The cost of chronicity - Pseudomonas aeruginosa’s silent evolution in the urinary tract

Sep 29, 2026

More than a century after Koch’s postulates defined microbial causes of disease, the article argues that pathogenicity is a contextual outcome of adaptation rather than an intrinsic trait. It summarizes genomic, phenotypic, and proteomic analyses of sequential Pseudomonas aeruginosa urinary isolates, showing progressive loss of virulence traits coupled with reinforced metabolic resilience. Chronic persistence is framed as an adaptive trade-off between acute infection and long-term colonization, with the urinary tract acting as a niche for persistence rather than a battlefield.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Abstract

Koch’s paradox and contextual virulence

Opportunism and the urinary tract as a persistence niche

Study design and intrapatient adaptation

Evolutionary cost: trading virulence for persistence

Proteomic and metabolic remodeling

Iron acquisition shifts and methodological strengths

| Microbial Pathogenesis | Commentary The cost of chronicity: Pseudomonas aeruginosa’s silent evolution in the urinary tract Sébastien Bontemps-Gallo1 AUTHOR AFFILIATION See affiliation list on p. 3. ABSTRACT More than a century after Koch’s postulates defined the microbial causes of disease, Stanley Falkow reminded us that pathogenicity is not an intrinsic property but a contextual outcome of microbial adaptation. The recent study by C. Martin-Duval, S. Dahyot, I. Coquisart, B. Bernay, et al. (Microbiol Spectr 13:e00456-25, 2025, [https://](https://)[ ](https://)[doi.org/10.1128/spectrum.00456-25](doi.org/10.1128/spectrum.00456-25) illustrates this concept. By combining genomic,)[) illustrates this concept. By combining genomic,](doi.org/10.1128/spectrum.00456-25) illustrates this concept. By combining genomic,)[ ](doi.org/10.1128/spectrum.00456-25) illustrates this concept. By combining genomic,)phenotypic, and proteomic analyses of sequential urinary isolates, the authors show how Pseudomonas aeruginosa progressively abandons virulence traits while reinforcing metabolic resilience during urinary tract infections. This commentary discusses how these findings challenge classical views of pathogenic success, highlighting the “cost of chronicity” as an adaptive trade-off between acute infection and long-term colonization. The urinary tract thus emerges not as a battlefield, but as a niche of persistence for P. aeruginosa. KEYWORDS Pseudomonas aeruginosa, stress adaptation, urinary tract infection, virulence, persistence, Koch postulate M ore than a century after Robert Koch proposed his postulates to demonstrate the causal relationship between a microorganism and a disease, Stanley Falkow reframed the debate (1, 2) . For him, virulence is not an intrinsic trait of a bacterium but a dynamic relationship, i.e., the phenotypic expression of adaptive success. Bacteria do not evolve to cause disease, but to survive. The study by Martin-Duval et al. in Microbiology Spectrum (3) provides a compelling modern illustration of this principle. Through genomic, phenotypic, and proteomic analyses of Pseudomonas aeruginosa urinary isolates collected sequentially from patients with recurrent infections, the authors show that chronic persistence arises not from enhanced virulence but from its progressive loss. The urinary tract thus becomes a model of Falkow’s paradox: the pathogen that survives is not the one that fights hardest, but the one that learns to live quietly. P. aeruginosa is a paradigmatic opportunist. Usually harmless to healthy individuals, P. aeruginosa can become a pathogen in immunocompromised hosts. Its capacity to form biofilms and its resistance to antimicrobial agents make the treatment of this pathogen difficult, often leading to recurrent relapses and the establishment of chronic infections. Moreover, P. aeruginosa’s large genome, reflecting its ubiquitous nature, encodes remarkable metabolic adaptability, allowing it to thrive in the cystic fibrosis lung, in burn wounds, or within the urinary tract (4). Yet, unlike the respiratory niche, the urinary tract is metabolically, chemically dynamic but immunologically restrained. Martin-Duval et al. compared early and late isolates from three patients experiencing recurrent urinary infections, two of whom were immunocompromised. Choosing patient-derived isolates rather than laboratory strains or experimental evolution models provides a biologically relevant framework for understanding the bacterium’s intrapatient adaptive capacities. At the genomic level, late isolates carried large deletions and Editor Estela Maria Galvan, Universidad Maimonides, Buenos Aires, Argentina Address correspondence to Sébastien BontempsGallo, [sebastien.bontemps-gallo@cnrs.fr](sebastien.bontemps-gallo@cnrs.fr). The author declares no conflict of interest. The views expressed in this article do not necessarily reflect the views of the journal of numerous single-nucleoti

FAQs

What does the article mean by “the cost of chronicity”?

It describes chronic persistence as an adaptive trade-off where Pseudomonas aeruginosa sacrifices maximal acute virulence to better persist long-term in the urinary tract.

How do late urinary isolates differ from early ones in the study?

Late isolates show slower growth, decreased motility, attenuated virulence, and a shift toward energy-efficient metabolism, alongside genomic changes affecting regulatory systems and metabolism.

What metabolic and proteomic shifts support persistence in nutrient-limited urine?

Proteomic results show enrichment of pathways such as the glyoxylate shunt, pyruvate metabolism, and oxidative phosphorylation, indicating optimization for efficient energy use under limited nutrients.

Sep 29, 2026

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