BRIEF RESEARCH REPORT article
Front. Aging
Sec. Healthy Longevity
Volume 6 - 2025 | doi: 10.3389/fragi.2025.1566034
This article is part of the Research TopicMicrobial Influences on Aging: Insights from the Gut MicrobiomeView all articles
Oropharyngeal detection of specific gut-derived gram-negative bacteria is associated with increased respiratory infection risk in older adults
Provisionally accepted
Sophie J Miller1,2
Frank Zhang3Steven L Taylor1,2
Andrew Shoubridge1,2Erin Flynn3Egi Vasil1,2
Richard Woodman4
Lito Papanicolas1,2,3
Geraint Rogers1,2*- 1Infection and Immunity, South Australian Health and Medical Research Institute, Adelaide, Australia
- 2Infection and Immunity, Flinders University, Adelaide, South Australia, Australia
- 3Microbiology and Infectious Diseases, SA Pathology, Adelaide, Australia
- 4Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, Australia
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Respiratory tract infections (RTI) are a major contributor to morbidity and mortality in later life. RTI risk factors in older populations, including declining general health, altered airway physiology, and increased pharmaceutical exposures, also contribute to changes in the oropharyngeal (OP) microbiota. We sought to investigate whether such changes predict future incidence of RTI. OP microbiota characteristics were measured in 190 residents of long-term aged care. Fifty-four participants (28.4%) experienced one or more study-defined RTIs during the 12-month follow-up period, of which 28 (14.7%) occurred within 90 days of sample collection. OP microbiota composition was significantly associated with days to RTI event (F=1.74, R 2 =1.02%, p=0.04). Detection of Enterobacterales species (Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, and Proteus mirabilis) were independently associated with RTI risk after covariate adjustment (subdistribution HR: 4.84; 95% CI: 1.65-14.19; p=0.002). Strain-level analysis performed on metagenomes from contemporaneous OP and stool samples identified co-carriage of indistinguishable Enterobacterales strains in those with Enterobacterales-positive OP samples, suggesting intra-participant strain acquisition. We report OP carriage of Enterobacterales species to be a marker of future RTI risk in long-term aged care residents, reflecting the independent influence of common ageing-associated risk exposures.
Keywords: older people, Nursing Homes, Pneumonia, microbiome, Enterobacterales
Received: 24 Jan 2025; Accepted: 14 May 2025.
Copyright: © 2025 Miller, Zhang, Taylor, Shoubridge, Flynn, Vasil, Woodman, Papanicolas and Rogers. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Geraint Rogers, Infection and Immunity, South Australian Health and Medical Research Institute, Adelaide, Australia
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