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Higgins C, Huber L. Rhodococcus equi: challenges to treat infections and to mitigate antimicrobial resistance. J Equine Vet Sci 2023:104845. [PMID: 37295760 DOI: 10.1016/j.jevs.2023.104845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/01/2023] [Accepted: 06/03/2023] [Indexed: 06/12/2023]
Abstract
Rhodococcus equi, a gram-positive facultative intracellular pathogen and a soil saprophyte, is one of the most common causes of pneumonia in young foals. It poses a threat to the economy in endemic horse-breeding farms and to animal welfare annually. Many farms use thoracic ultrasonographic screening and antimicrobial treatment of subclinically affected foals as a preventive measure against severe R. equi infections. The wide use antimicrobials to treat subclinically affected foals has contributed to the emergence of multidrug resistant (MDR)-R. equi in both clinical isolates from sick foals and in the environment of horse-breeding farms. Alternatives to treat foals infected with MDR-R. equi are scarce and the impact of the emergence of MDR-R. equi in the environment of farms is still unknown. The aim of this review is to discuss the emergence of MDR-R. equi in the United States and the challenges faced to guide antimicrobial use practices. Reduction of antimicrobial use at horse-breeding farms is essential for the preservation of antimicrobial efficacy and, ultimately, human, animal, and environmental health.
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Affiliation(s)
- Courtney Higgins
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, 1130 Wire Road, Auburn, Alabama, USA 36832.
| | - Laura Huber
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, 1130 Wire Road, Auburn, Alabama, USA 36832.
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Sanz MG. Rhodococcus equi-What is New This Decade? Vet Clin North Am Equine Pract 2023; 39:1-14. [PMID: 36898784 DOI: 10.1016/j.cveq.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
Abstract
Foals become infected shortly after birth; most develop subclinical pneumonia and 20% to 30% develop clinical pneumonia that requires treatment. It is now well established that the combination of screening programs based on thoracic ultrasonography and treatment of subclinical foals with antimicrobials has led to the development of resistant Rhodococcus equi strains. Thus, targeted treatment programs are needed. Administration of R equi-specific hyperimmune plasma shortly after birth is beneficial as foals develop less severe pneumonia but does not seem to prevent infection. This article provides a summary of clinically relevant research published during this past decade.
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Bordin AI, Huber L, Sanz M, Cohen N. Rhodococcus equi Foal Pneumonia: Update on Epidemiology, Immunity, Treatment, and Prevention. Equine Vet J 2022; 54:481-494. [PMID: 35188690 DOI: 10.1111/evj.13567] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/03/2022] [Accepted: 02/17/2022] [Indexed: 11/25/2022]
Abstract
Pneumonia in foals caused by the bacterium Rhodococcus equi has a worldwide distribution and is a common cause of disease and death for foals. The purpose of this narrative review is to summarise recent developments pertaining to the epidemiology, immune responses, treatment, and prevention of rhodococcal pneumonia of foals. Screening tests have been used to implement earlier detection and treatment of foals with presumed subclinical R. equi pneumonia to reduce mortality and severity of disease. Unfortunately, this practice has been linked to the emergence of antimicrobial resistant R. equi in North America. Correlates of protective immunity for R. equi infections of foals remain elusive, but recent evidence indicates that innate immune responses are important both for mediating killing and orchestrating adaptive immune responses. A macrolide antimicrobial in combination with rifampin remains the recommended treatment for foals with R. equi pneumonia. Great need exists to identify which antimicrobial combination is most effective for treating foals with R. equi pneumonia and to limit emergence of antimicrobial-resistant strains. In the absence of an effective vaccine against R. equi, passive immunisation remains the only commercially-available method for effectively reducing the incidence of R. equi pneumonia. Because passive immunisation is expensive, labour-intensive, and carries risks for foals, great need exists to develop alternative approaches for passive and active immunisation.
