title: A comparative in vitro photoinactivation study of clinical isolates of multidrug-resistant pathogens.
abstract: Photodynamic inactivation (PDI) has been investigated to cope with the increasing incidence of multidrug-resistant (MDR) pathogens. In Hong Kong, methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are the two commonest MDR pathogens. Here, we studied the photodynamic inactivation (PDI) mediated by poly-L-lysine chlorin(e6) conjugate (pL-ce6) and toluidine blue O (TBO) in clinical MRSA and ESBL producing E. coli, together with their corresponding American Type Culture Collection (ATCC) strains. Both pL-ce6 and TBO mediated a light- and drug dose-dependent efficacy for the four pathogens. pL-ce6 was more effective. pL-ce6 at 8 microM, 30 Jcm(-2), attained 5 log killing for ESBL-producing E. coli and E. coli (ATCC 25922); 4 log killing for MRSA, and 3 log killing for S. aureus (ATCC 25923). TBO at 80 microM, 30 Jcm(-2), only exhibited 3 log killing in MRSA and 2 log killing in S. aureus (ATCC 25923). TBO (400 microM, 30 Jcm(-2)) induced equal killing for ESBL-producing E. coli and E. coli (ATCC 25922). Our studied MRSA isolate responded better than S. aureus (ATCC 25923). Thus, pL-ce6-mediated PDI in other MRSA isolates deserves further investigation.
authors: Department of Health Technology and Informatics, Medical Laboratory Science Section, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, SAR.
authors: Hi M
authors: HM
authors: Tang
authors: Michael R
authors: MR
authors: Hamblin
authors: Christine M N
authors: CM
authors: Yow
mesh_terms: D002735:Chlorophyllides; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008027:Light; D011166:Porphyrins / Q000494:pharmacology*; D011836:Radiation Tolerance / Q000187:drug effects; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D014048:Tolonium Chloride / Q000494:pharmacology*
chemical_list: D002735:Chlorophyllides; D011166:Porphyrins; D011838:Radiation-Sensitizing Agents; D014048:Tolonium Chloride; C062985:phytochlorin