title: New strategy for rapid diagnosis and characterization of fungal infections: the example of corneal scrapings.
abstract: OBJECTIVE
  The prognosis of people infected with Fungi especially immunocompromised depends on rapid and accurate diagnosis to capitalize on time administration of specific treatments. However, cultures produce false negative results and nucleic-acid amplification techniques require complex post-amplification procedures to differentiate relevant fungal types. The objective of this work was to develop a new diagnostic strategy based on real-time polymerase-chain reaction high-resolution melting analysis (PCR-HRM) that a) detects yeasts and filamentous Fungi, b) differentiates yeasts from filamentous Fungi, and c) discriminates among relevant species of yeasts.
  
  
  METHODS
  PCR-HRM detection limits and specificity were assessed with a) isolated strains; b) human blood samples experimentally infected with Fungi; c) blood experimentally infected with other infectious agents; d) corneal scrapings from patients with suspected fungal keratitis (culture positive and negative) and e) scrapings from patients with suspected bacterial, viral or Acanthamoeba infections. The DNAs were extracted and mixed with primers diluted in the MeltDoctor® HRM Master Mix in 2 tubes, the first for yeasts, containing the forward primer CandUn (5'CATGCCTGTTTGAGCGTC) and the reverse primer FungUn (5'TCCTCCGCTT ATTGATATGCT) and the second for filamentous Fungi, containing the forward primer FilamUn (5'TGCCTGTCCGAGCGTCAT) and FungUn. Molecular probes were not necessary. The yields of DNA extraction and the PCR inhibitors were systematically monitored.
  
  
  RESULTS
  PCR-HRM detected 0.1 Colony Forming Units (CFU)/µl of yeasts and filamentous Fungi, differentiated filamentous Fungi from yeasts and discriminated among relevant species of yeasts. PCR-HRM performances were higher than haemoculture and sensitivity and specificity was 100% for culture positive samples, detecting and characterizing Fungi in 7 out 10 culture negative suspected fungal keratitis.
  
  
  CONCLUSIONS
  PCR-HRM appears as a new, sensitive, specific and inexpensive test that detects Fungi and differentiates filamentous Fungi from yeasts. It allows direct fungal detection from clinical samples and experimentally infected blood in less than 2.30 h after DNA extraction.
authors: Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, France. pablogol@aol.com
authors: Pablo
authors: P
authors: Goldschmidt
authors: Sandrine
authors: S
authors: Degorge
authors: Patricia
authors: P
authors: Che Sarria
authors: Djida
authors: D
authors: Benallaoua
authors: Oudy
authors: O
authors: Semoun
authors: Vincent
authors: V
authors: Borderie
authors: Laurent
authors: L
authors: Laroche
authors: Christine
authors: C
authors: Chaumeil
mesh_terms: D004271:DNA, Fungal / Q000235:genetics; D015821:Eye Infections, Fungal / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology*; D005260:Female; D005658:Fungi / Q000235:genetics*; D006801:Humans; D007634:Keratitis / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology*; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods*
chemical_list: D004271:DNA, Fungal