Infectious Disease · Medical Literature
[Correspondence] Clinically dominant AbST23 iuc3 plasmids are widespread in animal-derived Klebsiella pneumoniae
Abstract
We read with interest the Article published in The Lancet Microbe by Marjorie J Gibbon and colleagues.1 Despite the clinical importance of iuc3-harbouring virulence plasmids in invasive human disease, genomic evidence from animal reservoirs remains inadequate worldwide, underscoring the need for One Health-integrated surveillance of iuc3-positive Klebsiella pneumoniae.2,3
Clinical relevance
Are clinically dominant AbST23 iuc3-carrying virulence plasmids widespread in animal-derived Klebsiella pneumoniae, and does the existing genomic surveillance of animal reservoirs adequately characterize their One Health significance? __SNAPSHOT__ {"studyDesign":"Correspondence (expert commentary letter) responding to a published population genomic analysis; no independent original data presented in the correspondence itself","setting":"Not reported (correspondence references global genomic surveillance data; the index article [Gibbon et al., Lancet Microbe 2026;7:101236] drew on One Health cohorts in Italy [SpARK] and Thailand [OH-DART] plus NCBI public repositories)","sampleSize":"Not reported (correspondence only); index article: n=4,148 Klebsiella spp. isolates from two One Health cohorts plus 330 iuc3-positive isolates from NCBI","population":"Not reported in correspondence; index article included Klebsiella isolates from pigs (n=191), clinical sources (n=635), hospital and community carriage (n=1,040), and other sources (n=2,282)","intervention":"Not applicable (observational genomic surveillance correspondence)","comparator":"Not applicable","primaryOutcome":"Not formally defined in correspondence; the central argument concerns the adequacy of genomic surveillance of iuc3-positive K. pneumoniae in animal reservoirs from a One Health perspective","followUp":"Not reported","fundingSource":"Not reported for the correspondence; the index article (Gibbon et al.) was funded by UKRI, JPIAMR, Evolution Education Trust, and a Schlumberger Foundation Fellowship"}
Key findings
This is a two-sentence expert correspondence and contains no original quantitative findings, effect sizes, p-values, confidence intervals, or NNT/NNH values. The authors assert that iuc3-harbouring virulence plasmids are clinically important in invasive human disease and that the AbST23 plasmid subtype is 'clinically dominant,' but no primary data supporting this specific claim are presented within the correspondence itself. For critical context from the index article (Gibbon et al., Lancet Microbe 2026): of 127 iuc3-positive Klebsiella isolates identified across the SpARK (Italy) and OH-DART (Thailand) One Health cohorts, 73 (57.5%) were from pig or pork meat sources and only 3 (2.4%) were from clinical sources. From NCBI-sourced data (n=330 iuc3-positive isolates), 120 (30.9%) were from pigs and 83 (21.4%) were from clinical sources. Phylogenetic and clustering analysis of the index article resolved iuc3 plasmids into three groups; Group 3 plasmids — predominantly carrying the AbST23 sub-variant — were strongly associated with Asian clinical isolates (140/158, 88.6%, were of Asian origin) and harboured multiple antimicrobial resistance genes, including carbapenemase genes in two cases. The correspondence authors specifically highlight that genomic evidence from animal reservoirs worldwide remains inadequate and call for One Health-integrated surveillance of iuc3-positive K. pneumoniae. No additional statistics, risk estimates, or adverse event data are reported within the correspondence.
Practice implications
This correspondence does not constitute an independent study and cannot be evaluated for internal validity or effect size in the conventional sense. Its primary value is to place the Gibbon et al. population genomic findings within a broader One Health and global surveillance framework, drawing attention to the under-characterization of animal reservoirs as potential sources of clinically important iuc3 virulence plasmids. The index article established that iuc3-carrying plasmids in K. pneumoniae are predominantly animal-associated (particularly porcine) across two geographically distinct One Health cohorts, that three phylogenetically distinct iuc3 plasmid groups exist, and that one group (Group 3/AbST23) is disproportionately associated with clinical isolates in Asia and carries multiple antimicrobial resistance determinants — including, in isolated cases, carbapenemase genes — representing a potential convergence of hypervirulence and multidrug resistance. What has NOT been established: (1) direct zoonotic transmission of AbST23 iuc3 plasmids from animals to humans causing clinical disease; (2) whether AbST23 confers enhanced virulence relative to other iuc3 sub-variants (the index article explicitly notes AbST23 is not notably diverged from other iuc3 AbST types at the locus level); (3) the clinical outcome impact of iuc3-positive versus iuc3-negative K. pneumoniae infections in the populations studied; and (4) the adequacy of current clinical or veterinary diagnostic workflows for detecting iuc3 plasmid subtypes. The findings apply most directly to settings with high swine-human interface density in Asia, and generalizability to North America, sub-Saharan Africa, and other regions is limited by the geographic scope of the source data. Only the abstract of the correspondence was available for this summary, which is a critical limitation. __LIMITATIONS__ The item is a two-sentence correspondence with no original data, methods, statistical analysis, or defined endpoints — it cannot be evaluated as a primary study.,All quantitative claims relevant to this correspondence derive from the index article (Gibbon et al.) and are not independently verifiable from the correspondence abstract alone.,Geographic representation in the index article is limited to Italy, Thailand, and NCBI-deposited sequences; major animal-producing regions (e.g., North America, sub-Saharan Africa, South Asia) are underrepresented or absent.,The index article's One Health cohorts used amoxicillin resistance as a selection criterion for Italian isolates, potentially introducing selection bias that underestimates or skews the prevalence of iuc3-carrying strains.,The plasmid-level association of AbST23 with clinical dominance is an epidemiological observation; causal virulence enhancement by AbST23 relative to other iuc3 sub-variants has not been demonstrated mechanistically.,Cross-species and cross-interface transmission chains (animal-to-food-to-human) are inferred from co-occurrence and phylogenetic clustering, not from contact-tracing or prospective epidemiological linkage.,Only the abstract of the correspondence was available; full text, supplementary data, and any referenced original data from Wang et al. could not be reviewed.,No clinical outcome data (mortality, severity of invasive infection, treatment failure) are reported in either the correspondence or, from available abstracts, the index article. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This expert correspondence highlights a critical One Health surveillance gap: AbST23 iuc3 virulence plasmids in K. pneumoniae — a subtype associated with clinical isolates throughout Asia and carrying multiple resistance genes — are predominantly identified in animal reservoirs, yet genomic characterization of animal-derived strains remains globally inadequate. Clinicians and infection control practitioners should recognize that convergent hypervirulent, multidrug-resistant K. pneumoniae may have under-appreciated animal reservoir origins, underscoring the need for integrated genomic surveillance across human, animal, and food-chain interfaces. No immediate change to individual clinical practice is indicated by this correspondence alone, but it reinforces the urgency of institutional and public health investment in One Health-structured K. pneumoniae surveillance programs.