Theophylline as a quorum sensing and biofilm inhibitor in Pseudomonas aeruginosa and Chromobacterium violaceum.

Quorum sensing (QS) is pivotal in coordinating virulence factors and biofilm formation in various pathogenic bacteria, making it a prime target for disrupting bacterial communication. Pseudomonas aeruginosa is a member of the "ESKAPE" group of bacterial pathogens known for their association with antimicrobial resistance and biofilm formation. The current antibiotic arsenal falls short of addressing biofilm-related infections effectively, highlighting the urgent need for novel therapeutic agents. In this study, we explored the anti-QS and anti-biofilm properties of theophylline against two significant pathogens, Chromobacterium violaceum and P. aeruginosa. The production of violacein, pyocyanin, rhamnolipid, and protease was carried out, along with the evaluation of biofilm formation through methods including crystal violet staining, triphenyl tetrazolium chloride assay, and fluorescence microscopy. Furthermore, computational analyses were conducted to predict the targets of theophylline in the QS pathways of P. aeruginosa and C. violaceum. Our study demonstrated that theophylline effectively inhibits QS activity and biofilm formation in C. violaceum and P. aeruginosa. In P. aeruginosa, theophylline inhibited the production of key virulence factors, including pyocyanin, rhamnolipid, protease, and biofilm formation. The computational analyses suggest that theophylline exhibits robust binding affinity to CviR in C. violaceum and RhlR in P. aeruginosa, key participants in the QS-mediated biofilm pathways. Furthermore, theophylline also displays promising interactions with LasR and QscR in P. aeruginosa. Our study highlights theophylline as a versatile anti-QS agent and offers a promising avenue for future research to develop novel therapeutic strategies against biofilm-associated infections.

Antibiofilm potential of gallic acid against Klebsiella pneumoniae and Enterobacter hormaechei: in-vitro and in-silico analysis.

Biofilm refers to a community of microorganisms that adhere to a substrate and play a crucial role in microbial pathogenesis and developing infections associated with medical devices. Enterobacter hormaechei and Klebsiella pneumoniae are classified as significant nosocomial pathogens within the ESKAPE category and cause diverse infections. In addition to their reputation as prolific biofilm formers, these pathogens are increasingly becoming drug-resistant and pose a substantial threat to the healthcare setting. Due to the inherent resistance of biofilms to conventional therapies, novel strategies are imperative for effectively controlling E. hormaechei and K. pneumoniae biofilms. This study aimed to assess the anti-biofilm activity of gallic acid (GA) against E. hormaechei and K. pneumoniae. The results of biofilm quantification assays demonstrated that GA exhibited significant antibiofilm activity against E. hormaechei and K. pneumoniae at concentrations of 4 mg mL-1, 2 mg mL-1, 1 mg mL-1, and 0.5 mg mL-1. Similarly, GA exhibited a dose-dependent reduction in violacein production, a QS-regulated purple pigment, indicating its ability to suppress violacein production and disrupt QS mechanisms in Chromobacterium violaceum. Additionally, computational tools were utilized to identify the potential target involved in the biofilm formation pathway. The computational analysis further indicated the strong binding affinity of GA to essential biofilm regulators, MrkH and LuxS, suggesting its potential in targeting the c-di-GMP and quorum sensing (QS) pathways to hinder biofilm formation in K. pneumoniae. These compelling findings strongly advocate GA as a promising drug candidate against biofilm-associated infections caused by E. hormaechei and K. pneumoniae.

Synergistic Effect of Thymol-Ciprofloxacin Combination on Planktonic Cells and Biofilm of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic bacteria causing severe and life-threatening infections in individuals with weakened immune systems. P. aeruginosa forms antibiotic-resistant biofilms, rendering it challenging to treat; hence, alternate therapies are required to eliminate it. Treatment of infections using a combination of drugs is gaining momentum to combat drug-resistant pathogens, including P. aeruginosa. This study explores the synergistic effects of Thymol in combination with Ciprofloxacin, Amikacin and Colistin against planktonic cells and biofilm of P. aeruginosa. Thymol in combination with Ciprofloxacin yields the fractional inhibitory concentration index values 0.156 and 0.375 in P. aeruginosa strains, GC14 and ATCC 9027, respectively, highlighting a robust synergistic effect on both the planktonic and biofilm of P. aeruginosa. The results showed that Thymol (512 µg/mL) and Ciprofloxacin (0.125 µg/mL) were the most effective combination with 95 and 93.5% total biofilm inhibition in GC14 and PA27, respectively, compared to the Thymol (512 µg/mL) and Ciprofloxacin (0.125 µg/mL) alone. Our findings suggest that the combinations of Thymol and Ciprofloxacin may be a potential therapeutic strategy to address the issue of infections caused by P. aeruginosa biofilms.