A novel method to screen genomic libraries that combines genomic immunization with the prime-boost strategy.

We employed a prime-boost regimen in combination with the expression library immunization protocol to improve the protective effectiveness of a genomic library used as immunogen. To demonstrate the feasibility of this novel strategy, we used as a prime a serogroup B Neisseria meningitidis random genomic library constructed in a eukaryotic expression vector. Mice immunized with different fractions of this library and boosted with a single dose of meningococcal outer membrane vesicles elicited higher bactericidal antibody titers compared with mice primed with the empty vector. After the boost, passive administration of sera from mice primed with two of these fractions significantly reduced the number of viable bacteria in the blood of infant rats challenged with live N. meningitidis. The method proposed could be applied to the identification of subimmunogenic antigens during vaccine candidate screening by employing expression library immunization.

The product of platelet and neutrophil counts (PN product) at presentation as a predictor of outcome in children with meningococcal disease.

BACKGROUND: Despite improvement in the treatment of Neisseria meningitidis infection, meningococcal diseases (MD) are still an important cause of morbidity and mortality around the world. This study assessed the performance of the product of platelet and neutrophil counts (PN product) at the time of presentation to hospital as a predictor of outcome in children with MD. METHODS: Retrospective evaluation of children with clinical MD admitted to two paediatric intensive care units in Brazil. RESULTS: Seventy-two children aged 2-156 months were studied. Overall mortality was 19.7%. The PN product, the Glasgow Meningococcal Septicaemia Prognostic Score and the Paediatric Risk of Mortality score discriminated between survivors and non-survivors. A PN < or = 113 had a sensitivity of 28.6% (95% CI 8.6-58.1), specificity of 96.6% (95% CI 88.1-99.5) and positive and negative predictive values of 66.7% and 84.8%. The area under the receiver operating characteristic curve was 0.85 (95% CI 0.74-0.92). CONCLUSION: The PN product had a lower performance than reported in previous studies from a developed country. The PN product, however, is a good indicator of mortality in MD but needs to be validated for the population to which it is being applied.

[Studying the levels of endotoxemia in meningococcal sepsis. Its relations to pregnancy and antibiotic treatment]. / Estudio de los niveles de endotoxemia en las sepsis meningococias. Su relación con la gravedad del proceso y el tratamiento antibiótico.

The most frequent cause of toxic shock in our area is meningococcal sepsis. It is currently assumed that endotoxin produce by this bacteria, a lipopolysaccharide with toxic properties, is able to trigger shock and DIC by stimulating both arachidonic acid pathways, among other actions. Previous studies in our laboratory demonstrated significant differences (p +/- 0.001) in the amounts of endotoxins released in vitro by strains from patients and healthy carriers and statistically related criteria of severity with mortality in 256 patients in our center over the last 10 years. In the present study we attempted to establish whether plasma levels of endotoxin were correlated with the severity of the disease. We studied 32 patients with meningococcal sepsis, dividing the subjects into two groups: those in whom six or more criteria of severity were present, and those in whom less than six criteria were found. Blood levels of endotoxin were determined upon admission and after the administration of antibiotics (penicillin and chloramphenicol) using the limulus test with a chromogenic substrate (Coatest, Endotoxin, Kabivitrum, Sweden). Levels of endotoxins were significantly higher in patients with more than six criteria of severity both upon admission (0.6 +/- 0.03) ng/ml) and 4 h. afterward (0.74 +/- 0.006 ng/ml) in comparison to children in whom the clinical picture was less serious (0.27 +/- 0.18 ng/ml and 0.27 +/- 0.18 ng/ml and 0.27 +/- 0.16 ng/ml7 t = 5.8 y t = 5.6 respectively. Endotoxin levels were highest in patients presenting shock, disseminated intravascular coagulation in the hypocoagulability phase and more than 8 criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinación de cortisol plasmático en pacientes con enfermedad meningocóccica / Determination of plasma cortisol in patients with meningococcal disease

Se estudiaron 20 niños de tres meses a 14 años de edad, con diagnóstico confirmado de enfermedad meningocóccica (ocho pacientes con meningococemia y 12 con meningoencefalitis meningocóccica), incluyendo tres fallecidos. A todos se les determinó el nivel de cortisol en sangre antes de recibir tratamiento alguno, mediante el método de radioinmunoensayo. Ningún paciente presento una cifra inferior a la normal. Un niño tuvo cifras normales y el resto las presentó elevadas. No existió relación estadísticamente significativa entre las cifras basales de cortisol, la forma clínica, ni la presencia de shock. La función adrenal un mes más tarde no estaba normalizada pues algunos pacientes mantuvieron cifras basales altas. Estos resultados concuerdan con el criterio de que no hay insuficiencia suprarrenal en estos pacientes durante la fase aguda

Myocardial dysfunction in children with acute meningococcemia.

Acute meningococcemia is frequently associated with cardiovascular collapse of uncertain cause. Review of the records of 12 consecutive children revealed clinical evidence of myocardial dysfunction in six (50%). Subsequently myocardial function was prospectively assessed clinically and echocardiographically in 12 children. Seven (58%) of the 12 children had echocardiographic evidence of myocardial dysfunction as defined by a depressed left ventricular shortening fraction (LVSF). The mean LVSF in these seven children was 0.25 +/- 0.03, as compared with the mean LVSF of 0.39 +/- 0.7 in the remaining children. The LVSF estimate of myocardial function strongly correlated with cardiac output as measured by standard thermodilution (r = 0.98, P less than 0.01). Acute meningococcemia was not fatal in those children without evidence of myocardial dysfunction. In contrast, three of the seven children with evidence of myocardial dysfunction died. In four children, echocardiographic evidence of left ventricular dysfunction preceded cardiovascular collapse and clinical recognition of myocardial dysfunction. In children with an initially low LVSF, recovery of LVSF was associated with survival. Children with acute meningococcemia may have impaired myocardial function as indicated by depressed LVSF, resulting in low cardiac output despite normal intravascular volume. Thus, in addition to restoring intravascular volume, knowledge of the status of myocardial function may help direct therapy toward optimizing myocardial contractility.