Subanalytic sets and feedback control

AbstractThe theory of subanalytic sets is used to prove: If a real analytic control system is completely controllable, then for every point p in the state space there exists a piecewise analytic feedback control that steers every state into p

Timing and sequence of vaccination against COVID-19 and influenza (TACTIC):a single-blind, placebo-controlled randomized clinical trial

Background: Novel mRNA-based vaccines have been used to protect against SARS-CoV-2, especially in vulnerable populations who also receive an annual influenza vaccination. The TACTIC study investigated potential immune interference between the mRNA COVID-19 booster vaccine and the quadrivalent influenza vaccine, and determined if concurrent administration would have effects on safety or immunogenicity. Methods: TACTIC was a single-blind, placebo-controlled randomized clinical trial conducted at the Radboud University Medical Centre, the Netherlands. Individuals ≥60 years, fully vaccinated against COVID-19 were eligible for participation and randomized into one of four study groups: 1) 0.5 ml influenza vaccination Vaxigrip Tetra followed by 0.3 ml BNT162b2 COVID-19 booster vaccination 21 days later, (2) COVID-19 booster vaccination followed by influenza vaccination, (3) influenza vaccination concurrent with the COVID-19 booster vaccination, and (4) COVID-19 booster vaccination only (reference group). Primary outcome was the geometric mean concentration (GMC) of IgG against the spike (S)-protein of the SARS-CoV-2 virus, 21 days after booster vaccination. We performed a non-inferiority analysis of concurrent administration compared to booster vaccines alone with a predefined non-inferiority margin of −0.3 on the log10-scale. Findings: 154 individuals participated from October, 4, 2021, until November, 5, 2021. Anti-S IgG GMCs for the co-administration and reference group were 1684 BAU/ml and 2435 BAU/ml, respectively. Concurrent vaccination did not meet the criteria for non-inferiority (estimate −0.1791, 95% CI −0.3680 to −0.009831) and antibodies showed significantly lower neutralization capacity compared to the reference group. Reported side-effects were mild and did not differ between study groups. Interpretation: Concurrent administration of both vaccines is safe, but the quantitative and functional antibody responses were marginally lower compared to booster vaccination alone. Lower protection against COVID-19 with concurrent administration of COVID-19 and influenza vaccination cannot be excluded, although additional larger studies would be required to confirm this. Trial registration number: EudraCT: 2021-002186-17 Funding: The study was supported by the ZonMw COVID-19 Programme.</p

Phage-derived protein induces increased platelet activation and is associated with mortality in patients with invasive pneumococcal disease

To improve our understanding about the severity of invasive pneumococcal disease (IPD), we investigated the association between the genotype of Streptococcus pneumoniae and disease outcomes for 349 bacteremic patients. A pneumococcal genome-wide association study (GWAS) demonstrated a strong correlation between 30-day mortality and the presence of the phage-derived gene pblB, encoding a platelet-binding protein whose effects on platelet activation were previously unknown. Platelets are increasingly recognized as key players of the innate immune system, and in sepsis, excessive platelet activation contributes to microvascular obstruction, tissue hypoperfusion, and finally multiorgan failure, leading to mortality. Our in vitro studies revealed that pblB expression was induced by fluoroquinolones but not by the beta-lactam antibiotic penicillin G. Subsequently, we determined pblB induction and platelet activation by incubating whole blood with the wild type or a pblB knockout mutant in the presence or absence of antibiotics commonly administered to our patient cohort. pblB-dependent enhancement of platelet activation, as measured by increased expression of the ɑ-granule protein P-selectin, the binding of fibrinogen to the activated ɑ IIbβ3 receptor, and the formation of platelet-monocyte complex occurred irrespective of antibiotic exposure. In conclusion, the presence of pblB on the pneumococcal chromosome potentially leads to increased mortality in patients with an invasive S. pneumoniae infection, which may be explained by enhanced platelet activation. This study highlights the clinical utility of a bacterial GWAS, followed by functional characterization, to identify bacterial factors involved in disease severity. IMPORTANCE The exact mechanisms causing mortality in invasive pneumococcal disease (IPD) patients are not completely understood. We examined 349 patients with IPD and found in a bacterial genome-wide association study (GWAS) that the presence of the phage-derived gene pblB was associated with mortality in the first 30 days after hospitalization. Although pblB has been extensively studied in Streptococcus mitis, its consequence for the interaction between platelets and Streptococcus pneumoniae is largely unknown. Platelets are important in immunity and inflammation, and excessive platelet activation contributes to microvascular obstruction and multiorgan failure, leading to mortality. We therefore developed this study to assess whether the expression of pblB might increase the risk of death for IPD patients through its effect on enhanced platelet activation. This study also shows the value of integrating extensive bacterial genomics and clinical data in predicting and understanding pathogen virulence, which in turn will help to improve prognosis and therapy

Genetic Diversity of Tn916-Related Transposons among Drug-Resistant Streptococcus pneumoniae Isolates Colonizing Healthy Children in Venezuela▿

Among a collection of 48 multidrug-resistant pneumococcal strains colonizing healthy children in a small municipality of Mérida, Venezuela, we identified sequence types (STs) related to a variety of internationally spreading drug-resistant clones, as well as ST135, thus far isolated only in Europe. The clones invariably harbored one or more of the Tn916-related transposons Tn3872, Tn5253, Tn6002, Tn2009, and Tn2010. Finally, our data suggest both structural rearrangements in certain transposons and occurrence of novel transposable elements

A novel flow cytometry-based assay for the quantification of antibody-dependent pneumococcal agglutination.

