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1.
Emerg Infect Dis ; 29(1): 175-178, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36573611

RESUMO

Whole blood is the optimal specimen for anaplasmosis diagnosis but might not be available in all cases. We PCR tested serum samples collected in Canada for Anaplasma serology and found 84.8%-95.8% sensitivity and 2.8 average cycle threshold elevation. Serum can be acceptable for detecting Anaplasma spp. when whole blood is unavailable.


Assuntos
Anaplasma phagocytophilum , Anaplasmose , Animais , Humanos , Anaplasmose/diagnóstico , Reação em Cadeia da Polimerase em Tempo Real , Anaplasma phagocytophilum/genética , Canadá/epidemiologia
2.
Clin Microbiol Rev ; 34(3)2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-33980687

RESUMO

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory disease coronavirus 2 (SARS-CoV-2), has led to millions of confirmed cases and deaths worldwide. Efficient diagnostic tools are in high demand, as rapid and large-scale testing plays a pivotal role in patient management and decelerating disease spread. This paper reviews current technologies used to detect SARS-CoV-2 in clinical laboratories as well as advances made for molecular, antigen-based, and immunological point-of-care testing, including recent developments in sensor and biosensor devices. The importance of the timing and type of specimen collection is discussed, along with factors such as disease prevalence, setting, and methods. Details of the mechanisms of action of the various methodologies are presented, along with their application span and known performance characteristics. Diagnostic imaging techniques and biomarkers are also covered, with an emphasis on their use for assessing COVID-19 or monitoring disease severity or complications. While the SARS-CoV-2 literature is rapidly evolving, this review highlights topics of interest that have occurred during the pandemic and the lessons learned throughout. Exploring a broad armamentarium of techniques for detecting SARS-CoV-2 will ensure continued diagnostic support for clinicians, public health, and infection prevention and control for this pandemic and provide advice for future pandemic preparedness.


Assuntos
Teste de Ácido Nucleico para COVID-19/métodos , Teste Sorológico para COVID-19/métodos , COVID-19/diagnóstico por imagem , COVID-19/diagnóstico , SARS-CoV-2/genética , Técnicas Biossensoriais , Genoma Viral/genética , Humanos , Técnicas de Amplificação de Ácido Nucleico/métodos , Testes Imediatos , SARS-CoV-2/imunologia , Manejo de Espécimes/métodos
3.
Emerg Infect Dis ; 28(6): 1292-1294, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35608954

RESUMO

In July 2021, a PCR-confirmed case of locally acquired Babesia microti infection was reported in Atlantic Canada. Clinical features were consistent with babesiosis and resolved after treatment. In a region where Lyme disease and anaplasmosis are endemic, the occurrence of babesiosis emphasizes the need to enhance surveillance of tickborne infections.


Assuntos
Anaplasma phagocytophilum , Anaplasmose , Babesia microti , Babesiose , Borrelia burgdorferi , Ixodes , Doença de Lyme , Anaplasmose/diagnóstico , Anaplasmose/tratamento farmacológico , Anaplasmose/epidemiologia , Animais , Babesiose/diagnóstico , Babesiose/tratamento farmacológico , Babesiose/epidemiologia , Canadá/epidemiologia , Doença de Lyme/diagnóstico , Doença de Lyme/epidemiologia
4.
J Clin Microbiol ; 58(7)2020 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-32321781

RESUMO

Compared to the standard two-tiered testing (STTT) algorithm for Lyme disease serology using an enzyme immunoassay (EIA) followed by Western blotting, data from the United States suggest that a modified two-tiered testing (MTTT) algorithm employing two EIAs has improved sensitivity to detect early localized Borrelia burgdorferi infections without compromising specificity. From 2011 to 2014, in the Canadian province of Nova Scotia, where Lyme disease is hyperendemic, sera submitted for Lyme disease testing were subjected to a whole-cell EIA, followed by C6 EIA and subsequently IgM and/or IgG immunoblots on sera with EIA-positive or equivocal results. Here, we evaluate the effectiveness of the MTTT algorithm compared to the STTT approach in a Nova Scotian population. Retrospective chart reviews were performed on patients testing positive with the whole-cell and C6 EIAs (i.e., the MTTT algorithm). Patients were classified as having Lyme disease if they had a positive STTT result, a negative STTT result but symptoms consistent with Lyme disease, or evidence of seroconversion on paired specimens. Of the 10,253 specimens tested for Lyme disease serology, 9,806 (95.6%) were negative. Of 447 patients who tested positive, 271 charts were available for review, and 227 were classified as patients with Lyme disease. The MTTT algorithm detected 25% more early infections with a specificity of 99.56% (99.41 to 99.68%) compared to the STTT. These are the first Canadian data to show that serology using a whole-cell sonicate EIA followed by a C6 EIA (MTTT) had improved sensitivity for detecting early B. burgdorferi infection with specificity similar to that of two-tiered testing using Western blots.


