Cytology Brush Test Proves Superior for Mucosal Leishmaniasis

The cytology brush PCR test has been compared with traditional methods of diagnosing such as biopsy with histopathology, which are insensitive and require collection of an invasive diagnostic specimen.

Scientists at the University of Toronto (ON, Canada) working with colleagues in Peru, enrolled 28 patients, of whom 23 fulfilled criteria for a diagnosis of ML. They compared standard invasive procedures including biopsy histopathology, biopsy PCR, and leishmanin skin test (LST) to a novel, noninvasive, cytology-brush based PCR for the diagnosis of ML in Lima (Peru). Consensus reference standard was 2/4 tests positive, and outcome measures were sensitivity and specificity. Leishmania species identification was performed by PCR-based assays of positive specimens.

Two different cytology brushes CerviSoft and Histobrush (Puritan Medical Products; Guilford, ME, USA) were tested and compared with the other tests. Disaggregated tissue and cytology brushes were processed for DNA isolation using the High Pure PCR Template Preparation Kit (Roche, Mannheim, Germany). PCR assays were performed using the HotStar Taq Plus DNA Polymerase kit (QIAGEN; Hilden, Germany).

Subjective tolerability of the CerviSoft brush was superior to that of the Histobrush as it was reported to cause less discomfort and was softer on the mucosa, particularly in the nose. All healthy control volunteers had negative CerviSoft and Histobrush cytology brush PCR. Sensitivity and specificity of biopsy with histopathology were 21.7% and 100%; 69.6% and 100% for LST; 95.7% and 100% for biopsy PCR; and 95.7% and 90% for cytology brush PCR using both CerviSoft and Histobrush cervical cytology brushes. Represented species identified by PCR- Restriction Fragment Length Polymorphism (RFLP) included four L. braziliensis, and three L. peruviana.

The authors concluded that use of commercial grade cytology brush PCR for diagnosis of ML is sensitive, rapid, well tolerated, and carries none of the risks of invasive diagnostic procedures such as biopsy. Further optimization is required for adequate species identification. Further evaluation of this method in field and other settings is warranted. The study was published on October 27, 2011, in the online journal Public Library of Science One.

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