Diagnostic Performance of Rapid Antigen Testing for SARS-CoV-2: The COVid-19 AntiGen (COVAG) study

Background Rapid diagnostic testing for SARS-Cov-2 antigens is used to combat the ongoing pandemic. In this study we aimed to compare two RDTs, the SD Biosensor Q SARS-CoV-2 Rapid Antigen Test (Roche) and the Panbio COVID-19 Ag Rapid Test (Abbott), against rRT-PCR. Methods We included 2,215 all-comers at a diagnostic center between February 1 and March 31, 2021. rRT-PCR-positive samples were examined for SARS-CoV-2 variants. Findings Three hundred and thirty eight participants (15%) were rRT-PCR-positive for SARS-CoV-2. The sensitivities of Roche-RDT and Abbott-RDT were 60.4 and 56.8% ( P < 0.0001) and specificities 99.7% and 99.8% ( P = 0.076). Sensitivity inversely correlated with rRT-PCR-Ct values. The RDTs had higher sensitivities in individuals referred by treating physicians (79.5%, 78.7%) than in those referred by health departments (49.5%, 44.3%) or tested for other reasons (50%, 45.8%), in persons without any comorbidities (74.4%, 71%) compared to those with comorbidities (38.2%, 34.4%), in individuals with COVID-19 symptoms (75.2%, 74.3%) compared to those without (31.9%, 23.3%), and in the absence of SARS-CoV-2 variants (87.7%, 84%) compared to Alpha variant carriers (77.1%, 72.3%). If 10,000 symptomatic individuals are tested of which 500 are truly positive, the RDTs would generate 38 false-positive and 124 false-negative results. If 10,000 asymptomatic individuals are tested, including 50 true positives, 18 false-positives and 34 false-negatives would be generated. Interpretation The sensitivities of the two RDTs for asymptomatic SARS-CoV-2 carriers are unsatisfactory. Their widespread use may not be effective in the ongoing SARS-CoV-2 pandemic. The virus genotype influences the sensitivity of the two RDTs. RDTs should be evaluated for different SARS-CoV-2 variants

Comparision of different selectiveenrichment steps for the Salmonella sp. isolation from swine feces

