Clinical Utilization of DiaSorin Molecular Polymerase Chain Reaction in Pneumocystis Pneumonia.

BACKGROUND: Pneumocystis jirovecii polymerase chain reaction (PCR) testing is a sensitive diagnostic tool but does not distinguish infection from colonization. Cycle threshold (CT) may correlate with fungal burden and could be considered in clinical decision making. Clinical use of PCR and significance of CT values have not previously been examined with the DiaSorin Molecular platform. METHODS: Retrospective review of P jirovecii PCR, CT values and clinical data from 18 months in a multihospital academic health system. The diagnostic performance of PCR with respect to pathology and correlation of CT with severity were examined. RESULTS: Ninety-nine of 1006 (9.8%) assays from 786 patients in 919 encounters were positive. Among 91 (9.9%) encounters in which P jirovecii pneumonia (PJP) was treated, 41 (45%) were influenced by positive PCR. Negative PCR influenced discontinuation of therapy in 35 cases. Sensitivity and specificity of PCR were 93% (95% CI, 68%-100%) and 94% (95% CI, 91%-96%) with respect to pathology. CT values from deep respiratory specimens were significantly different among treated patients (P = .04) and those with positive pathology results (P < .0001) compared to patients not treated and those with negative pathology, respectively, and was highly predictive of positive pathology results (area under the curve = 0.92). No significant difference was observed in comparisons based on indicators of disease severity. CONCLUSIONS: Pneumocystis jirovecii PCR was a highly impactful tool in the diagnosis and management of PJP, and use of CT values may have value in the treatment decision process in select cases. Further investigation in a prospective manner is needed.

Validation of High-Sensitivity Severe Acute Respiratory Syndrome Coronavirus 2 Testing for Stool-Toward the New Normal for Fecal Microbiota Transplantation.

INTRODUCTION: Mounting evidence demonstrates potential for fecal-oral transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The US Food and Drug Administration now requires SARS-CoV-2 testing of potential feces donors before the use of stool manufactured for fecal microbiota transplantation. We sought to develop and validate a high-sensitivity SARS-CoV-2 reverse transcriptase polymerase chain reaction (RT-PCR) procedure for testing stool specimens. METHODS: A modified extraction method was used with an RT-PCR assay adapted from the Centers for Disease Control and Prevention PCR protocol for respiratory specimens. Contrived specimens were created using pre-COVID-19 banked stool specimens and spiking in known concentrations of SARS-CoV-2-specific nucleic acid. The highest transcript concentration at which 2/2 or 1/2 SARS-CoV-2 targets were detected in 9/10 replicates was defined as the dual-target limit and single-target limit of detection, respectively. The clinical performance of the assay was evaluated with stool samples collected from 17 nasopharyngeal swab RT-PCR-positive patients and 14 nasopharyngeal RT-PCR-negative patients. RESULTS: The dual-target and single-target limit of detection were 56 copies/µL and 3 copies/µL, respectively. SARS-CoV-2 was detected at concentrations as low as 0.6 copies/µL. Clinical stool samples from known COVID-19-positive patients demonstrated the detection of SARS-CoV-2 in stool up to 29 days from symptom onset with a high agreement with nasopharyngeal swab tests (kappa statistic of 0.95, P value < 0.001). DISCUSSION: The described RT-PCR test is a sensitive and flexible approach for the detection of SARS-CoV-2 in stool specimens. We propose an integrated screening approach that incorporates this stool test to support continuation of fecal microbiota transplantation programs.