In vitro fungicidal photodynamic effect of hypericin on Candida species.

Hypericin is a natural photosensitizer considered for the new generation of photodynamic therapy (PDT) drugs. The aim of this study was to evaluate the in vitro fungicidal effect of hypericin PDT on various Candida spp., assessing its photocytotoxicity to keratinocytes (HaCaT) and dermal fibroblasts (hNDF) to determine possible side effects. A 3 log fungicidal effect was observed at 0.5 McFarland for two Candida albicans strains, Candida parapsilosis and Candida krusei with hypericin concentrations of 0.625, 1.25, 2.5 and 40 µm, respectively, at a fluence of 18 J cm(-2) (LED lamp emitting at 602 ± 10 nm). To obtain a 6 log reduction, significantly higher hypericin concentrations and light doses were needed (C. albicans 5 µM, C. parapsilosis 320 µM and C. krusei 320 µM; light dose 37 J cm(-2)). Keratinocytes and fibroblasts can be preserved by keeping the hypericin concentration below 1 µm and the light dose below 37 J cm(-2). C. albicans appears to be suitable for treatment with hypericin PDT without significant damage to cutaneous cells.

Unsuspected and extensive transmission of a drug-susceptible Mycobacterium tuberculosis strain.

BACKGROUND: A large and unsuspected tuberculosis outbreak involving 18.7% of the total of the tuberculosis cases studied, was detected in a population-based molecular epidemiological study performed in Zaragoza (Spain) from 2001 to 2004. METHODS: The Mycobacterium tuberculosis drug-susceptible strain, named MTZ strain, was genetically characterized by IS6110-RFLP, Spoligotyping and by MIRU-VNTR typing and the genetic patterns obtained were compared with those included in international databases. The characteristics of the affected patients, in an attempt to understand why the MTZ strain was so highly transmitted among the population were also analyzed. RESULTS: The genetic profile of the MTZ strain was rare and not widely distributed in our area or elsewhere. The patients affected did not show any notable risk factor for TB. CONCLUSION: The M. tuberculosis strain MTZ, might have particular transmissibility or virulence properties, and we believe that greater focus should be placed on stopping its widespread dissemination.