Antimicrobial Action of Water-Soluble β-Chitosan against Clinical Multi-Drug Resistant Bacteria

Abstract

Recently, the number of patients infected by drug-resistant pathogenic microbes has increased remarkably worldwide, and a number of studies have reported new antibiotics from natural sources. Among them, chitosan, with a high molecular weight and α-conformation, exhibits potent antimicrobial activity, but useful applications as an antibiotic are limited by its cytotoxicity and insolubility at physiological pH. In the present study, the antibacterial activity of low molecular weight water-soluble (LMWS) α-chitosan (α1k, α5k, and α10k with molecular masses of 1, 5, and 10 kDa, respectively) and β-chitosan (β1k, β5k, and β10k) was compared using a range of pathogenic bacteria containing drug-resistant bacteria isolated from patients at different pH. Interestingly, β5k and β10k exhibited potent antibacterial activity, even at pH 7.4, whereas only α10k was effective at pH 7.4. The active target of β-chitosan is the bacterial membrane, where the leakage of calcein is induced in artificial PE/PG vesicles, bacterial mimetic membrane. Moreover, scanning electron microscopy showed that they caused significant morphological changes on the bacterial surfaces. An in vivo study utilizing a bacteria-infected mouse model found that LMWS β-chitosan could be used as a candidate in anti-infective or wound healing therapeutic applications.

“Smart” Triiodide Compounds: Does Halogen Bonding Influence Antimicrobial Activities?

“…NaI proves to be more effective through the attraction of the positively charged sodium ion to the negatively charged outer membranes of the Gram-negative microorganisms. This is the same mechanism of other ions entering the cell membrane of Gram-negative bacteria through cation-selective porins and causing toxicity [59]. The mechanisms of bacterial resistance include the occurrence of diminished protein channels on the bacterial outer membrane to decrease drug entry and/or the presence of efflux pumps to decrease the amount of drug accumulated within the cells [12,51,53].…”

Modification of Chitosan for the Generation of Functional Derivatives

“…However, the membrane composition and fluidity may influence the subsequent consequences of CS treatment [97,112]; (ii) Some studies suggest a subsequent separation of the cell wall from the cell membrane, whilst others only mention a morphological change. Interaction with the membrane leads to altered cell permeability and may disrupt energy generation pathways [89,108,[112][113][114][115][116][117][118]; (iii) CS also causes agglutination and precipitation of the undesired microorganisms [77,106]. Indeed, E. coli was shown to protect itself by forming aggregates in the presence of chitooligosaccharides (COS), which only displayed a bacteriostatic effect and the bacteria could rapidly grow after separation from the CS by membrane filtration [108,119].…”

Extraction and characterization of chitin, chitosan and chitooligosaccharides from crab shell waste

“…Chitin and chitosan have excellent properties, such as biodegradability, biocompatibility and non-toxicity adsorption (Majeti and Kumar, 2000). Chitosan and its oligomers are known for its various important biological properties such as antimicrobial (Park et al, 2015), antifungal (Hussain et al, 2012), antioxidant (Younes and Rinaudo, 2015), neuroprotective (Pangestuti and Kim, 2010) and anti-inflammatory (Yang et al, 2010). Besides having versatile biological functions, major drawbacks in application of chitosan is its insolubility in water and high molecular weight (Shen et al 2009).…”