Assuntos
Borrelia burgdorferi , Doença de Lyme , Algoritmos , Anticorpos Antibacterianos , Humanos , Técnicas Imunoenzimáticas , Imunoglobulina M , Doença de Lyme/diagnóstico , Nova Escócia , Estudos Retrospectivos , Sensibilidade e Especificidade , Testes Sorológicos
5.
Mol Microbiol ; 108(5): 536-550, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29509331

RESUMO

Enteropathogenic Escherichia coli (EPEC) use a type 3 secretion system (T3SS) for injection of effectors into host cells and intestinal colonization. Here, we demonstrate that the multicargo chaperone CesT has two strictly conserved tyrosine phosphosites, Y152 and Y153 that regulate differential effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine strongly attenuated EPEC type 3 effector injection into host cells, and limited Tir effector mediated intimate adherence during infection. EPEC expressing a CesT Y152F variant were deficient for NleA effector expression and exhibited significantly reduced translocation of NleA into host cells during infection. Other effectors were observed to be dependent on CesT Y152 for maximal translocation efficiency. Unexpectedly, EPEC expressing a CesT Y153F variant exhibited significantly enhanced effector translocation of many CesT-interacting effectors, further implicating phosphosites Y152 and Y153 in CesT functionality. A mouse infection model of intestinal disease using Citrobacter rodentium revealed that CesT tyrosine substitution variants displayed delayed colonization and were more rapidly cleared from the intestine. These data demonstrate genetically separable functions for tandem tyrosine phosphosites within CesT. Therefore, CesT via its C-terminal tyrosine phosphosites, has relevant roles beyond typical type III secretion chaperones that interact and stabilize effector proteins.


Assuntos
Escherichia coli Enteropatogênica/patogenicidade , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/metabolismo , Chaperonas Moleculares/metabolismo , Organofosfatos/metabolismo , Polímeros/metabolismo , Fatores de Virulência/metabolismo , Animais , Modelos Animais de Doenças , Escherichia coli Enteropatogênica/genética , Escherichia coli O157 , Proteínas de Escherichia coli/genética , Feminino , Células HeLa , Humanos , Enteropatias/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Chaperonas Moleculares/genética , Tirosina/genética , Virulência/genética , Fatores de Virulência/genética
6.
Plasmid ; 98: 45-51, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-30217467

RESUMO

BACKGROUND: Serotyping of Streptococcus pneumoniae is an integral part of disease surveillance, with over 92 serotypes characterized to date using traditional serotyping. To identify the most predominant disease causing serotypes, molecular serotyping methods are now increasingly being used, like conventional and real-time multiplex PCR (cmPCR and rmPCR, respectively). Given that cmPCR consists of eight reactions spanning 41 targets, and rmPCR consists of seven triplex reactions, standardizing positive controls for these assays is challenging. As such, a 43-target plasmid for cmPCR (pSpn-CM1) and a 23 target plasmid for rmPCR (pSpn-RM1) were designed and validated. METHODS: Plasmid pSpn-RM1 was designed and synthesized as chimeric DNA sequences to include all PCR target primer binding sites sequences for cmPCR. Plasmid pSpn-RM1 consisted of all primer and probe sequences required for rmPCR. Additional targets (lytA and cpsA) were included in both plasmids for quantification, following their propagation and purification from Escherichia coli. RESULTS: When tested using the cmPCR reactions, all targets could be reproducibly be detected using pSpn-CM1 as template, with good amplicon visibility at a concentration of 1.4 (± 0.3) × 105 copies/ml was used. For the rmPCR reactions, all targets were reproducibly amplified with a concentration of 1.1 (± 0.2) × 104 copies/ml of pSpn-RM1, and the PCR efficiency for each target was equivalent to DNA extracted from representative S. pneumoniae serotypes. CONCLUSIONS: These quantifiable multi-target plasmids simplify the preparation of controls for PCR-based serotyping of S. pneumoniae, and methods herein could be extended to other highly multiplexed PCR assays.