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Affiliation(s)
- Angela I Bordin
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843-4475, USA
| | - Laura Huber
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, 36849, USA
| | - Macarena Sanz
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-6610, USA
| | - Noah Cohen
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, 77843-4475, USA
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Nielsen SS, Bicout DJ, Calistri P, Canali E, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortázar C, Herskin M, Michel V, Miranda Chueca MÁ, Padalino B, Pasquali P, Roberts HC, Spoolder H, Ståhl K, Velarde A, Viltrop A, Winckler C, Baldinelli F, Broglia A, Kohnle L, Alvarez J. Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial-resistant Rhodococcus equi in horses. EFSA J 2022; 20:e07081. [PMID: 35136423 PMCID: PMC8808660 DOI: 10.2903/j.efsa.2022.7081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rhodococcus equi (R. equi) was identified among the most relevant antimicrobial-resistant (AMR) bacteria in the EU for horses in a previous scientific opinion. Thus, it has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as in Article 9 and Article 8 for listing animal species related to the bacterium. The assessment has been performed following a methodology previously published. The outcome is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with uncertain outcome. According to the assessment here performed, it is uncertain whether AMR R. equi can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (10-66% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that the bacterium does not meet the criteria in Sections 1 and 2 (Categories A and B; 5-10% and 10-33% probability of meeting the criteria, respectively), and the AHAW Panel is uncertain whether it meets the criteria in Sections 3, 4 and 5 (Categories C, D and E; 10-66% probability of meeting the criteria in all three categories). The animal species to be listed for AMR R. equi according to Article 8 criteria are mainly horses and other species belonging to the Perissodactyla and Artiodactyla orders.
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Goebel B, Freise F, Venner M. Comparison of the efficacy of rifampin/azithromycin and rifampin/tulathromycin for the treatment of foals affected with pneumonia. EQUINE VET EDUC 2021. [DOI: 10.1111/eve.13575] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- B. Goebel
- Clinic for Horses University of Veterinary Medicine Hanover Hanover Germany
| | - F. Freise
- Institute for Biometry Epidemiology and Information Processing University of Veterinary Medicine Hanover Germany
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Leventhal HR, McKenzie HC, Estell K, Council-Troche M, Davis JL. Pharmacokinetics and pulmonary distribution of Draxxin ® (tulathromycin) in healthy adult horses. J Vet Pharmacol Ther 2021; 44:714-723. [PMID: 33719056 DOI: 10.1111/jvp.12968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 10/27/2020] [Accepted: 02/27/2021] [Indexed: 11/28/2022]
Abstract
The objective of this study was to determine the pharmacokinetics and tolerability of tulathromycin (Draxxin® ; 2.5 mg/kg once) after intramuscular (IM), subcutaneous (SC), and slow intravenous (IV) administration to six adult horses. A three-phase design and 4-week washout period were used. Drug concentrations in blood and bronchoalveolar lavage (BAL) samples were determined by ultra-performance liquid chromatography tandem mass spectrometry and pharmacokinetic parameters calculated using noncompartmental analysis. Following SC and IM administration, all horses exhibited sweating, discomfort, and periods of recumbency. As signs were more severe after SC administration this route was only used in 3/6 horses. Intravenous administration of tulathromycin was well tolerated in all horses. Mean bioavailability was 99.4% IM and 115% SC. Mean maximum plasma concentration was 645 ng/ml IM and 373 ng/ml SC. Mean half-life was 59.8 h, 54.8 h, and 57.9 h for IV, IM, and SC administration, respectively. Mean clearance was 3.25 ml/kg/min, and mean volume of distribution was 16.8 L/kg following IV administration. Drug was detectable in plasma and BAL samples for 120 h following all routes; however, adverse effects may prevent IM use and SC use is not recommended. Tulathromycin may be a practical and affordable antimicrobial for use in adult equine patients.
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Affiliation(s)
- Hannah R Leventhal
- Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, USA
| | - Harold C McKenzie
- Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, USA
| | - Krista Estell
- Marion duPont Scott Equine Medical Center, Virginia-Maryland College of Veterinary Medicine, Leesburg, VA, USA
| | - McAlister Council-Troche
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, USA
| | - Jennifer L Davis
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, USA
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Rosa B. Equine Drug Transporters: A Mini-Review and Veterinary Perspective. Pharmaceutics 2020; 12:pharmaceutics12111064. [PMID: 33171593 PMCID: PMC7695171 DOI: 10.3390/pharmaceutics12111064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 11/16/2022] Open
Abstract
Xenobiotic transport proteins play an important role in determining drug disposition and pharmacokinetics. Our understanding of the role of these important proteins in humans and pre-clinical animal species has increased substantially over the past few decades, and has had an important impact on human medicine; however, veterinary medicine has not benefitted from the same quantity of research into drug transporters in species of veterinary interest. Differences in transporter expression cause difficulties in extrapolation of drug pharmacokinetic parameters between species, and lack of knowledge of species-specific transporter distribution and function can lead to drug–drug interactions and adverse effects. Horses are one species in which little is known about drug transport and transporter protein expression. The purpose of this mini-review is to stimulate interest in equine drug transport proteins and comparative transporter physiology.
