Resistance studies of erythromycin and rifampin for Rhodococcus equi over a 10-year period.
Abstract: This study sought to determine whether an increase in resistance of Rhodococcus equi to the antibiotics rifampin and erythromycin occurred over a 10-year period. This was carried out by the use of E test strips for rifampin and erythromycin to determine the MIC (minimum inhibitory concentration) values of Rhodococcus equi to this combination of antibiotics.The findings of this study indicated that there was an increase in resistance of Rhodococcus equi to rifampin and erythromycin over the 10-year period. The MIC for rifampin increased from 0.081 μg/ml in 1996 to 0.187 μg/ml in 2006 and from 0.258 μg/ml for erythromycin during the years prior to 2000 to 0.583 μg/ml in 2006.This finding suggests that there may be a problem in the treatment of Rhodococcus equi infections in foals in the future, particularly as the number of drugs available for treatment of Rhodococcus equi infection is limited because of the intracellular capabilities of this bacterium. Antibiotics used in its treatment have to be able to penetrate the polysaccharide cell wall of Rhodococcus equi as well as the alveolar macrophages in which the bacterium is capable of surviving.
Publication Date: 2007-12-01 PubMed ID: 21851690PubMed Central: PMC3113830DOI: 10.1186/2046-0481-60-12-728Google Scholar: Lookup
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- Journal Article
Summary
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The research article examines how the resistance of the bacterium Rhodococcus equi to the antibiotics erythromycin and rifampin has increased over a decade. The conclusion drawn is that the increasing resistance could pose challenges to treating infections caused by Rhodococcus equi in the future.
Research Methodology
- Using E test strips, the study tested for Rhodococcus equi’s minimum inhibitory concentrations (MICs) to rifampin and erythromycin (antibiotics used to treat conditions caused by this bacterium).
- The MIC value indicates the lowest concentration of an antimicrobial agent that inhibits visible growth of a microorganism.
- By assessing MIC values from the 10-year span, the researchers aimed to determine if resistance to these antibiotics increased over time.
Findings
- Over the 10-year period, there was a significant increase in the MICs of Rhodococcus equi for both rifampin and erythromycin.
- The MIC for rifampin markedly increased from 0.081 μg/ml in 1996 to 0.187 μg/ml in 2006.
- Similarly, the MIC for erythromycin also saw an increase, moving from 0.258 μg/ml before 2000 to 0.583 μg/ml in 2006.
Implications
- This upward trend in resistance suggests that in the future there might be challenges in treating infections caused by Rhodococcus equi, especially in foals, using the currently available antibiotics.
- This issue is furthermore complicated by the limited number of drugs able to combat Rhodococcus equi infection due to the bacteria’s ability to exist intracellularly. To be effective, treatments not only have to penetrate the bacterium’s robust polysaccharide cell wall but also the alveolar macrophages where the bacterium can survive.
Cite This Article
APA
Buckley T, McManamon E, Stanbridge S.
(2007).
Resistance studies of erythromycin and rifampin for Rhodococcus equi over a 10-year period.
Ir Vet J, 60(12), 728-731.
https://doi.org/10.1186/2046-0481-60-12-728 Publication
Researcher Affiliations
- Irish Equine Centre, Johnstown, Naas, Co, Kildare, Ireland. tbuckley@equine-centre.ie.
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Citations
This article has been cited 11 times.- Lord J, Carter C, Smith J, Locke S, Phillips E, Odoi A. Antimicrobial resistance among Streptococcus equi subspecies zooepidemicus and Rhodococcus equi isolated from equine specimens submitted to a diagnostic laboratory in Kentucky, USA. PeerJ 2022;10:e13682.
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