AI Article Synopsis
- There is a rising resistance to fluoroquinolones (FQs) like norfloxacin and enrofloxacin, highlighting the need for new antimicrobial drugs and strategies.
- The study found that a luxS mutant of Streptococcus suis is more susceptible to FQs, indicating that the LuxS/AI-2 quorum-sensing system affects FQ resistance.
- Research showed that the ΔluxS strain accumulated more enrofloxacin and had altered gene expression related to antibiotic resistance, suggesting that targeting the LuxS/AI-2 system could be a promising approach for developing new antimicrobial therapies.
Article Abstract
Increasing resistance to fluoroquinolones (FQs), such as norfloxacin and enrofloxacin, supports the need for the discovery of novel molecules and alternative approaches in antimicrobial therapy. Quorum sensing (QS) is a promising target for next-generation anti-infective agents designed to address the evolving drug resistance in bacterial pathogens. Given that the LuxS/autoinducer-2 (AI-2) quorum-sensing system regulates microbial group behaviors, we hypothesized that this system influences the FQ susceptibility in Streptococcus suis. It was found that a luxS mutant (ΔluxS) of S. suis possesses an increased susceptibility to FQs compared to the wild type strain. When grown in the presence of sub-MIC of antibiotics, the ΔluxS strain showed a significant decrease in growth rate and biofilm formation. These results suggest that the FQ resistance in S. suis could involve a signaling mechanism associated with the LuxS/AI-2 quorum-sensing system. HPLC (High Performance Liquid Chromatography) analyses showed a significant increase in the intracellular accumulation of enrofloxacin in the ΔluxS strain compared to the wild type strain. This increase was less pronounced in the presence of exogenous AI-2. Moreover, the expression of satA and satB genes was decreased in the ΔluxS strain. Exogenous AI-2 reversed the down-regulated gene expression observed in the ΔluxS strain. Our study brought strong evidence that the LuxS/AI-2 system in S. suis is involved in FQ susceptibility by regulating the efflux pump SatAB. LuxS is highly conserved among Gram-positive bacteria and may therefore represent a novel antimicrobial target for an alternative approach in antimicrobial therapy.
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| http://dx.doi.org/10.1016/j.vetmic.2019.05.006 | DOI Listing |
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