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Affiliation(s)
- Brielle Rosa
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, TRW 2D01, Calgary, Alberta T2N 4Z6, Canada
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Assessment of Antimicrobial Susceptibility of Virulent Strains of Rhodococcus equi Isolated From Foals and Soil of Horse Breeding Farms With and Without Endemic Infections. J Equine Vet Sci 2020; 91:103114. [PMID: 32684259 DOI: 10.1016/j.jevs.2020.103114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 03/27/2020] [Accepted: 04/27/2020] [Indexed: 12/21/2022]
Abstract
Rhodococcus equi is an opportunistic, intracellular saprophyte that causes severe pyogranulomatous pneumonia in foals. The bacterium displays in vitro susceptibility to many antibiotics. The highest efficacy against R. equi in vitro and in vivo is achieved by using a combination of rifampicin and macrolide antibiotics. Recent years have seen an upward trend in the minimum inhibitory concentration (MIC) of rifampicin and erythromycin, suggesting increasing resistance of R. equi to these antibiotics. The aim of the study was to determine the antimicrobial activity of 24 selected antibiotics against R. equi strains isolated from dead foals and from the environment of horse breeding farms with and without endemic R. equi infections. Minimum inhibitory concentration gradient strips were used to determine the lowest concentration of the antibiotic that inhibited the growth of R. equi. Based on normal MIC distribution, an epidemiologic cutoff values (ECOFF) were assessed for particular antibiotics and R. equi strains. The results were compared with ECOFFs for S. aureus, according to the European Committee on Antimicrobial Susceptibility Testing data. The data indicate that the lowest MIC values were obtained for clarithromycin, rifampicin, imipenem, and vancomycin. The majority of R. equi strains can be classified as wild type in relation to the majority of antibiotics. A small percentage of strains presented non-WT (NWT) with the exception of SXT, for which 35% of strains were classified as NWT. The lack of interpretative criteria for R. equi creates a real problem in the assessment of antibiotic sensitivity both for clinical and scientific purposes.
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Arnold‐Lehna D, Venner M, Berghaus LJ, Berghaus R, Giguère S. Changing policy to treat foals with
Rhodococcus equi
pneumonia in the later course of disease decreases antimicrobial usage without increasing mortality rate. Equine Vet J 2020; 52:531-537. [DOI: 10.1111/evj.13219] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 10/07/2019] [Accepted: 11/22/2019] [Indexed: 01/03/2023]
Affiliation(s)
| | | | | | - Roy Berghaus
- Department of Population Health University of Georgia Athens Georgia USA
| | - Steeve Giguère
- Large Animal Medicine University of Georgia Athens Georgia USA
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Wetzig M, Venner M, Giguère S. Efficacy of the combination of doxycycline and azithromycin for the treatment of foals with mild to moderate bronchopneumonia. Equine Vet J 2020; 52:613-619. [PMID: 31769897 DOI: 10.1111/evj.13211] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/21/2019] [Accepted: 11/15/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND Given the importance of rifampin in treatment protocols for tuberculosis in people, its use in veterinary medicine is under increasing scrutiny in some countries and alternatives might be needed in the near future. OBJECTIVES This study was set up to evaluate whether azithromycin combined with doxycycline is effective for the treatment of bronchopneumonia in foals and noninferior to the combination of azithromycin and rifampin. STUDY DESIGN This is a controlled, randomised and double-blinded clinical trial. Two hundred and forty foals on a farm endemic for infections caused by Rhodococcus equi were involved. METHODS Foals with ultrasonographic pulmonary lesions (lesion score 10-15 cm) were allocated to 3 groups: azithromycin-doxycycline orally (n = 81); azithromycin-rifampin orally (n = 81); or untreated controls (n = 78). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were considered treatment failures and removed from the study. RESULTS The proportion of foals that recovered was significantly higher for foals treated with azithromycin-doxycycline (80 of 81) or azithromycin-rifampin (81 of 81) compared with that of control foals (57 of 78). The difference in the percentage of efficacy of azithromycin-rifampin vs azithromycin-doxycycline was 1.2% (90% CI = -0.78% to 3.5%) which did not cross the predetermined noninferiority limit of 10%. Therefore, azithromycin-doxycycline was noninferior to azithromycin-rifampin within the predetermined noninferiority limit. MAIN LIMITATIONS The study was performed on a single farm, and recovery rates may differ in other locations. CONCLUSION Azithromycin-doxycycline was noninferior to azithromycin-rifampin for the treatment of bronchopneumonia in this farm.
