Issue 1, 2013

Dirty hands: photodynamic killing of human pathogens like EHEC, MRSA and Candida within seconds

Abstract

Hand hygiene is one of the most important interventions for reducing transmission of nosocomial life-threatening microorganisms, like methicillin resistant Staphylococcus aureus (MRSA), enterohemorrhagic Escherichia coli (EHEC) or Candida albicans. All three pathogens have become a leading cause of infections in hospitals. Especially EHEC is causing severe diarrhoea and, in a small percentage of cases, haemolytic-uremic syndrome (HUS) as reported for E. coli 104:H4 in Germany 2011. We revealed the possibility to inactivate very fast and efficiently MRSA, EHEC and C. albicans using the photodynamic approach. MRSA, EHEC and C. albicans were incubated in vitro with different concentrations of TMPyP for 10 s and illuminated with visible light (50 mW cm−2) for 10 and 60 s. 1 μmol l−1 of TMPyP and an applied radiant exposure of 0.5 J cm−2 achieved a photodynamic killing of ≥99.9% of MRSA and EHEC. Incubation with higher concentrations (up to 100 μmol l−1) of TMPyP caused bacteria killing of >5 log10 (≥99.999%) after illumination. Efficient Candida killing (≥99.999%) was achieved first at a higher light dose of 12 J cm−2. Different rise and decay times of singlet oxygen luminescence signals could be detected in Candida cell suspensions for the first time, indicating different oxygen concentrations in the surrounding for the photosensitizer and singlet oxygen, respectively. This confirms that TMPyP is not only found in the water-dominated cell surrounding, but also within the C. albicans cells. Applying a water–ethanol solution of TMPyP on ex vivo porcine skin, fluorescence microscopy of histology showed that the photosensitizer was exclusively localized in the stratum corneum regardless of the incubation time. TMPyP exhibited a fast and very effective killing rate of life-threatening pathogens within a couple of seconds that encourages further testing in an in vivo setting. Being fast and effective, antimicrobial photodynamic applications might become acceptable as a tool for hand hygiene procedures and also in other skin areas.

Graphical abstract: Dirty hands: photodynamic killing of human pathogens like EHEC, MRSA and Candida within seconds

Article information

Article type
Paper
Submitted
29 May 2012
Accepted
06 Jul 2012
First published
02 Aug 2012

Photochem. Photobiol. Sci., 2013,12, 135-147

Dirty hands: photodynamic killing of human pathogens like EHEC, MRSA and Candida within seconds

A. Eichner, F. P. Gonzales, A. Felgenträger, J. Regensburger, T. Holzmann, W. Schneider-Brachert, W. Bäumler and T. Maisch, Photochem. Photobiol. Sci., 2013, 12, 135 DOI: 10.1039/C2PP25164G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements