Cross-sectional studycited by the Tayebat archivefull text checked★ key study A-CHK-01 in-depth review

Resistant Staphylococcus on US meat

Multidrug-Resistant Staphylococcus aureus in US Meat and Poultry.

Overview

Waters AE et al.. Clin Infect Dis 2011 · PMID 21498385 · DOI 10.1093/cid/cir181

Almost half of meat samples carried S. aureus; about half of the isolates were multidrug-resistant, but for chicken it was about a quarter and no MRSA was found on chicken.

Does the study support the specific claim? Yes · Methodological quality: moderate

Original publication

Plain-language summary

Study explained simply

What did the researchers want to find out?: What are the prevalence, resistance and genotypes of S. aureus in US meat and poultry?
How was the study done?: Cross-sectional microbiological survey of retail meat and poultry with susceptibility testing and genotyping
How many people, animals or samples were studied?: 136 samples; Retail meat and poultry samples
What was actually found?: S. aureus: turkey 77%, pork 42%, chicken 41%, beef 37%; multidrug resistance 52% overall (chicken 26%); MRSA 3 isolates, none from chicken.
How large was the observed effect?: Proportions; comparisons between sample types
What do the results mean in everyday life?: Raw meat can carry resistant bacteria; hygiene and cooking matter.
What are the study's limitations?: Small convenience sample; mixed meats; no human outcomes; funded by an advocacy foundation; authors say public-health relevance is unclear.
What does it say about Elawady's specific claim?: Supports presence of resistant bacteria on meat.
Do the results apply to Germany and Europe?: Moderate; EU AMR monitoring covers MRSA.
What can explicitly not be concluded from this study?: Cannot show how many people get sick.

Scientific in-depth review

1. Full reference

Authors: Waters AE, Contente-Cuomo T, Buchhagen J, Liu CM, Watson L, Pearce K, Foster JT, Bowers J, Driebe EM, Engelthaler DM, Keim PS, Price LB
Journal: Clin Infect Dis
Year: 2011
Identifier: PMID 21498385 DOI 10.1093/cid/cir181 · PMC3079400
Verification: verified – PubMed E-utilities efetch, 2026-10-25
Retracted: no
Corrections: none
Extent checked: full text
Conflicts of interest and funding: Funded by the Pew Charitable Trusts (which campaigned on antibiotic use in food animals); two authors (L.B.P., A.E.W.) are Pew consultants; P.S.K. and D.M.E. part-own PathoGene LLC, whose femA PCR assay was used for confirmation.

2. Research question

What are the prevalence, resistance and genotypes of S. aureus in US meat and poultry?

3. Study design and population

Study design: Cross-sectional study – Cross-sectional microbiological survey of retail meat and poultry (brief report) with selective culture, PCR confirmation, MLST genotyping and broth-microdilution susceptibility testing
Population: Retail beef (ground), chicken (breasts, thighs), pork (chops, ground) and turkey (ground, cutlets) from 80 brands in 26 grocery stores
Country: USA (Chicago, Washington DC, Fort Lauderdale, Los Angeles, Flagstaff)
Period: Sampling dates not stated in the article (published 2011)
Sample size: 136 samples (46 chicken, 38 beef, 26 pork, 26 turkey); 79 unique S. aureus isolates
Inclusion and exclusion criteria: Convenience retail purchase across 5 cities; no stated sampling frame or randomisation.

4. Methods and endpoints

Exposure / intervention: Meat type
Comparator: Between sample types
Endpoints: S. aureus prevalence; multidrug resistance; genotypes
Statistical methods: Proportions; comparisons between sample types

5. Actual results

Results: S. aureus prevalence: turkey 77% (20/26), pork 42% (11/26), chicken 41% (19/46), beef 37% (14/38); overall 47%. 96% of isolates resistant to >=1 antimicrobial; multidrug resistance (>=3 classes, intermediate or complete) in 52% overall: turkey 79% (22/28), pork 64% (7/11), beef 35% (6/17), chicken 26% (6/23). ST5 and ST398 dominated chicken (74%) and turkey (79%) isolates. Only 3 MRSA isolates (ST8 from beef and turkey; ST5 from pork); no MRSA from chicken. One vancomycin-intermediate and one daptomycin-resistant isolate. Fluoroquinolone-resistant S. aureus uniquely prevalent in chicken.
Absolute risks: not applicable (contamination survey; no human exposure or infection data)
Authors' conclusion: Food animal-specific contamination suggested.

