{
  "abstract": "OXA-48-like {beta}-lactamases, such as OXA-163, OXA-181, OXA-405, OXA-505, among others, are class D carbapenem-hydrolyzing enzymes increasingly reported worldwide, yet some variants remain poorly characterized at the phenotypic levels. Here, we report OXA-439, a variant of OXA-163, in a producing uropathogenic Escherichia coli (UPEC) in Uruguay, recovered from a catheter-associated urinary tract infection with discordant routine susceptibility results. The specific contribution of OXA-439, bla-OXA-48, bla-OXA-163, and bla-OXA-439 were cloned into pET24a vector and expressed in Escherichia coli BL21(DE3), and their activity was evaluated by MIC microdilution against a panel of penicillins, ESCs, carbapenems, and {beta}-lactam/{beta}-lactamase inhibitor combinations. OXA-439 exhibited a substrate profile highly similar to OXA-163 conferring resistance to piperacillin and third-generation cephalosporins while remaining susceptible to carbapenems but with globally reduced MIC values and a complete loss of activity toward amoxicillin and clavulanate. These data suggest that the Y123H substitution, located near the catalytic Ser70/Lys73 region, subtly perturbs the active-site environment and decreases penicillinase efficiency.",
  "abstract_shown": true,
  "affiliations": [
    "Institut Pasteur de Montevideo"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "name": "V. Florez-Cardona"
    },
    {
      "name": "E. Ticona-Morales"
    },
    {
      "name": "M. Charlo"
    },
    {
      "affs": [
        0
      ],
      "name": "B. Manta"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5xeht67e9e1g8.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.12.751137",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.12.751137v1.full",
  "id": "5xeht67e9e1g8",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.12.751137v1",
  "language": null,
  "licence": "CC-BY-ND",
  "licence_label": "CC BY-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "microbiology"
    ],
    [
      "openalex",
      "1313|Antibiotic Resistance in Bacteria"
    ]
  ],
  "openalex": "W7213331338",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.12.751137v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-12",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5xeht67e9e1g8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:33Z",
      "native_id": "10.64898/2026.09.12.751137",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.12.751137v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:microbiology",
      "subfield": "microbiology"
    }
  ],
  "title": "Phenotypic Characterization of OXA-439, an OXA-163 variant, isolated from uropathogenic Escherichia coli",
  "title_text": "Phenotypic Characterization of OXA-439, an OXA-163 variant, isolated from uropathogenic Escherichia coli",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:33Z",
  "url": "https://research.draconitic.com/paper/5xeht67e9e1g8",
  "venue": "bioRxiv",
  "versions": []
}