Assuntos
Técnicas de Tipagem Bacteriana/métodos , Reação em Cadeia da Polimerase Multiplex/métodos , Plasmídeos/genética , Infecções Pneumocócicas/diagnóstico , Controle de Qualidade , Reação em Cadeia da Polimerase em Tempo Real/métodos , Streptococcus pneumoniae/classificação , DNA Bacteriano , Ensaios de Triagem em Larga Escala , Humanos , Infecções Pneumocócicas/microbiologia , Infecções Pneumocócicas/prevenção & controle , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/isolamento & purificação
7.
J Bacteriol ; 199(5)2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-27994017

RESUMO

Nominally an environmental organism, Legionella pneumophila is an intracellular parasite of protozoa but is also the causative agent of the pneumonia termed Legionnaires' disease, which results from inhalation of aerosolized bacteria by susceptible humans. Coordination of gene expression by a number of identified regulatory factors, including OxyR, assists L. pneumophila in adapting to the stresses of changing environments. L. pneumophila OxyR (OxyRLp) is an ortholog of Escherichia coli OxyR; however, OxyRLp was shown elsewhere to be functionally divergent, such that it acts as a transcription regulator independently of the oxidative stress response. In this study, the use of improved gene deletion methods has enabled us to generate an unmarked in-frame deletion of oxyR in L. pneumophila Lack of OxyRLp did not affect in vitro growth or intracellular growth in Acanthamoeba castellanii protozoa and U937-derived macrophages. The expression of OxyRLp does not appear to be regulated by CpxR, even though purified recombinant CpxR bound a DNA sequence similar to that reported for CpxR elsewhere. Surprisingly, a lack of OxyRLp resulted in elevated activity of the promoters located upstream of icmR and the lpg1441-cpxA operon, and OxyRLp directly bound to these promoter regions, suggesting that OxyRLp is a direct repressor. Interestingly, a strain overexpressing OxyRLp demonstrated reduced intracellular growth in A. castellanii but not in U937-derived macrophages, suggesting that balanced expression control of the two-component CpxRA system is necessary for survival in protozoa. Taken together, this study suggests that OxyRLp is a functionally redundant transcriptional regulator in L. pneumophila under the conditions evaluated herein.IMPORTANCELegionella pneumophila is an environmental pathogen, with its transmission to the human host dependent upon its ability to replicate in protozoa and survive within its aquatic niche. Understanding the genetic factors that contribute to L. pneumophila survival within each of these unique environments will be key to limiting future point-source outbreaks of Legionnaires' disease. The transcriptional regulator L. pneumophila OxyR (OxyRLp) has been previously identified as a potential regulator of virulence traits warranting further investigation. This study demonstrated that oxyR is nonessential for L. pneumophila survival in vitro and in vivo via mutational analysis. While the mechanisms of how OxyRLp expression is regulated remain elusive, this study shows that OxyRLp negatively regulates the expression of the cpxRA two-component system necessary for intracellular survival in protozoa.


Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Legionella pneumophila/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismo , Acanthamoeba castellanii/microbiologia , Proteínas de Bactérias/genética , Humanos , Legionella pneumophila/genética , Macrófagos/microbiologia , Mutação , Proteínas Repressoras/genética , Fatores de Transcrição/genética , Células U937
8.
Can J Infect Dis Med Microbiol ; 2016: 1280247, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27366155

