title: In vitro photoinactivation of bovine mastitis related pathogens.
abstract: BACKGROUND
  Bovine mastitis is considered the most important disease of worldwide dairy industry. Treatment of this disease is based on the application intramammary antibiotic, which favors an increase in the number of resistant bacteria in the last decade. Photodynamic inactivation (PDI) has been investigated in different areas of Health Sciences, and has shown great potential for inactivating different pathogens, without any selection of resistant microorganisms. The objective of this study was to investigate the efficacy of PDI in the inactivation of pathogens associated with bovine mastitis.
  
  
  METHODS
  We tested the effectiveness of PDI against antibiotic resistant strains, isolated from bovine mastitis, from the following species: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Corynebacterium bovis, and the alga Prototheca zopfii. Nine experimental groups were evaluated: control, no treatment; light only, irradiation of a red light-emitting diode (λ=662 (20) nm) for 180 s; exposure to 50 μM methylene blue alone for 5 min; and PDI for 5, 10, 30, 60, 120 and 180 s.
  
  
  RESULTS
  S. dysgalactiae, S. aureus, and C. bovis were inactivated after 30s of irradiation, whereas S. agalactiae was inactivated after 120 s and P. zopfii at 180 s of irradiation.
  
  
  CONCLUSIONS
  These results show that PDI can be an interesting tool for inactivating pathogens for bovine mastitis.
authors: Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87 - Cidade Universitária, 05508-270, São Paulo, SP, Brazil. Electronic address: fsellera@usp.br.
authors: Fábio Parra
authors: FP
authors: Sellera
authors: Center for Lasers and Applications, Av. Lineu Prestes, 2242 - Cidade Universitária, 05508-000, São Paulo,SP, Brazil. Electronic address: caetanosabino@gmail.com.
authors: Caetano Padial
authors: CP
authors: Sabino
authors: Center for Lasers and Applications, Av. Lineu Prestes, 2242 - Cidade Universitária, 05508-000, São Paulo,SP, Brazil. Electronic address: marthasr@usp.br.
authors: Martha Simões
authors: MS
authors: Ribeiro
authors: Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87 - Cidade Universitária, 05508-270, São Paulo, SP, Brazil. Electronic address: gargano21@gmail.com.
authors: Ronaldo Gomes
authors: RG
authors: Gargano
authors: Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87- Cidade Universitária, 05508-270, São Paulo SP, Brazil. Electronic address: benites@usp.br.
authors: Nilson Roberti
authors: NR
authors: Benites
authors: Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87- Cidade Universitária, 05508-270, São Paulo SP, Brazil. Electronic address: melville@usp.br.
authors: Priscilla Anne
authors: PA
authors: Melville
authors: Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87 - Cidade Universitária, 05508-270, São Paulo, SP, Brazil. Electronic address: fabiocp@usp.br.
authors: Fabio Celidonio
authors: FC
authors: Pogliani
mesh_terms: D000818:Animals; D018407:Bacterial Physiological Phenomena / Q000187:drug effects* / Q000528:radiation effects; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D008414:Mastitis, Bovine / Q000188:drug therapy* / Q000382:microbiology* / Q000473:pathology; D008892:Milk / Q000382:microbiology; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D011525:Prototheca / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects; D013242:Sterilization / Q000379:methods
chemical_list: D017319:Photosensitizing Agents
keywords: Antimicrobial; Dairy cows; Photodynamic inactivation; Treatment; Veterinary medicine