Multi-component meningococcal serogroup B (MenB)-4C vaccine induces effective opsonophagocytic killing in children with a complement deficiency

Vaccination against meningococcal serogroup B is recommended for patients with a complement deficiency; however, although immunogenicity in this patient group has been shown, efficacy has not yet been established. In this study, we collected serum from children with a complement deficiency in the alternative pathway or in late terminal pathway before and after vaccination with multi‐component meningococcal serogroup B (MenB)‐4C. MenB‐4C is a multi‐component, protein‐based vaccine against MenB consisting of factor H‐binding protein, Neisserial heparin‐binding protein, Neisserial adhesion A and outer membrane vesicles containing Porin A. We assessed the vaccine immunogenicity and vaccine‐mediated protection by a whole cell enzyme‐linked immunosorbent assay with Neisseria meningitidis serogroup B strains H44/76, 5/99 and NZ98/254, which shows that vaccination induced antibody titers against meningococcus. We show that the classical serum bactericidal activity assay with exogenous serum indicates the presence of vaccine‐induced antibodies and capacity to activate complement‐mediated pathogen lysis. However, in children with a late terminal pathway deficiency, no complement‐mediated pathogen lysis was observed when autologous serum was applied in the serum bactericidal activity assay, demonstrating a lack of serum bactericidal activity in children with complement deficiencies. However, MenB‐4C vaccination still induced effective complement‐dependent opsonophagocytic killing against N. meningitidis serogroup B in reconstituted whole blood with autologous serum from children with an alternative pathway or late terminal pathway deficiency. These findings support the recommendation to vaccinate all complement‐deficient children against MenB.

Bacteremia in Childhood Life-Threatening Infections in Urban Gambia: EUCLIDS in West Africa

Background

The limited availability of microbiology services in sub-Saharan Africa impedes accurate diagnosis of bacterial pathogens and understanding of trends in prevalence and antibiotic sensitivities. We aimed to characterize bacteremia among hospitalized children in The Gambia and to identify factors associated with bacteremia and mortality.

Methods

We prospectively studied children presenting with suspected severe infection to 2 urban hospitals in The Gambia, between January 2013 and September 2015. Demographic and anthropometric data, clinical features, management, and blood culture results were documented. Urine screens for antibiotic activity were performed in a subset of participants.

Results

Of 411 children enrolled (median age, 29 months; interquartile range, 11–82), 79.5% (325 of 409) reported prehospital antibiotic use. Antimicrobial activity by urinary screen for antibiotic activity was detected in 70.8% (n = 80 of 113). Sixty-six bacterial pathogens were identified in 65 (15.8%) participants and Staphylococcus aureus predominated. Gram-positive organisms were more commonly identified than Gram-negative (P < .01). Antibiotic resistance against first-line antimicrobials (ampicillin and gentamicin) was common among Gram-negative bacteria (39%; range, 25%–100%). Factors significantly associated with bacteremia included the following: gender, hydration status, musculoskeletal examination findings, admission to the Medical Research Council The Gambia at London School of Hygiene & Tropical Medicine hospital, and meeting sepsis criteria. Those associated with increased mortality were presence of a comorbidity, clinical pallor, tachypnea, and altered consciousness. Tachycardia was associated with reduced mortality.

Conclusions

The bacteremia rate in children with suspected childhood life-threatening infectious diseases in The Gambia is high. The pattern of pathogen prevalence and antimicrobial resistance has changed over time compared with previous studies illustrating the importance of robust bacterial surveillance programs in resource-limited settings.

Virological and Social Outcomes of HIV-Infected Adolescents and Young Adults in The Netherlands Before and After Transition to Adult Care

BACKGROUND

As a result of effective combination antiretroviral therapy (cART) and advanced supportive healthcare, a growing number of human immunodeficiency virus (HIV)-infected children survive into adulthood. The period of transition to adult care is often associated with impaired adherence to treatment and discontinuity of care. We aimed to evaluate virological and social outcomes of HIV-infected adolescents and young adults (AYAs) before and after transition, and explore which factors are associated with virological failure.