RESUMO

Background. Norovirus is the leading cause of viral gastroenteritis, with GII.4 being the most common circulating genotype. Recently, outbreaks in China revealed that norovirus GII.17 GII.P17 had become predominant. Objective. This study aimed to characterize the distribution of norovirus genotypes circulating in Nova Scotia. Methods. Stool specimens were collected from gastrointestinal outbreaks in Nova Scotia between Jan 2014 and June 2015 and subjected to real-time RT-PCR. Norovirus-positive specimens were referred to the National Microbiology Laboratory for sequence-based genotyping. Results. The first norovirus GII.P17-GII.17 outbreak in Canada was identified, but no widespread activity was observed in Nova Scotia. Discussion. It is unknown whether GII.P17-GII.17 is more widespread in Canada since contributions to Canadian surveillance are too sparse to effectively monitor the epidemiology of emerging norovirus genotypes. Conclusions. Presence of norovirus GII.17:P17 in Canada highlights the need for more systematic surveillance to ensure that molecular targets used for laboratory detection are effective and help understand norovirus evolution, epidemiology, and pathogenesis.

9.
J Clin Microbiol ; 53(5): 1748-51, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25740765

RESUMO

The recent emergence of a severe respiratory disease caused by enterovirus D68 prompted investigation into whether Canadian hospital and provincial laboratories can detect this virus using commercial and laboratory-developed assays. This study demonstrated analytical sensitivity differences between commercial and laboratory-developed assays for the detection of enterovirus D68.


Assuntos
Técnicas de Laboratório Clínico/métodos , Testes Diagnósticos de Rotina/métodos , Enterovirus Humano D/isolamento & purificação , Infecções por Enterovirus/diagnóstico , Ensaio de Proficiência Laboratorial , Infecções Respiratórias/diagnóstico , Canadá , Infecções por Enterovirus/virologia , Humanos , Infecções Respiratórias/virologia , Sensibilidade e Especificidade
10.
J Clin Microbiol ; 52(6): 2186-8, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24696023

RESUMO

The Viper HSV-Q(x) assay was evaluated for the detection of herpes simplex virus 1 (HSV-1) and HSV-2 in specimens from oral, anogenital, and other miscellaneous sites. The HSV-Q(x) assay was found to be highly sensitive and accurate; however, a gray zone may be required for specimens with values falling between 50 and 800 maximum relative fluorescence units.


Assuntos
Herpes Genital/diagnóstico , Herpes Genital/virologia , Herpes Simples/diagnóstico , Herpes Simples/virologia , Técnicas de Diagnóstico Molecular/métodos , Simplexvirus/classificação , Simplexvirus/isolamento & purificação , Fluorescência , Genitália/virologia , Humanos , Técnicas de Diagnóstico Molecular/normas , Boca/virologia , Sensibilidade e Especificidade
11.
Virol J ; 11: 129, 2014 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-25037234

RESUMO

BACKGROUND: Although national surveillance programs are in place to monitor norovirus epidemiology, the emergence of new strains and the genetic diversity among genotypes can be challenging for clinical laboratories. This study evaluated the analytical and clinical performance characteristics of one real-time RT-PCR and two end-point RT-PCRs commonly used in microbiology laboratories. METHODS: Lower limit of detection (LoD) was determined using 10-fold dilutions of noroviruses belonging to different genotypes. The clinical performance of the real-time and end-point RT-PCRs was assessed in parallel using nucleic acids extracted from 186 stool specimens. RESULTS: The real-time RT-PCR was highly sensitive and specific for the detection of norovirus genotypes that are currently circulating in Canada. In contrast, the two end-point RT-PCRs displayed poor analytical sensitivity or complete failure to detect certain norovirus genotypes, which was correlated to sequence mismatches in the primer-binding sites. In an attempt to improve norovirus detection with the end-point RT-PCRs, both assays were processed concurrently and detection from either assay was considered a positive result. Concurrent testing resulted in only a modest increase in clinical sensitivity (75.0%) compared to each assay alone (62.5% and 71.9%). However, the false positivity rate increased from 1.98% and 3.36% for the assays alone to 5.47% with concurrent testing. CONCLUSIONS: This study emphasizes the benefits of a real-time method and provides support for routine surveillance to monitor norovirus epidemiology and ongoing proficiency testing to ensure detection of circulating norovirus genotypes.


