scholarly journals Distribution of a Specific 500-Base-Pair Fragment in Mycobacterium bovis Isolates from Sardinian Cattle

2000 ◽  
Vol 38 (10) ◽  
pp. 3837-3839 ◽  
Author(s):  
Leonardo A. Sechi ◽  
Ilaria Duprè ◽  
Guido Leori ◽  
Giovanni Fadda ◽  
Stefania Zanetti
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Bovis ◽  
Base Pair ◽  
False Negative ◽  
Negative Results ◽  
False Negative Results ◽  
Base Pair Fragment ◽  
Pair Fragment

Amplification of a specific, 500-bp fragment fromMycobacterium bovis isolates and use of the fragment to differentiate between Mycobacterium tuberculosis andM. bovis was previously reported (J. G. Rodriguez, G. A. Meja, P. Del Portillo, M. E. Patarroyo, and L. A. Murillo, Microbiology 141:2131–2138, 1995). In the present study, 30M. bovis isolates from Sardinian cattle were examined for the presence of this 500-bp fragment; 4 of the 30 isolates lacked the fragment. This result indicates that identification of M. bovis strains by amplification of the 500-bp sequence may lead to false-negative results.

scholarly journals A unique strain of Mycobacterium tuberculosis and a cautionary tale for users of molecular techniques

2004 ◽  
Vol 25 (4) ◽  
pp. 32
Author(s):  
C Frank Haverkort ◽  
Christopher Gilpin
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Binding Sites ◽  
Direct Detection ◽  
False Negative ◽  
Molecular Techniques ◽  
Cautionary Tale ◽  
Testing Methods ◽  
Negative Results ◽  
False Negative Results ◽  
Unique Strain

Molecular techniques are now widely applied in Australia and elsewhere for the direct detection of Mycobacterium tuberculosis DNA in clinical specimens and culturally enhanced material. All nucleic acid testing methods have the potential to give false negative results due to mutations that may arise at primer or probe binding sites. We describe one such strain of M. tuberculosis that was encountered in 1995 and that has not been encountered in Australia since.

scholarly journals Internal control in PCR for Mycobacterium tuberculosis: usefulness and improvement of the diagnosis

2008 ◽  
Vol 51 (4) ◽  
pp. 485-491 ◽  
Author(s):  
Elizabeth Cortez-Herrera ◽  
Rosa Dea Sperhacke ◽  
Daniela Becker ◽  
Afrânio Kritski ◽  
Arnaldo Zaha ◽  
...  
Keyword(s):  
Public Health ◽  
Mycobacterium Tuberculosis ◽  
Internal Control ◽  
False Negative ◽  
Clinical Results ◽  
Public Health Laboratory ◽  
Negative Results ◽  
False Negative Results ◽  
Diagnostic Fragment ◽  
Pcr Test

The aim of this work was to construct and test a plasmidial Internal Control (IC) to detect the inhibition in the PCR test for M. tuberculosis and also its contribution for a Public Health Laboratory routine. The IC was a 600-bp of DNA linked to a plasmid with the same primer sites, allowing the amplification with the 245-bp diagnostic fragment. The amplification of the positive samples rendered the IC and the diagnostic fragment; instead negative samples only showed the IC. A total of 149 tuberculosis samples were studied and introduced the IC to monitor. Results showed 3.3% of the samples without amplification of the IC, suggesting the inhibition. These samples showed results in accordance with the clinical results. The objective of the IC was to identify the false negative results.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Scoring System for the Diagnosis of COVID-19

2020 ◽  
Vol 13 (1) ◽  
pp. 413-414 ◽  
Author(s):  
Mohamed Farouk Allam
Keyword(s):  
Scoring System ◽  
Clinical Symptoms ◽  
False Negative ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Negative Results ◽  
False Negative Results ◽  
Symptoms And Signs

Due to the international spread of COVID-19, the difficulty of collecting nasopharyngeal swab specimen from all suspected patients, the costs of RT-PCR and CT, and the false negative results of RT-PCR assay in 41% of COVID-19 patients, a scoring system is needed to classify the suspected patients in order to determine the need for follow-up, home isolation, quarantine or the conduction of further investigations. A scoring system is proposed as a diagnostic tool for suspected patients. It includes Epidemiological Evidence of Exposure, Clinical Symptoms and Signs, and Investigations (if available). This scoring system is simple, could be calculated in a few minutes, and incorporates the main possible data/findings of any patient.

Detection of Streptococcus pneumoniae in Sputum Samples by Real- Time PCR.

2020 ◽  
Vol 18 ◽  
Author(s):  
Pegah Shakib ◽  
Mohammad Reza Zolfaghari
Keyword(s):  
Streptococcus Pneumoniae ◽  
Real Time ◽  
Real Time Pcr ◽  
False Negative ◽  
Cross Sectional Study ◽  
Laboratory Culture ◽  
Cross Sectional ◽  
Negative Results ◽  
False Negative Results ◽  
Pcr Method

Background: Conventional laboratory culture-based methods for diagnosis of Streptococcus pneumoniae are time-consuming and yield false negative results. Molecular methods including real-time (RT)-PCR rapid methods and conventional PCR due to higher sensitivity and accuracy have been replaced instead traditional culture assay. The aim of the current study was to evaluate lytA gene for detection of Streptococcus pneumoniae in the cerebrospinal fluid of human patients with meningitis using real-time PCR assay. Material and Methods: In this cross-sectional study, a total of 30 clinical specimens were collected from patients in a period from September to December 2018. In order to evaluate the presence of lytA gene, conventional and real-time PCR methods were used without culture. Results: From 30 sputum samples five (16.66%) isolates were identified as S. pneumoniae by lytA PCR and sequencing. Discussion: In this research, an accurate and rapid real-time PCR method was used, which is based on lytA gene for diagnosis of bacteria so that it can be diagnosed. Based on the sequencing results, the sensitivity for detection of lytA gene was 100% (5/5).

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