Clinical Outcomes of Acutely Ill Children According to Cycle Threshold Values of Respiratory Viruses Detected by Multiplex PCR Testing.
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ABSTRACT:
SUBMITTER: Mattila S
PROVIDER: S-EPMC10977037 | biostudies-literature | 2023 Oct
REPOSITORIES: biostudies-literature
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Clinical Outcomes of Acutely Ill Children According to Cycle Threshold Values of Respiratory Viruses Detected by Multiplex PCR Testing.
Mattila Suvi S Honkila Minna M Paalanne Niko N Mäki-Koivisto Vesa V Halt Kimmo K Jartti Tuomas T Ruuskanen Olli O Waris Matti M Pokka Tytti T Tapiainen Terhi T
Journal of the Pediatric Infectious Diseases Society 20231001 10
In this cohort study of 800 children attending a pediatric emergency department at Oulu University Hospital, Finland with fever or respiratory symptoms, the cycle threshold values of point-of-care multiplex polymerase chain reaction testing for respiratory viruses were not associated with hospitalization, respiratory support, or need for intensive care. ...[more]
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Project description:BackgroundPresented work studies the association of COVID-19 severity, patient demographics, and clinical history with cycle threshold (Ct) values of SARS CoV2-rRT-PCR. We studied the Ct values for Orf1ab, N, and RdRp genes in association with all the factors mentioned above.Methods and resultsWe examined the individuals (n = 6331) that consulted two private diagnostic centers for COVID-19 testing. SARS-CoV-2 was detected by RT-PCR assays using different commercial kits. Clinical and demographic information was collected by the attending health care professional. Ct values were not associated with the age, sex, or clinical history of the patient. Orf1ab and N genes Ct values were only weakly associated with symptoms at the time of the SARS-CoV-2 RT-PCR test. Also, the distributions of Ct values in SARS-CoV-2 positive patients are very similar irrespective of symptomatology.ConclusionWe conclude that the Ct values may have limitations in reliably predicting COVID-19 severity and should be used or reported with caution.
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Project description:BackgroundThe ability to proactively predict the epidemiological dynamics of infectious diseases such as coronavirus disease 2019 (COVID-19) would facilitate efficient public health responses and may help guide patient management. Viral loads of infected people correlate with infectiousness and, therefore, could be used to predict future case rates.AimIn this systematic review, we determine whether there is a correlation between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) real-time reverse-transcription polymerase chain reaction (RT-PCR) cycle threshold (Ct) values (a proxy for viral load) and epidemiological trends in patients diagnosed with COVID-19, and whether Ct values are predictive of future cases.MethodsA PubMed search was conducted on August 22 2022, based on a search strategy of studies reporting correlations between SARS-CoV-2 Ct values and epidemiological trends.ResultsData from 16 studies were relevant for inclusion. RT-PCR Ct values were measured from national (n = 3), local (n = 7), single-unit (n = 5), or closed single-unit (n = 1) samples. All studies retrospectively examined the correlation between Ct values and epidemiological trends, and seven evaluated their prediction model prospectively. Five studies used the temporal reproduction number (Rt) as the measure of the population/epidemic growth rate. Eight studies reported a prediction time in the negative cross-correlation between Ct values and new daily cases, with seven reporting a prediction time of ~1-3 weeks, and one reporting 33 days.ConclusionCt values are negatively correlated with epidemiological trends and may be useful in predicting subsequent peaks in variant waves of COVID-19 and other circulating pathogens.
