Crispr-cas 12a combination to alleviate the false-positive in loop-mediated isothermal amplification-based diagnosis of Neisseria meningitidis

Abstract Loop mediated Isothermal amplicafication (LAMP) was recently suggested as a diagnostic tool for the identification of Neisseria meningitides. Howevere, this isothermal amplification is challenged by the fact its amplification leads to risks of obtaining false-positive results. Whereas, with abilities to accurately recognize specific sequence, the CRISPR/Cas12a can forms complexes with cognate RNA sensors and cleave pathogen’s DNA targets complimerntary to its cognate RNA and acquires collateral activity to unbiasedly cut nearby off-target fragments. Therefore, if relevant fluorescent-quencher-nucleic probes are present in the reaction, the non-specific cleavage of probes releases fluorescences and establish diagnostic read-outs. In this study, we demonstrate a proof-of-concept that in relevant biochemical conditions, CRISPR/Cas12a and LAMP can work synchronously to identify genetics materials of Nesseria menitigistis at the level of 0.00004% in less than 2 h. Additionally, our clinical data also showed that the combinatory of CRISPR/Cas12a help to alleviate false positive result therefore enhance the specificity gained by the LAMP assays.

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Occurrence of False-Positive Results of Inhibitor on Milk Samples Using the Delvotest SP Assay

Journal of Food Protection ◽

10.4315/0362-028x-64.8.1211 ◽

2001 ◽

Vol 64 (8) ◽

pp. 1211-1215 ◽

Cited By ~ 10

Author(s):

JEONG-HUN KANG ◽

FUSAO KONDO

Keyword(s):

Heat Treatment ◽

Positive Result ◽

False Positive ◽

Reading Time ◽

False Positive Result ◽

Bulk Tank Milk ◽

Milk Samples ◽

Cell Counts ◽

Bulk Tank ◽

Positive Results

Three hundred twenty-one quarter, 207 whole udder, 310 bulk tank, and 93 tank-lorry milk samples were examined for confirmation of the presence of inhibitor by Delvotest SP assay. Four hundred twenty-six Holstein cows of no drug treatment for at least 30 days from January 1998 to September 1999 were used. Reading time was 2.50, 2.75, and 3.00 h, and results of sampling were recorded by four types according to comparison with the color of the well containing the control milk sample. False-positive outcome was identified by Delvotest SP assay in quarter (13 of 321), whole udder (9 of 207), and bulk tank milk samples (4 of 310), but was not shown on tank-lorry milk samples (0 of 93) at the reading time of 2.50 h. All of the 26 false-positive samples were negative from the examination after heat treatment at 82°C for 5 min. But, two bulk tank milk samples that appeared to have positive results in LacTek and Charm II tests were positive from the test following heat treatment. Somatic cell counts (SCC) were related to the probability of a false-positive result. The more SCC increased, the more the occurrence of a false-positive result increased. In our investigations, 4 of 310 bulk tank milk samples at the reading time of 2.50 h produced false-positive results, and no false-positive results were apparent at a reading time of 2.75 h. Also, the occurrence of false-positive results in quarter and whole udder milk samples decreased when agar was cultured for 2.75 to 3.00 h. There were no false-positive results from tank-lorry milk samples. These results indicate that the Delvotest SP assay may provide a suitable means for the detection of drug residues in not only quarter and whole udder milk of cows but also in bulk tank and tank-lorry milk following reading times of 2.75 to 3.00 h.

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False positivity of anti aquaporin-4 antibodies in natalizumab-treated patients

Multiple Sclerosis Journal ◽

10.1177/1352458516630823 ◽

2016 ◽

Vol 22 (9) ◽

pp. 1231-1234 ◽

Cited By ~ 8

Author(s):

Mikael Cohen ◽

Jérome De Sèze ◽

Romain Marignier ◽

Christine Lebrun

Keyword(s):

Positive Result ◽

False Positive ◽

Aquaporin 4 ◽

Neuromyelitis Optica Spectrum Disorders ◽

False Positive Result ◽

Disease Modifying Drugs ◽

Technical Issues ◽

Disease Modifying ◽

Spectrum Disorders ◽

Positive Results

Background: Neuromyelitis optica spectrum disorders (NMOSD) represent a differential diagnosis of multiple sclerosis (MS). Detection of anti-aquaporin-4 antibodies (AQP4-Ab) is the strongest argument to confirm NMOSD. Diagnosing NMOSD is a major concern because specific MS disease modifying drugs can lead to neurological worsening. Objective: To report the case of two natalizumab (NTZ) treated patients who presented a false positive result for AQP4-Ab. Methods: A retrospective analysis of NTZ-treated patients who were tested positive for AQP4-Ab in our MS center. Results: Two patients treated by NTZ presented a false positive result. Conclusions: Clinicians should be aware of potential technical issues in detecting AQP4-Ab in NTZ-treated patients leading to false positive results.

