Researchers conducted a retrospective analysis to determine how difficult-to-treat resistant Pseudomonas aeruginosa, abbreviated as DTRPA, transmits within hospital settings.
The investigation focused on clinical DTRPA isolates collected between 2019 and 2024. The research team subjected these isolates to whole-genome sequencing to identify genetic relationships. They defined genetic clusters using core genome multilocus sequence typing thresholds, specifically looking for allelic differences of 11 or fewer and 3 or fewer.
Among the 190 DTRPA isolates analyzed, carbapenemase-negative DTRPA was the predominant form, accounting for 79.5% of the samples. In contrast, carbapenemase-producing DTRPA made up 20.5% of the isolates. The carbapenemase-producing strains were mainly characterized by the presence of the blaVIM-2 gene.
The study identified twelve distinct genetic clusters involving a total of 39 patients. Of these, seven clusters showed possible epidemiological relatedness, meaning the patients had overlapping hospital stays, direct interpatient contact, or shared environmental exposures. The composition of these clusters varied, with four consisting solely of carbapenemase-producing DTRPA, two consisting solely of carbapenemase-negative DTRPA, and one being a mixed cluster containing both types.
Statistical analysis revealed a strong association between carbapenemase-producing DTRPA and clustered transmission. The odds ratio for carbapenemase-producing isolates being associated with genetic clusters was 17.47, with a 95% confidence interval ranging from 7.43 to 41.08. These isolates were also frequently linked to environmental transmission routes. Instead, their transmission was often linked to interpatient spread of carbapenem-susceptible P. aeruginosa, followed by the emergence of resistance after prolonged antibiotic exposure.
The findings suggest that carbapenemase-negative DTRPA may arise primarily through antibiotic-driven resistance development in patients who were already colonized with susceptible strains.
Current international guidelines recommend equal infection prevention and control measures for all difficult-to-treat resistant Pseudomonas aeruginosa. However, this study highlights the need to evaluate differentiated strategies. For carbapenemase-producing DTRPA, targeted screening and environmental interventions may be more effective due to their association with outbreaks and environmental transmission. For carbapenemase-negative DTRPA, the focus might shift toward antimicrobial stewardship to prevent the emergence of resistance in precolonized patients. The authors emphasize that multicentre studies are required to develop evidence-based infection control policies that account for these distinct transmission patterns.
Subject of Research: Transmission dynamics of difficult-to-treat resistant Pseudomonas aeruginosa
Article Title: Retrospective analysis of the transmission of difficult-to-treat resistant Pseudomonas aeruginosa – genotype beats phenotype
Article References: Jasuja, J. K., Maurer, P. M., Carlsen, L., Klupp, E.-M. T., Belmar Campos, C. E., Rohde, H., Aepfelbacher, M., & Knobloch, J. K.-M. (2026). Retrospective analysis of the transmission of difficult-to-treat resistant Pseudomonas aeruginosa – genotype beats phenotype. Antimicrobial Resistance & Infection Control, 15(1), Article 134. https://doi.org/10.1186/s13756-026-01851-3
Image Credits: AI Generated
DOI: 10.1186/s13756-026-01851-3
Keywords: Pseudomonas aeruginosa, Antimicrobial resistance, Whole-genome sequencing, Infection control, Carbapenem resistance, Hospital epidemiology, Genetic clustering, Retrospective analysis, Retrospective, analysis, transmission, difficult-to-treat
News Source: Juliet Wilcox. (November 7, 2026). Genotype Outperforms Phenotype in Pseudomonas Transmission Analysis. Scienmag.
