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Irish veterinary journal2015; 68; 23; doi: 10.1186/s13620-015-0051-4

Minimum inhibitory concentrations of erythromycin and rifampin for Rhodococcus equi during the years 2007-2014.

Abstract: Rhodococcus equi is a gram positive, intracellular pathogen of foals worldwide. The aim of this study was to determine whether there was an increasing resistance occurring in Rhodococcus equi towards the antibiotics rifampin and erythromycin over a seven year period. The investigation was carried out with the use of E test strips (epsilometers) for rifampin and erythromycin in order to determine the Minimum Inhibitory Concentrations (MIC) values of Rhodococcus equi to these antibiotics. Results: The main results of this study found that the mean MICs were higher for erythromycin than for rifampin for every year analysed apart from 2008. The results highlight that 75 % (6/8) of the mean MICs for erythromycin were above the threshold of susceptibility of 0.5 μg/ml and one of the yearly mean MICs for rifampin (2008) was above the level of ≤ 1 μg/ml. Two soil samples analysed had high MIC values of 2 μg/ml and 3 μg/ml for rifampin and erythromycin respectively. These samples can be said to have acquired resistance as they are above 1 μg/ml. Conclusions: The significance of these findings is that R. equi is already a problematic pathogen to treat and if the bacteria keeps gaining resistance to these antibiotics at rate that has been shown over the last decade, then a new form of treatment will have to be introduced. Further research into the genomics of Rhodococcus equi will, in time, shed more light on possible alternatives such as vaccines or new, more effective antimicrobials.
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Publication Date: 2015-10-06 PubMed ID: 26445669PubMed Central: PMC4594895DOI: 10.1186/s13620-015-0051-4Google 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 examines the increasing resistance of Rhodococcus equi, a globally prevalent infection in foals, to antibiotics rifampin and erythromycin over seven years. The results indicate a significant rise in the bacteria’s resistance to these drugs, suggesting the need for research into new treatments.

Study Aim and Methodology

  • The purpose of this study was to investigate whether the Rhodococcus equi bacteria, responsible for causing infections in foals, is growing increasingly resistant to common antibiotics erythromycin and rifampin over a period of seven years (2007-2014).
  • For scientifically assessing this possible resistance, the researchers employed a tool called E test strips (epsilometers). These strips are employed to figure out the Minimum Inhibitory Concentrations (MIC) – the lowest concentration of an antimicrobial agent that prevents visible growth of a microorganism.

Major Findings

  • Throughout nearly every year analyzed, the median MICs for erythromycin were higher than those for rifampin, except in 2008. Which suggests that Rhodococcus equi may have a higher resistance to erythromycin.
  • 75% of the mean MICs for erythromycin surpassed the susceptibility threshold of 0.5 μg/ml, indicating a significant level of resistance. Moreover, the mean MIC for rifampin in 2008 was also high, going above the tolerance level of ≤ 1 μg/ml.
  • Two examined soil samples had high MIC values (2 μg/ml for rifampin and 3 μg/ml for erythromycin), indicating acquired resistance as these values are above 1 μg/ml.

Study Implications and Conclusion

  • The findings are concerning since Rhodococcus equi is already a difficult-to-treat pathogen. If the bacteria’s resistance to erythromycin and rifampin continues to increase at the rate identified in this study, the development of alternative treatment strategies will become a necessity.
  • The researchers propose that further investigation into the genomics of Rhodococcus equi could provide insight into potential alternatives, such as new vaccines or more effective antimicrobials.

Cite This Article

APA
Fenton CS, Buckley TC. (2015). Minimum inhibitory concentrations of erythromycin and rifampin for Rhodococcus equi during the years 2007-2014. Ir Vet J, 68, 23. https://doi.org/10.1186/s13620-015-0051-4

Publication

Irish veterinary journal
ISSN: 0368-0762
NlmUniqueID: 0100762
Country: Ireland
Language: English
Volume: 68
Pages: 23
PII: 23

Researcher Affiliations

Fenton, Caitriona S
  • University College Dublin, Belfield, Dublin, Ireland.
Buckley, Thomas C
  • Irish Equine Centre, Johnstown, Naas, Co. Kildare Ireland.