A detecção de Salmonella sp. é fundamental nos programas de controle de salmonelose. Métodos de detecção mais eficientes permitem uma melhor determinação do nível de infecção dos rebanhos, um melhor entendimento da epidemiologia da infecção por Salmonella sp. e o desenvolvimento de programas de controle do patógeno, que visem a segurança biológica do alimento. Nos métodos convencionais, o enriquecimento seletivo é uma etapa crítica, pois inibe a microbiota competitiva e permite a multiplicação de Salmonella sp. Vários caldos de enriquecimento seletivo têm sido comparados quanto à eficiência na recuperação de Salmonella sp. a partir de alimentos, contudo existem poucos estudos relativos a fezes de suínos. O objetivo deste trabalho foi comparar caldos de enriquecimento seletivo para o isolamento de Salmonella sp. a partir de fezes de suínos. Numa primeira fase, amostras de fezes foram contaminadas artificialmente e os caldos Rappaport-Vassiliadis incubado a 42°C (RV), Tetrationato Müller-Kauffmann a 37°C (TMK37) e 42°C (TMK42), e Selenito Cistina (SC) a 37°C foram testados, em associação com meios sólidos seletivos: Rambach (RA), Xilose Lisina Tergitol 4 (XLT4), e Verde Brilhante Vermelho de Fenol Lactose Sacarose (VB). Na segunda fase os caldos RV, TMK37 e TMK42, semeados nos meios XLT4 e VB, foram testados com amostras naturalmente contaminadas. Na primeira fase o RV, TMK42 e TMK37 foram mais eficientes que o SC. No isolamento de Salmonella sp. em amostras naturalmente contaminadas os caldos TMK42 e RV foram superiores ao TMK37. O desempenho destes influenciou diretamente a capacidade seletiva e indicadora dos meios sólidos seletivos. No presente estudo, a associação TMK42/XLT4 demonstrou ser mais sensível, e a RV/XLT4 mais específica. O ágar VB também é recomendado para aumentar a probabilidade de detecção do patógeno. Desta forma os caldos RV e TMK42 e o ágar XLT4 e o VB foram considerados os mais indicados para a implantação de protocolos de detecção de Salmonella sp. em fezes suínas.Detection of Salmonella is a key point in veterinary Salmonella research and surveillance programs. Through an efficient method for pathogen detection, the herd infection leveI could be better determinated, which would permit the understanding of Salmonella infection epidemiology and the developing of pathogen control programs in order to achieve biological food safety. In a conventional isolation method, the selective enrichment is a critical step because it suppresses competitive microflora and permits Salmonella sp. to proliferate. Several selective enrichment broths have been compared for recovering Salmonella sp. from foods. However the isolation ITomswine feces has been conduct in a few studies. The aim of this study was to compare the efficiency of different selective enrichment methods for the isolation of Salmonella sp. from swine feces. In a first step, swine feces samples were artificially contaminated and Rappaport- Vassiliadis broth incubated at 42°C (RV), MüIler-Kauffmann tetrathionate broth at 37°C (MKT37) and 42°C (MKT42), and Selenite Cystine broth at 37°C (SC) were tested, in association with selective plating media: Xylose Lisine Tergitol 4 (XLT4), Brilliant Green Phenol Red Lactose Sucrose (BG). Later, in a second step, RV, MKT42 and MKT37 broths were streaked in XLT4 and BG media and tested with naturally contaminated samples. At the first step RV, MKT42 and MKT37 broths were more efficient than SC broth. When Salmonella sp. were isolated from naturally contaminated samples MKT42 and RV broth were superior to MKT37. The performance of the broths affected the selectivity and differentiation capacity of the selective plating media used. In the present study the association MKT42/XLT4 was the most sensitive and RV/XLT4 was the most specific. The use of BG agar is also recommended to improve the likelihood of Salmonella sp. detection. Therefore, RVand MKT42 broth, and XLT4 and VB media were considered the most appropriated to be used in detection protocols of Salmonella sp. from swine feces

Comparision of different selectiveenrichment steps for the Salmonella sp. isolation from swine feces

