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

Hematologic Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference

CONTEXT

Studies of organ dysfunction in children are limited by a lack of consensus around organ dysfunction criteria.

OBJECTIVES

To derive evidence-informed, consensus-based criteria for hematologic dysfunction in critically ill children.

DATA SOURCES

Data sources included PubMed and Embase from January 1992 to January 2020.

STUDY SELECTION

Studies were included if they evaluated assessment/scoring tools to screen for hematologic dysfunction and assessed outcomes of mortality, functional status, organ-specific outcomes, or other patient-centered outcomes. Studies of adults or premature infants, animal studies, reviews/commentaries, small case series, and non-English language studies with inability to determine eligibility were excluded.

DATA EXTRACTION

Data were abstracted from each eligible study into a standard data extraction form along with risk of bias assessment.

RESULTS

Twenty-nine studies were included. The systematic review supports the following criteria for hematologic dysfunction: thrombocytopenia (platelet count <100000 cells/µL in patients without hematologic or oncologic diagnosis, platelet count <30000 cells/µL in patients with hematologic or oncologic diagnoses, or platelet count decreased ≥50% from baseline; or leukocyte count <3000 cells/µL; or hemoglobin concentration between 5 and 7 g/dL (nonsevere) or <5 g/dL (severe).

LIMITATIONS

Most studies evaluated pre-specified thresholds of cytopenias. No studies addressed associations between the etiology or progression of cytopenias overtime with outcomes, and no studies evaluated cellular function.

CONCLUSIONS

Hematologic dysfunction, as defined by cytopenia, is a risk factor for poor outcome in critically ill children, although specific threshold values associated with increased mortality are poorly defined by the current literature.

Prognostic markers of meningococcal disease in children: recent advances and future challenges

Meningococcal disease is a life-threatening condition and a major cause of bacterial meningitis and sepsis worldwide. In many fatal cases, meningococcal disease is rapidly progressive and death occurs within hours of the initial symptoms. The early identification of patients at high risk of death would be useful in order to provide aggressive and more personalized clinical management with the proper level of supportive therapy required, contributing to an improvement in the survival rate and reduction in sequelae. The current study aims to review the current published literature about prognostic markers of meningococcal sepsis in children in order to elaborate conclusions and recommendations that could guide clinical practice and further research.

Pathogenic Neisseria hitchhike on the uropod of human neutrophils

Polymorphonuclear neutrophils (PMNs) are important components of the human innate immune system and are rapidly recruited at the site of bacterial infection. Despite the effective phagocytic activity of PMNs, Neisseria gonorrhoeae infections are characterized by high survival within PMNs. We reveal a novel type IV pilus-mediated adherence of pathogenic Neisseria to the uropod (the rear) of polarized PMNs. The direct pilus-uropod interaction was visualized by scanning electron microscopy and total internal reflection fluorescence (TIRF) microscopy. We showed that N. meningitidis adhesion to the PMN uropod depended on both pilus-associated proteins PilC1 and PilC2, while N. gonorrhoeae adhesion did not. Bacterial adhesion elicited accumulation of the complement regulator CD46, but not I-domain-containing integrins, beneath the adherent bacterial microcolony. Electrographs and live-cell imaging of PMNs suggested that bacterial adherence to the uropod is followed by internalization into PMNs via the uropod. We also present data showing that pathogenic Neisseria can hitchhike on PMNs to hide from their phagocytic activity as well as to facilitate the spread of the pathogen through the epithelial cell layer.