publication – Rossi Microbiology Lab

This year, we celebrate Christmas early!

We are happy to announce the publication of our latest study, which identifies the sirB2 gene as a key fitness determinant of Pseudomonas aeruginosa under host-relevant, oxygen-limited conditions. In particular, we show that SirB2 supports redox homeostasis and anaerobic respiration, thereby contributing to bacterial adaptation in cystic fibrosis (CF) airways.

In particular, loss of sirB2 leads to redox imbalance and impaired anaerobic fitness, thereby triggering the emergence of rugose small-colony variants (RSCVs), enhanced biofilm formation, and increased virulence in multiple infection models. Our findings reveal a tight connection between metabolic state, phenotypic diversification, and pathogenic potential, highlighting redox homeostasis as a critical driver of chronic infection adaptation.

A particular thank you to Dr. Valerio Baldelli and Dr. Stacy Julisa Carrasco Aliaga, who jointly led this work and all collaborators involved in this multidisciplinary effort.

Reference:
Baldelli, V., Carrasco Aliaga, S.J., Colque, C.A., Mazzola, F., Ravishankar, S., Johansen, H.K., Molin, S., Raffaelli, N., Paroni, M., Landini, P., & Rossi, E. (2025). The Pseudomonas aeruginosa sirB2 gene is a fitness determinant of anaerobic growth and its inactivation affects virulence and rugose small colony variants emergence. Virulence.

We are excited to announce the publication of our latest study, which reveals that the antimycotic drug 5-fluorocytosine (5-FC) functions as a potent virulence inhibitor against uropathogenic Escherichia coli (UPEC). Notably, our findings demonstrate that 5-FC not only disrupts key pathogenic traits of UPEC but also effectively kills bacteria within preformed biofilms—a major challenge in treating chronic and recurrent infections. This study highlights the potential of repurposing non-antibiotic compounds to combat bacterial infections while mitigating resistance development.

We extend our warmest congratulations to Dr. Srikanth Ravishankar, a former PhD student of our lab, who led this work and recently started a new position at the Institut Pasteur in Paris. We look forward to seeing his continued contributions to microbiology!

Reference:
Ravishankar, S., Conte, A.L., Aliaga, S.J.C., Baldelli, V., Nielsen, K.L., Paroni, M., et al. (2025) The antimycotic 5-fluorocytosine is a virulence inhibitor of uropathogenic Escherichia coli and eradicates biofilm-embedded bacteria synergizing with β-lactams. Antimicrob agents Chemother e0028025.