{
  "abstract": "Vancomycin-resistant enterococci (VRE), particularly vancomycin-resistant Enterococcus faecium, are important healthcare-associated pathogens, and vanA is a major acquired determinant of high-level glycopeptide resistance. The conventional polymerase chain reaction (PCR) method is reliable for molecular detection of vanA but requires thermal cycling and, in conventional formats, post-amplification analysis. In this study, we developed and evaluated a closed-tube colorimetric loop-mediated isothermal amplification assay using hydroxy naphthol blue (LAMP-HNB) for visual detection of vanA. A total of 130 Enterococcus isolates were tested, comprising 100 previously characterized in our published LAMP–lateral flow dipstick (LAMP-LFD) study (52 vanA-positive and 48 vanA-negative) and an additional 30 (13 vanA-positive and 17 vanA-negative), yielding 65 PCR-positive and 65 PCR-negative isolates overall. Reaction conditions were optimized sequentially, and the final LAMP-HNB protocol took place at 63 °C for 45 min with 4.0 mM MgSO4 and 5 μM HNB. The visual endpoint was confirmed by 2% agarose gel electrophoresis. LAMP-HNB correctly classified all 65 PCR-positive and all 65 PCR-negative isolates, yielding 100% sensitivity (65/65; exact 95% CI: 94.48–100%), 100% specificity (65/65; 95% CI: 94.48–100%), and 100% overall agreement (130/130; 95% CI: 97.20–100%). The limit of detection was 8.67 × 103 genome copies/µL (28.52 pg/µL) for LAMP-HNB compared with 8.67 × 104 genome copies/µL (285.2 pg/µL) for conventional PCR, representing a 10-fold lower DNA concentration endpoint under the experimental conditions employed. In the 100-isolate overlapping cohort, LAMP-HNB, the previously reported LAMP-LFD platform, and PCR were concordant. With its 45 min requirement for amplification after DNA preparation, the HNB format provides a rapid, closed-tube visual endpoint without a labeled probe, lateral flow strip, running buffer, or post-amplification hybridization step. These findings support LAMP-HNB as a promising molecular screening approach for vanA-positive enterococci, while larger, fully independent multicenter validation remains necessary before routine implementation.",
  "abstract_shown": true,
  "affiliations": [
    "Faculty of Medical Technology, Rangsit University, Pathum Thani 12000, Thailand",
    "Center of Excellence in Biosensors, Panyananthaphikhu Chonprathan Medical Center, Srinakharinwirot University, Nonthaburi 11120, Thailand",
    "Nopparatrajathanee Hospital, Bangkok 10230, Thailand",
    "Strategic Wisdom and Research Institute, Srinakharinwirot University, Bangkok 10110, Thailand"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 11,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Sawanya Pongparit",
      "orcid": "0000-0001-6238-1070"
    },
    {
      "affs": [
        0
      ],
      "name": "Kantima Choosang",
      "orcid": "0000-0002-4561-4319"
    },
    {
      "affs": [
        0
      ],
      "name": "Bajaree Jantrapanukorn",
      "orcid": "0000-0001-6292-1591"
    },
    {
      "affs": [
        0
      ],
      "name": "Rungnapa Veeramano"
    },
    {
      "affs": [
        0
      ],
      "name": "Suphitcha Augkarawaritsawong"
    },
    {
      "affs": [
        0
      ],
      "name": "Khurawan Kumkrong"
    },
    {
      "affs": [
        0
      ],
      "name": "Parthompong Ves-urai"
    },
    {
      "affs": [
        1
      ],
      "name": "Pongbun Tangjitrungrot"
    },
    {
      "affs": [
        2
      ],
      "name": "Naiyana Wattanakul"
    },
    {
      "affs": [
        3
      ],
      "name": "Kosum Chansiri"
    },
    {
      "affs": [
        0
      ],
      "name": "Saranthum Phurijaruyangkun",
      "orcid": "0009-0007-4012-6360"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1negj3ktc5mp4.bib",
  "cited_by": 0,
  "doi": "10.3390/ijms27219927",
  "fulltext_url": null,
  "id": "1negj3ktc5mp4",
  "issns": [
    "1422-0067"
  ],
  "landing_url": "https://www.mdpi.com/1422-0067/27/21/9927",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
  "openalex": null,
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-05",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/1negj3ktc5mp4.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T00:21:14Z",
      "native_id": "10.3390/ijms27219927",
      "source": "crossref",
      "url": "https://www.mdpi.com/1422-0067/27/21/9927"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "issn:1422-0067",
      "subfield": "general"
    }
  ],
  "title": "Colorimetric Detection of the vanA Gene in Vancomycin-Resistant Enterococcus Using Loop-Mediated Isothermal Amplification with Hydroxy Naphthol Blue",
  "title_text": "Colorimetric Detection of the vanA Gene in Vancomycin-Resistant Enterococcus Using Loop-Mediated Isothermal Amplification with Hydroxy Naphthol Blue",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T00:21:12Z",
  "url": "https://research.draconitic.com/paper/1negj3ktc5mp4",
  "venue": "International Journal of Molecular Sciences",
  "versions": []
}