A clinical isolate of Proteus mirabilis recovered in the United States in 2024 was identified as carrying the class D carbapenemase gene blaOXA-23. This detection was made through testing performed by the Antimicrobial Resistance Laboratory Network. The finding was reported by Orazi et al. in a letter published in Emerging Infectious Diseases (Aug 2026) and is indexed under PMID 42521500 and DOI 10.3201/eid3208.260588.
According to the published abstract, the blaOXA-23–positive P. mirabilis isolate was characterized in a way that demonstrated close relatedness to OXA-23 producers previously identified in Europe. The authors state the US isolate is closely related to European OXA-23–producing strains, indicating possible dissemination or shared mobile genetic elements across regions. The PubMed abstract does not provide technical details of the laboratory methods, sequencing platforms, or the specific epidemiologic typing used to determine relatedness; those procedural details were not reported in the abstract portion on PubMed.
The authors interpret this detection in the context of growing international observations and propose that members of Enterobacterales may act as a silent reservoir for carbapenemase genes that are more commonly associated with Acinetobacter species (for example, genes encoding OXA-type carbapenemases). If Enterobacterales can harbour and potentially disseminate blaOXA-23 and similar carbapenemase genes, this has implications for antimicrobial resistance surveillance and for clinical detection strategies, because carbapenemase genes typically linked to one genus may appear in others.
The abstract highlights concern about under-recognized reservoirs of resistance determinants but does not report clinical outcomes, patient-level data, or treatment details for the case from which the isolate was obtained.
The PubMed entry connects this US detection to similar international findings and cites that such occurrences have been reported elsewhere. The authors note that, combined with analogous reports internationally, their finding supports the hypothesis that Enterobacterales species could be silent carriers of carbapenemase genes commonly associated with Acinetobacter. The PubMed abstract itself lists related literature in the Similar Articles section, indicating ongoing detection of OXA-type carbapenemases in Proteus and other Enterobacterales in multiple countries.
The PubMed abstract provides a concise summary but omits several details that clinicians and laboratory professionals often seek. Specifically, the abstract does not report the clinical source of the isolate (body site or infection type), patient demographics or epidemiologic links, antimicrobial susceptibility profile beyond the presence of blaOXA-23, the genomic context of the gene (chromosomal vs plasmid or associated transposon), or the precise laboratory methods used to detect and compare the isolate to European strains. The authors’ conclusion about Enterobacterales as potential silent reservoirs is based on this detection in combination with other international reports, but the abstract does not provide size, scope, or quantitative measures of prevalence.
When interpreting this report, readers should consult the full text for any additional methods or data that were not included in the PubMed abstract; however, PubMed’s abstract page does not include those additional details.
This report was published as a Letter in Emerging Infectious Diseases (2026 Aug;32[8]:1379–1382). The PubMed record lists the authors (Orazi G and colleagues), PMID 42521500, and DOI 10.3201/eid3208.260588. The abstract’s keyword list emphasizes terms relevant to surveillance and resistance mechanisms: Acinetobacter baumannii; Antimicrobial Resistance Laboratory Network; Enterobacterales; Proteus mirabilis; United States; antimicrobial resistance; bacteria; carbapenem; class D carbapenemase gene.
Acknowledgement: This summary is restricted to the facts presented in the PubMed abstract (PMID 42521500). Details not reported in the abstract are explicitly noted as not reported above.