# The Role of Carbenicillin as an Inhibitor of the Biofilm Regulator CsgD in Salmonella Typhimurium

## TL;DR

This study shows that carbenicillin can disrupt biofilms in Salmonella Typhimurium by inhibiting the CsgD protein, offering a new way to fight infections.

## Contribution

The study identifies carbenicillin as a novel CsgD inhibitor for combating S. Typhimurium biofilms.

## Key findings

- Carbenicillin showed high binding affinity to CsgD through molecular docking.
- MBIC and MBEC of carbenicillin were determined as 1 and 4 μg/mL, respectively.
- Carbenicillin disrupted biofilm architecture and reduced curli production in S. Typhimurium.

## Abstract

Salmonella Typhimurium, a major foodborne pathogen, forms biofilms that enhance its environmental persistence and resistance to antibiotics, presenting significant public health challenges. The CsgD protein, a key transcriptional regulator, orchestrates biofilm formation by regulating curli fimbriae and cellulose production. This study aimed to identify and evaluate potential CsgD inhibitors to disrupt S. Typhimurium biofilms using a combination of computational and experimental methodologies. Molecular docking was performed to screen 145 FDA‐approved antibiotics from DrugBank against the CsgD protein. Carbenicillin, identified as a top candidate, was further analyzed through 100 ns molecular dynamics simulations to assess the stability of the carbenicillin‐CsgD complex. Experimental evaluations determined the minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) of carbenicillin against S. Typhimurium isolates. Biofilm structure and curli production were examined using scanning electron microscopy (SEM) and Congo red agar assays, respectively. Molecular docking revealed carbenicillin's high binding affinity to CsgD. Molecular dynamics simulations confirmed the structural stability of the carbenicillin‐CsgD complex. Experimental assays established MBIC and MBEC at 1 and 4 μg/mL, respectively. SEM analysis showed morphological changes and disrupted biofilm architecture at 0.5–1 μg/mL carbenicillin, while Congo red agar assays demonstrated dose‐dependent suppression of curli production. Carbenicillin exhibits significant potential as a CsgD‐targeted anti‐biofilm agent, providing a foundation for novel therapeutic strategies to combat S. Typhimurium infections and address their public health burden.

Salmonella Typhimurium biofilms, driven by the CsgD protein, enhance antibiotic resistance and pose public health concerns. This study employed molecular docking to screen 145 FDA‐approved antibiotics, identifying carbenicillin as a potent CsgD inhibitor. Molecular dynamics simulations confirmed stable carbenicillin‐CsgD binding. Experimental assays revealed a minimum biofilm inhibitory concentration (MBIC) of 1 μg/mL and minimum biofilm eradication concentration (MBEC) of 4 μg/mL. Scanning electron microscopy and Congo red agar assays demonstrated disrupted biofilm architecture and reduced curli production. Carbenicillin's anti‐biofilm efficacy highlights its potential as a novel therapeutic to combat S. Typhimurium infections.