Assuntos
Infecções por Caliciviridae/diagnóstico , Infecções por Caliciviridae/virologia , Gastroenterite/diagnóstico , Gastroenterite/virologia , Genótipo , Norovirus/genética , Humanos , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade
12.
Sci Rep ; 14(1): 18378, 2024 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-39112632

RESUMO

We developed and validated the Influenza Severity Scale (ISS), a standardized risk assessment for influenza, to estimate and predict the probability of major clinical events in patients with laboratory-confirmed infection. Data from the Canadian Immunization Research Network's Serious Outcomes Surveillance Network (2011/2012-2018/2019 influenza seasons) enabled the selecting of all laboratory-confirmed influenza patients. A machine learning-based approach then identified variables, generated weighted scores, and evaluated model performance. This study included 12,954 patients with laboratory-confirmed influenza infections. The optimal scale encompassed ten variables: demographic (age and sex), health history (smoking status, chronic pulmonary disease, diabetes mellitus, and influenza vaccination status), clinical presentation (cough, sputum production, and shortness of breath), and function (need for regular support for activities of daily living). As a continuous variable, the scale had an AU-ROC of 0.73 (95% CI, 0.71-0.74). Aggregated scores classified participants into three risk categories: low (ISS < 30; 79.9% sensitivity, 51% specificity), moderate (ISS ≥ 30 but < 50; 54.5% sensitivity, 55.9% specificity), and high (ISS ≥ 50; 51.4% sensitivity, 80.5% specificity). ISS demonstrated a solid ability to identify patients with hospitalized laboratory-confirmed influenza at increased risk for Major Clinical Events, potentially impacting clinical practice and research.


Assuntos
Influenza Humana , Índice de Gravidade de Doença , Humanos , Influenza Humana/diagnóstico , Influenza Humana/epidemiologia , Masculino , Canadá/epidemiologia , Feminino , Pessoa de Meia-Idade , Adulto , Idoso , Medição de Risco/métodos , Adulto Jovem , Adolescente
13.
Viruses ; 16(8)2024 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-39205254

RESUMO

Despite the provision of a mumps vaccination program in Canada for over three decades, mumps has not reached elimination. Instead, a re-emergence has been observed in vaccinated populations, particularly in young adults. These outbreaks have been almost exclusively due to genotype G infections, a trend that has been seen in other countries with high mumps vaccination rates. To characterize mumps outbreaks in Canada, genomes from samples from Manitoba (n = 209), Newfoundland (n = 25), and Nova Scotia (n = 48) were sequenced and analysed by Bayesian inference. Whole genome sequencing was shown to be highly discriminatory for outbreak investigations compared to traditional Sanger sequencing. The results showed that mumps virus genotype G most likely circulated endemically in Canada and between Canada and the US. Overall, this Canadian outbreak data from different provinces and ancestral strains demonstrates the benefits of molecular genomic data to better characterize mumps outbreaks, but also suggests genomics could further our understanding of the reasons for potential immune escape of mumps genotype G and evolution in highly vaccinated populations. With a possible endemic circulation of mumps genotype G and the remaining risk of new imported cases, increased surveillance and alternative vaccination strategies may be required for Canada to reach the current target for mumps or a future elimination status.


Assuntos
Surtos de Doenças , Genoma Viral , Genótipo , Vírus da Caxumba , Caxumba , Filogenia , Caxumba/epidemiologia , Caxumba/virologia , Caxumba/transmissão , Humanos , Canadá/epidemiologia , Vírus da Caxumba/genética , Vírus da Caxumba/classificação , Vírus da Caxumba/isolamento & purificação , Adulto , Adulto Jovem , Masculino , Adolescente , Feminino , Criança , Sequenciamento Completo do Genoma , Genômica/métodos , Pessoa de Meia-Idade , Pré-Escolar , Doenças Endêmicas , Lactente , Teorema de Bayes
14.
Vaccine ; 42(7): 1768-1776, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38368226