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Affiliation(s)
- Maria Wetzig
- Equine Clinic, School of Veterinary Medicine, Hanover, Germany
| | | | - Steeve Giguère
- Veterinary Medical Center, University of Georgia, Athens, GA, USA
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Chen QF, Zhang YW. [Clinical effect of Saccharomyces boulardii powder combined with azithromycin sequential therapy in treatment of children with diarrhea secondary to Mycoplasma pneumoniae pneumonia]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2018; 20:116-120. [PMID: 29429459 PMCID: PMC7389243 DOI: 10.7499/j.issn.1008-8830.2018.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 01/10/2018] [Indexed: 06/08/2023]
Abstract
OBJECTIVE To investigate the clinical effect of Saccharomyces boulardii powder combined with azithromycin sequential therapy in the treatment of children with diarrhea secondary to Mycoplasma pneumoniae pneumonia. METHODS A total of 88 children with diarrhea secondary to Mycoplasma pneumoniae pneumonia between June 2015 and March 2017 were divided into control group and study group using a random number table, with 44 children in each group. The children in the control group were given routine treatment combined with azithromycin sequential therapy, and those in the study group were given oral Saccharomyces boulardii powder in addition to the treatment in the control group until the end of azithromycin sequential therapy. After the treatment ended, the two groups were compared in terms of time to improvement of clinical symptoms, length of hospital stay, clinical outcome, defecation frequency before and after treatment, condition of intestinal dysbacteriosis, and incidence of adverse events. RESULTS Compared with the control group, the study group had significantly shorter time to improvement of clinical symptoms and length of hospital stay (P<0.05). The study group had a significantly higher response rate than the control group (P<0.05). On days 3 and 5 of treatment, the study group had a significant reduction in defecation frequency compared with the control group (P<0.05). The study group had a significantly lower rate of intestinal dysbacteriosis than the control group (P<0.05). There was no significant difference in the incidence of adverse events between the two groups (P>0.05). CONCLUSIONS In the treatment of children with diarrhea secondary to Mycoplasma pneumoniae pneumonia, Saccharomyces boulardii powder combined with azithromycin sequential therapy can improve clinical symptoms, shorten the length of hospital stay, reduce defecation frequency and the incidence of intestinal dysbacteriosis, and improve clinical outcomes, and does not increase the risk of adverse events.
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Affiliation(s)
- Qi-Fen Chen
- Department of Pediatrics, Central Hospital of Jiangjin District, Chongqing 402260, China.
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Giguère S, Cohen ND. Controversies in therapy of infections caused byRhodococcus equiin foals. EQUINE VET EDUC 2017. [DOI: 10.1111/eve.12870] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- S. Giguère
- University of Georgia; Athens Georgia USA
| | - N. D. Cohen
- Texas A&M University; College Station Texas USA
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Rutenberg D, Venner M, Giguère S. Efficacy of Tulathromycin for the Treatment of Foals with Mild to Moderate Bronchopneumonia. J Vet Intern Med 2017; 31:901-906. [PMID: 28421633 PMCID: PMC5435035 DOI: 10.1111/jvim.14717] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 03/01/2017] [Accepted: 03/20/2017] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND There is conflicting data regarding the efficacy of tulathromycin for the treatment of foals with bronchopneumonia. HYPOTHESES Tulathromycin is effective for the treatment of bronchopneumonia in foals and noninferior to the combination of azithromycin and rifampin. ANIMALS A total of 240 foals on a farm endemic for infections caused by Rhodococcus equi. METHODS In a controlled, randomized, and double-blinded clinical trial, foals with ultrasonographic pulmonary lesions (abscess score 10-15 cm) were allocated to 3 groups: 1-tulathromycin IM q 7 days (n = 80); 2-azithromycin-rifampin, orally q24h (n = 80); or 3-untreated controls (n = 80). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were considered treatment failures and removed from the study. RESULTS The proportion of foals that recovered was significantly higher for foals treated with tulathromycin (70 of 79) or azithromycin-rifampin (76 of 80) compared to that of control foals (22 of 80). The difference in the percentage of efficacy of azithromycin-rifampin versus tulathromycin was 6.4% (90% CI = -0.72-13.5%). Given that the confidence interval crossed the predetermined noninferiority limit of 10%, the null hypothesis that the response rate in the azithromycin-rifampin group is superior to that of the tulathromycin group could not be rejected. Resolution of ultrasonographic lesions occurred faster in foals treated with azithromycin-rifampin than in foals treated with tulathromycin. CONCLUSION AND CLINICAL IMPORTANCE Tulathromycin was effective for the treatment of bronchopneumonia in foals at this farm but not as effective as the combination of azithromycin-rifampin.
