title: Isolation and characterization of two bacteriophages with strong in vitro antimicrobial activity against Pseudomonas aeruginosa isolated from dogs with ocular infections.
abstract: OBJECTIVE
  To isolate and characterize bacteriophages with strong in vitro lytic activity against various pathogenic Pseudomonas aeruginosa strains isolated from dogs with ocular infections.
  
  
  METHODS
  26 genetically distinct P aeruginosa isolates.
  
  
  METHODS
  P aeruginosa strains were derived from dogs with naturally acquired ulcerative keratitis. From a large-scale screening for bacteriophages with potential therapeutic benefit against canine ocular infections, 2 bacteriophages (P2S2 and P5U5) were selected; host ranges were determined, and phage nucleic acid type and genetic profile were identified via enzymatic digestion. Electron microscopy was used to characterize bacteriophage ultrastructure. Bacteriophage temperature and pH stabilities were assessed by use of double-layer agar overlay titration. A cocultivation assay was used to evaluate the effect of the bacteriophages on bacterial host growth.
  
  
  RESULTS
  P5U5 was active against all P aeruginosa isolates, whereas P2S2 formed lytic plaques on plates of 21 (80.8%) isolates. For each bacteriophage, the genomic nucleic acid was DNA; each was genetically distinct. Ultrastructurally, P2S2 and P5U5 appeared likely to belong to the Podoviridae and Siphoviridae families, respectively. The bacteriophages were stable within a pH range of 4 to 12; however, titers of both bacteriophages decreased following heating for 10 to 50 minutes at 45° or 60°C. Growth of each P aeruginosa isolate was significantly inhibited in coculture with P2S2 or P5U5; the dose response was related to the plaque-forming unit-to-CFU ratios.
  
  
  CONCLUSIONS
  Bacteriophages P2S2 and P5U5 appear to be good candidates for phage treatment of infection caused by pathogenic P aeruginosa in dogs.
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Thiago M A
authors.initials: TM
authors.lastname: Santos
authors.forename: Eric C
authors.initials: EC
authors.lastname: Ledbetter
authors.forename: Luciano S
authors.initials: LS
authors.lastname: Caixeta
authors.forename: Marcela L S
authors.initials: ML
authors.lastname: Bicalho
authors.forename: Rodrigo C
authors.initials: RC
authors.lastname: Bicalho
mesh_terms: D000818:Animals; D001434:Bacteriophage Typing; D001435:Bacteriophages / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification* / Q000648:ultrastructure; D003320:Corneal Ulcer / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D004279:DNA, Viral / Q000032:analysis; D004283:Dog Diseases / Q000382:microbiology / Q000517:prevention & control*; D004285:Dogs; D015817:Eye Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D014644:Genetic Variation; D058507:Host Specificity; D017902:Podoviridae / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000648:ultrastructure; D011552:Pseudomonas Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000821:virology*; D017906:Siphoviridae / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000648:ultrastructure
chemical_list: D004279:DNA, Viral