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Chitosan augments photodynamic inactivation of gram-positive and gram-negative bacteria.

ABSTRACT: Antimicrobial photodynamic inactivation (PDI) was shown to be a promising treatment modality for microbial infections. This study explores the effect of chitosan, a polycationic biopolymer, in increasing the PDI efficacy against Gram-positive bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and methicillin-resistant S. aureus (MRSA), as well as the Gram-negative bacteria Pseudomonas aeruginosa and Acinetobacter baumannii. Chitosan at <0.1% was included in the antibacterial process either by coincubation with hematoporphyrin (Hp) and subjection to light exposure to induce the PDI effect or by addition after PDI and further incubation for 30 min. Under conditions in which Hp-PDI killed the microbe on a 2- to 4-log scale, treatment with chitosan at concentrations of as low as 0.025% for a further 30 min completely eradicated the bacteria (which were originally at ?10(8) CFU/ml). Similar results were also found with toluidine blue O (TBO)-mediated PDI in planktonic and biofilm cells. However, without PDI treatment, chitosan alone did not exert significant antimicrobial activity with 30 min of incubation, suggesting that the potentiated effect of chitosan worked after the bacterial damage induced by PDI. Further studies indicated that the potentiated PDI effect of chitosan was related to the level of PDI damage and the deacetylation level of the chitosan. These results indicate that the combination of PDI and chitosan is quite promising for eradicating microbial infections.

SUBMITTER: Tsai T

PROVIDER: S-EPMC3088195 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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Chitosan augments photodynamic inactivation of gram-positive and gram-negative bacteria.

Tsai Tsuimin T Chien Hsiung-Fei HF Wang Tze-Hsien TH Huang Ching-Tsan CT Ker Yaw-Bee YB Chen Chin-Tin CT

Antimicrobial agents and chemotherapy 20110131 5

Antimicrobial photodynamic inactivation (PDI) was shown to be a promising treatment modality for microbial infections. This study explores the effect of chitosan, a polycationic biopolymer, in increasing the PDI efficacy against Gram-positive bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and methicillin-resistant S. aureus (MRSA), as well as the Gram-negative bacteria Pseudomonas aeruginosa and Acinetobacter baumannii. Chitosan at <0.1% was includ ...[more]

PMID: 21282440

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Project description:Chitosan-copper oxide (CHT-CuO) nanocomposite was synthesized using olive leaf extract (OLE) as reducing agent and CuSO4⋅5H2O as precursor. CHT-CuO nanocomposite was prepared using an in situ method in which OLE was added to a solution of chitosan and CuSO4⋅5H2O mixture in the ratio of 1:5 (v/v) and heated at a temperature of 90 °C. The obtained CHT-CuO nanocomposite was characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectrophotometry, energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (TEM). TEM results indicated that CHT-CuO nanocomposite are spherical in shape with size ranging from 3.5 to 6.0 nm. Antibacterial activity of the synthesized nanocomposites was evaluated against Gram-positive (Bacillus cereus, Staphyloccous haemolytica and Micrococcus Luteus) and Gram-negative (Escherichia coli, Pseudomonas citronellolis, Pseudomonas aeruginosa, kliebisella sp., Bradyrhizobium japonicum and Ralstonia pickettii) species by cup platting or disc diffusion method. Overall, against all tested bacterial strains, the diameters of the inhibition zone of the three nanocomposites fell between 6 and 24 mm, and the order of the antimicrobial activity was as follows: CuO-1.0 > CuO-0.5 > CuO-2.0. The reference antibiotic amoxicillin and ciprofloxacin showed greater activity based on the diameter of zones of inhibition (between 15-32 mm) except for S. heamolytica and P. citronellolis bacteria strains. The nanocomposites MIC/MBC were between 0.1 and 0.01% against all tested bacteria, except S. heamolityca (>0.1%). Based on MIC/MBC values, CuO-0.5 and CuO-1.0 were more active than CuO-2.0, in line with the observations from the disc diffusion experiment. The findings indicate that these nanocomposites are efficacious against bacteria; however, Gram-positive bacteria were less susceptible. The synthesized CHT-CuO nanocomposite shows promising antimicrobial activities and could be utilized as an antibacterial agent in packaging and medical applications.

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Chitosan augments photodynamic inactivation of gram-positive and gram-negative bacteria.

Publications

Chitosan augments photodynamic inactivation of gram-positive and gram-negative bacteria.

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