Biology subjects

Duperthuy, M.

Publications and source records attributed to Duperthuy, M..

3 recordsLinked to original sources

bioRxiv2023

Elevated concentrations of polymyxin B elicit a biofilm-specific resistance mechanism in Vibrio cholerae

Vibrio cholerae can form biofilms both in the aquatic environment and in the human intestine, facilitating the release of hyper-infectious aggregates. Due to the increasing antibiotic resistance that impedes treatment of infections, alternatives need to be found. One of these alternatives is antimicrobial peptides, including polymyxin B (PmB), which is already used to treat infections caused by antibiotic-resistant bacteria. In this study, we first investigated the resistance of V. cholerae O1 El Tor strain A1552 to various antimicrobials under aerobic and anaerobic conditions. An increased resistance to PmB is observed in anaerobiosis, with a 3-fold increase in the dose required for 50% growth inhibition. We then studied the impact of the PmB on the formation and the degradation of V. cholerae biofilms to PmB. Our results show that PmB affects more efficiently biofilm formation under anaerobic conditions. On the other hand, preformed biofilms are susceptible to degradation by PmB at concentrations close to the minimum inhibitory concentration (MIC), resulting in approximately 50% reduction of the biomass. At higher concentrations, we observed less degradation and an opacification of the biofilm structures within 20 minutes post-treatment, suggesting a densification of the structure. This densification does not seem to result from the overexpression of matrix genes but rather from the release of DNA through cellular lysis, forming a protective shield that limits the penetration of the PmB into the biofilm. ImportanceVibrio cholerae is an intestinal pathogen capable of forming biofilms and resisting antimicrobials both in the aquatic environment and during infection. Understanding and determining the resistance of V. cholerae to antimicrobials during the infection is crucial to improve patient care. During the infection and in the aquatic environment, V. cholerae form biofilms, structures that are known for their significance in antimicrobial resistance. In this study, we investigated the antimicrobial resistance of V. cholerae in both aerobic and anaerobic conditions, in their planktonic and biofilm forms. The major finding of this study is the identification of a resistance mechanism specific to elevated concentrations of polymyxin B, a last-resort antimicrobial used in the treatment of infections caused by multidrug-resistant Gram-negative bacteria. This resistance mechanism likely involves the lysis of bacterial cells on the surface of the biofilm, resulting in the release of DNA that provides a protective shield against PmB for bacteria within the biofilm matrix.

microbiology↗

bioRxiv2022

Comprehension of Antimicrobial Peptides Modulation of the Type VI Secretion System in Vibrio cholerae

The Type VI secretion System (T6SS) is a versatile weapon used by bacteria for virulence, resistance to grazing and competition with other bacteria. We previously demonstrated that the role of the T6SS in interbacterial competition and in resistance to grazing is enhanced in Vibrio cholerae in the presence of subinhibitory concentrations of polymyxin B (PmB). In this study, we performed a global quantitative proteomic analysis by liquid chromatography coupled to mass spectrometry and a transcriptomic analysis by quantitative PCR of the T6SS known regulators in V. cholerae grown with and without PmB. The proteome of V. cholerae is greatly modified in the presence of PmB at subinhibitory concentrations with more than 39 % of the identified cellular proteins displaying a difference in their abundance, including T6SS-related proteins (Hcp, VasC, TsaB and ClpV). We identified a regulator whose abundance and expression are increased in the presence of PmB, vxrB, the response regulator of the two-component system VxrAB. In a vxrAB deficient mutant, the expression of hcp measured by quantitative PCR, although globally reduced, was not modified in the presence of PmB, confirming its role in hcp upregulation with PmB. The upregulation of the T6SS in the presence of PmB appears to be, at least in part, due to the two-component system VxrAB. ImportanceThe type VI secretion system is important for bacterial competition, virulence and resistance to grazing by predators. In this study, we investigated the regulation leading to the type VI secretion system activation in the presence of polymyxin B (PmB), an antimicrobial used in veterinary and human health to treat infection caused by multi-resistant Gram-negative bacteria, in V. cholerae. In addition to making an overall portrait of the modifications to the proteome, we identified the VxrAB two-component system as the main regulator responsible for this activation. Our results provide evidence that subinhibitory concentrations of antimicrobials are responsible for important modifications of the proteome of pathogenic bacteria, inducing the production of proteins involved in virulence, host colonisation, resistance and environmental survival.

microbiology↗

bioRxiv2021

Experimental evolution of Vibrio cholerae: Identification of genes involved in motility in presence of polymyxin B

Vibrio cholerae is the bacteria responsible for the cholera disease and a natural inhabitant of aquatic environments. Biofilm formation is important for human colonization and environmental survival. Motility is essential for adhesion and biofilm formation by V. cholerae. In a previous study, we showed that motility and biofilm formation are altered in the presence of sub-inhibitory concentrations of polymyxin B in V. cholerae. In this study, we performed an experimental evolution to identify genes rescuing the motility in the presence of polymyxin B. Mutations in 5 genes have been identified: ihfA, vacJ (mlaA), mlaF, dacB and ccmH. The details of these mutations, their potential impact on the function of the proteins they encode and on the motility in presence of polymyxin B are discussed.

microbiology↗