6. Strengths

Multi-city, multi-brand sampling
Molecular confirmation and MLST genotyping linking strain populations to meat type
Standardised CLSI susceptibility testing including drugs of last resort

7. Weaknesses

Small sample; authors state it was insufficient to estimate prevalence accurately
Convenience sampling; sampling period not reported
Multidrug resistance definition counts intermediate resistance
Chicken had the lowest MDR rate (26%) and no MRSA
No human colonisation or infection outcomes; authors state public-health relevance is unclear
Funder with advocacy position and commercial interest of authors in the PCR assay

8. Risk of bias

Orienting tool: none (microbiological prevalence survey; no standard RoB tool applies)
Type of assessment: structured assessment based on the full text by a single reviewer (no formal double review)
Full formal assessment: no
Overall risk of bias: some concerns
Rationale: Unchanged (some_concerns). Single-reviewer structured judgement; a formal assessment would need two independent reviewers.

8. Risk of bias
Domain	Judgement	Rationale
Sampling/selection	some concerns	Convenience purchases in 26 stores/5 cities; no sampling frame, dates not reported.
Laboratory measurement	low	Selective enrichment, PCR confirmation, MLST, CLSI broth microdilution.
Outcome definition	some concerns	MDR includes intermediate resistance, inflating MDR proportion.
Precision/reporting	some concerns	Small subgroup counts without CIs; detailed methods only in supplement.
Conflicts of interest	some concerns	Advocacy funder and author stake in assay company.

Full-text review (25 October 2026): Added per-meat prevalence and MDR (chicken 41% and 26%), MRSA 3 isolates none from chicken, ST5/ST398 in poultry, Pew funding and assay-company COI; archive derivation downgraded to partly overinterpreted. Bias unchanged.

9. Assessment of the statistical interpretation

Descriptive proportions without CIs; with 46 chicken samples and 23 chicken isolates, the chicken-specific estimates are very imprecise (e.g. 6/23 MDR).

10. Relevance to the specific claim

C-CHK-05.

11. Independent contrary findings

Cooking kills S. aureus; no infection data.

12. Transferability to Germany and Europe

Moderate; EU AMR monitoring covers MRSA.

13. Overall methodological judgement

Small descriptive survey showing that US retail meats commonly carry S. aureus, often multidrug-resistant; for chicken specifically the MDR proportion was lowest and no MRSA was found. It supports contamination of the food chain, not human harm via chicken.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	low
Directness	indirect
Reproducibility	partly replicated
Consistency with the overall evidence	consistent
Regional transferability	moderate
Adequacy of the interpretation (by the archive)	partly correct but over-interpreted

14. Open questions

Human colonisation/infection attributable to meat-borne S. aureus; representativeness; EU/Egyptian retail prevalence.

15. Linked fact checks

Industrial chicken is raised with routine antibiotics, and antibiotic-resistant bacteria (e.g., ESBL E. coli, MRSA, resistant Campylobacter, mcr-1) spread from poultry to humans via the food chain. – Studies supporting the claim

Use by the Tayebat archive

Note: according to the archive, the studies were compiled by the archive operators. Whether Dr. Elawady himself cited this study is not established.

What the archive says about the study: S. aureus contaminated 47% of US retail meat and poultry samples; 52% of isolates were multidrug-resistant.
A. What was actually studied?: S. aureus in US retail meat and poultry.
B. What did the authors find?: S. aureus in 47% of 136 samples (chicken 41%); MDR in 52% of isolates overall but 26% of chicken isolates; ST5/ST398 dominated chicken and turkey isolates; 3 MRSA isolates, none from chicken.
C. What conclusions do the authors themselves draw?: Retail meat and poultry are frequently contaminated with multidrug-resistant S. aureus, probably of food-animal origin, but the public-health relevance is unclear (EFSA judged MRSA risk from food low).
D. What does the archive derive from it?: Supports resistant bacteria from industrial chicken reaching consumers.
E. Is this derivation scientifically justified?: Partly. Headline numbers are quoted correctly and the 'ST398 concentrated in poultry' remark is broadly supported (ST5 and ST398 dominated chicken and turkey isolates). But the 47%/52% figures pool all meats; turkey drives the MDR figure, chicken had the lowest MDR rate (26%) and no MRSA, and the authors state public-health relevance is unclear.
Adequacy of the interpretation (by the archive): partly correct but over-interpreted