Evaluation of a widely used culture-based method for detection of livestock-associated meticillin-resistant Staphylococcus aureus (MRSA), Denmark and Norway, 2014 to 2016
Abstract:We evaluated a widely used culture-based method for detection of livestock-associated meticillin-resistant Staphylococcus aureus (LA-MRSA) in samples collected from pigs and the environment inside pig stables in Denmark and Norway. Selective enrichment in tryptic soy broth containing cefoxitin and aztreonam led to a high ratio of false-negative results (26%; 57/221). On this basis, we recommend reconsidering the use of selective enrichment for detection of LA-MRSA in animal and environmental samples.
“…The EURL-AR has recently updated the protocol for isolation of MRSA from animals and the environment, to reflect recent findings on the relative sensitivity of different selective culture methods (Larsen et al, 2017). The previous technical specifications (EFSA, 2012b) were based on the data available at that time and recommended a two-stage isolation method, rather than that currently recommended by the EURL-AR, which reflects recent findings and adopts a one-stage protocol (Larsen et al, 2017).…”
Section: Harmonisation Of Isolation Methods Of Mrsamentioning
confidence: 99%
“…The previous technical specifications (EFSA, ) were based on the data available at that time and recommended a two‐stage isolation method, rather than that currently recommended by the EURL‐AR, which reflects recent findings and adopts a one‐stage protocol (Larsen et al., ). The one‐stage method has been shown to have increased relative sensitivity when applied to pigs (Larsen et al., ), though differences between the methods were not apparent in studies on cattle or poultry (Nemeghaire et al., , ).…”
Section: Rationale For Revising the Current Amr Monitoring Systemmentioning
Proposals to update the harmonised monitoring and reporting of antimicrobial resistance (AMR) from a public health perspective in Salmonella, Campylobacter coli, Campylobacter jejuni, Escherichia coli, Enterococcus faecalis, Enterococcus faecium and methicillin-resistant Staphylococcus aureus (MRSA) from food-producing animals and derived meat in the EU are presented in this report, accounting for recent trends in AMR, data collection needs and new scientific developments. Phenotypic monitoring of AMR in bacterial isolates, using microdilution methods for testing susceptibility and interpreting resistance using epidemiological cut-off values is reinforced, including further characterisation of those isolates of E. coli and Salmonella showing resistance to extended-spectrum cephalosporins and carbapenems, as well as the specific monitoring of ESBL/AmpC/carbapenemase-producing E. coli. Combinations of bacterial species, food-producing animals and meat, as well as antimicrobial panels have been reviewed and adapted, where deemed necessary. Considering differing sample sizes, numerical simulations have been performed to evaluate the related statistical power available for assessing occurrence and temporal trends in resistance, with a predetermined accuracy, to support the choice of harmonised sample size. Randomised sampling procedures, based on a generic proportionate stratified sampling process, have been reviewed and reinforced. Proposals to improve the harmonisation of monitoring of prevalence, genetic diversity and AMR in MRSA are presented. It is suggested to complement routine monitoring with specific cross-sectional surveys on MRSA in pigs and on AMR in bacteria from seafood and the environment. Whole genome sequencing (WGS) of isolates obtained from the specific monitoring of ESBL/AmpC/carbapenemase-producing E. coli is strongly advocated to be implemented, on a voluntary basis, over the validity period of the next legislation, with possible mandatory implementation by the end of the period; the gene sequences encoding for ESBL/AmpC/carbapenemases being reported to EFSA. Harmonised protocols for WGS analysis/ interpretation and external quality assurance programmes are planned to be provided by the EU-Reference Laboratory on AMR.
