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Killing of methicillin-resistant Staphylococcus aureus in vitro using aluminium disulphonated phthalocyanine, a
M A Griffiths1, B W Wren, M Wilson
1Department of Microbiology, Eastman Dental Institute for Oral Health Care Sciences, University of London, UK.
Abstract:
The aim of this study was to determine whether 16 epidemic methicillin-resistant strains of Staphylococcus aureus (EMRSA) could be killed by the light-activated antimicrobial agent aluminium disulphonated phthalocyanine (AIPcS2). EMRSA suspensions were irradiated with light from a laser diode in the presence of AIPcS2 and survivors enumerated. All strains were susceptible to killing, the bactericidal effect being dependent on the AIPcS2 concentration and the light dose. AIPcS2 rendered the bacteria light-sensitive almost immediately and killing was unaffected by the growth phase of the organism. Scavengers of singlet oxygen and free radicals protected the bacteria from killing. These results imply that light-activated antimicrobial agents may be useful in eliminating EMRSA from wounds or carriage sites.
Insights
This study shows that light-activated aluminium disulphonated phthalocyanine (AIPcS2) effectively kills epidemic methicillin-resistant Staphylococcus aureus (EMRSA). The antimicrobial agent offers a promising strategy for eliminating EMRSA infections.
Area of Science:
- Photodynamic therapy
- Antimicrobial research
- Bacteriology
Background:
- Epidemic methicillin-resistant Staphylococcus aureus (EMRSA) poses a significant public health threat.
- Conventional treatments for EMRSA infections are becoming less effective due to rising resistance.
- Novel antimicrobial strategies are urgently needed to combat EMRSA.
Purpose of the Study:
- To evaluate the efficacy of aluminium disulphonated phthalocyanine (AIPcS2) as a light-activated antimicrobial agent against EMRSA.
- To determine the factors influencing the bactericidal activity of AIPcS2.
- To explore the mechanism of AIPcS2-mediated bacterial killing.
Main Methods:
- Susceptibility testing of 16 EMRSA strains to AIPcS2 and laser diode irradiation.
- Enumeration of surviving bacteria post-treatment.
- Investigation of the role of singlet oxygen and free radicals using scavengers.
Main Results:
- All tested EMRSA strains were susceptible to killing by light-activated AIPcS2.
- Bactericidal effect was dependent on AIPcS2 concentration and light dose.
- Killing mechanism involved singlet oxygen and free radicals, and was immediate, independent of bacterial growth phase.
Conclusions:
- Light-activated AIPcS2 demonstrates potent bactericidal activity against EMRSA.
- AIPcS2-based photodynamic therapy is a potential therapeutic approach for EMRSA elimination.
- This approach may be beneficial for treating EMRSA in wounds or carriage sites.