RESUMO

BACKGROUND: Two prefusion F protein-based vaccines, Arexvy and Abrysvo, have been approved by Health Canada for protecting older adults against respiratory syncytial virus (RSV)-associated lower respiratory tract disease. We estimated the health benefits and cost-effectiveness of these vaccines under a publicly funded single-dose vaccination program in Ontario that targets residents of long-term care homes (LTCHs). Additionally, we evaluated an extended program that broadens vaccination to include community-dwelling older adults. METHODS: A discrete-event simulation model was parameterised with the burden of RSV disease including outpatient care, hospitalisation, and death among adults aged 60 years or older in Ontario, Canada. Accounting for direct and indirect costs (in 2023 Canadian dollars) associated with RSV-related outcomes, we calculated the net monetary benefit using quality-adjusted life-year (QALY) gained, and determined the range of price-per-dose (PPD) for vaccination programs to be cost-effective from both healthcare and societal perspectives over two RSV seasons. The incremental cost-effectiveness ratio (ICER) was calculated to estimate the additional costs required to gain one QALY. RESULTS: Using a willingness-to-pay of $50,000 per QALY gained, we found that vaccinating 90% of residents in LTCHs with Arexvy would be cost-effective from a societal perspective for a PPD up to $163, producing a mean ICER value of $49,984 (95% CI: $47,539 to $52,704) per QALY gained with a two-year budget impact of $463,468 per 100,000 older adults. The reduction of hospitalizations was estimated at 7.0% compared to the no-vaccination scenario. Extending the program to include community-dwelling older adults with a 74% coverage akin to influenza vaccination, Arexvy remains cost-effective for a PPD up to $139, with a mean ICER value of $49,698 (95% CI: 48,022 to 51,388) per QALY gained and a two-year budget impact of $8.63 million. Compared to the no-vaccination scenario, the extended program resulted in a 57.3% reduction in RSV-related hospitalisations. CONCLUSIONS: Vaccinating residents of LTCHs against RSV disease would be cost-effective depending on PPD; extending the program to community-dwelling older adults would provide substantial health benefits, averting significant direct healthcare costs and productivity losses.


Assuntos
Doenças Transmissíveis , Infecções por Vírus Respiratório Sincicial , Vacinas contra Vírus Sincicial Respiratório , Vírus Sincicial Respiratório Humano , Vacinas , Vacinas Virais , Humanos , Idoso , Análise Custo-Benefício , Ontário , Infecções por Vírus Respiratório Sincicial/prevenção & controle , Vacinação , Anos de Vida Ajustados por Qualidade de Vida
15.
Microbiol Spectr ; 12(5): e0407323, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38567975

RESUMO

Antigen-based rapid diagnostic tests (Ag-RDTs) were widely deployed to enhance SARS-CoV-2 testing capacity during the COVID-19 pandemic. Consistent with national guidance for low prevalence settings, positive Ag-RDTs were confirmed using nucleic acid amplification tests (NAATs) to avoid false positive results. However, increasing demands for positive Ag-RDT confirmation competed with other testing priorities in clinical laboratories. This work hypothesized that real-time RT-PCR without nucleic acid extraction (NAE) would be sufficiently sensitive to support positive Ag-RDT confirmation. Ag-RDT and NAAT results from community-based asymptomatic testing sites prior to the omicron variant wave were compared to calculate the weekly false positive rate (FPR) and false detection rate (FDR). Real-time RT-PCR was compared with and without NAE using 752 specimens previously tested positive for SARS-CoV-2 using commercial NAATs and 344 specimens from Ag-RDT-positive individuals. The impact of SARS-CoV-2 prevalence on laboratory resources required to sustain Ag-RDT confirmation was modeled for the RT-PCR with and without NAE. Overall, FPR was low [0.07% (222/330,763)] in asymptomatic testing sites, but FDR was high [30.7% (222/724)]. When RT-PCR was compared with and without NAE, 100% concordance was obtained with NAAT-positive specimens, including those from Ag-RDT-positive individuals. NAE-free RT-PCR significantly reduced time to results, human resources, and overall costs. A 30.7% FDR reaffirms the need for NAAT-based confirmation of positive Ag-RDT results during low SARS-CoV-2 prevalence. NAE-free RT-PCR was shown to be a simple and cost-sparing NAAT-based solution for positive Ag-RDT confirmation, and its implementation supported data-driven broader Ag-RDT deployment into communities, workplaces, and households. IMPORTANCE: Rapid antigen testing for SARS-CoV-2 was widely deployed during the COVID-19 pandemic. In settings of low prevalence, national guidance recommends that positive antigen test results be confirmed with molecular testing. Given the high testing burden on clinical laboratories during the COVID-19 pandemic, the high volume of positive antigen tests submitted for confirmatory testing posed challenges for laboratory workflow. This study demonstrated that a simple PCR method without prior nucleic acid purification is an accurate and cost-effective solution for positive rapid antigen test confirmation. Implementing this method allowed molecular confirmatory testing for positive antigen tests to be sustained as antigen testing was expanded into large populations such as workplaces, schools, and households.