A detecção de Salmonella sp. é fundamental nos programas de controle de salmonelose. Métodos de detecção mais eficientes permitem uma melhor determinação do nível de infecção dos rebanhos, um melhor entendimento da epidemiologia da infecção por Salmonella sp. e o desenvolvimento de programas de controle do patógeno, que visem a segurança biológica do alimento. Nos métodos convencionais, o enriquecimento seletivo é uma etapa crítica, pois inibe a microbiota competitiva e permite a multiplicação de Salmonella sp. Vários caldos de enriquecimento seletivo têm sido comparados quanto à eficiência na recuperação de Salmonella sp. a partir de alimentos, contudo existem poucos estudos relativos a fezes de suínos. O objetivo deste trabalho foi comparar caldos de enriquecimento seletivo para o isolamento de Salmonella sp. a partir de fezes de suínos. Numa primeira fase, amostras de fezes foram contaminadas artificialmente e os caldos Rappaport-Vassiliadis incubado a 42°C (RV), Tetrationato Müller-Kauffmann a 37°C (TMK37) e 42°C (TMK42), e Selenito Cistina (SC) a 37°C foram testados, em associação com meios sólidos seletivos: Rambach (RA), Xilose Lisina Tergitol 4 (XLT4), e Verde Brilhante Vermelho de Fenol Lactose Sacarose (VB). Na segunda fase os caldos RV, TMK37 e TMK42, semeados nos meios XLT4 e VB, foram testados com amostras naturalmente contaminadas. Na primeira fase o RV, TMK42 e TMK37 foram mais eficientes que o SC. No isolamento de Salmonella sp. em amostras naturalmente contaminadas os caldos TMK42 e RV foram superiores ao TMK37. O desempenho destes influenciou diretamente a capacidade seletiva e indicadora dos meios sólidos seletivos. No presente estudo, a associação TMK42/XLT4 demonstrou ser mais sensível, e a RV/XLT4 mais específica. O ágar VB também é recomendado para aumentar a probabilidade de detecção do patógeno. Desta forma os caldos RV e TMK42 e o ágar XLT4 e o VB foram considerados os mais indicados para a implantação de protocolos de detecção de Salmonella sp. em fezes suínas.Detection of Salmonella is a key point in veterinary Salmonella research and surveillance programs. Through an efficient method for pathogen detection, the herd infection leveI could be better determinated, which would permit the understanding of Salmonella infection epidemiology and the developing of pathogen control programs in order to achieve biological food safety. In a conventional isolation method, the selective enrichment is a critical step because it suppresses competitive microflora and permits Salmonella sp. to proliferate. Several selective enrichment broths have been compared for recovering Salmonella sp. from foods. However the isolation ITomswine feces has been conduct in a few studies. The aim of this study was to compare the efficiency of different selective enrichment methods for the isolation of Salmonella sp. from swine feces. In a first step, swine feces samples were artificially contaminated and Rappaport- Vassiliadis broth incubated at 42°C (RV), MüIler-Kauffmann tetrathionate broth at 37°C (MKT37) and 42°C (MKT42), and Selenite Cystine broth at 37°C (SC) were tested, in association with selective plating media: Xylose Lisine Tergitol 4 (XLT4), Brilliant Green Phenol Red Lactose Sucrose (BG). Later, in a second step, RV, MKT42 and MKT37 broths were streaked in XLT4 and BG media and tested with naturally contaminated samples. At the first step RV, MKT42 and MKT37 broths were more efficient than SC broth. When Salmonella sp. were isolated from naturally contaminated samples MKT42 and RV broth were superior to MKT37. The performance of the broths affected the selectivity and differentiation capacity of the selective plating media used. In the present study the association MKT42/XLT4 was the most sensitive and RV/XLT4 was the most specific. The use of BG agar is also recommended to improve the likelihood of Salmonella sp. detection. Therefore, RVand MKT42 broth, and XLT4 and VB media were considered the most appropriated to be used in detection protocols of Salmonella sp. from swine feces

Comparison of different selective enrichment steps to isolate Salmonella sp. from feces of finishing swine Comparação de diferentes etapas de enriquecimento seletivo no isolamento de Salmonella sp. de fezes de suínos de terminação

