Nahiara Garmendia will Defend Her Doctoral Thesis on 23 October
Nahiara Garmendia Antoñana, a predoctoral researcher in the Microbial Pathogenesis Unit at Navarrabiomed, will defend her doctoral thesis at the Public University of Navarra (UPNA) on Friday, 23 October, at 11:00 a.m. in the assembly hall of Navarrabiomed.
Entitled “Mechanisms of Adaptation of Staphylococcus aureus to the Infection Environment”, the doctoral research was carried out at Navarrabiomed under the supervision of Iñigo Lasa Uzcudun, Principal Investigator of the Microbial Pathogenesis Unit.
The thesis addresses the major challenge posed by the remarkable adaptive capacity of Staphylococcus aureus, one of the most successful and difficult-to-eradicate bacterial pathogens due to its high levels of antibiotic resistance. This adaptability is driven by its extensive genetic plasticity, fuelled by horizontal gene transfer and by sophisticated regulatory networks such as Two-Component Systems (TCSs), which serve as the primary interface for detecting and responding to environmental stimuli. At a time when therapeutic options are increasingly limited, the challenge lies in understanding the molecular and evolutionary mechanisms underlying this adaptability and, paradoxically, exploiting these same pathways to develop precision antimicrobial therapies.
Research Phases and Key Findings
Nahiara Garmendia’s doctoral work explores the biology of Staphylococcus aureus by integrating the study of the evolution of its sensory networks with the design of novel genetic therapies.
In the first chapters, focused on evolution and adaptation, the thesis describes how in vivo experimental evolution studies were used to reconstruct the mechanisms through which the bacterium functionally integrates heterologous regulatory systems (TCSs) acquired from other bacterial species.
The research demonstrated that the principal evolutionary barrier is the compatibility of the genetic promoter. Once this architectural barrier is overcome, a single mutation in the sensor kinase is sufficient to activate the signalling pathway. The study also revealed that the greater the diversity and complexity of the bacterium’s natural sensors, the more evolutionary routes it can exploit to mutate and adapt to stressful conditions.
The third chapter focuses on control and therapy. From a biotechnology perspective, genetic engineering approaches were used to design phage-inducible chromosomal islands (ePICIs) capable of infecting Staphylococcus aureus and delivering CRISPR-Cas9 modules targeting essential regions of the bacterial chromosome, resulting in irreversible DNA cleavage.
These genetic elements function as non-replicative vectors and can be regarded as molecular “Trojan horses.” In an in vivo murine mastitis infection model, the engineered ePICIs demonstrated bactericidal efficacy comparable to that of vancomycin, even overcoming the differences in susceptibility associated with distinct extracellular matrix biofilm types observed in vitro.
This thesis establishes a strong bridge between bacterial evolutionary biology and translational biotechnology. On the one hand, it uncovers the fundamental principles governing how pathogens integrate new regulatory networks, improving our ability to predict and understand the evolutionary diversification of multidrug-resistant bacteria. On the other hand, it validates CRISPR-based ePICIs as a safe, versatile, non-replicative antimicrobial platform with proven in vivo efficacy, offering an innovative and viable strategy to combat the growing clinical challenge of multidrug-resistant Staphylococcus aureus infections.
Dissemination of Results
Part of the findings generated through this research have been protected through a patent application.
In addition, the results were published in February 2026 in the journal npj Biofilms and Microbiomes and have been presented at several scientific conferences, including:
• The New Microbiology (Spetses, Greece, 2025)
• Synthetic Phage-Inducible Chromosomal Islands Efficiency Depends on Biofilm (Cardiff, United Kingdom, 2025)
• Molecular Microbiology Group Meeting (Granada, 2022; Burgos, 2023; and Madrid, 2024)
Nahiara Garmendia’s doctoral research was funded through the National Programme for the Training of Research Personnel (FPI) of the Spanish Ministry of Science, Innovation and Universities. As part of her doctoral training, she also completed a research stay at the University of St Andrews (United Kingdom).


