title: Non-invasive cytology brush PCR for the diagnosis and causative species identification of American cutaneous leishmaniasis in Peru.
abstract: BACKGROUND
  Traditional methods of detecting Leishmania from cutaneous lesions involve invasive diagnostic procedures, such as scrapings, which cause discomfort, require technical expertise, and carry risks of invasive procedures. We compared the performance of 2 novel, molecular-based non-invasive methods for the diagnosis of cutaneous leishmaniasis (CL).
  
  
  METHODS
  Consecutive patients presenting to the Leishmania Clinic at the Hospital Nacional Cayetano Heredia were enrolled. PCR was performed on filter paper lesion impressions (FPLIs), cytology brushes, and lancets for detection of Leishmania DNA. Smears from lesion scrapings and leishmanin skin test were also performed. Outcome measures were sensitivity and specificity. Composite reference standard was any 2 of 5 tests positive. Species identification was performed by PCR assays of positive specimens.
  
  
  RESULTS
  Ninety patients with 129 lesions were enrolled, 117 of which fulfilled reference criteria for a diagnosis of CL. Of these 117 lesions, 113 were positive by PCR of lancets used for lesion scrapings versus 116 by PCR of FPLIs (p=0.930) or 116 by PCR of cytology brushes (p=0.930). Sensitivity and specificity of PCR on lancets were 96.6% [95% CI 93.3-99.9%] and 100%, respectively. Sensitivity and specificity of FPLI PCR were 99.1% [95% CI 97.4-100%] and 100%, respectively. Sensitivity and specificity of cytology brush PCR were 99.1% [95% CI 97.4-100%] and 100%, respectively. Giemsa-stained lesion smear and leishmanin skin test had inferior sensitivities at 47.9% [95% CI 38.9-57.0%] and 82.3% [95% CI 73.9-90.7%], respectively, compared to PCR of invasive or non-invasive specimens (p<0.001).
  
  
  CONCLUSIONS
  Cytology brush PCR constitutes a sensitive and specific alternative to traditional diagnostic assays performed on invasive specimens such as lesion scrapings. It performs comparatively to non-invasive FPLI PCR. This novel, rapid, and well-tolerated method has the potential for widespread use in the field and in pediatric populations where traditional specimen collection is difficult.
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru.
authors.forename: Braulio Mark
authors.initials: BM
authors.lastname: Valencia
authors.forename: Nicolas
authors.initials: N
authors.lastname: Veland
authors.forename: Milena
authors.initials: M
authors.lastname: Alba
authors.forename: Vanessa
authors.initials: V
authors.lastname: Adaui
authors.forename: Jorge
authors.initials: J
authors.lastname: Arevalo
authors.forename: Donald E
authors.initials: DE
authors.lastname: Low
authors.forename: Alejandro
authors.initials: A
authors.lastname: Llanos-Cuentas
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Boggild
mesh_terms: D004247:DNA / Q000378:metabolism; D018105:DNA, Kinetoplast / Q000378:metabolism; D006801:Humans; D016773:Leishmaniasis, Cutaneous / Q000175:diagnosis* / Q000235:genetics*; D010209:Paper; D010568:Peru; D016133:Polymerase Chain Reaction / Q000379:methods*; D012150:Polymorphism, Restriction Fragment Length; D012680:Sensitivity and Specificity; D012867:Skin / Q000737:chemistry / Q000382:microbiology; D012882:Skin Tests / Q000379:methods; D013045:Species Specificity; D013048:Specimen Handling / Q000379:methods
chemical_list: D018105:DNA, Kinetoplast; D004247:DNA