bioMérieux (Brazil)

In this study, a total of 248 ground beef samples were analyzed for the presence of Shiga toxin-producing Escherichia coli (STEC). Out of these samples, only one (0.4%) tested positive for STEC. Further analysis using PCR confirmed the presence of all tested genes associated with STEC, including stx1, stx2, eae, ehx, uid, rfbO157, and fliCH7 in this isolate. Interestingly, no STEC strains were detected in the remaining 100 beef cut samples or the 100 chicken cut samples, indicating the absence of detectable STEC contamination in those specific samples. The isolated strain exhibited significant cytotoxic activity in Vero cells, indicating its ability to produce cytotoxic Shiga toxins. To further investigate the strain, whole-genome sequencing (WGS) analyses were performed. The resistome analysis revealed the absence of acquired antimicrobial resistance genes, indicating a pan-susceptible phenotype. However, this strain presented chromosomal mutations in gyrA, gyrB, parC, parE, pmrA, pmrB, and folP. Plasmid analysis identified the presence of two plasmids, namely IncFIB(AP001918) and IncFII. The multi-locus sequence typing (MLST) identified the strain as belonging to sequence type (ST) 11, which is associated with E. coli O157:H7 strains. The virulome analysis confirmed the presence of several canonical virulence markers, including stx1, stx2, eae-g01-gamma, ehxA, stx1a-O157, and stx2a-O157. Overall, this study identified for the first time a rare occurrence of STEC contamination in ground beef, with the isolated strain belonging to the highly virulent O157:H7 serotype. These findings contribute to our understanding of STEC prevalence and characteristics in food samples, highlighting the importance of effective food safety measures to prevent potential health risks associated with STEC contamination.

Abstract Following severe adverse reactions in patients vaccinated with the AstraZeneca ChadOx1 (Chad) vaccine, European health authorities have recommended that patients under the age of 55 who received one dose of Chad vaccine receive a second dose of Pfizer BNT162b2 (BNT) vaccine as a booster. However, the effectiveness and the immunogenicity of this vaccination regimen have not been formally tested. Here, we show that the heterologous Chad/BNT combination confers better protection against SARS-CoV-2 infection than the homologous BNT/BNT combination in a population of health care workers. To understand the underlying mechanism, we monitored in a longitudinal way the anti-spike immunity conferred by each vaccinal combination. Both combinations induced strong anti-spike antibody responses after boost in all vaccinated individuals. However, sera from heterologous vaccinated individuals displayed a stronger neutralizing activity, regardless of the SARS-CoV-2 variant analyzed, and this was associated with more switched memory RBD-specific B cells with an activated phenotype and less IgA. The Chad vaccine induced a stronger T cell response than the BNT vaccine after the priming dose, and the reciprocal was true for the IgG response, which could explain the complementarity of both vaccines when used in an heterologous setting. This strongly protective vaccination regimen could be therefore particularly suitable for immunocompromised individuals.

Abstract BackgroundPseudomonas aeruginosa is a ubiquitous environmental microorganism and also a common cause of infection. Its ability to survive in many different environments and persistently colonize humans is linked to its presence in biofilms formed on indwelling device surfaces. Biofilm promotes adhesion to, and survival on surfaces, protects from desiccation and the actions of antibiotics and disinfectants. ResultsWe examined the genetic basis for biofilm production on polystyrene at room (22°C) and body temperature (37°C) within 280 P. aeruginosa. 69% of isolates (n=193) produced more biofilm at 22°C, whilst those producing more biofilm at 37°C had reduced genetic diversity. Using GWAS and pan-GWAS, we found a number of accessory genes significantly associated with this phenotype. Many of these are present on a 165kb region containing genes for heavy metal resistance (arsenic, copper, mercury and cadmium) transcriptional regulators and methytransferases. We also discovered multiple core genome SNPs in the A-type flagellin gene and Type II secretion system gene xpsD. Analysis of biofilm production of isolates of the MDR ST111 and ST235 lineages on stainless-steel revealed several accessory genes associated with enhanced biofilm production. These include a putative translocase with homology to a Helicobacter pylori type IV secretion system protein, a TA system II toxin gene and the alginate biosynthesis gene algA, several transcriptional regulators and methytransferases as well as core SNPs in genes involved in quorum sensing and protein translocation. ConclusionsGWAS and pan-GWAS approaches have great potential as a first step in characterizing the genetic basis of novel bacterial phenotypes.