METHODS

We included 59 HIV-infected AYAs from the Netherlands who had entered into pediatric care and transitioned from pediatric to adult healthcare. We used HIV RNA load and cART data from the Dutch Stichting HIV Monitoring database (1996-2014), and collected social and treatment data from patients' medical records from all Dutch pediatric HIV treatment centers and 14 Dutch adult treatment centers involved. We evaluated risk factors for virological failure (VF) in a logistic regression model adjusted for repeated measurements.

RESULTS

HIV VF occurred frequently during the study period (14%-36%). During the transition period (from 18 to 19 years of age) there was a significant increase in VF compared with the reference group of children aged 12-13 years (odds ratio, 4.26 [95% confidence interval, 1.12-16.28]; P = .03). Characteristics significantly associated with VF were low educational attainment and lack of autonomy regarding medication adherence at transition.

CONCLUSIONS

HIV-infected AYAs are vulnerable to VF, especially during the transition period. Identification of HIV-infected adolescents at high risk for VF might help to improve treatment success in this group.

Central line bloodstream infections can be reduced in newborn infants using the modified Seldinger technique and care bundles of preventative measures

AIM

There has been no evidence to show whether care bundles of preventive measures reduce central line-associated bloodstream infection (CLABSI) in peripherally inserted central catheters using the modified Seldinger technique, which requires more specific skills than the traditional technique. The aim of this study was to address that gap in our knowledge and to determine whether other variables influenced the outcome.

METHODS

This prospective observational study was conducted on a neonatal intensive care unit. We observed the incidence of CLABSI in 45 newborn infants with peripheral catheters before the introduction of bundles of preventative measures and 88 infants after the introduction.

RESULTS

Laboratory-confirmed CLABSI decreased after the introduction of the bundles, from 12.9 per 1000 days to 4.7/1000 days (p = 0.09). When we combined the rates for laboratory-confirmed CLABSI and clinical CLABSI in a survival analysis, the incidence reduced significantly after introduction of the bundles (p = 0.02). There were no other variables that affected the outcome.

CONCLUSION

Cost-effective care bundles reduced CLABSI in peripherally inserted central catheters using the modified Seldinger technique, despite the specific insertion skills that were required. The bundles of preventative measures may increase healthcare professionals' awareness of the need to care for central catheters and reduce CLABSI infections.

Antibody neutralization of vascular endothelial growth factor (VEGF) fails to attenuate vascular permeability and brain edema in experimental pneumococcal meningitis

To determine the contribution of vascular endothelial growth factor (VEGF) to cerebral edema formation in bacterial meningitis, we used a VEGF neutralizing antibody to block VEGF in rabbits, following induction of meningitis by intracisternal inoculation with 10(9) heat-killed pneumococci. At 8 h, cerebrospinal fluid (CSF) VEGF was significantly elevated in infected untreated animals, and correlated with CSF white blood cell (WBC) count (r=0.56, P=0.004), and brain water content (r=0.42, P=0.04). Blocking of VEGF did not attenuate brain edema, blood-brain barrier disruption, or CSF pleocytosis. The functional role of VEGF in the pathophysiology of BM remains elusive.

Reprogramming the host response in bacterial meningitis: how best to improve outcome?

Despite effective antibiotic therapy, bacterial meningitis is still associated with high morbidity and mortality in both children and adults. Animal studies have shown that the host inflammatory response induced by bacterial products in the subarachnoid space is associated with central nervous system injury. Thus, attenuation of inflammation early in the disease process might improve the outcome. The feasibility of such an approach is demonstrated by the reduction in neurologic sequelae achieved with adjuvant dexamethasone therapy. Increased understanding of the pathways of inflammation and neuronal damage has suggested rational new targets to modulate the host response in bacterial meningitis, but prediction of which agents would be optimal has been difficult. This review compares the future promise of benefit from the use of diverse adjuvant agents. It appears unlikely that inhibition of a single proinflammatory mediator will prove useful in clinical practice, but several avenues to reprogram a wider array of mediators simultaneously are encouraging. Particularly promising are efforts to adjust combinations of cytokines, to inhibit neuronal apoptosis and to enhance brain repair.