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Affiliation(s)
- D Rutenberg
- Equine Clinic, School of Veterinary Medicine, Hanover, Germany
| | - M Venner
- Veterinary Clinic, Destedt, Germany
| | - S Giguère
- Veterinary Medical Center, University of Georgia, Athens, GA
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Giguère S. Treatment of Infections Caused by Rhodococcus equi. Vet Clin North Am Equine Pract 2017; 33:67-85. [DOI: 10.1016/j.cveq.2016.11.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Barton AK, Rieger M, Teschner D, Gehlen H. Procalcitonin—A Useful Biomarker for Pneumonia Associated with <i>Rhodococcus equi</i>? ACTA ACUST UNITED AC 2016. [DOI: 10.4236/mri.2016.52002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hildebrand F, Venner M, Giguère S. Efficacy of gamithromycin for the treatment of foals with mild to moderate bronchopneumonia. J Vet Intern Med 2015; 29:333-8. [PMID: 25619521 PMCID: PMC4858060 DOI: 10.1111/jvim.12504] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/13/2014] [Accepted: 10/13/2014] [Indexed: 12/02/2022] Open
Abstract
Background Gamithromycin is active in vitro against the bacterial agents most commonly associated with bronchopneumonia in older foals. However, the clinical efficacy and safety of this drug have not been investigated. Hypothesis Gamithromycin is effective for the treatment of bronchopneumonia in foals. Animals One hundred and twenty‐one foals on a farm endemic for infections caused by Rhodococcus equi. Methods In a controlled, randomized, and double blinded clinical trial, foals with ultrasonographic evidence of pulmonary abscesses (abscess score 8.0–20 cm) were randomly allocated in 3 treatment groups: (1) gamithromycin IM q7 days (n = 40); (2) azithromycin with rifampin, PO q24h (n = 40); or (3) no antimicrobial treatment (controls; n = 41). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were removed from the study. Results The proportion of foals that recovered without the need to be removed from the study was significantly higher for foals treated with gamithromycin (38 of 40) or azithromycin with rifampin (39 of 40) than for controls (32 of 41). Treatment with gamithromycin or with azithromycin‐rifampin resulted in a significantly faster decrease in the clinical score and abscess score compared to the controls. Adverse reactions characterized by colic (n = 18) and hind limb lameness (n = 14) were observed only in foals treated with gamithromycin. Conclusion and Clinical Importance Gamithromycin was noninferior to azithromycin with rifampin for the treatment of bronchopneumonia in the study population but had a higher frequency of adverse reactions.
