ABSTRACT
The growth of respiratory diseases, as witnessed through the SARS and COVID-19 outbreaks, and antimicrobial-resistance together pose a serious threat to humanity. One reason for antimicrobial resistance is formation of bacterial biofilms. In this study the sulphated polysaccharides from green algae Chlamydomonas reinhardtii (Cr-SPs) is tested for its antibacterial and antibiofilm potential against Klebsiella pneumoniae and Serratia marcescens. Agar cup assay clearly indicated the antibacterial potential of Cr-SPs. Minimum inhibitory concentration (MIC50) of Cr-SPs against Klebsiella pneumoniae was found to be 850 µg/ml, and it is 800 µg/ml in Serratia marcescens. Time-kill and colony-forming ability assays suggest the concentration-dependent bactericidal potential of Cr-SPs. Cr-SPs showed 74-100% decrease in biofilm formation in a concentration-dependent manner by modifying the cell surface hydrophobic properties of these bacteria. Cr-SPs have also distorted preformed-biofilms by their ability to interact and destroy the extra polymeric substance and eDNA of the matured biofilm. Scanning electron microscopy analysis showed that Cr-SPs effectively altered the morphology of these bacterial cells and distorted the bacterial biofilms. Furthermore reduced protease, urease and prodigiosin pigment production suggest that Cr-SPs interferes the quorum sensing mechanism in these bacteria. The current study paves way towards developing Cr-SPs as a control strategy for treatment of respiratory tract infections.
Subject(s)
Biofilms/drug effects , Polysaccharides/pharmacology , Quorum Sensing/drug effects , Respiratory Tract Infections/drug therapy , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Biofilms/growth & development , COVID-19/virology , Chlorophyta/chemistry , Humans , Klebsiella pneumoniae/growth & development , Klebsiella pneumoniae/pathogenicity , Microbial Sensitivity Tests , Polysaccharides/chemistry , Respiratory Tract Infections/microbiology , SARS-CoV-2/drug effects , Serratia marcescens/growth & development , Serratia marcescens/pathogenicity , COVID-19 Drug TreatmentABSTRACT
Quorum sensing (QS) inhibition is an essential strategy to combat bacterial infection. Previously, we have synthesized a series of thymidine derivatives bearing isoxazole and 1,2,3-triazole rings (TITL). Herein, the inhibitory effects of TITL on QS of Pseudomonas aeruginosa PAO1 were evaluated. In vitro results demonstrated that TITL effectively inhibited biofilm formation and reduced the virulence factors of P. aeruginosa PAO1. In combination with antibiotics, our TITL compounds significantly prolonged the lifespans of Caenorhabditis elegans N2 nematodes that were infected with P. aeruginosa PAO1 in vivo. In conclusion, TITL compounds are promising candidates for the treatment of antibiotic-resistant P. aeruginosa PAO1.