Biofilm formation capacity of Pseudomonas aeruginosa is significantly enhanced by sub-inhibitory concentrations of Tomatidine

• Published in: Gene reports 2022-06, Vol.27, p.101570, Article 101570
• Main Authors: Noori, Hadi Ghoomdost, Tadjrobehkar, Omid, Moazamian, Elham
• Format: Article
• Language: English
• Subjects: Biofilm; LasIR; P. aeruginosa; RhlIR; Tomatidine
• ISSN: 2452-0144; 2452-0144
• DOI: 10.1016/j.genrep.2022.101570

Biofilm associated infections of Pseudomonas aeruginosa are regarded as a huge problem in eradication antibiotic therapy. In this regard, other alternatives such as anti-biofilm or anti-virulence candidates are needed. This study was performed to investigate the effect of sub-inhibitory concentrations of Tomatidine on biofilm formation capacity and the expression of biofilm associated genes in some local isolates of P. aeruginosa. PAO1 strain and 20 local clinical isolates of P. aeruginosa were used in all assessments. Microtiter plate assay was used in phenotypic detection of biofilm formation. RNA was extracted from all bacteria and expression level of lasI, lasR, rhlI, rhlR and algD genes was investigated. All experiments were done in untreated condition and after treatment with 32 and 512 mg/L of Tomatidine. Fifty-five percent of isolates were weak biofilm producers and 45% were strong biofilm producers. Majority of multiple drug resistant and extensively drug resistant isolates were weak biofilm producers. Biofilm formation and expression of all investigated genes were significantly increased by a dose dependent manner after treatment with two sub-inhibitory concentrations of Tomatidine. The lasI and rhlR were the most and the least Tomatidine affected genes, respectively. Among the five investigated genes only rhlR was expressed significantly more in weak biofilm producers in comparison to strong biofilm producers. Sub-inhibitory concentrations of Tomatidine significantly induce biofilm formation and also expression of QS associated genes of P. aeruginosa. Therefore, many antibiotic agents and natural bioactive agents are regarded as double edged swords in the battle against the bacterial infections. We believe that the revision of empirical therapy regiments especially in Gram negative biofilm associated infections can be an important approach that has to be considered in development of future therapeutic guidelines. •Tomatidine has no inhibitory effects against P. aeruginosa up to 2 mg/ml.•Biofilm formation of P. aeruginosa increased by Tomatidine•Expression of quorum-sensing associated genes increased by Tomatidine•Induction of Biofilm formation in P. aeruginosa by Tomatidine is dose-dependent.