Vol. 43 No. 5 (2026): October
Original Article

Comparison of bacterial susceptibility and morphological changes in Pseudomonas aeruginosa biofilm in response to antibiotic therapies

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  • Sofía Cabezón Leighton,
  • Karen Moreno,
  • María Paz Durán,
  • Jaime Figueroa Valverde
Sofía Cabezón Leighton
Universidad Austral de Chile
Karen Moreno
Universidad Austral de Chile, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Edificio Ciencias II, Campus Isla Teja, Valdivia, Chile. y Centro FONDAP-ANID, Intersdisciplinary Center for Aquaculture Research (INCAR), O’Higgins 1695, Concepción, Chile.
María Paz Durán
²Universidad Austral de Chile, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Edificio Ciencias II, Campus Isla Teja, Valdivia, Chile. 3Centro FONDAP-ANID, Intersdisciplinary Center for Aquaculture Research (INCAR), O’Higgins 1695, Concepción, Chile.
Jaime Figueroa Valverde
²Universidad Austral de Chile, Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Edificio Ciencias II, Campus Isla Teja, Valdivia, Chile. 3Centro FONDAP-ANID, Intersdisciplinary Center for Aquaculture Research (INCAR), O’Higgins 1695, Concepción, Chile.
DOI: https://doi.org/10.4067/s0716-10182026000500159

Published 2026-10-01

Keywords

How to Cite

1.
Cabezón Leighton S, Moreno K, Durán MP, Figueroa Valverde J. Comparison of bacterial susceptibility and morphological changes in Pseudomonas aeruginosa biofilm in response to antibiotic therapies. Rev. Chilena. Infectol. [Internet]. 2026 Oct. 1 [cited 2026 Oct. 1];43(5). Available from: https://revinf.cl/index.php/revinf/article/view/2682

Copyright (c) 2026 Sofía Cabezón Leighton, Karen Moreno, María Paz Durán, Jaime Figueroa Valverde

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This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Background: Pseudomonas aeruginosa is an opportunistic pathogen known for its significant capacity to form biofilms, which contributes to its resistance in nosocomial infections.

Aim: To compare bacterial susceptibility and morphological changes in P. aeruginosa biofilms in response to trimethoprim (TMP) and cotrimoxazole (TMP/SXT).

Materials and Methods: The minimum inhibitory concentration (MIC) was determined by optical density (OD) based on concentrations established by EUCAST. Biofilm formation was assessed by scanning electron microscopy (SEM) and an area fraction analysis using ImageJ, applying a standardized threshold.

Results: Resistance to both antimicrobials was detected. However, biofilm coverage decreased from 18.55% in the control group to 1.47% with TMP and 1.29% with TMP/SXT. At 20,000x magnification, a lower bacterial density and an increased presence of extracellular matrix were noted in the treated samples.

Conclusions: Antimicrobials do not entirely inhibit bacterial growth; instead, they alter the morphology of the biofilm, suggesting an effect on the structural arrangement rather than on the viability.

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