Investigation into the susceptibility of Burkholderia cepacia complex isolates to photodynamic antimicrobial chemotherapy (PACT)

C. M. Cassidy; A. L. Watters; R. F. Donnelly; M. M. Tunney

doi:10.1117/12.822874

13 July 2009 Investigation into the susceptibility of Burkholderia cepacia complex isolates to photodynamic antimicrobial chemotherapy (PACT)

C. M. Cassidy, A. L. Watters, R. F. Donnelly, M. M. Tunney

Author Affiliations +

Proceedings Volume 7380, Photodynamic Therapy: Back to the Future; 738039 (2009) https://doi.org/10.1117/12.822874
Event: 12th World Congress of the International Photodynamic Association, 2009, Seattle, Washington, United States

Abstract

The main cause of morbidity and mortality in cystic fibrosis (CF) sufferers is progressive pulmonary damage caused by recurrent and often unremitting respiratory tract infection. Causative organisms include Pseudomonas aeruginosa and Haemophilus influenzae, but in recent years the Burkholderia cepacia complex has come to the fore. This group of highly drug-resistant Gram-negative bacteria are associated with a rapid decline in lung function and the often fatal cepacia syndrome, with treatment limited to patient segregation and marginally effective antibacterial regimens. Thus, development of an effective treatment is of the upmost importance. PACT, a non-target specific therapy, has proven successful in killing both Gram-positive and Gram-negative bacteria. In this study, planktonic cultures of six strains of the B. cepacia complex were irradiated (635 nm, 200 J cm^-2,10 minutes irradiation) following 30 seconds incubation with methylene blue (MB) or meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate (TMP). Rates of kill of > 99 % were achieved with MB- and TMP-PACT. A MB concentration of 50 μg ml^-1 and TMP concentration of 500 μg ml^-1 were associated with highest percentage kills for each photosensitizer. PACT is an attractive option for treatment of B.cepacia complex infection. Further study, involving biofilm culture susceptibility, delivery of light to the target and in vivo testing will be necessary before it PACT becomes a viable treatment option for CF patients who are colonised or infected with B. cepacia complex.

Citation Download Citation

C. M. Cassidy, A. L. Watters, R. F. Donnelly, and M. M. Tunney "Investigation into the susceptibility of Burkholderia cepacia complex isolates to photodynamic antimicrobial chemotherapy (PACT)", Proc. SPIE 7380, Photodynamic Therapy: Back to the Future, 738039 (13 July 2009); https://doi.org/10.1117/12.822874

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