scholarly journals A novel droplet digital polymerase chain reaction for diagnosis of pneumocystis pneumonia (PCP)—a clinical performance study and survey of sulfamethoxazole-trimethoprim resistant mutations

2021 ◽  
Author(s):  
Anupop Jitmuang ◽  
Anapat Nititammaluk ◽  
Thitaya Boonsong ◽  
Patsharaporn Techasintana Sarasombath ◽  
Suree Sompradeekul ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Clinical Performance ◽  
Pneumocystis Pneumonia ◽  
Performance Study ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

scholarly journals Clinical Performance of (1,3) Beta-D Glucan for the Diagnosis of Pneumocystis Pneumonia (PCP) in Cancer Patients Tested With PCP Polymerase Chain Reaction

2018 ◽  
Vol 69 (8) ◽  
pp. 1303-1309 ◽  
Author(s):  
Sejal Morjaria ◽  
John Frame ◽  
Alexandra Franco-Garcia ◽  
Alexander Geyer ◽  
Mini Kamboj ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Cancer Patients ◽  
Predictive Value ◽  
Clinical Performance ◽  
Reference Method ◽  
Pneumocystis Pneumonia ◽  
Clinical Syndrome ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
High Risk Cancer

Abstract Background Serum (1,3)-beta-D glucan (BDG) is increasingly used to guide the management of suspected Pneumocystis pneumonia (PCP). BDG lacks specificity for PCP, and its clinical performance in high-risk cancer patients has not been fully assessed. Polymerase chain reaction (PCR) for PCP detection is highly sensitive, but cannot differentiate between colonization and infection. We evaluated the diagnostic performance of serum BDG in conjunction with PCP PCR on respiratory samples in patients with cancer and unexplained lung infiltrates. Methods We performed a retrospective analysis of adult patients evaluated for PCP at our institution from 2012 to 2015, using serum BDG and PCP PCR. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the serum BDG at different thresholds were evaluated using PCP PCR alone or in conjunction with clinical presentation in PCP PCR–positive patients. Results With PCP PCR alone as the reference method, BDG (≥80 pg/mL) had a sensitivity of 69.8%, specificity of 81.2%, PPV of 34.6%, and NPV of 95.2% for PCP. At ≥200 pg/mL in patients with a positive PCR and a compatible PCP clinical syndrome, BDG had a sensitivity of 70%, specificity of 100%, PPV of 100%, and NPV of 52.0% for PCP. Conclusions Patients negative by both BDG and PCR were unlikely to have PCP. In patients with a compatible clinical syndrome for PCP, higher BDG values (>200 pg/mL) were consistently associated with clinically-significant PCP infections among PCP PCR–positive oncology patients.

scholarly journals Digital Droplet PCR for SARS-CoV-2 Resolves Borderline Cases

2021 ◽  
Author(s):  
Jing Xu ◽  
Timothy Kirtek ◽  
Yan Xu ◽  
Hui Zheng ◽  
Huiyu Yao ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
False Negative ◽  
Accurate Method ◽  
Viral Envelope ◽  
Chain Reaction ◽  
Borderline Cases ◽  
Droplet Pcr ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Abstract Objectives The Bio-Rad SARS-CoV-2 ddPCR Kit (Bio-Rad Laboratories) was the first droplet digital polymerase chain reaction (ddPCR) assay to receive Food and Drug Administration (FDA) Emergency Use Authorization approval, but it has not been evaluated clinically. We describe the performance of ddPCR—in particular, its ability to confirm weak-positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) results. Methods We clinically validated the Bio-Rad Triplex Probe ddPCR Assay. The limit of detection was determined by using serial dilutions of SARS-CoV-2 RNA in an artificial viral envelope. The ddPCR assay was performed according to the manufacturer’s specifications on specimens confirmed to be positive (n = 48) or negative (n = 30) by an FDA-validated reverse transcription–polymerase chain reaction assay on the m2000 RealTime system (Abbott). Ten borderline positive cases were also evaluated. Results The limit of detection was 50 copies/mL (19 of 20 positive). Forty-seven specimens spanning a range of quantification cycles (2.9-25.9 cycle numbers) were positive by this assay (47 of 48; 97.9% positive precent agreement), and 30 negative samples were confirmed as negative (30 of 30; 100% negative percent agreement). Nine of 10 borderline cases were positive when tested in triplicate. Conclusions The ddPCR of SARS-CoV-2 is an accurate method, with superior sensitivity for viral RNA detection. It could provide definitive evaluation of borderline positive cases or suspected false-negative cases.

scholarly journals EXPRESS: Clinical performance of the Elecsys® Anti-SARS-CoV-2 combined in an algorithm with two specific anti-IgG immunoassays for the evaluation of the serological response of patients with COVID-19 in a population with a high prevalence of infection