References

This article includes 13 references
  1. Muscatello G, Leadon DP, Klayt M, Ocampo-Sosa A, Lewis DA, Fogarty U, Buckley T, Gilkerson JR, Meijer WG, Vazquez-Boland JA. Rhodococcus equi infection in foals: the science of 'rattles'.. Equine Vet J 2007 Sep;39(5):470-8.
    doi: 10.2746/042516407X209217pubmed: 17910275google scholar: lookup
  2. Goodfellow M, Alderson G. The actinomycete-genus Rhodococcus: a home for the "rhodochrous" complex.. J Gen Microbiol 1977 May;100(1):99-122.
    doi: 10.1099/00221287-100-1-99pubmed: 874450google scholar: lookup
  3. Giguère S, Roberts GD. Association between radiographic pattern and outcome in foals with pneumonia caused by Rhodococcus equi.. Vet Radiol Ultrasound 2012 Nov-Dec;53(6):601-4.
    doi: 10.1111/j.1740-8261.2012.01964.xpubmed: 22742474google scholar: lookup
  4. Venner M, Rödiger A, Laemmer M, Giguère S. Failure of antimicrobial therapy to accelerate spontaneous healing of subclinical pulmonary abscesses on a farm with endemic infections caused by Rhodococcus equi.. Vet J 2012 Jun;192(3):293-8.
    doi: 10.1016/j.tvjl.2011.07.004pubmed: 21924651google scholar: lookup
  5. Flynn O, Quigley F, Costello E, O'Grady D, Gogarty A, Mc Guirk J, Takai S. Virulence-associated protein characterisation of Rhodococcus equi isolated from bovine lymph nodes.. Vet Microbiol 2001 Feb 12;78(3):221-8.
    doi: 10.1016/S0378-1135(00)00297-2pubmed: 11165066google scholar: lookup
  6. Muscatello G. Rhodococcus equi pneumonia in the foal--part 2: diagnostics, treatment and disease management.. Vet J 2012 Apr;192(1):27-33.
    doi: 10.1016/j.tvjl.2011.08.009pubmed: 22036870google scholar: lookup
  7. Giguère S, Cohen ND, Chaffin MK, Slovis NM, Hondalus MK, Hines SA, Prescott JF. Diagnosis, treatment, control, and prevention of infections caused by Rhodococcus equi in foals.. J Vet Intern Med 2011 Nov-Dec;25(6):1209-20.
    doi: 10.1111/j.1939-1676.2011.00835.xpubmed: 22092608google scholar: lookup
  8. Vázquez-Boland JA, Giguère S, Hapeshi A, MacArthur I, Anastasi E, Valero-Rello A. Rhodococcus equi: the many facets of a pathogenic actinomycete.. Vet Microbiol 2013 Nov 29;167(1-2):9-33.
    doi: 10.1016/j.vetmic.2013.06.016pubmed: 23993705google scholar: lookup
  9. 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
  10. Buckley T, McManamon E, Stanbridge S. Resistance studies of erythromycin and rifampin for Rhodococcus equi over a 10-year period.. Ir Vet J 2007 Dec 1;60(12):728-31.
    doi: 10.1186/2046-0481-60-12-728pmc: PMC3113830pubmed: 21851690google scholar: lookup
  11. Boyen F, Pasmans F, Haesebrouck F. Acquired antimicrobial resistance in equine Rhodococcus equi isolates.. Vet Rec 2011 Jan 29;168(4):101a.
    doi: 10.1136/vr.c5289pubmed: 21257598google scholar: lookup
  12. Burton AJ, Giguère S, Sturgill TL, Berghaus LJ, Slovis NM, Whitman JL, Levering C, Kuskie KR, Cohen ND. Macrolide- and rifampin-resistant Rhodococcus equi on a horse breeding farm, Kentucky, USA.. Emerg Infect Dis 2013 Feb;19(2):282-5.
    doi: 10.3201/eid1902.121210pmc: PMC3559061pubmed: 23347878google scholar: lookup
  13. Berghaus LJ, Giguère S, Guldbech K. Mutant prevention concentration and mutant selection window for 10 antimicrobial agents against Rhodococcus equi.. Vet Microbiol 2013 Oct 25;166(3-4):670-5.
    doi: 10.1016/j.vetmic.2013.07.006pubmed: 23915992google scholar: lookup

Citations

This article has been cited 5 times.
  1. Zúñiga MP, Badillo E, Abalos P, Valencia ED, Marín P, Escudero E, Galecio JS. Antimicrobial susceptibility of Rhodococcus equi strains isolated from foals in Chile. World J Microbiol Biotechnol 2023 Jun 22;39(9):231.
    doi: 10.1007/s11274-023-03677-2pubmed: 37347336google scholar: lookup
  2. Swanner KD, Patel R, Nguyen TT, Patel FN, Magadia R, Rifai AO, Davenport M. A Rare Presentation of Rhodococcus Equi Bacteremia as a Result of Right Upper Arm Cellulitis: A Case Report and Literature Review. Cureus 2023 Apr;15(4):e38295.
    doi: 10.7759/cureus.38295pubmed: 37255906google scholar: lookup
  3. Gray AD, Bernhardt E. Are nitrogen and carbon cycle processes impacted by common stream antibiotics? A comparative assessment of single vs. mixture exposures. PLoS One 2022;17(1):e0261714.
    doi: 10.1371/journal.pone.0261714pubmed: 34986185google scholar: lookup
  4. Ruocco NA 3rd, Luedke LK, Fortier LA, Ducharme NG, Reesink HL. Rhodococcus equi Joint Sepsis and Osteomyelitis Is Associated With a Grave Prognosis in Foals. Front Vet Sci 2019;6:503.
    doi: 10.3389/fvets.2019.00503pubmed: 31993449google scholar: lookup
  5. Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
    doi: 10.1111/avj.70003pubmed: 40903020google scholar: lookup
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