Loop-mediated isothermal amplification method for diagnosing Pneumocystis pneumonia in HIV-uninfected immunocompromised patients with pulmonary infiltrates

Abstract Loop-mediated isothermal amplification (LAMP) is becoming an established nucleic acid amplification method offering rapid, accurate, and cost-effective diagnosis of infectious diseases. We retrospectively evaluated 78 consecutive HIV-uninfected patients who underwent LAMP method for diagnosing Pneumocystis pneumonia (PCP). Diagnosis of PCP was made by the detection of Pneumocystis jirovecii ( P. jirovecii ) with positive LAMP or conventional staining (CS) (Grocott methenamine silver staining or Diff-Quick™) on the basis of compatible clinical symptoms and radiologic findings. Additionally, we reviewed HIV-uninfected immunocompromised patients who underwent subcontract PCR as a historical control. LAMP was positive in 10 (90.9%) of 11 positive-CS patients. Among 13 negative-CS patients with positive LAMP, 11 (84.6%) had PCP, and the remaining 2 were categorized as having P. jirovecii colonization. LDH levels in negative-CS PCP were higher than in positive-CS PCP ( p  = 0.026). (1 → 3)- β -D-glucan levels in negative-CS PCP were lower than in positive-CS PCP ( p  = 0.011). The interval from symptom onset to diagnosis as PCP in LAMP group (3.45 ± 1.77 days; n  = 22) was shorter than in subcontract PCR group (6.90 ± 2.28 days; n  = 10; p n  = 10) was shorter than in subcontract PCR group (7; 7–12.25 days; n  = 6; p  = 0.003). LAMP showed higher sensitivity (95.4%) and positive predictive value (91.3%) than subcontract PCR did. Pneumocystis LAMP method is a sensitive and cost-effective diagnostic method and is easy to administer in general hospitals. In-house LAMP method would realize early diagnosis of PCP, resulting in improving PCP prognosis and reducing unnecessary PCP-specific treatment.