Assuntos
Antígenos Virais , COVID-19 , SARS-CoV-2 , Humanos , COVID-19/diagnóstico , COVID-19/epidemiologia , SARS-CoV-2/genética , SARS-CoV-2/imunologia , SARS-CoV-2/isolamento & purificação , Sensibilidade e Especificidade , Prevalência , Reações Falso-Positivas , Teste Sorológico para COVID-19/métodos , Teste de Ácido Nucleico para COVID-19/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Reação em Cadeia da Polimerase em Tempo Real/métodos
16.
J Clin Microbiol ; 51(11): 3835-8, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23966485

RESUMO

The recent emergence of influenza A virus (H7N9) emphasizes the need for its rapid detection. While commercial nucleic acid amplification tests (NAATs) are commonly used to detect seasonal influenza virus, this study demonstrated that the analytical sensitivity of commercial assays is highly variable compared to that of CDC-based in-house NAATs for the detection of H7N9.


Assuntos
Subtipo H7N9 do Vírus da Influenza A/isolamento & purificação , Influenza Humana/diagnóstico , Influenza Humana/virologia , Técnicas de Diagnóstico Molecular/métodos , Virologia/métodos , Humanos , Subtipo H7N9 do Vírus da Influenza A/genética , Sensibilidade e Especificidade
17.
Virol J ; 10: 184, 2013 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-23758993

RESUMO

Compared to traditional testing strategies, nucleic acid amplification tests such as real-time PCR offer many advantages for the detection of human adenoviruses. However, commercial assays are expensive and cost prohibitive for many clinical laboratories. To overcome fiscal challenges, a cost effective strategy was developed using a combination of homogenization and heat treatment with an "in-house" real-time PCR. In 196 swabs submitted for adenovirus detection, this crude extraction method showed performance characteristics equivalent to viral DNA obtained from a commercial nucleic acid extraction. In addition, the in-house real-time PCR outperformed traditional testing strategies using virus culture, with sensitivities of 100% and 69.2%, respectively. Overall, the combination of homogenization and heat treatment with a sensitive in-house real-time PCR provides accurate results at a cost comparable to viral culture.


Assuntos
Infecções por Adenoviridae/diagnóstico , Adenovírus Humanos/isolamento & purificação , Técnicas de Diagnóstico Molecular/métodos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Manejo de Espécimes/métodos , Virologia/métodos , Adenovírus Humanos/genética , Humanos , Técnicas de Diagnóstico Molecular/economia , Reação em Cadeia da Polimerase em Tempo Real/economia , Sensibilidade e Especificidade , Manejo de Espécimes/economia , Virologia/economia
18.
Sci Total Environ ; 889: 164261, 2023 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-37201817

RESUMO

A multiplex quantitative reverse transcription polymerase chain reaction (RT-qPCR)-based method was designed for the simultaneous detection of influenza A, SARS-CoV-2, respiratory syncytial virus, and measles virus. The performance of the multiplex assay was compared to four monoplex assays for relative quantification using standard quantification curves. Results showed that the multiplex assay had comparable linearity and analytical sensitivity to the monoplex assays, and the quantification parameters of both assays demonstrated minimal differences. Viral reporting recommendations for the multiplex method were estimated based on the corresponding limit of quantification (LOQ) and the limit of detection at 95 % confidence interval (LOD) values for each viral target. The LOQ was determined by the lowest nominal RNA concentrations where %CV values were ≤35 %. Corresponding LOD values for each viral target were between 15 and 25 gene copies per reaction (GC/rxn), and LOQ values were within 10 to 15 GC/rxn. The detection performance of a new multiplex assay was validated in the field by collecting composite wastewater samples from a local treatment facility and passive samples from three sewer shed locations. Results indicated that the assay could accurately estimate viral loads from various sample types, with samples collected from passive samplers showing a greater range of detectable viral concentrations than composite wastewater samples. This suggests that the sensitivity of the multiplex method may be improved when paired with more sensitive sampling methods. Laboratory and field results demonstrate the robustness and sensitivity of the multiplex assay and its applicability to detect the relative abundance of four viral targets among wastewater samples. Conventional monoplex RT-qPCR assays are suitable for diagnosing viral infections. However, multiplex analysis using wastewater provides a fast and cost-effective way to monitor viral diseases in a population or environment.


