 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.

The research paper investigates the problem of growing resistance to the antibiotic rifampin in a bacterium called Rhodococcus equi, particularly in strains isolated from infected foals and their environments in Japan.

Research Methodology and Findings

  • The study assessed the levels of rifampin susceptibility in 640 R. equi strains — 64 strains from infected foals, 98 from the soil in horse-breeding farms and 39 from human cases, including some with AIDS.
  • Nearly all strains were sensitive to rifampin, except those from one foal and two AIDS patients, which demonstrated resistance.
  • The researchers chose to focus on why resistance had emerged in the infected foal which had been given rifampin as the sole treatment for a month before being euthanized.
  • From the lesions and intestinal contents of this foal, they analyzed 99 and 20 isolates, evaluating factors such as their rifampin susceptibilities, pathogenicities and ribotypes.
  • Of the strains gathered from the lesions, all of which were virulent forms of R. equi, 91% were found to be resistant to rifampin.
  • From the intestinal isolates, 55% demonstrated rifampin resistance.
  • Among these antibiotic-resistant strains, some were found to be harmless, avirulent strains of R. equi.
  • Upon further investigation, it was found that the antibiotic-resistant strains had a variety of ribotype patterns, showcasing at least eight distinct kinds of rifampin-resistant R. equi bacteria found in the lesions and intestinal contents.

Significance of the Study

  • This research offers valuable insights into the growing problem of antibiotic resistance among pathogens of veterinary relevance, specifically in the case of R. equi, which poses considerable risks for foals and can also infect humans, especially those with compromised immune systems such as AIDS patients.
  • By identifying the different types of rifampin-resistant R. equi strains co-existing within a single host, the researchers have helped to advance our understanding of how antibiotic resistance can evolve and proliferate within a population of pathogens.
  • This work may inform future efforts to tackle the problem of antibiotic resistance in R. equi and other bacterial pathogens in both human medicine and veterinary practice.

Cite This Article

APA
Takai S, Takeda K, Nakano Y, Karasawa T, Furugoori J, Sasaki Y, Tsubaki S, Higuchi T, Anzai T, Wada R, Kamada M. (1997). Emergence of rifampin-resistant Rhodococcus equi in an infected foal. J Clin Microbiol, 35(7), 1904-1908. https://doi.org/10.1128/jcm.35.7.1904-1908.1997

Publication

Journal of clinical microbiology
ISSN: 0095-1137
NlmUniqueID: 7505564
Country: United States
Language: English
Volume: 35
Issue: 7
Pages: 1904-1908

Researcher Affiliations

Takai, S
  • Department of Animal Hygiene, School of Veterinary Medicine and Animal Sciences, Kitasato University, Towada, Aomori, Japan. takai@vmas.kitasato-u.ac.jp
Takeda, K
    Nakano, Y
      Karasawa, T
        Furugoori, J
          Sasaki, Y
            Tsubaki, S
              Higuchi, T
                Anzai, T
                  Wada, R
                    Kamada, M

                      MeSH Terms

                      • Actinomycetales Infections / microbiology
                      • Actinomycetales Infections / veterinary
                      • Animals
                      • Antibiotics, Antitubercular / pharmacology
                      • Drug Resistance, Microbial
                      • Horse Diseases / microbiology
                      • Horses
                      • Humans
                      • Japan
                      • Microbial Sensitivity Tests
                      • Rhodococcus equi / drug effects
                      • Rhodococcus equi / isolation & purification
                      • Rifampin / pharmacology

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                      This article has been cited 13 times.
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