title: Antimicrobial activity of photodynamic therapy in combination with colistin against a pan-drug resistant Acinetobacter baumannii isolated from burn patient.
abstract: Nosocomially-acquired multi-, extensively-, and pandrug resistant (MDR, XDR, and PDR) strains of microorganisms such as Acinetobacter baumannii remain a serious cause of infection and septic mortality in burn patients. Treatment of patients with nosocomial burn wound infections is often complicated by drug-resistant strains of A. baumannii. Today, many researchers are focusing on the investigation of novel non-antibiotic strategies such as photodynamic therapy (PDT). We report a new PDT strategy that suppresses colistin resistance in PDR A. baumannii by interfering with the expression of a pmrA/pmrB two-component system. In the current study, A. baumannii with a PDR feature isolated from a burn patient was used as a test strain. PDT was carried out using toluidine blue O (TBO) and light-emitting diode (LED) as a photosensitizer and radiation source, respectively. The antimicrobial susceptibility profiles were assessed for cells surviving PDT. The effects of sub-lethal PDT (sPDT) on the expression of the pmrA/pmrB two-component signal transduction system were evaluated by real-time quantitative reverse transcription PCR. Results of drug susceptibly testing (DST) in LED and TBO groups separately showed that the bacteria were resistant to all tested antibiotics, while the DST result of the LED+TBO group showed highly declining bacterial growth when compared with the control group. Reduction in the expression of pmrA and pmrB was observed in the treated strains after sPDT. This represents the first conclusive example of a direct role for the PDT in breaking antibiotic resistance by directly modulating two-component system activity.
authors.affiliation: Private practice, and Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: e.boluki@outlook.com.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Boluki
authors.affiliation: Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: Hosayn.kazemian@yahoo.com.
authors.forename: Hossein
authors.initials: H
authors.lastname: Kazemian
authors.affiliation: Department of Microbiology, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran. Electronic address: h.piridogahe@gmail.com.
authors.forename: Hadi
authors.initials: H
authors.lastname: Peeridogaheh
authors.affiliation: Department of Microbiology, Medical School, Hamadan University of Medical Sciences, Hamadan, Iran. Electronic address: y.alikhani.phd@gmail.com.
authors.forename: Mohammad Yousef
authors.initials: MY
authors.lastname: Alikhani
authors.affiliation: Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: s.shahabi.1973@gmail.com.
authors.forename: Sima
authors.initials: S
authors.lastname: Shahabi
authors.affiliation: Department of Microbiology, school of Medicine, International Campus, Tehran University of Medical Sciences (IC-TUMS), Tehran, Iran. Electronic address: shapee32@yahoo.com.
authors.forename: Leili
authors.initials: L
authors.lastname: Beytollahi
authors.affiliation: Private practice, Tehran, Iran. Electronic address: r.gdent81@gmail.com.
authors.forename: Roghayeh
authors.initials: R
authors.lastname: Ghorbanzadeh
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000528:radiation effects; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology; D002056:Burns / Q000188:drug therapy / Q000382:microbiology; D003091:Colistin / Q000008:administration & dosage* / Q000494:pharmacology*; D003131:Combined Modality Therapy; D003666:Decontamination; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000528:radiation effects; D006801:Humans; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000494:pharmacology; D014048:Tolonium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D014048:Tolonium Chloride; D003091:Colistin
keywords: Acinetobacter baumannii; Antimicrobial resistance; Expression; Photodynamic therapy; Sub-lethal; pmrA; pmrB; qRT-PCR