Assuntos
COVID-19 , Influenza Humana , Sarampo , Viroses , Humanos , Vírus Sinciciais Respiratórios , SARS-CoV-2 , Águas Residuárias , Sensibilidade e Especificidade , Reação em Cadeia da Polimerase Multiplex/métodos
19.
Front Public Health ; 11: 1142602, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37181684

RESUMO

Introduction: After the initial onset of the SARS-CoV-2 pandemic, the government of Canada and provincial health authorities imposed restrictive policies to limit virus transmission and mitigate disease burden. In this study, the pandemic implications in the Canadian province of Nova Scotia (NS) were evaluated as a function of the movement of people and governmental restrictions during successive SARS-CoV-2 variant waves (i.e., Alpha through Omicron). Methods: Publicly available data obtained from community mobility reports (Google), the Bank of Canada Stringency Index, the "COVID-19 Tracker" service, including cases, hospitalizations, deaths, and vaccines, population mobility trends, and governmental response data were used to relate the effectiveness of policies in controlling movement and containing multiple waves of SARS-CoV-2. Results: Our results indicate that the SARS-CoV-2 pandemic inflicted low burden in NS in the initial 2 years of the pandemic. In this period, we identified reduced mobility patterns in the population. We also observed a negative correlation between public transport (-0.78), workplace (-0.69), retail and recreation (-0.68) and governmental restrictions, indicating a tight governmental control of these movement patterns. During the initial 2 years, governmental restrictions were high and the movement of people low, characterizing a 'seek-and-destroy' approach. Following this phase, the highly transmissible Omicron (B.1.1.529) variant began circulating in NS at the end of the second year, leading to increased cases, hospitalizations, and deaths. During this Omicron period, unsustainable governmental restrictions and waning public adherence led to increased population mobility, despite increased transmissibility (26.41-fold increase) and lethality (9.62-fold increase) of the novel variant. Discussion: These findings suggest that the low initial burden caused by the SARS-CoV-2 pandemic was likely a result of enhanced restrictions to contain the movement of people and consequently, the spread of the disease. Easing public health restrictions (as measured by a decline in the BOC index) during periods of high transmissibility of circulating COVID-19 variants contributed to community spread, despite high levels of immunization in NS.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Nova Escócia/epidemiologia , COVID-19/epidemiologia , COVID-19/prevenção & controle , Controle de Doenças Transmissíveis
20.
Microbiol Spectr ; 11(6): e0277223, 2023 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-37962351

RESUMO

IMPORTANCE: In hospitals during the COVID-19 pandemic, laboratory testing was important to reduce SARS-CoV-2 transmissions, while facilitating patient flow in the emergency department and pre-operative settings, and allowing for the safe return to work of exposed healthcare workers. Delayed test results from laboratory nucleic acid amplification tests (NAATs) posed a barrier to maximizing efficient patient flow and minimizing staffing shortages. This quality improvement project sought to evaluate the analytical and clinical performance of the Lucira Check-It COVID-19 Test, a point-of-care test that used NAAT technology, in the perioperative setting, emergency department, and community testing sites. We found the Lucira Check-It to have comparable performance to laboratory NAATs. It can be employed with little training for specimen collection, processing, and interpretation, and at a cost justifiable from the resources saved from avoiding sample transport and laboratory testing.


Assuntos
COVID-19 , Humanos , COVID-19/diagnóstico , SARS-CoV-2/genética , Técnicas de Laboratório Clínico/métodos , Teste para COVID-19 , Técnicas de Diagnóstico Molecular/métodos , Pandemias , Sensibilidade e Especificidade
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