title: Effective photodynamic therapy against microbial populations in human deep tissue abscess aspirates.
abstract: OBJECTIVE
  The primary therapy for deep tissue abscesses is drainage accompanied by systemic antimicrobial treatment. However, the long antibiotic course required increases the probability of acquired resistance, and the high incidence of polymicrobial infections in abscesses complicates treatment choices. Photodynamic therapy (PDT) is effective against multiple classes of organisms, including those displaying drug resistance, and may serve as a useful adjunct to the standard of care by reduction of abscess microbial burden following drainage.
  
  
  METHODS
  Aspirates were obtained from 32 patients who underwent image-guided percutaneous drainage of the abscess cavity. The majority of the specimens (24/32) were abdominal, with the remainder from liver and lung. Conventional microbiological techniques and nucleotide sequence analysis of rRNA gene fragments were used to characterize microbial populations from abscess aspirates. We evaluated the sensitivity of microorganisms to methylene blue-sensitized PDT in vitro both within the context of an abscess aspirate and as individual isolates.
  
  
  RESULTS
  Most isolates were bacterial, with the fungus Candida tropicalis also isolated from two specimens. We examined the sensitivity of these microorganisms to methylene blue-PDT. Complete elimination of culturable microorganisms was achieved in three different aspirates, and significant killing (P < 0.0001) was observed in all individual microbial isolates tested compared to controls.
  
  
  CONCLUSIONS
  These results and the technical feasibility of advancing optical fibers through catheters at the time of drainage motivate further work on including PDT as a therapeutic option during abscess treatment.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, 14642; Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, 14642.
authors.forename: Constantine G
authors.initials: CG
authors.lastname: Haidaris
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Foster
authors.forename: David L
authors.initials: DL
authors.lastname: Waldman
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Mathes
authors.forename: Joanne
authors.initials: J
authors.lastname: McNamara
authors.forename: Timothy
authors.initials: T
authors.lastname: Curran
mesh_terms: D018784:Abdominal Abscess / Q000188:drug therapy / Q000382:microbiology / Q000601:surgery; D000038:Abscess / Q000188:drug therapy* / Q000382:microbiology / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D041022:Candida tropicalis / Q000302:isolation & purification; D002177:Candidiasis / Q000188:drug therapy* / Q000382:microbiology / Q000601:surgery; D003131:Combined Modality Therapy; D004322:Drainage / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology / Q000601:surgery; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology / Q000601:surgery; D006801:Humans; D008169:Lung Abscess / Q000188:drug therapy / Q000382:microbiology / Q000601:surgery; D008297:Male; D008751:Methylene Blue / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D016133:Polymerase Chain Reaction; D013396:Suction; D055815:Young Adult
chemical_list: D017319:Photosensitizing Agents; D008751:Methylene Blue
keywords: antimicrobial; bacteria; fungi; image-guided; methylene blue