2021 ◽  
pp. 000456322110380
Author(s):  
Xavier Gabaldó-Barrios ◽  
Simona Iftimie ◽  
Anna Hernández-Aguilera ◽  
Isabel Pujol ◽  
Frederic Ballester ◽  
...  
Keyword(s):  
Immune Response ◽  
Polymerase Chain Reaction ◽  
Predictive Value ◽  
Clinical Performance ◽  
Polymerase Chain Reaction Test ◽  
Serological Response ◽  
Chain Reaction ◽  
Automated Assay ◽  
High Prevalence ◽  
Polymerase Chain

Background: Anti-SARS-CoV-2 antibodies have been used in the study of the immune response in infected patients. However, differences in sensitivity and specificity have been reported, depending on the method of analysis. The aim of the present study was to evaluate the diagnostic accuracy of an algorithm in which a high-throughput automated assay for total antibodies was used for screening and two semi-automated IgG-specific methods were used to confirm the results, and also to correlate the analytical results with the clinical data and the time elapsed since infection. Methods: We studied 306 patients, some hospitalized and some outpatients, belonging to a population with a high prevalence of COVID-19. One-hundred and ten patients were classified as SARS-CoV-2 negative and 196 as positive by polymerase chain reaction. Results: The algorithm and automated assay alone had a specificity and a positive predictive value of 100%, although the sensitivity and negative predictive value of the algorithm was higher. Both methods showed a good sensitivity from day 11 of the onset of symptoms in asymptomatic and symptomatic patients. The absorbance of the total antibodies was significantly higher in severely symptomatic than in asymptomatic or mildly symptomatic patients, which suggests the antibody level was higher. We found 15 patients that did not present seroconversion at 12 days from the onset of symptoms or the first polymerase chain reaction test. Conclusion: This study highlights the proper functioning of algorithms in the diagnosis of the immune response to COVID-19, which can help to define testing strategies against this disease.

Comparison of Droplet Digital Polymerase Chain Reaction (ddPCR) and Real-Time Quantitative Polymerase Chain Reaction (qPCR) in Detecting Neonatal Invasive Fungal Infections

2021 ◽  
Vol 11 (3) ◽  
pp. 373-379
Author(s):  
Huitao Li ◽  
Xueyu Chen ◽  
Xiaomei Qiu ◽  
Weimin Huang ◽  
Chuanzhong Yang
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
Quantitative Polymerase Chain Reaction ◽  
Diagnostic Methods ◽  
Chain Reaction ◽  
Fungal Isolation ◽  
Blood Samples ◽  
Fungal Strains ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Invasive fungal infection (IFI) is the leading cause of death in neonatal patients, yet the diagnosis of IFI remains a major challenge. At present, most IFI laboratory diagnostic methods are based on classical, but limited, methods such as fungal isolation and culture and histopathological examination. Recently, quantitative polymerase chain reaction (qPCR) and droplet digital polymerase chain reaction (ddPCR) technology have been adopted to quantify nucleic-acid identification. In this study, we established qPCR and ddPCR assays for IFI diagnosis and quantification. qPCR and ddPCR were carried out using identical primers and probe for the amplification of 18S rRNA. Assay results for three fungal strains were positive, whereas ten non-fungal strains had negative results, indicating 100% specificity for both ddPCR and qPCR methods. Genomic DNA of Candida albicans was tested after a serial dilution to compare the sensitivity of the two PCR methods. The limit of detection of ddPCR was 3.2 copies/L, which was a ten-fold increase compared with that of the qPCR method (32 copies/L). Blood samples from 127 patients with high-risk factors and clinical symptoms for IFI were collected from a NICU in Shenzhen, China, and analyzed using qPCR and ddPCR. Thirty-four blood samples from neonates had a proven or probable diagnosis of IFI, and 25 of these were positive by qPCR, whereas 30 were positive by ddPCR. Among the 93 blood samples from neonates who had a possible IFI or no IFI, 24 were positive using qPCR, and 7 were positive using ddPCR. In conclusion, ddPCR is a rapid and accurate pan-fungal detection method and provides a promising prospect for IFI clinical screening.

Diagnosis of pneumocystis pneumonia in a 2-year-old King Charles Cavalier Spaniel using the polymerase chain reaction

2018 ◽  
Vol 47 (1) ◽  
pp. 146-149 ◽  
Author(s):  
Ayeley A. K. Okine ◽  
Seth Chapman ◽  
Roger A. Hostutler ◽  
Robert Livingston
Keyword(s):  
Polymerase Chain Reaction ◽  
Pneumocystis Pneumonia ◽  
Chain Reaction ◽  
Polymerase Chain
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