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

Tsui-Min Tsai, Hsiung-Fei Chien, Tze Hsien Wang, Ching Tsan Huang, Yaw Bee Ker, Chin Tin Chen

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58 Citations (Scopus)


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 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.

Original languageEnglish
Pages (from-to)1883-1890
Number of pages8
JournalAntimicrobial Agents and Chemotherapy
Issue number5
Publication statusPublished - May 2011

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Pharmacology
  • Infectious Diseases


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