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Project description:As the COVID-19 pandemic continues, efforts to better understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral shedding and transmission in both unvaccinated and vaccinated populations remain critical to informing public health policies and vaccine development. The utility of using real time RT-PCR cycle threshold values (CT values) as a proxy for infectious viral litres from individuals infected with SARS-CoV-2 is yet to be fully understood. This retrospective observational cohort study compares quantitative infectious viral litres derived from a focus-forming viral titre assay with SARS-CoV-2 RT-PCR CT values in both unvaccinated and vaccinated individuals infected with the Delta strain. Nasopharyngeal swabs positive for SARS-CoV-2 by RT-PCR with a CT value <27 collected from 26 June to 17 October 2021 at the University of Vermont Medical Center Clinical Laboratory for which vaccination records were available were included. Partially vaccinated and individuals <18 years of age were excluded. Infectious viral litres were determined using a micro-focus forming assay under BSL-3 containment. In total, 119 specimens from 22 unvaccinated and 97 vaccinated individuals met all inclusion criteria and had sufficient residual volume to undergo viral titring. A negative correlation between RT-PCR CT values and viral litres was observed in both unvaccinated and vaccinated groups. No difference in mean CT value or viral titre was detected between vaccinated and unvaccinated groups. Viral litres did not change as a function of time since vaccination. Our results add to the growing body of knowledge regarding the correlation of SARS-CoV-2 RNA levels and levels of infectious virus. At similar CT values, vaccination does not appear to impact an individual's potential infectivity when infected with the Delta variant.
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Project description:ObjectivesIt is unclear whether real-time (rt)-PCR cycle threshold (Ct) values can be utilized to guide clinical and infection-control decisions. This systematic review assesses the association between respiratory pathogen rt-PCR Ct values and clinical presentation or outcomes.MethodsWe searched MEDLINE, EMBASE and Cochrane library databases on 14-17 January 2020 for studies reporting the presence or absence of an association between Ct values and clinical presentation or outcomes, excluding animal studies, reviews, meta-analyses, and non-English language studies.ResultsAmong 33 studies identified (reporting on between 9 and 4918 participants by pathogen), influenza (n = 11 studies; 4918 participants), human rhinovirus (HRV, n = 11; 2012) and respiratory syncytial virus (RSV, n = 8; 3290) were the most-studied pathogens. Low influenza Ct values were associated with mortality in 1/3 studies, with increased disease severity/duration or ICU admission in 3/9, and with increased hospitalization or length of hospital stay (LOS) in 1/6. Low HRV Ct values were associated with increased disease severity/duration or ICU admission in 3/10 studies, and with increased hospitalization or LOS in 1/3. Low RSV Ct values were associated with increased disease severity/duration or ICU admission in 3/6 studies, and with increased hospitalization or LOS in 4/4. Contradictory associations were also identified for other respiratory pathogens.ConclusionsRespiratory infection Ct values may inform clinical and infection-control decisions. However, the study heterogeneity observed in this review highlights the need for standardized workflows to utilize Ct values as a proxy of genomic load and confirm their value for respiratory infection management.
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Project description:There is no stand-alone Clostridium difficile diagnostic that can sensitively and rapidly detect fecal free toxins. We investigated the performance of the C. difficile PCR cycle threshold (CT ) for predicting free toxin status. Consecutive stool samples (n = 312) positive for toxigenic C. difficile by the GeneXpert C. difficile/Epi tcdB PCR assay were tested with the rapid membrane C. Diff Quik Chek Complete immunoassay (RMEIA). RMEIA toxin-negative samples were tested with the cell cytotoxicity neutralization assay (CCNA) and tgcBIOMICS enzyme-linked immunosorbent assay (ELISA). Using RMEIA alone or in combination with CCNA and/or ELISA as the reference method, the accuracy of CT was measured at different CT cutoffs. Using RMEIA as the reference method, a CT cutoff of 26.35 detected toxin-positive samples with a sensitivity, specificity, positive predictive value, and negative predictive value of 96.0% (95% confidence interval [CI], 90.2% to 98.9%), 65.9% (95% CI, 59.0% to 72.2%), 57.4% (95% CI, 52.7% to 62%), and 97.1% (95% CI, 92.8% to 98.9), respectively. Inclusion of CCNA in the reference method improved CT specificity to 78.0% (95% CI, 70.7% to 84.2%). Intercartridge lot CT variability measured as the average coefficient of variation was 2.8% (95% CI, 1.2% to 3.2%). Standardizing the input stool volume did not improve CT toxin specificity. The median CT values were not significantly different between stool samples with Bristol scores of 5, 6, and 7, between pediatric and adult samples, or between presumptive 027 and non-027 strains. In addition to sensitively detecting toxigenic C. difficile in stool, on-demand PCR may also be used to accurately predict toxin-negative stool samples, thus providing additional results in PCR-positive stool samples to guide therapy.
