Transferable genes putatively conferring elevated minimum inhibitory concentrations of narasin in Enterococcus faecium from Swedish broilers

Nilsson, Oskar; Myrenås, Mattias; Ågren, Joakim

doi:10.1016/j.vetmic.2016.01.012

Cited by 18 publications

(34 citation statements)

References 14 publications

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“…Peer-reviewed literature has noted the public health implications of ionophore use, such as the potential linkage between transferrable decreased susceptibility to narasin and maintenance of vancomycin resistance in Enterococci [32]. The risks of ionophore (narasin, monensin and salinomycin) resistance development among Enterococci/gut flora have been cited [33,34] warranting further research to assess their impact on the environment (e.g., residues) and in humans.…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial use surveillance in broiler chicken flocks in Canada, 2013-2015

et al. 2017

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There is a paucity of data on the reason for and the quantity of antimicrobials used in broiler chickens in Canada. To address this, the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) implemented surveillance of antimicrobial use (AMU) and antimicrobial resistance (AMR) in broiler chicken flocks in 2013. Shortly after this (2014), the poultry industry banned the preventive use of ceftiofur in broiler chickens. The objectives of this analysis were to describe antimicrobial use (AMU) in Canadian broiler chickens between 2013 and 2015 (n = 378 flocks), compare these results to other animal species in Canada, to highlight the utility of farm surveillance data to evaluate the impact of a policy change, and to explore how different antimicrobial use metrics might affect data interpretation and communication. The surveillance data indicated that the poultry industry policy resulted in lower antimicrobial use and resistance, and they successfully captured information on when, where, why, and how much antimicrobials were being used. The majority of antimicrobials were administered via the feed (95%). The relative frequency of antimicrobial classes used in broiler chickens differed from those used in swine or in food animal production in general. Coccidiostats were the most frequently used antimicrobial classes (53% of total kg). Excluding coccidiostats, the top three most frequently used antimicrobial classes were bacitracin (53% of flocks), virginiamycin (25%) and avilamycin (21%), mainly used for the prevention of necrotic enteritis. Depending on the AMU metric utilized, the relative rankings of the top antimicrobials changed; hence the choice of the AMU metric is an important consideration for any AMU reporting. When using milligrams/Population Correction Unit (mg/PCU) the top three antimicrobial classes used were bacitracins (76 mg/PCU), trimethoprim-sulfonamides (24 mg/PCU), and penicillins (15 mg/PCU), whereas when using a number of Defined Daily Doses in animals using Canadian standards /1,000 chicken-days at risk (nDDDvetCA/1,000 CD) the ranking was bacitracins (223 nDDDvetCA/1,000 CD), streptogramins (118 nDDDvetCA/1,000 CD), and trimethoprim-sulfonamides (87 nDDDvetCA/1,000 CD). The median animal treatment days in feed for one cycle (ATD/cycle) during the three-year study were 34 ATD/cycle; this was equal to the mean age of the flocks at pre-harvest sampling day (days at risk), indicating that the studied flocks except those that were raised without antibiotics and organic, were fed with medicated rations throughout the observation period. Overall, more than half (59%) of antimicrobials used in broiler chickens were in classes not used in human medicine, such as ionophores and chemical coccidiostats aimed to prevent coccidiosis. Compared to grower-finisher pigs and in production animal species (national sales data), the mg/PCU of antimicrobials used in broiler chickens was relatively lower. The findings of this paper highlighted the importance of farm-level AMU surveillance in mea...

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Section: Discussionmentioning

confidence: 99%

Antimicrobial use surveillance in broiler chicken flocks in Canada, 2013-2015

et al. 2017

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“…Narasin resistance has been associated with a region on large transferrable plasmids encoding an uncharacterized ABC-type membrane transporter (Nilsson et al, 2016). In this study, we performed the first detailed characterization of this putative efflux pump and show that expression of the operon encoding it is induced by narasin, and that these genes are sufficient for achieving reduced susceptibility to narasin.…”

