Clinical use of polymerase chain reactionperformed on peripheral blood and bone marrow samples for the diagnosis and monitoring of visceral leishmaniasis in HIV-infected and HIV-uninfected patients: a single-center, 8-year experience in Italy and review of the literature

Background. To overcome some of the limitations of conventional microbiologic techniques, polymerase chainreaction (PCR)–based assays are proposed as useful tools for the diagnosis of visceral leishmaniasis.Patients and methods. A comparative study using conventional microbiologic techniques (i.e., serologic testing,microscopic examination, and culture) and a Leishmania species–specific PCR assay, using peripheral blood andbone marrow aspirate samples as templates, was conducted during an 8-year period. The study cohort consistedof 594 Italian immunocompetent (adult and pediatric) and immunocompromised (adult) patients experiencingfebrile syndromes associated with hematologic alterations and/or hepatosplenomegaly. Identification of the infectingprotozoa at the species level was directly obtained by PCR of peripheral blood samples, followed by restrictionfragment–length polymorphism analysis of the amplified products, and the results were compared with those ofisoenzyme typing of Leishmania species strains from patients, which were isolated in vitro.Results. Sixty-eight patients (11.4%) had a confirmed diagnosis of visceral leishmaniasis. Eleven cases wereobserved in human immunodeficiency virus (HIV)–uninfected adults, 20 cases were observed in HIV-infectedadults, and the remaining 37 cases were diagnosed in HIV-uninfected children. In the diagnosis of primary visceralleishmaniasis, the sensitivities of the Leishmania species–specific PCR were 95.7% for bone marrow aspirate samplesand 98.5% for peripheral blood samples versus sensitivities of 76.2%, 85.5%, and 90.2% for bone marrow aspirateisolation, serologic testing, and microscopic examination of bone marrow biopsy specimens, respectively. None of229 healthy blood donors or 25 patients with imported malaria who were used as negative control subjects hadPCR results positive for Leishmania species in peripheral blood samples (i.e., specificity of Leishmania species–specific PCR, 100%). PCR and restriction fragment–length polymorphism analysis for Leishmania species identificationrevealed 100% concordance with isoenzyme typing in the 19 patients for whom the latter data wereavailable.Conclusions. PCR assay is a highly sensitive and specific tool for the diagnosis of visceral leishmaniasis in bothimmunocompetent and immunocompromised patients and can be reliably used for rapid parasite identificationat the species level.