A two-phase study was conducted to compare the efficacy of several enrichment selective-broth steps associated to different plating media for recovery of Salmonella sp. from finishing swine feces. In a first phase, Rappaport-Vassiliadis broth (RV) incubated at 42ºC, Tetrathionate Müller-Kauffmann broth at 37ºC (TMK37) and 42ºC (TMK42), and Selenite Cystine broth (SC) at 37ºC, in combination with three selective plating media Rambach agar (RA), Xylose-Lysine-Tergitol 4 agar (XLT4), and Brilliant-Green Phenol-Red Lactose Sucrose agar (VB) were compared for recovery of Salmonella from artificially contaminated swine feces. In a second phase, RV, TMK37, and TMK42, associated with XLT4 and VB , were tested with naturally contaminated swine feces. In this study RV, TMK42 and TMK37 were superior to SC for isolating Salmonella sp. from artificially contaminated feces. TMK42 and RV were more productive than TMK37 for recovery of Salmonella from naturally contaminated feces samples. Selectivity and indication capability of the plating media were remarkably affected by the selective enrichment step effectiveness. The TMK42/XLT4 association was the most sensitive and RV/XLT4 the most specific. The use of VB agar is also recommended to increase the likelihood of isolating atypical H2S-late producing/ non-producing Salmonella. In this study RV and TMK42 were the most efficient selective enrichment for recovery of Salmonella sp. from swine feces.<br>Através de um estudo em duas fases comparou-se a eficiência de etapas de enriquecimento seletivo, associadas a diferentes meios seletivos, na recuperação de Salmonella sp. de fezes de suínos de terminação. Em uma primeira fase, as amostras foram contaminadas artificialmente e os caldos Rappaport-Vassiliadis (RV) incubado a 42ºC, Tetrationato Müller-Kauffmann a 37ºC (TMK37) e 42ºC (TMK42), e Selenito Cistina (SC) a 37ºC foram testados, em associação com meios sólidos seletivos: ágar Rambach (RA), ágar Xilose-Lisina-Tergitol 4 (XLT4), e ágar Verde-brilhante Vermelho-neutro Lactose Sacarose (VB). Na segunda fase os caldos RV, TMK37, and TMK42, semeados nos meios XLT4 and VB, foram testados com amostras naturalmente contaminadas. No isolamento de Salmonella sp. em amostras artificialmente contaminadas o RV, TMK42 e TMK37 foram superiores ao SC. Na segunda fase o TMK42 e RV foram mais eficientes que o TMK37. O desempenho destas etapas de enriquecimento seletivo influenciou diretamente a capacidade seletiva e indicadora dos meios sólidos seletivos utilizados. No presente estudo, a associação TMK42/XLT4 demonstrou ser a mais sensível, e a RV/XLT4 a mais específica. O uso do meio VB também é recomendado para aumentar a probabilidade do isolamento de colônias atípicas de Salmonella - produtoras tardias ou não produtoras de H2S. No presente estudo, RV e TMK42 foram as etapas de enriquecimento seletivo mais eficientes para o isolamento de Salmonella de fezes de suínos

Padrão eletroforético de amostras de Pasteurella multocida isoladas de pulmões de suínos abatidos no Rio Grande do Sul

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Padrão eletroforético de amostras de Pasteurella multocida isoladas de pulmões de suínos abatidos no Rio Grande do Sul

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Detecção de genes de virulência in Salmonella enteritidis isoladas de diferentes fontes

A presença de três genes de virulência (invA, spvR e spvC) foi determinada em Salmonella Enteritidis isoladas de aves, suínos, humanos e alimentos. Todos os isolados foram positivos para o gene invA, 91,2% também foram positivos para o spvR e 90,2% para o spvC. Não existiu diferença significativa na prevalência dos genes de virulência entre isolados de diferentes origens. Os resultados indicaram que, provavelmente, exista um alto potencial de virulência nos isolados de S. Enteritidis caracterizados.The presence of three virulence genes, invA, spvR, and spvC, was determined in Salmonella Enteritidis isolated from poultry, pigs, humans and food. All isolates were positive for the invA gene, with 91.2% being positive for spvR and 90.2% for spvC. There was no significant difference in the prevalence of the virulence genes between isolates from different sources. The results indicate that there is a putative high virulence potential for the S. Enteritidis isolates characterized

Sorotipos de Salmonella isolados em uma propriedade de suínos de terminação no sul do Brasil

Em uma granja de suínos, foram isolados quinze sorotipos diferentes de Salmonella. Dois dos sorotipos isolados, Mbandaka e Tennessee, foram também encontrados na ração fornecida aos animais. Este estudo demonstrou a diversidade de sorotipos que podem estar presentes em uma granja e a necessidade de um melhor ptFifteen different serovars of Salmonella were isolated from a swine farm, two of the isolated serovars, Mbandaka and Tennessee, were also found in the feed supplied to the animals. This study demonstrated the diversity of serovars that could occur in a farm and the need of a better understanding on epidemiology of Salmonella infection

Comparação de diferentes etapas de enriquecimento seletivo no isolamento de Salmonella sp. a partir de fezes de suínos de terminação

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