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Affiliation(s)
- F Hildebrand
- Equine Clinic, School of Veterinary Medicine, Hanover, Germany
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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:e0136586. [PMID: 26305682 PMCID: PMC4549325 DOI: 10.1371/journal.pone.0136586] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 08/05/2015] [Indexed: 02/01/2023] Open
Abstract
In equids, susceptibility to disease caused by Rhodococcus equi occurs almost exclusively in foals. This distribution might be attributable to the age-dependent maturation of immunity following birth undergone by mammalian neonates that renders them especially susceptible to infectious diseases. Expansion and diversification of the neonatal microbiome contribute to development of immunity in the gut. Moreover, diminished diversity of the gastrointestinal microbiome has been associated with risk of infections and immune dysregulation. We thus hypothesized that varying composition or reduced diversity of the intestinal microbiome of neonatal foals would contribute to increased susceptibility of their developing R. equi pneumonia. The composition and diversity indices of the fecal microbiota at 3 and 5 weeks of age were compared among 3 groups of foals: 1) foals that subsequently developed R. equi pneumonia after sampling; 2) foals that subsequently developed ultrasonographic evidence of pulmonary abscess formation or consolidation but not clinical signs (subclinical group); and, 3) foals that developed neither clinical signs nor ultrasonographic evidence of pulmonary abscess formation or consolidation. No significant differences were found among groups at either sampling time, indicating absence of evidence of an influence of composition or diversity of the fecal microbiome, or predicted fecal metagenome, on susceptibility to subsequent R. equi pneumonia. A marked and significant difference identified between a relatively short interval of time appeared to reflect ongoing adaptation to transition from a milk diet to a diet including available forage (including hay) and access to concentrate fed to the mare.
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Cohen ND, Slovis NM, Giguère S, Baker S, Chaffin MK, Bernstein LR. Gallium maltolate as an alternative to macrolides for treatment of presumed Rhodococcus equi pneumonia in foals. J Vet Intern Med 2015; 29:932-9. [PMID: 25868480 PMCID: PMC4895420 DOI: 10.1111/jvim.12595] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 03/09/2015] [Accepted: 03/17/2015] [Indexed: 11/29/2022] Open
Abstract
Background Macrolide‐resistant isolates of Rhodococcus equi are emerging, prompting the search for clinically effective alternative antimicrobials. Hypothesis The proportion of foals with ultrasonographic evidence of pneumonia presumed to be caused by R. equi that had a successful outcome when administered gallium maltolate (GaM) PO would not be more than 10% inferior (ie, lower) than that of foals receiving standard treatment. Animals Fifty‐four foals with subclinical pulmonary abscesses among 509 foals at 6 breeding farms in Kentucky. Methods Controlled, randomized, prospective noninferiority study. Foals with ultrasonographic lesions >1 cm in diameter (n = 54) were randomly allocated to receive per os either clarithromycin combined with rifampin (CLR+R) or GaM, and followed up for 28 days by daily physical inspections and weekly (n = 1 farm) or biweekly (n = 4 farms) thoracic ultrasound examinations by individuals unaware of treatment‐group assignments. Treatment success was defined as resolution of ultrasonographically identified pulmonary abscesses within 28 days of initiating treatment. Noninferiority was defined as a 90% confidence interval for the observed difference in CLR+R minus GaM that was ≤10%. Results The proportion of GaM‐treated foals that resolved (70%; 14/20) was similar to that of foals treated with CLR+R (74%; 25/34), but we failed to demonstrate noninferiority for GaM relative to CLR+R; however, GaM was noninferior to CLR+R treatment when results from a noncompliant farm were excluded. Conclusions and Clinical Importance Gallium maltolate is not inferior to macrolides for treating foals with subclinical pneumonia. Use of GaM might reduce pressure for macrolide‐resistance in R. equi.
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Affiliation(s)
- Noah D Cohen
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
| | - Nathan M Slovis
- McGee Medicine Center, Hagyard Equine Medical Institute, Lexington, KY
| | - Steeve Giguère
- Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA
| | - Samantha Baker
- McGee Medicine Center, Hagyard Equine Medical Institute, Lexington, KY
| | - M Keith Chaffin
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, TX
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Reuss SM, Cohen ND. Update on Bacterial Pneumonia in the Foal and Weanling. Vet Clin North Am Equine Pract 2015; 31:121-35. [DOI: 10.1016/j.cveq.2014.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Activity of clarithromycin or rifampin alone or in combination against experimental Rhodococcus equi infection in mice. Antimicrob Agents Chemother 2015; 59:3633-6. [PMID: 25824218 DOI: 10.1128/aac.04941-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/23/2015] [Indexed: 01/07/2023] Open
Abstract
Treatment of mice with the combination of clarithromycin with rifampin resulted in a significantly lower number of Rhodococcus equi CFU in the organs of mice than treatment with either drug alone or placebo. There was no significant difference in the number of R. equi CFU between mice treated with clarithromycin monotherapy, rifampin monotherapy, or placebo. The combination of clarithromycin with rifampin conferred a clear advantage over either drug as monotherapy in this model of chronic R. equi infection.
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