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Project description:Background & objectivesGenotyping has now become one of the major diagnostic means for almost all diseases. Among the advanced techniques that are used to study single nucleotide polymorphisms (SNPs), only a few are applicable for routine disease diagnosis. Their applicability mainly depends on three factors: cost, time, and accuracy. The primary objective of this study was to propose allele-specific real-time PCR as a rapid, low cost and simple genotyping method for routine diagnostics.MethodsTwo SNPs, rs3014866 and rs2149356 were analysed using allele-specific real-time PCR. The polymerase chain reaction was carried out using RealQ PCR master mix containing SYBR Green DNA I dye followed by melt curve analysis. The results were validated by agarose gel electrophoresis and DNA sequencing.ResultsThe allelic discrimination and zygosity of the two SNPs were assessed by combined cycle threshold (Ct) and melting temperature (T m ) values. Variations in Ct and T m values among the two alleles were observed in both rs3014866 (Ct: C allele - 24 ± 1, T allele - 27 ± 1; T m: C allele - 82.5 ± 0.3, T allele - 86.3 ± 0.2) and rs2149356 (Ct: C allele - 24 ± 1, A allele - 26 ± 1; T m: C allele - 79.4 ± 0.2, A allele - 80.4 ± 0.3). Based on the variations, homozygous and heterozygous alleles were detect ed. Agarose gel electrophoresis and DNA sequencing also confirmed the allelic variation and zygosity observed in real-time PCR.Interpretation & conclusionsIn diagnostic settings where a large number of samples are analysed daily, allele-specific real-time PCR assay may serve as a simple, low cost and efficient method of genotyping.
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Project description:Background: Quantitative (q) polymerase chain reaction (PCR) cycle threshold (Ct) values represent the number of amplification cycles required for a positive PCR result and are a proxy of pathogen quantity in the tested sample. The clinical utility of Ct values remains unclear for gastrointestinal infections. Objectives: This systematic review assesses the global medical literature for associations between Ct values of gastrointestinal pathogens and patient presentation and clinical outcomes. Data Sources: MEDLINE, EMBASE, Cochrane library databases: searched January 14-17, 2020. Study Eligibility Criteria: Studies reporting on the presence or absence of an association between Ct values and clinical outcomes in adult and pediatric populations were included. Animal studies, reviews, meta-analyses, and non-English language studies were excluded. Participants: Humans infected with gastrointestinal pathogens, detected with qPCR. Interventions: Diagnostics assessing Ct values. Extracted data were reported narratively. Results: Thirty-three eligible studies were identified; the most commonly studied pathogens were Clostridioides difficile (n = 15), norovirus (n = 10), and rotavirus (n = 9). Statistically significant associations between low C. difficile Ct values and increased symptom severity or poor outcome were reported in 4/8 (50%) studies, and increased risk of death in 1/2 (50%) studies; no significant associations were found between Ct value and duration of symptoms or length of hospital stay. Among studies of norovirus, 5/7 (71%), mainly genogroup II, reported symptomatic cases with significantly lower median Ct values than controls. Significantly lower rotavirus Ct values were also observed in symptomatic cases vs. controls in 3/7 (43%) studies, and associated with more severe symptoms in 2/2 studies. Contradictory associations were identified for non-C. difficile bacterial and parasitic pathogens. Conclusions: In conclusion, some studies reported clinically useful associations between Ct values and patient or healthcare outcomes; additional, well-designed, large-scale trials are warranted based on these findings. Systematic Review Registration: [PROSPERO], identifier [CRD42020167239].
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