Sae regulator factor impairs the response to photodynamic inactivation mediated by Toluidine blue in Staphylococcus aureus.
Photodynamic inactivation (PDI) involves the combined use of light and a photosensitizer, which, in the presence of oxygen, originates cytotoxic species capable of inactivating bacteria. Since the emergence of multi-resistant bacterial strains is becoming an increasing public health concern, PDI becomes an attractive choice. The aim of this work was to study the differential susceptibility to Toluidine blue (TB) mediated PDI (TB-PDI) of S. aureus mutants (RN6390 and Newman backgrounds) for different key regulators of virulence factors related to some extent to oxidative stress. Complete bacteria eradication of planktonic cultures of RN6390 S. aureus photosensitized with 13μM TB was obtained upon illumination with a low light dose of 4.2J/cm2from a non-coherent light source. Similarly, complete cell death was achieved applying 1.3μM TB and 19J/cm2light dose, showing that higher light doses can lead to equal cell death employing low photosensitizer concentrations. Interestingly, RN6390 in planktonic culture responded significantly better to TB-PDI than the Newman strain. We showed that deficiencies in rsbU, mgrA (transcription factors related to stress response) or agr (quorum sensing system involved in copper resistance to oxidative stress) did not modify the response of planktonic S. aureus to PDI. On the other hand, the two component system sae impaired the response to TB-PDI through a mechanism not related to the Eap adhesin. More severe conditions were needed to inactivate S. aureus biofilms (0.5mM TB, 157J/cm2laser light). In mutant sae biofilms, strain dependant differential susceptibilities are not noticed.
Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET and Hospital de Clínicas José de San Martín, University of Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires, CP1120AAF, Argentina.
Lautaro
L
Gándara
Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET and Hospital de Clínicas José de San Martín, University of Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires, CP1120AAF, Argentina.
Leandro
L
Mamone
Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM), CONICET-UBA, Argentina.
Cristian
C
Dotto
Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM), CONICET-UBA, Argentina.
Fernanda
F
Buzzola
Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET and Hospital de Clínicas José de San Martín, University of Buenos Aires, Córdoba 2351 1er subsuelo, Ciudad de Buenos Aires, CP1120AAF, Argentina. Electronic address: adricasas@live.com.
Adriana
A
Casas
D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004203:Disinfection / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008027:Light; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects; D014048:Tolonium Chloride / Q000008:administration & dosage*; D037521:Virulence Factors / Q000378:metabolism*
D017319:Photosensitizing Agents; D037521:Virulence Factors; D014048:Tolonium Chloride
Photodynamic inactivation; Sae; Staphylococcus aureus; Toliudine blue