The respiratory pathogen Streptococcus pneumoniae is a major cause of diseases such as otitis media, pneumonia, sepsis and meningitis. The first step towards infection is colonization of the nasopharynx. Recently, it was shown that agglutinating antibodies play an important role in the prevention of mucosal colonization with S. pneumoniae. Here, we present a novel method to quantify antibody-dependent pneumococcal agglutination in a high-throughput manner using flow cytometry. We found that the concentration of agglutinating antibodies against pneumococcal capsule are directly correlated with changes in the size and complexity of bacterial aggregates, as measured by flow cytometry and confirmed by light microscopy. Using the increase in size, we determined the agglutination index. The cutoff value was set by measuring a series of non-agglutinating antibodies. With this method, we show that not only anti-polysaccharide capsule antibodies are able to induce agglutination but that also anti-PspA protein antibodies have agglutinating capabilities. In conclusion, we have described and validated a novel method to quantify pneumococcal agglutination, which can be used to screen sera from murine or human vaccination studies, in a high-throughput manner

Nonencapsulated Streptococcus pneumoniae resists extracellular human neutrophil elastase- and cathepsin G-mediated killing

Contains fulltext : 108852.pdf (publisher's version ) (Closed access)Although the Streptococcus pneumoniae polysaccharide capsule is an important virulence factor, ~ 15% of carriage isolates are nonencapsulated. Nonencapsulated S. pneumoniae are a cause of mucosal infections. Recent studies have shown that neutrophils kill S. pneumoniae predominately through neutrophil proteases, such as elastase and cathepsin G. Another recent finding is that nonencapsulated pneumococci have greater resistance to resist cationic antimicrobial peptides that are important in mucosal immunity. We here show that nonencapsulated pneumococci have greater resistance to extracellular human neutrophil elastase- and cathepsin G-mediated killing than isogenic encapsulated pneumococci. Resistance to extracellular neutrophil protease-mediated killing is likely to be of greater relative importance on mucosal surfaces compared to other body sites

Pneumococcal agglutination by anti-capsule antibodies can be quantified using flow cytometry.

<p>Agglutination with two pneumococcal strains (TIGR4 and EF3030) incubated with different concentrations of serotype-specific rabbit antiserum (serotype 4 or serotype 19F) and rabbit antiserum against a heterologous serotype (serotype 14) (performed in duplicate). Individual histograms of a representative measurement are shown for the forward scatter of TIGR4 and for EF3030 following incubation with type-specific antiserum <b>(A),</b> overlays of the different concentrations of type-specific antiserum are shown <b>(B)</b> and all data (type-specific and heterologous antiserum) is summarized in a single graph <b>(C)</b>. The dashed line represents the agglutination cutoff value.</p

Agglutination of <i>S</i>. <i>pneumoniae</i> by anti-capsule antibodies can be detected by flow cytometry.

<p><i>S</i>. <i>pneumoniae</i> TIGR4 were incubated with a serotype specific polyclonal rabbit antiserum (serotype 4; α-ST4; right panel) and with rabbit antiserum against a heterologous serotype (serotype 14; α-ST14; left panel). Agglutination was assessed by flow cytometry and is represented as dot plots of the FSC-A vs the SSC-A <b>(A)</b> and histograms of the FSC-A signal <b>(B)</b> and by phase contrast microscopy <b>(C)</b>.</p

Nasopharyngeal colonisation dynamics of bacterial pathogens in patients with fever in rural Burkina Faso: an observational study

BACKGROUND: Nasopharyngeal colonisation with clinically relevant bacterial pathogens is a risk factor for severe infections, such as pneumonia and bacteraemia. In this study, we investigated the determinants of nasopharyngeal carriage in febrile patients in rural Burkina Faso. METHODS: From March 2016 to June 2017, we recruited 924 paediatric and adult patients presenting with fever, hypothermia or suspicion of severe infection to the Centre Medical avec Antenne Chirurgicale Saint Camille de Nanoro, Burkina Faso. We recorded a broad range of clinical data, collected nasopharyngeal swabs and tested them for the presence of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Klebsiella pneumoniae by quantitative polymerase chain reaction. Using logistic regression, we investigated the determinants of carriage and aimed to find correlations with clinical outcome. RESULTS: Nasopharyngeal colonisation with S. pneumoniae, H. influenzae and M. catarrhalis was highly prevalent and strongly dependent on age and season. Females were less likely to be colonised with S. pneumoniae (OR 0.71, p = 0.022, 95% CI 0.53–0.95) and M. catarrhalis (OR 0.73, p = 0.044, 95% CI 0.54–0.99) than males. Colonisation rates were highest in the age groups < 1 year and 1–2 years of age and declined with increasing age. Colonisation also declined towards the end of the rainy season and rose again during the beginning of the dry season. K. pneumoniae prevalence was low and not significantly correlated with age or season. For S. pneumoniae and H. influenzae, we found a positive association between nasopharyngeal carriage and clinical pneumonia [OR 1.75, p = 0.008, 95% CI 1.16–2.63 (S. pneumoniae) and OR 1.90, p = 0.004, 95% CI 1.23–2.92 (H. influenzae)]. S. aureus carriage was correlated with mortality (OR 4.01, p < 0.001, 95% CI 2.06–7.83), independent of bacteraemia caused by this bacterium. CONCLUSIONS: Age, sex and season are important determinants of nasopharyngeal colonisation with S. pneumoniae, H. influenzae and M. catarrhalis in patients with fever in Burkina Faso. S. pneumoniae and H. influenzae carriage is associated with clinical pneumonia and S. aureus carriage is associated with mortality in patients with fever. These findings may help to understand the dynamics of colonisation and the associated transmission of these pathogens. Furthermore, understanding the determinants of nasopharyngeal colonisation and the association with disease could potentially improve the diagnosis of febrile patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-021-06996-7