Induced protoporphyrin IX accumulation by the δ-aminolevulinic acid in bacteria and its potential use in the photodynamic therapy

Brígido Aparicio Cyntiha, Ramón Gallegos Eva, Arenas Huertero Francisco Jesús, Uribe Hernández Raúl

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations

Abstract

The increasing incident of resistant strains to antibiotic has encouraged the search of new antibacterial treatments, such as the photodynamic therapy. In recent years, photodynamic therapy has demonstrated being a good technology for the treatment of recurrent bacteria infection. PDT presents a hopeful approach to eliminate Gram positive and negative bacteria in immunological compromised patients. This therapy uses a laser in combination with a photosensibilizer in presence of intracellular molecular oxygen. The process generates an effect of phototoxicity in bacterial cells. The aim of this work was to determine the in vitro conditions to accumulate PpIX in effective concentrations in Staphylococcus aureus ATCC25923 and Streptococcus pyogenes, which are responsible of human cutaneous diseases. A cellular suspension of both strains was prepared in TSB to obtain growth in Log-phase, then, the suspensions were adjusted to a final concentration of 2.61×108 cells/mL. The strains were exposed to increasing concentrations from 0 to 160 μg/mL of δ-ALA in order to determinate the concentration that induces the biggest accumulation, of PpIX. PpIX was measured using the Piomelli method modified for bacteria. The concentration selected was 40 mg/mL of ALA. It was found that in basal concentration of δ-ALA (0 μg/mL) both strains accumulated similar amount of PpIX. In concentrations of 5 mg/mL of δ-ALA it was observed a significant (p <0.00.1) increment in PpIX concentration. Finally it was realized a kinetic to determinate the optimal accumulation over the time at 0, 5, 10, 15 and 30 min, and 1, 2, 4, 8, 16 and 32 h. It was found that the ideal time for PDT application, in both strains, was 24 h because in smaller times there was not statistically significant difference. The S. aureus ATCC25923 accumulated significantly the biggest concentration of PpIX with regard to S. pyogenes. In conclusion, it was found that the optimal conditions to apply PDT will be to expose both strains to 40 mg/mL of ALA and to irradiate at 24 h after the exposition.

Original languageEnglish
Title of host publicationMedical Physics - Tenth Mexican Symposium on Medical Physics
Pages283-287
Number of pages5
DOIs
StatePublished - 2008
Event10th Mexican Symposium on Medical Physics - Mexico City, Mexico
Duration: 17 Mar 200819 Mar 2008

Publication series

NameAIP Conference Proceedings
Volume1032
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference10th Mexican Symposium on Medical Physics
Country/TerritoryMexico
CityMexico City
Period17/03/0819/03/08

Keywords

  • Aminolevulinic acid
  • Photodynamic therapy
  • S aureus
  • S pyogenes

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