BackgroundA comprehensive assessment of COVID-19 in healthcare workers (HCWs) including the investigation of viral shedding duration is critical.MethodsA longitudinal study including 319 HCWs was conducted. After SARS-CoV-2 screening with RT-PCR assay, other respiratory pathogens were tested with a multiplex molecular panel. For SARS-CoV-2 positive HCWs, the normalized viral load was determined weekly; viral culture and virus neutralization assays were also performed. For 190 HCWs tested negative, SARS-CoV-2 serological testing was performed one month after the inclusion.FindingsOf the 319 HCWs included, 67 (21.0%) were tested positive for SARS-CoV-2; two of them developed severe COVID-19. The proportion of smell and taste dysfunction was significantly higher in SARS-CoV-2 positive HCWs than in negative ones (38.8% vs 9.5% and 37.3% vs 10.7%, respectively, p<0.001). Of the 67 positive patients, 9.1% were tested positive for at least another respiratory pathogen (vs19.5%, p=0.07). The proportion of HCWs with a viral load > 5.0 log10cp/ml (Ct value <25) was less than 15% at 8 days after symptom onset; 12% of them were still positive after 40 days (Ct >37). More than 90% of culturable virus had a viral load > 4.5 log10cp/ml (Ct < 26) and were collected within 10 days after symptom onset. From HCWs tested negative, 6/190 (3.2%) exhibited seroconversion for IgG antibodies.InterpretationOur data suggest that the determination of normalized viral load (or its estimation through Ct values) can be useful for discontinuing isolation of HCWs and facilitating their safe return to work. HCWs presenting mild COVID-19 are unlikely infectious 10 days after symptom onset.FundingFondation des Hospices Civils de Lyon. bioMérieux provided diagnostic kits.

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Este estudo constitui uma análise do desempenho do teste sorológico treponêmico ELISA Recombinante Wiener lab. e de seis testes não treponêmicos (Laborclin: VDRL Bras, RPR Brás e RPR TRUST; Wama: VDRL e RPR; Wiener: USR) na triagem sorológica de doadores de sangue. Os resultados  repetidamente reagentes (RR) foram confirmados por meio de três testes treponêmicos: FTA abs (Wama), WB (in house) e TPHA (bioMérieux). Foram analisadas 2.990 amostras de soro. O teste VDRL (USR), utilizado inicialmente na triagem sorológica, apresentou reatividade em 11 (0,4 %) amostras, com títulos variando de 1/1 até 1/32. Nos demais testes não treponêmicos, observou-se reatividade em um número de amostras que variou de 4 a 14, num total de 20 (0,7 %) amostras das 2.990 analisadas. O teste treponêmico ELISA apresentou resultados RR em 42 (1,4 %) das amostras analisadas, entre as quais 8 (0,3 %) se mostraram reagentes a, pelo menos, um teste não treponêmico. Das 42 amostras RR pelo teste ELISA submetidas aos testes confirmatórios de FTA-abs, TPHA e WB, 9 (21,4 %) foram negativas para os três testes, 8 (19,1 %) foram positivas para WB e TPHA e negativas para o FTA-abs e 25 (59,5 %) foram positivas para os três testes. A especificidade do teste ELISA atingiu 99,7%, considerando-se o WB e o TPHA como confirmatórios. As 12 amostras que apresentaram resultados não reagentes no teste ELISA, mas mostraram algum tipo de reatividade para os testes não treponêmicos, tiveram resultado negativo nos testes confirmatórios utilizados. Mesmo que o descarte de bolsas seja maior quando se utiliza teste treponêmico, essa conduta parece ser a mais segura na triagem sorológica de doadores de sangue.

A set of physical and chemical criteria have been identified which provide a basis for the categorization of heterophase free radical polymerization processes, and the development of a systematic nomenclature. These include three quantitative transitional thresholds: a surface tension driving force, the type of stability (kinetic, thermodynamic), and the level of surfactant with respect to the critical micelle concentration. The nucleation mechanism and the average number of macroradicals within the polymer particles provide a secondary criterion for process distinction. Four mutually exclusive domains have been identified: I. Macroemulsion Polymerization, consisting of subdomains where Suspension (Ia) and Emulsion (Ib) behavior dominate, II. Inverse-Macroemulsion Polymerization, a water-in-oil analogy to the preceding encompassing Inverse-Suspension (IIa) and Inverse-Emulsion (IIb), and the thermodynamically stable Microemulsion (III) and Inverse-Microemulsion (IV) polymerizations. Within each domain a unique set of physical and chemical phenomena dominate. A reaction mechanism or model of colloidal behavior must, therefore, be specific for each regime. This is particularly important for water-in-oil polymerizations due to the unique chemistry of various organic phases and interfacial recipes. It is recommended that further development proceed independently for Inverse-Suspension, Inverse-Emulsion and Inverse-Microemulsion polymerizations, as has been the precedent for the more extensively researched oil-in-water polymerizations. A set of criteria is also developed to define and distinguish physically or kinetically identical “emulsion” and “suspension” polymerization processes.