Evidence map›Paper›PMID 40001400›Full record

ArticleAntibiotics (Basel, Switzerland)2025

Agar-Dilution Is Comparable to Broth Dilution for MIC Determination in

Edward A R Portal, Caitlin Farley, Teresa Iannetelli, Juliana Coelho, Androulla Efstratiou, Stephen D Bentley, Victoria J Chalker, Owen B Spiller

Abstract read
In one paragraph

Article in Antibiotics (Basel, Switzerland), 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

0numbers the graph read from it
0cells of the map it votes in
3citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

  1. Article
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Edward A R PortalDivision of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff University, Cardiff CF14 4XN, UK.ORCID 0000-0003-2142-3443
Caitlin FarleyDivision of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff University, Cardiff CF14 4XN, UK.ORCID 0009-0006-5309-2991
Teresa IannetelliDivision of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff University, Cardiff CF14 4XN, UK.ORCID 0009-0009-5985-6704
Juliana CoelhoReference Microbiology Division, United Kingdom Health Security Agency, London NW9 5EQ, UK.
Androulla EfstratiouReference Microbiology Division, United Kingdom Health Security Agency, London NW9 5EQ, UK.
Stephen D BentleyParasites and Microbes, Wellcome Sanger Institute, Cambridge CB10 1SA, UK.
Victoria J ChalkerReference Microbiology Division, United Kingdom Health Security Agency, London NW9 5EQ, UK.
Owen B SpillerDivision of Infection and Immunity, Department of Medical Microbiology, University Hospital of Wales, Cardiff University, Cardiff CF14 4XN, UK.ORCID 0000-0002-9117-6911

Funding

UK Health Security Agency AMR Juno Project workstream
6 · The paper itself

Abstract

background

objectiveTo demonstrate that agar-dilution AST provides equivalent results to broth dilution methods, with superior capacity for high-throughput screening.

methodsAgar-dilution and microdilution AST methods were compared using a panel of 24 characterised susceptible and resistant GBS strains for benzylpenicillin, chloramphenicol, clindamycin, erythromycin, gentamicin, levofloxacin, tetracycline, and vancomycin. Minimum inhibitory concentration (MIC) agreements were evaluated, and resistance profile correlations were assessed using Cohen's kappa values.

resultsAgar-dilution demonstrated >90% agreement with BMD MIC for most antimicrobials, except vancomycin (87.5%), erythromycin (83.33%), and tetracycline (52.78%). Cohen's kappa values indicated strong agreement (0.88-1.00) for resistance determination. Agar-dilution avoided "trailing growth" issues associated with BMD and facilitated easier detection of non-GBS contaminants.

conclusionsAgar-dilution is a valid method for high-throughput AMR surveillance of retrospective cohorts (96 isolates per plate) and is critical for identifying emerging GBS resistance trends and informing therapeutic guidelines. However, due to the large number of plates required per antimicrobial, it is impractical for routine clinical diagnostics.

Indexed as

antimicrobial resistanceantimicrobial susceptibility testingGBSmethod validationStreptococcus agalactiae

Identifiers

PMID40001400
PMCPMC11852353

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.