Section: Discussionmentioning

confidence: 90%

“…Previous publications report attempts to characterize polyether ionophore resistance mechanisms. The narAB operon occurs on pVEF3 (Nilsson et al, 2016), a sequenced and partially characterized plasmid from an E. faecium strain isolated from poultry in Norway (Sletvold et al, 2008). Sletvold et al (2008) cloned a putative ABC-type transporter encoded by an operon FIGURE 2 | Narasin induces transcription of the putative narasin resistance genes.…”

Section: Discussionmentioning

confidence: 99%

“…However, it has been shown that resistance to the polyether ionophore narasin can be transferred between strains of enterococci by conjugation (Nilsson et al, 2012), proving the existence of a genetically encoded narasin resistance mechanism. Evidence has also emerged suggesting that narasin resistance might be associated with an operon encoding an ABC-type membrane transporter (Nilsson et al, 2016), but this has not yet been directly confirmed experimentally.…”

Section: Introductionmentioning

confidence: 99%

“…However, it is not established if the narasin resistance mechanism offers cross-resistance to medically important antimicrobials. It has also been shown that narasin resistance and vancomycin resistance can be physically linked on transferrable plasmids (Sletvold et al, 2008;Nilsson et al, 2016), which indicates that use of narasin can co-select for vancomycin resistance. Vancomycin is used for the treatment of infections caused by Gram-positive bacteria (Alvarez et al, 2016), and is classified by WHO as a critically important antimicrobial for human medicine (WHO, 2017).…”

Section: Introductionmentioning

confidence: 99%

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NarAB Is an ABC-Type Transporter That Confers Resistance to the Polyether Ionophores Narasin, Salinomycin, and Maduramicin, but Not Monensin

et al. 2020

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Polyether ionophores are antimicrobial compounds used as feed additives in poultry feed to control diseases caused by coccidia. In addition to the anticoccidial activity of these compounds, polyether ionophores also contain antibacterial properties. Resistance to the polyether ionophore narasin was recently shown to exist on mobile plasmids in Enterococcus faecium and the resistance mechanism was suggested to be associated with a two-gene operon encoding an ABC-type transporter. In this study we demonstrate that the genes encoding the putative narasin resistance mechanism confers reduced susceptibility to the polyether ionophores narasin, salinomycin and maduramicin, but not to monensin and suggest that this resistance mechanism should be referred to as NarAB. Importantly, NarAB does not affect the susceptibility of E. faecium to any of the tested antimicrobial compounds that are used in clinical medicine. However, we show that conjugation in the presence of certain polyether ionophores increases the number of vancomycin resistant E. faecium suggesting that narasin and certain other polyether ionophores can contribute to the persistence of VRE in poultry populations.

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Impact assessment of the reduction or removal of ionophores used for controlling coccidiosis in the UK broiler industry

Parker¹,

Lister²,

Gittins

2021

Veterinary Record

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Coccidiosis is a complex parasitic disease ubiquitous in all types of poultry production. It can have both a direct effect on bird health and welfare with significant negative impacts on the production parameters and indirect effect as it predisposes to other pathogens. Ionophore coccidiostats have been used safely for over 45 years by poultry producers. Concerns have been raised that their use in livestock production could promote the development of antibiotic resistance, but their unique mode of action makes it unlikely. Conversely their removal can result in increased use of therapeutic antibiotics to treat disease posing a greater risk of antibiotic resistance development. Economic and environmental models examining the impact of the removal of ionophore coccidiostats from UK production suggest the annual cost to the broiler sector would be between £68.02-£109.95 million and result in an additional 84,000 tonnes CO 2 e being produced per annum. Any cost increase would make this wholesome and affordable animal protein less affordable to poorer sectors of society. Increased greenhouse gas production, demand for water and land as a result of less efficient production will impact on climate change targets.

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Transferable genes putatively conferring elevated minimum inhibitory concentrations of narasin in Enterococcus faecium from Swedish broilers

Cited by 18 publications

References 14 publications

Antimicrobial use surveillance in broiler chicken flocks in Canada, 2013-2015

Antimicrobial use surveillance in broiler chicken flocks in Canada, 2013-2015

NarAB Is an ABC-Type Transporter That Confers Resistance to the Polyether Ionophores Narasin, Salinomycin, and Maduramicin, but Not Monensin

Impact assessment of the reduction or removal of ionophores used for controlling coccidiosis in the UK broiler industry

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