Comparative genomics of dairy-associated Staphylococcus aureus from selected sub-Saharan African regions reveals milk as reservoir for human-and animal-d
The main results reproduced: recomputed values matched the published ones within tolerance.
Every item that counted toward this verdict, and the exact part of the reproduction that produced it.
- ✓Same input data as the authors
- ✓Reported values were directly comparable
- ✓No relevant deviation in data/preprocessing
- ✓No authors-side cause for any deviation
- ✓Reported values are derivable from the shared data
- ✓Any deviation was negligible
- ✓The central claim held under reproduction
- ✓Overall, the reproduction was clean
- Every checked point held up.
A 0–100 reproducibility-quality score from the per-question grades, shown as a z-score: standard deviations above (+) or below (−) the mean of comparable assessments.
▸Reproduction agent’s raw note
1:1 REPRODUCED. Third-party-tool-on-paper's-data (BRIEF P16): re-ran sanger-pathogens/assembly-stats v1.0.1 + GenBank .gbff feature parsing + tseemann/mlst v2.35.0 on all 20 deposited ILS S. aureus assemblies (PRJNA310553 -> 20 GCA accessions) on «our HPC» SLURM «job», compared to Table 1. 115/120 cells exact: genome length 20/20, contigs 20/20, CDS 20/20, genes 20/20 all EXACT; GC% 19/20 exact + 1 within 0.1 rounding (ILS-37). MLST 16/20 exact; the 4 non-exact MLST cells (ILS-12/49/71 unassignable, ILS-37 ST130->ST3602) are PubMLST S. aureus database evolution since 2022, NOT data discrepancies - the deterministic columns from the same assemblies all match. No fabrication signal: every reported Table 1 number is derivable from the deposited data. NOT attempted (out of scope): the pathogenwatch/cgMLST 956-genome phylogeny + clades (external web service), phenotypic AMR, yersiniabactin screen over external genomes.
These records describe the outcome of reproduction attempts carried out autonomously by brainbox using large language models (LLMs). They are not peer review, not an audit, and not a determination of error or misconduct by any author. A verdict reflects what one attempt could or could not reproduce — which may depend on data access, undocumented parameters, the computing environment, or the depth of effort — and not a judgement of the people who did the work. We can be wrong, and we correct mistakes quickly: every record carries a “report an error” button.
Assessment versions
Every reproduction run is kept as an immutable version — anchored to the data as it stood, with a tamper-evident chain hash. A rerun (e.g. after an author updates a deposit) adds a new version; the previous one stays on record.
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v1 current initial assessment Score 89assessed: 2026-06-21 ⛓ 4f4987873e8f
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Provenance — full disclosure
When this reproduction was carried out, which methodology version was used, and by whom — so the record can be audited and checked independently.
- Reproduced
- 2026-06-21
- Rubric version
- v1.0
- Assessed by
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🤖 AI curator · claude (ai-curator room) · v1.0 · run #1 2026-06-21no human curator yet
- Last updated
- 2026-08-05
Provisional, curator- or AI-assessed, and independently checkable. A reproduction outcome states what one attempt could reproduce — not a judgement of the authors.
Deep full-text extraction
Model: sonnetThe study aimed to use whole genome sequencing to characterize the population structure and genetic composition of sub-Saharan African dairy-associated S. aureus strains, in order to determine their relationship to human and animal strains and the public health risks they pose.