“…The EURL-AR has recently updated the protocol for isolation of MRSA from animals and the environment, to reflect recent findings on the relative sensitivity of different selective culture methods (Larsen et al, 2017). The previous technical specifications (EFSA, 2012b) were based on the data available at that time and recommended a two-stage isolation method, rather than that currently recommended by the EURL-AR, which reflects recent findings and adopts a one-stage protocol (Larsen et al, 2017).…”
Section: Harmonisation Of Isolation Methods Of Mrsamentioning
confidence: 99%
“…The previous technical specifications (EFSA, ) were based on the data available at that time and recommended a two‐stage isolation method, rather than that currently recommended by the EURL‐AR, which reflects recent findings and adopts a one‐stage protocol (Larsen et al., ). The one‐stage method has been shown to have increased relative sensitivity when applied to pigs (Larsen et al., ), though differences between the methods were not apparent in studies on cattle or poultry (Nemeghaire et al., , ).…”
Section: Rationale For Revising the Current Amr Monitoring Systemmentioning
Proposals to update the harmonised monitoring and reporting of antimicrobial resistance (AMR) from a public health perspective in Salmonella, Campylobacter coli, Campylobacter jejuni, Escherichia coli, Enterococcus faecalis, Enterococcus faecium and methicillin-resistant Staphylococcus aureus (MRSA) from food-producing animals and derived meat in the EU are presented in this report, accounting for recent trends in AMR, data collection needs and new scientific developments. Phenotypic monitoring of AMR in bacterial isolates, using microdilution methods for testing susceptibility and interpreting resistance using epidemiological cut-off values is reinforced, including further characterisation of those isolates of E. coli and Salmonella showing resistance to extended-spectrum cephalosporins and carbapenems, as well as the specific monitoring of ESBL/AmpC/carbapenemase-producing E. coli. Combinations of bacterial species, food-producing animals and meat, as well as antimicrobial panels have been reviewed and adapted, where deemed necessary. Considering differing sample sizes, numerical simulations have been performed to evaluate the related statistical power available for assessing occurrence and temporal trends in resistance, with a predetermined accuracy, to support the choice of harmonised sample size. Randomised sampling procedures, based on a generic proportionate stratified sampling process, have been reviewed and reinforced. Proposals to improve the harmonisation of monitoring of prevalence, genetic diversity and AMR in MRSA are presented. It is suggested to complement routine monitoring with specific cross-sectional surveys on MRSA in pigs and on AMR in bacteria from seafood and the environment. Whole genome sequencing (WGS) of isolates obtained from the specific monitoring of ESBL/AmpC/carbapenemase-producing E. coli is strongly advocated to be implemented, on a voluntary basis, over the validity period of the next legislation, with possible mandatory implementation by the end of the period; the gene sequences encoding for ESBL/AmpC/carbapenemases being reported to EFSA. Harmonised protocols for WGS analysis/ interpretation and external quality assurance programmes are planned to be provided by the EU-Reference Laboratory on AMR.
“… Isolation of MRSA from food‐producing animals and the farm environment In 2018, the European Union Reference Laboratory‐Antimicrobial Resistance (EURL‐AR) published revised recommendations for the isolation of MRSA from food‐producing animals and the farm environment, which omit the use of a second enrichment step with cefoxitin and aztreonam (EURL, 2018). Prior to this, the recommended method for the detection of MRSA comprised a pre‐enrichment step and a selective enrichment step (known as the 2‐S method).The revised recommendations followed a study of Danish and Norwegian pig herds which evaluated the sensitivity of the 2‐S method by comparison with an alternative 1‐S method (whereby the selective enrichment step was bypassed), with results confirming that the 1‐S method resulted in a lower proportion of false‐negative results than the 2‐S method (Larsen et al., 2017). The authors urged caution in extrapolating the results to animals other than pigs and commented that previous studies in Belgium in poultry and cattle did not find significant differences between the performance of the two methods.Notably, changes to the recommended method of isolation may impact longitudinal studies, since direct comparison of the data obtained using the different protocols should be performed with caution.…”
Section: Antimicrobial Resistance In Meticillin‐resistant Staphylococcus Aureus24mentioning
Data on antimicrobial resistance (
AMR
) in zoonotic and indicator bacteria from humans, animals and food are collected annually by the
EU
Member States (
MS
s), jointly analysed by the
EFSA
and the
ECDC
and reported in a yearly
EU
Summary Report. The annual monitoring of
AMR
in animals and food within the
EU
is targeted at selected animal species corresponding to the reporting year. The 2018 monitoring specifically focussed on poultry and their derived carcases/meat, while the monitoring performed in 2019 specifically focused on pigs and calves under 1 year of age, as well as their derived carcases/meat. Monitoring and reporting of
AMR
in 2018/2019 included data regarding
Salmonella
,
Campylobacter
and indicator
Escherichia coli
isolates, as well as data obtained from the specific monitoring of presumptive
ESBL
‐/AmpC‐/carbapenemase‐producing
E. coli
isolates. Additionally, some
MS
s reported voluntary data on the occurrence of meticillin‐resistant
Staphylococcus aureus
in animals and food, with some countries also providing data on antimicrobial susceptibility. This report provides an overview of the main findings of the 2018/2019 harmonised
AMR
monitoring in the main food‐producing animal populations monitored, in related carcase/meat samples and in humans. Where available, data monitoring obtained from pigs, calves, broilers, laying hens and turkeys, as well as from carcase/meat samples and humans were combined and compared at the
EU
level, with particular emphasis on multidrug resistance, complete susceptibility and combined resistance patterns to critically important antimicrobials, as well as
Salmonella
and
E. coli
isolates possessing
ESBL
‐/AmpC‐/carbapenemase phenotypes. The outcome indicators for
AMR
in food‐producing animals such as complete susceptibility to the harmonised panel of antimicrobials in
E. coli
and the prevalence of
ESBL
‐/AmpC‐producing
E. coli
have been also specifically analysed over the period 2015–2019.
