Macrolide- and Rifampin-Resistant<i>Rhodococcus equi</i>on a Horse Breeding Farm, Kentucky, USA

Burton, Alexandra J.; Giguère, Steeve; Sturgill, Tracy L.; Berghaus, Londa J.; Slovis, Nathan M.; Whitman, Jeremy L.; Levering, Court; Kuskie, Kyle R.; Cohen, Noah D.

doi:10.3201/eid1902.121210

Cited by 96 publications

(80 citation statements)

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“…These data indicate that TUS for screening for R. equi pneumonia would result in overuse of antimicrobials when foals with positive results of screening are treated with macrolides (+/− rifampin), the preferred treatment for R. equi pneumonia. Treating more foals with macrolides would result in increased prevalence of adverse adverse effects in foals and their dams and increased costs for treatments, and also can contribute to emergence of bacterial resistance 12, 13…”

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confidence: 99%

Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals

Madrigal

Shaw

Witkowski

et al. 2016

Veterinary Internal Medicne

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BackgroundCurrent screening tests for Rhodococcus equi pneumonia in foals lack adequate accuracy for clinical use. Real‐time, quantitative PCR (qPCR) for virulent R. equi in feces has not been systematically evaluated as a screening test.ObjectiveThe objective of this study was to evaluate the accuracy of qPCR for vapA in serially collected fecal samples as a screening test for R. equi pneumonia in foals.AnimalsOne hundred and twenty‐five foals born in 2011 at a ranch in Texas.MethodsFecal samples were collected concurrently with thoracic ultrasonography (TUS) screening examinations at ages 3, 5, and 7 weeks. Affected (pneumonic) foals (n = 25) were matched by age and date‐of‐birth to unaffected (n = 25) and subclinical (ie, having thoracic TUS lesions but no clinical signs of pneumonia) foals (n = 75). DNA was extracted from feces using commercial kits and concentration of virulent R. equi in feces was determined by qPCR.ResultsSubsequently affected foals had significantly greater concentrations of vapA in feces than foals that did not develop pneumonia (unaffected and subclinical foals) at 5 and 7 weeks of age. Accuracy of fecal qPCR, however, was poor as a screening test to differentiate foals that would develop clinical signs of pneumonia from those that would remain free of clinical signs (including foals with subclinical pulmonary lesions attributed to R. equi) using receiver operating characteristic (ROC) methods.Conclusions and Clinical ImportanceIn the population studied, serial qPCR on feces lacked adequate accuracy as a screening test for clinical R. equi foal pneumonia.

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Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals

Madrigal

Shaw

Witkowski

et al. 2016

Veterinary Internal Medicne

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“…Until recently, reports of macrolide resistance have been rare. Over the past decade, there has been an increase in the frequency of detection of macrolide and rifampin resistance in isolates of R. equi from pneumonic foals (8), and resistant isolates were cultured from up to 40% of affected foals at a large breeding farm (9). Because foals infected with macrolide and rifampin-resistant isolates are significantly more likely to die (8), it is of paramount importance to obtain accurate in vitro susceptibility testing results early in the disease process.…”

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Comparison of Etest, Disk Diffusion, and Broth Macrodilution for In Vitro Susceptibility Testing of Rhodococcus equi

et al. 2015

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“…azithromycin, erythromycin and roxithromycin. Macrolide resistance in R. equi has also been reported (Burton et al, 2013;Liu et al, 2014). A glycopeptides resistance operon vanO having potential implications in R. equi therapy has been described (Gudeta et al, 2014).…”

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Resistotypes of Rhodococcus equi isolated from foals with respiratory problems

Chhabra¹,

Khurana²,

Kapoor³

et al. 2016

JEBAS

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KEYWORDS Rhodococcus equi Foal Resistotype Marker ABSTRACTRhodococcus equi has been recognized primarily as a respiratory pathogen of equines particularly of foals between one and four months of age. R. equi is ranked among the most important disease problems in equines especially because of its high prevalence and mortality rate. R. equi being an intracellular pathogen is very fastidious and requires prolonged specific antibiotic combination therapy lasting up to three months for successful treatment. This assumes further importance as no effective vaccination is available for prevention. It has zoonotic potential and may be responsible for infection in immunocompromised humans. This study is aimed at analyzing the distribution pattern of the resistotypes (R-types) of various isolates of R. equi in different areas of Haryana and Rajasthan, India. Antimicrobial susceptibility pattern of R. equi isolates was determined by Kirby Bauer disc diffusion method following the Clinical and Laboratory Standards Institute (CLSI) guidelines. A total of twenty eight clinical isolates of R. equi from foals from different parts of Haryana and Rajasthan were used in this study. Antibiogram of R. equi isolates with 33 antibiotics revealed ten distinct R-types: R-type 1 to R-type 10, on the basis of variable results of four antibiotics i.e. amoxycillin, gentamycin, colistin and streptomycin. Out of ten resistotypes obtained the relative frequencies of R-1 resistotype and R-4 resistotype were found to be high i.e. 28.57% and 25%, respectively. Differentiation of R. equi strains into R-types is an important tool for therapeutics. In addition to direct foal management, it may have implication in identifying the source and spread of infection, and as epidemiological marker to correlate various isolates from various places, ultimately helping in therapeutics for timely control.

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Macrolide- and Rifampin-ResistantRhodococcus equion a Horse Breeding Farm, Kentucky, USA

Cited by 96 publications

References 10 publications

Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals

Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals

Comparison of Etest, Disk Diffusion, and Broth Macrodilution for In Vitro Susceptibility Testing of Rhodococcus equi

Resistotypes of Rhodococcus equi isolated from foals with respiratory problems

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