- ★ Milk serves as a reservoir for both human- and animal-derived S. aureus strains in sub-Saharan Africa finding
- ★ A putative novel siderophore (yersiniabactin-like) operon was identified in multiple strains forming a distinct animal-associated clade with strains of global origin finding
- ★ The putative siderophore shares high genetic identity with that of Streptococcus equi, suggesting possible horizontal gene transfer mechanism
- ★ Dairy-derived African S. aureus strains harbor virulence genes (pvl, scn, various enterotoxins, leucocidins) and antibiotic resistance genes, indicating public health risk requiring a One Health approach finding
- cgMLST-based WGS analysis provides high-resolution insight into S. aureus population structure compared to conventional MLST method
- PCR primers were designed targeting four core genes of the putative yersiniabactin siderophore operon for strain screening method
- Growth under iron-limited conditions was compared between yersiniabactin operon-positive and -negative strains to assess siderophore functional relevance method
| Assay | System | Perturbation | Readout | Platform |
|---|---|---|---|---|
| Whole genome sequencing / de novo assembly | 20 S. aureus ILS strains from camel, cow, and goat milk (Côte d'Ivoire, Kenya, Somalia) | none | genome sequence, size, GC content, gene/CDS counts, contigs | Illumina MiSeq 2x150bp, Nextera XT library prep, CLC Genomics Workbench v11 |
| cgMLST phylogenetic analysis | 956 S. aureus genomes (20 ILS + 936 global reference/African genomes) | none | clade assignment, phylogenetic relationships | WGSA.net / pathogen.watch |
| Comparative genomics / singleton (unique CDS) analysis | Reduced set of 79 S. aureus reference and African strains | none | presumably unique CDS per strain/group | EDGAR v2.3 |
| Virulence factor gene screening | S. aureus ILS genome assemblies | none | presence of virulence factor genes (bidirectional best hit, 70% identity cutoff) | VFDB with blastp |
| Antimicrobial resistance gene and plasmid replicon screening | S. aureus ILS genome assemblies | none | presence of ARGs and plasmid replicons | Mobtyper, ResFinder v4.1, Center for Genomic Epidemiology tools |
| Antibiotic disk diffusion sensitivity testing | 20 S. aureus ILS strains | bacitracin, ciprofloxacin, cefoxitin, penicillin, teicoplanin, fosfomycin, tetracycline disks | zone of inhibition / antibiotic sensitivity classification | CLSI disk diffusion method |
| Yersiniabactin operon BLAST screening and PCR validation | 928 S. aureus genomes; subset of strains for PCR | none | presence/absence of yersiniabactin siderophore operon genes (amp ligase, non-ribosomal peptide synthetase, polyketide synthase/synthetase) | CLC Genomics Workbench BLAST database; PCR with agarose gel electrophoresis |
| Growth curve analysis under iron limitation | S. aureus strains, yersiniabactin operon-positive (n=11) vs negative (n=18) | iron-chelated (Chelex-100) deferrated TSB (DTSB) vs normal TSB | lag phase (LPD), maximum growth rate (MGR), area under curve (AUC) from OD600 growth curves | Eon microtiter plate reader (BioTek); R package 'opm'; GraphPad Prism v9.3.1 |
- – The 20 ILS genomes had sizes of 2.66-2.82 Mb, GC content of 32.6-32.7%, and encoded 2,676-2,960 genes, assembled into 21-134 contigs
- – cgMLST of 956 S. aureus genomes identified seven clades, with five major clades represented by reference strains (USA300/COL/Newman/NCTC8325, TW20/JKD6008, Mu50/N315/JH1, HO50960412, MRSA252)
- – African human isolates (n=33) were distributed among all clades except clade 1, with the majority clustering in clades 6 and 7 n=33 total, n=12 in clades 6/7
- – A putative novel siderophore operon was detected in multiple strains forming a distinct animal-related clade containing strains of global origin
- – The putative siderophore showed high genetic identity to the siderophore of Streptococcus equi
- – Dairy isolates carried virulence genes including pvl, scn (human immune evasion factor), enterotoxins, leucocidins, and various antibiotic resistance genes
- – Yersiniabactin operon-positive (n=11) and negative (n=18) strains were compared for growth under iron limitation
- count 20 (number of African S. aureus dairy isolates (ILS strains) sequenced)
- count 956 (total genomes analyzed in cgMLST (20 ILS + 936 global/reference genomes))
- count seven clades (number of clades identified in cgMLST phylogenetic tree)
- count clade1=186, clade2=161, clade3=213, clade4=208, clade5=111 (isolate counts within the five major cgMLST clades)
- count 33 (number of African human-derived S. aureus isolates included in phylogenetic comparison)
- count 11 positive, 18 negative (strains classified by yersiniabactin siderophore operon presence for growth comparison assay)
- other 2.66-2.82 Mb (genome size range of the 20 ILS strains)
- other 32.6%-32.7% (G+C content range of the 20 ILS strains)
Statistical methods review
Model: sonnetA neutral, descriptive read of the statistical approach — what was done, and (for shared learning, not as criticism) what could also have been done.