“…This was unexpected given the literature on potential for settled dust and/or surfaces in the vicinity of positive animals to be contaminated (Agerso, et al 2014; Bos, et al 2016; Broens, et al 2011; Friese, et al 2012; Peterson, et al 2012; Pletinckx, et al 2013) and given that the protocol used in this study employs a non-selective enrichment arm as well as an antimicrobial-selective enrichment arm and was adapted from EFSA guidelines for identification of MRSA from swine confinement facilities (Davis, et al 2012; Davis, et al 2016; EFSA 2010). False-negatives have been noted previously with the antimicrobial-selective enrichment arm in the context of MRSA detection (Larsen, et al 2017). In addition, it is possible that the protocol performance is weaker for S. aureus including MDRSA than for MRSA strain detection under settings where other staphylococcal species are prevalent and possibly dominant.…”
Occupational exposure to swine has been associated with increased Staphylococcus aureus carriage, including antimicrobial-resistant strains, and increased risk of infections. To characterize animal and environmental routes of worker exposure, we optimized methods to identify S. aureus on operations that raise swine in confinement with antibiotics (industrial hog operation: IHO) versus on pasture without antibiotics (antibiotic-free hog operation: AFHO). We associated findings from tested swine and environmental samples with those from personal inhalable air samplers on worker surrogates at one IHO and three AFHOs in North Carolina using a new One Health approach. We determined swine S. aureus carriage status by collecting swab samples from multiple anatomical sites, and we determined environmental positivity for airborne bioaerosols with inhalable and impinger samplers and a single-stage impactor (ambient air) cross-sectionally. All samples were analyzed for S. aureus, and isolates were tested for antimicrobial susceptibility, absence of scn (livestock marker), and spa type. Seventeen of twenty (85%) swine sampled at the one IHO carried S. aureus at >1 anatomical sites compared to none of 30 (0%) swine sampled at the three AFHOs. All S. aureus isolates recovered from IHO swine and air samples were scn negative and spa type t337; almost all isolates (62/63) were multidrug resistant. S. aureus was recovered from eight of 14 (67%) ambient air and two (100%) worker surrogate personal air samples at the one IHO, whereas no S. aureus isolates were recovered from 19 ambient and six personal air samples at the three AFHOs. Personal worker surrogate inhalable sample findings were consistent with both swine and ambient air data, indicating the potential for workplace exposure. IHO swine and the one IHO environment could be a source of potential pathogen exposure to workers, as supported by the detection of multidrug-resistant S. aureus (MDRSA) with livestock-associated spa type t337 among swine, worker surrogate personal air samplers and environmental air samples at the one IHO but none of the three AFHOs sampled in this study. Concurrent sampling of swine, personal swine worker surrogate air, and ambient airborne dust demonstrated that IHO workers may be exposed through both direct (animal contact) and indirect (airborne) routes of transmission. Investigation of the effectiveness of contact and respiratory protections is warranted to prevent IHO worker exposure to multidrug-resistant livestock-associated S. aureus and other pathogens.
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