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False Positive Results With SARS-CoV-2 RT-PCR Tests and How to Evaluate a RT-PCR-Positive Test for the Possibility of a False Positive Result

Journal of Occupational and Environmental Medicine ◽

10.1097/jom.0000000000002138 ◽

2021 ◽

Vol Publish Ahead of Print ◽

Author(s):

Glenn D. Braunstein ◽

Lori Schwartz ◽

Pamela Hymel ◽

Jonathan Fielding

Keyword(s):

Positive Result ◽

False Positive ◽

Positive Test ◽

False Positive Result ◽

Rt Pcr ◽

Positive Results

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Urine opiate screening: false-positive result with levofloxacin

Canadian Medical Association Journal ◽

10.1503/cmaj.091508 ◽

2010 ◽

Vol 182 (15) ◽

pp. 1644-1645 ◽

Cited By ~ 3

Author(s):

Q. Shafiq ◽

A. Mutgi

Keyword(s):

Positive Result ◽

False Positive ◽

False Positive Result

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Subsequent attendance in a breast cancer screening program after a false-positive result in the Local Health Authority of Bologna (Italy)

Scientific Reports ◽

10.1038/s41598-021-87864-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Lorena Squillace ◽

Lorenzo Pizzi ◽

Flavia Rallo ◽

Carmen Bazzani ◽

Gianni Saguatti ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Screening ◽

Positive Result ◽

Breast Cancer Screening ◽

Health Authority ◽

False Positive ◽

Screening Program ◽

Local Health Authority ◽

Local Health ◽

False Positive Result

AbstractWe conducted a cross-sectional study to assess the likelihood of returning for routine breast cancer screening among women who have experienced a false-positive result (FPR) and to describe the possible individual and organizational factors that could influence subsequent attendance to the screening program. Several information were collected on demographic and clinical characteristics data. Electronic data from 2014 to 2016 related to breast screening program of the Local Health Authority (LHA) of Bologna (Italy) of women between 45 and 74 years old were reviewed. A total of 4847 women experienced an FPR during mammographic screening and were recalled to subsequent round; 80.2% adhered to the screening. Mean age was 54.2 ± 8.4 years old. Women resulted to be less likely to adhere to screening if they were not-Italian (p = 0.001), if they lived in the Bologna district (p < 0.001), if they had to wait more than 5 days from II level test to end of diagnostic procedures (p = 0.001), if the diagnostic tests were performed in a hospital with the less volume of activity and higher recall rate (RR) (p < 0.001) and if they had no previous participation to screening tests (p < 0.001). Our results are consistent with previous studies, and encourages the implementation and innovation of the organizational characteristics for breast cancer screening. The success of screening programs requires an efficient indicators monitoring strategy to develop and evaluate continuous improvement processes.

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Hepatitis C virus antibodies in chronic active hepatitis: pathogenetic factor or false-positive result?

The Lancet ◽

10.1016/0140-6736(90)90870-b ◽

1990 ◽

Vol 335 (8692) ◽

pp. 754-757 ◽

Cited By ~ 325

Author(s):

I MCFARLANE

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Positive Result ◽

Chronic Active Hepatitis ◽

False Positive ◽

False Positive Result ◽

Pathogenetic Factor

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Chromogranin a Measurement in Metastatic Well-Differentiated Gastroenteropancreatic Neuroendocrine Carcinoma: Screening for False Positives and a Prospective Follow-Up Study

The International Journal of Biological Markers ◽

10.5301/jbm.2011.8327 ◽

2011 ◽

Vol 26 (2) ◽

pp. 94-101 ◽

Cited By ~ 24

Author(s):

Delphine Vezzosi ◽

Thomas Walter ◽

Agnès Laplanche ◽

Jean Luc Raoul ◽

Clarisse Dromain ◽

...

Keyword(s):

False Positive ◽

Chromogranin A ◽

Morphological Changes ◽

Surrogate Marker ◽

False Positive Result ◽

Gastroenteropancreatic Neuroendocrine Tumors ◽

Follow Up Study ◽

Well Differentiated ◽

Positive Results

Background Multiple causes of false-positive chromogranin A (CgA) measurement have been reported that may affect its impact as a surrogate marker of RECIST progression in well-differentiated gastroenteropancreatic neuroendocrine tumors (WDGEPNET). Aims 1) To evaluate the frequency of false-positive CgA results. 2) To prospectively compare CgA variations with RECIST morphological changes in patients without known causes of false-positive CgA measurements. Methods First, the conditions responsible for potentially false-positive CgA measurements were screened in 184 consecutive patients with metastatic WDGEPNET. Secondly, a variation in CgA at a 6-month interval was compared to RECIST results at 6 months in 46 patients. Results Among 184 patients, elevated CgA was found in 130 cases (71%) including 99 patients with at least one cause of a false-positive result. Impaired kidney function as well as medication with proton pump inhibitors were found to be the 2 major causes of false-positive results. The sensitivity and specificity of CgA measurements compared with morphological tumor changes according to the RECIST criteria were 71% and 50%, respectively, at 6 months. Conclusion Routine screening for the causes of false-positive CgA measurements is mandatory in WDGEPNET patients. Our study does not validate the use of CgA as a surrogate marker of tumor progression.

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