[Fatal pneumonia in an adolescent due to community-acquired methicillin-resistant Staphylococcus aureus positive for Panton-Valentine-leukocidin]

A 15-year-old girl developed a severe Staphylococcus aureus pneumonia following an influenza virus infection. The patient was admitted to a paediatric intensive-care facility because of respiratory and circulatory failure. Despite aggressive therapy, she died on the third day following admission to the intensive care unit due to secondary hypoxic-ischaemic encephalopathy. Blood and respiratory aspirate cultures showed community-acquired methicillin-resistant S. aureus (CA-MRSA) with a normal antibiotic sensitivity except for betalactam antibiotics. PCR-based methods demonstrated that the isolate possessed the Panton-Valentine-leukocidin (PVL) gene, encoding an S. aureus exotoxin that is associated with fulminant necrotising pneumonia. This case shows that clinicians in the Netherlands should also be aware of the possibility of CA-MRSA in patients without risk factors for MRSA carriage. Especially in children and adolescents with an influenza virus infection, pneumonia due to PVL-positive S. aureus strains may be life-threatening.

Bilateral sequential facial palsy during chickenpox

Facial palsy is a rare neurological complication of chickenpox. A 5-year-old girl exhibited a right facial palsy followed by the appearance of the characteristic chicken pox exanthem. Subsequently she suffered a left facial palsy. In this patient both pathophysiological mechanisms responsible and their relation to the phase of infection are illustrated.

CONCLUSION

Facial palsy as a complication of chickenpox can result from pre-eruptive haematogenous or neurogenous spread of varicella-zoster virus.

Adherence of Streptococcus pneumoniae to immobilized fibronectin

Adherence to extracellular matrix proteins, such as fibronectin, affords pathogens with a mechanism to invade injured epithelia. Streptococcus pneumoniae was found to adhere to immobilized fibronectin more avidly than other streptococci and staphylococci do. Binding was dose, time, and temperature dependent. Trypsin treatment of the bacteria resulted in decreased binding, suggesting that the bacterial adhesive component was a protein. Fragments of fibronectin generated by proteolysis or by expression of recombinant gene segments were compared for the ability to bind pneumococci and to compete against bacterial binding to immobilized fibronectin. Fragments from the carboxy-terminal heparin binding domain were consistently active, suggesting that this region contains the pneumococcal binding site, a region distinct from that supporting the attachment of most other bacteria.

Peptide from a prokaryotic adhesin blocks leukocyte migration in vitro and in vivo

The integrin CD11b/CD18 promotes leukocyte extravasation during inflammation. Filamentous hemagglutinin (FHA) of Bordetella pertussis binds to CD11b/CD18, raising the possibility that peptides derived from FHA might inhibit leukocyte migration. The Arg-Gly-Asp (RGD) sequence of FHA has been suggested to modulate binding of ligands to CD11b/CD18. Peptides derived from this region inhibited adherence and transendothelial migration of neutrophils in vitro and prevented recruitment of leukocytes into the cerebrospinal fluid in an experimental model of meningitis in rabbits. The mechanism of the antiinflammatory effect may involve modulation of the activity of CD11b/CD18 through peptide interaction with the leukocyte response integrin/integrin-associated protein complex.

Inhibition of leukocyte-endothelial cell interactions and inflammation by peptides from a bacterial adhesin which mimic coagulation factor X

Factor X (factor ten) of the coagulation cascade binds to the integrin CD11b/CD18 during inflammation, initiating procoagulant activity on the surface of leukocytes (Altieri, D.C., O.R. Etingin, D.S. Fair, T.K. Brunk, J.E. Geltosky, D.P. Hajjar, and T. S. Edgington. 1991. Science [Wash.DC]. 254:1200-1202). Filamentous hemagglutinin (FHA), an adhesin of Bordetella pertussis also binds to the CD11b/CD18 integrin (Relman D., E. Tuomanen, S. Falkow, D.T. Golenbock, K. Saukkonen, and S.D. Wright. 1990. Cell. 61:1375-1382). FHA and the CD11b/CD18 binding loops of Factor X share amino acid sequence similarity. FHA peptides similar to Factor X binding loops inhibited 125I-Factor X binding to human neutrophils and prolonged clotting time. In addition, ETKEVDG and its Factor X analogue prevented transendothelial migration of leukocytes in vitro and reduced leukocytosis and blood brain barrier disruption in vivo. Interference with leukocyte migration by a coagulation-based peptide suggests a novel strategy for antiinflammatory therapy.