A review of the current state of antimicrobial susceptibility test methods forBrachyspira

Abstract

Abstract:The re-emergence of swine dysentery (Brachyspira-associated muco-haemorrhagic colitis) since the late 2000s has illuminated diagnostic challenges associated with this genus. The methods used to detect, identify, and characterize Brachyspira from clinical samples have not been standardized, and laboratories frequently rely heavily on in-house techniques. Particularly concerning is the lack of standardized methods for determining and interpreting the antimicrobial susceptibility of Brachyspira spp. The integration of laboratory data into a treatment plan is a critical component of prudent antimicrobial usage. Therefore, the lack of standardized methods is an important limitation to the evidence-based use of antimicrobials. This review will focus on describing the methodological limitations and inconsistencies between current susceptibility testing schemes employed for Brachyspira, provide an overview of what we do know about the susceptibility of these organisms, and suggest future directions to improve and standardize diagnostic strategies.Key words: Brachyspira, susceptibility test, method standardization, veterinary diagnostics, swine dysentery.Résumé : La réémergence de la dysenterie porcine (colite muco-hémorragique associée à Brachyspira) depuis la fin des années 2000 a mis en lumière les défis diagnostiques associés à ce genre. Les méthodes utilisées pour détecter, identifier et caractériser Brachyspira à partir d'échantillons cliniques n'ont jamais été standardisées et les laboratoires dépendent fréquemment et fortement de méthodes maison. L'absence de méthodes standardisées pour déterminer et interpréter la susceptibilité antimicrobienne de Brachyspira spp. est particulièrement inquiétante. L'intégration de données expérimentales à un plan de traitement est une composante importante de l'utilisation avisée d'antimicrobiens, et l'absence de méthodes standardisées constitue conséquemment une limite importante à l'utilisation d'antimicrobiens fondée sur des données probantes. Cette synthèse se concentrera sur la description des limites méthodologiques et des incohérences actuelles qui existent entre les programmes de tests utilisés pour Brachyspira, fournira un exposé général de ce que les auteurs connaissent de la susceptibilité de ces organismes et suggérera des orientations afin d'améliorer et standardiser les stratégies diagnostiques. [Traduit par la Rédaction] Mots-clés : Brachyspira, test de susceptibilité, standardisation de méthodes, diagnostics vétérinaires, dysenterie porcine.

Identification of a New Antimicrobial Resistance Gene Provides Fresh Insights Into Pleuromutilin Resistance in Brachyspira hyodysenteriae, Aetiological Agent of Swine Dysentery

“…Antibiotic treatment is critical for control of disease on infected units, and is also part of treatment and elimination programmes for SD, especially as no commercial vaccines against SD are available. In most jurisdictions however the number of efficacious antibiotics available to treat SD is severely limited (Hampson, 2012 ; Kulathunga and Rubin, 2017 ). For example, in the UK antibiotics authorised for the treatment of SD are limited to the pleuromutilins tiamulin and valnemulin, the macrolides tylosin and tylvalosin, and lincomycin (a lincosamide); although off-label use of other antibiotics (e.g., doxycycline) is permitted under the cascade system, a risk-based decision tree that allows veterinarians to employ clinical judgement to treat an animal with an alternative product when there is no appropriate authorised veterinary medicine available.…”

In vitro evaluation of gentamicin activity against Spanish field isolates of Brachyspira hyodysenteriae

“…Thus, susceptibility testing of clinical isolates recovered from SD outbreaks has become an important need for the swine practitioner. Among aminoglycosides, gentamicin has been proposed for the treatment and prevention of Brachyspira diseases in pigs [2,8,9]. Its mechanism of action involves the inhibition of bacterial protein synthesis by binding to the 16S rRNA in the 30S subunit of ribosomes [10].…”

“…Its mechanism of action involves the inhibition of bacterial protein synthesis by binding to the 16S rRNA in the 30S subunit of ribosomes [10]. Nowadays, gentamicin is labelled for the treatment of SD in the United States and several European countries such as Spain or Italy but it has not been widely used for this purpose [2,9] and there is limited information on Brachyspira resistance to this antibiotic. The present study aimed to determine the in vitro susceptibility of B. hyodysenteriae eld isolates against gentamicin and investigate the molecular mechanisms underlying decreased susceptibility to gentamicin.…”

In vitro evaluation of gentamicin activity against Spanish field isolates of Brachyspira hyodysenteriae

“…Among aminoglycosides, gentamicin has been proposed for the treatment and prevention of Brachyspira diseases in pigs [ 2 , 8 , 9 ]. Its mechanism of action involves the inhibition of bacterial protein synthesis by binding to the 16S rRNA in the 30S subunit of ribosomes [ 10 ].…”

“…Its mechanism of action involves the inhibition of bacterial protein synthesis by binding to the 16S rRNA in the 30S subunit of ribosomes [ 10 ]. Nowadays, gentamicin is labelled for the treatment of SD in the United States and several European countries such as Spain and Italy but it has not been widely used for this purpose [ 2 , 9 ] and there is limited information on Brachyspira resistance to this antibiotic. The present study aimed to determine the in vitro susceptibility of B. hyodysenteriae field isolates against gentamicin and investigate the molecular mechanisms underlying decreased susceptibility to gentamicin.…”