The study is primarily descriptive comparative genomics: whole-genome sequences of 20 African dairy-associated S. aureus strains were compared to a global collection via cgMLST phylogenetics, and genomes were screened for virulence, resistance, and siderophore-operon genes using BLAST-based homology searches, without an inferential statistical framework applied to these genomic comparisons. Phenotypic data (antibiotic disk diffusion, iron-limited growth curves) were also generated. For one specific comparison — growth parameters (lag phase, maximum growth rate, area under the curve) derived from OD600 growth curves — yersiniabactin operon-positive (n=11) versus negative (n=18) strains were compared using the nonparametric Mann-Whitney U rank-sum test, run in GraphPad Prism (v9.3.1) on values standardized relative to iron-replete (TSB) growth.
| Test | Applied to | n | Assumptions |
|---|---|---|---|
| Mann-Whitney U rank-sum test | Standardized DTSB (iron-limited) growth parameters (lag phase duration, maximum growth rate, area under the curve) compared between yersiniabactin operon-positive and negative S. aureus strains | n=11 (operon-positive) vs n=18 (operon-negative) strains, each strain assessed in 3 independent biological experiments performed in duplicate | not stated |
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Growth parameter differences between operon-positive and operon-negative strains were assessed with the Mann-Whitney U test.↳ Could also: An unpaired two-tailed Student's t-test (if parameter distributions are approximately normal) or a linear mixed-effects model incorporating strain and biological-replicate as random effects — A parametric test can offer more statistical power when normality holds, and a mixed-effects model would formally account for the nested structure of three biological replicates run in duplicate per strain rather than treating replicate-derived values as fully independent.
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Three growth parameters (lag phase, maximum growth rate, area under the curve) were each tested separately for the same group comparison.↳ Could also: A multiplicity correction such as Bonferroni or Benjamini-Hochberg FDR applied across the three parameter tests — Since all three parameters test the same underlying group comparison, a family-wise or false-discovery correction would help contextualize the joint chance of at least one false-positive result across the parameter set.
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Growth curves were reduced to three summary parameters (LPD, MGR, AUC) before statistical comparison.↳ Could also: Functional data analysis or nonlinear mixed-model fitting of the full OD600-versus-time trajectories — Modeling the entire growth curve can reveal timing or shape differences between groups that summary parameters alone might not fully capture.
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The Mann-Whitney U comparison reports (implicitly, per the methods) a significance test without an accompanying effect-size statistic.↳ Could also: A rank-biserial correlation or Hodges-Lehmann estimator alongside the U test — An effect-size measure would convey the magnitude of the difference between operon-positive and operon-negative strains, complementing the significance result, which is particularly informative given the modest group sizes (11 vs 18).
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Genomic features such as yersiniabactin operon presence are described across clades and geographic/host origins in narrative and tabular form without a formal test of association.↳ Could also: Fisher's exact test or chi-square test of independence between operon presence and categorical variables (e.g., clade, host species, country) — A formal association test, with Fisher's exact test being well suited to small cell counts, could quantify whether the observed distribution patterns depart from what would be expected by chance.
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Antibiotic sensitivity testing was performed in duplicate on two separate occasions, with results presumably reported as categorical susceptibility calls.↳ Could also: Reporting inter-assay agreement statistics (e.g., percent agreement or a concordance measure) between the two testing occasions — A concordance metric would communicate the reproducibility of the disk-diffusion results across the two independent testing occasions.
What was reproduced
The exact results taken into scope, with each reported value next to the value our attempt produced.
Assessments & scoring basis
Each contributor’s verdict, the per-question basis, and the auditable, itemised worksheet behind it.
An automated assessment. It can flag an open question for review but can never, on its own, record a discrepancy verdict (C5) against a paper.
Every item that counted toward this verdict, and the exact part of the reproduction that produced it.
1:1 reproduction. Re-running assembly-stats, GenBank .gbff parsing, and tseemann/mlst on all 20 deposited ILS assemblies (PRJNA310553) reproduces Table 1 with 115/120 cells exact. The only deviations are one GC% rounding (ILS-37 32.7 vs 32.8, Δ0.1) and 4 MLST cells explained by PubMLST database drift since 2022 — both on the technical/expected side, not the authors' or a data-availability defect. Every reported value is derivable from the deposited data with no fabrication signal; the broader phylogeny/cgMLST/reservoir conclusions were legitimately out of scope (external web service).
Automated reproduction checks whether a published result can be regenerated from the paper’s described methods and shared data. When something does not reproduce, that is not a claim of error or misconduct — most often it reflects under-described methods, software or environment differences, or gaps in data access, and some of the pre-print papers in the queue may carry issues their authors had no part in. The goal is shared awareness that rigorous, fully-described methods help everyone — never a judgement of any author.
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Reproduction footprint
claude-opus-4-8Measured resources invested to assess this paper — sanitised (machine class only, no job ids/paths). Compute = HPC accounting (SLURM); tokens = the AI agent's session.