title: Photodynamic inactivation of multidrug-resistant bacteria in hospital wastewaters: influence of residual antibiotics.
abstract: One environmental concern related to hospital effluents is discharge of them without preliminary treatment. Antimicrobial photodynamic inactivation (PDI) may represent an alternative to the traditional expensive, unsafe and not always effective disinfection methods. The main goal of this work was to assess the efficiency of PDI on clinical multidrug-resistant (MDR) bacteria in hospital wastewaters in order to evaluate its potential use in treating hospital effluents. The efficiency of PDI was assessed using a cationic porphyrin as the photosensitizer (PS), four MDR bacteria either in phosphate buffered saline or in filtrated hospital wastewaters. The synergistic effect of PDI and antibiotics (ampicillin and chloramphenicol) was also evaluated, as well as the effect of the surfactant sodium dodecyl sulfate (SDS). The results show the efficient inactivation of MDR bacteria in PBS (reduction of 6-8 log after 270 min of irradiation at 40 W m(-2) with 5.0 μM of PS). In wastewater, the inactivation of the four MDR bacteria was again efficient and the decrease in bacterial survival starts even sooner. A faster decrease in bacterial survival occurred when PDI was combined with the addition of antibiotics, at sub-inhibitory and inhibitory concentrations, but the SDS did not affect the PDI efficiency. It can be concluded that PDI has potential to be an effective alternative for the inactivation of MDR bacteria in hospital wastewaters and that the presence of antibiotics may enhance its effectiveness.
authors: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal. faustino@ua.pt aalmeida@ua.pt.
authors: Joana
authors: J
authors: Almeida
authors: João P C
authors: JP
authors: Tomé
authors: Maria G P M S
authors: MG
authors: Neves
authors: Augusto C
authors: AC
authors: Tomé
authors: José A S
authors: JA
authors: Cavaleiro
authors: Ângela
authors: Â
authors: Cunha
authors: Liliana
authors: L
authors: Costa
authors: Maria A F
authors: MA
authors: Faustino
authors: Adelaide
authors: A
authors: Almeida
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects / Q000528:radiation effects; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D058491:Bacterial Load; D002701:Chloramphenicol / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects / Q000528:radiation effects; D006761:Hospitals; D055668:Photochemical Processes; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011166:Porphyrins / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000528:radiation effects; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000528:radiation effects; D013501:Surface-Active Agents / Q000494:pharmacology; D013997:Time Factors; D062065:Wastewater / Q000382:microbiology*; D018508:Water Purification / Q000379:methods*
chemical_list: D000667:Ampicillin; D000900:Anti-Bacterial Agents; D002701:Chloramphenicol; D017319:Photosensitizing Agents; D011166:Porphyrins; D012967:Sodium Dodecyl Sulfate; D013501:Surface-Active Agents; D062065:Wastewater