Initial clinical presentation may be non-specific (especially in younger age groups).
Given the time-critical nature of severe sepsis and septic shock, when sepsis is suspected on clinical grounds it is usually best to initiate sepsis investigations and treatment, including fluid resuscitation, and to continue until sepsis has been excluded.
Progression to organ failure and shock is often very rapid, so early recognition and treatment is crucial.
Apart from antibiotics, there are currently no specific therapies of proven value. Other treatment after antibiotics is supportive, and should be delivered according to internationally recognised consensus-based guidelines.
Sepsis is a clinical syndrome resulting from a dysregulated immune response to infection.  It is characterised by derangements in multiple pathobiological processes, which may lead to widespread tissue injury.  It encompasses a clinical spectrum of severity, including septic shock and multi-organ failure.  Sepsis is a leading cause of morbidity and mortality in children worldwide. 
The international consensus definitions for sepsis and septic shock in adults were revised in 2016.  According to the revised definitions, sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. The revised definition of sepsis replaces the previous definition of sepsis as the presence of systemic inflammatory response syndrome (SIRS) in the presence of suspected or proven infection. 
Septic shock has been redefined as a subset of sepsis in which underlying circulatory and cellular metabolism abnormalities are profound enough to substantially increase mortality.
The revised definitions of sepsis and septic shock in adults take into account an improved understanding of the pathobiology and epidemiology of sepsis. New clinical criteria by which sepsis and septic shock can be identified in adults are also recommended in the revised definition.
At present there are no revisions to the international consensus definition of paediatric sepsis, which dates from 2005. 
In 2016, the National Institute of Health and Care Excellence (NICE) published guidance on the recognition, diagnosis and early management of sepsis for all age groups, which highlighted that the international consensus definitions of sepsis have limited use in the early identification of people at risk of sepsis.  The NICE guidelines proposed a move away from using the SIRS and sequential organ failure assessment (SOFA) criteria recommended by the international consensus definitions, instead proposing a risk stratification approach to identify early those patients (including children and neonates) at low risk, moderate to high risk, or high risk of severe illness and death from sepsis based on patient history, behaviour, appearance, and clinical evaluations (e.g., respiratory, circulation, hydration, and temperature).
Consultant Paediatric Intensivist
University Hospitals of Leicester NHS Trust
JT is an author involved in the Paediatric Sepsis 6 initiative, cited in this monograph.
Dr Jeremy Tong would like to gratefully acknowledge Dr Adrian Plunkett, a previous contributor to this monograph. AP is an author involved in the Paediatric Sepsis 6 initiative, cited in this monograph.
Professor of Paediatric Immunology & Infectious Diseases
Director, NIHR Wellcome Trust Clinical Research Facility
University of Southampton
SNF declares that he has no competing interests.
Texas Children's Hospital and Baylor College of Medicine
MP declares that he has no competing interests.
Faculty, Pediatric Critical Care Medicine
Seattle Children's Hospital
University of Washington School of Medicine
JJZ receives research grant support from NIH/NICHD and ImmuneXpress; travel reimbursement from the Society of Critical Care Medicine to attend board meetings; and royalties from Elsevier for action as a co-editor for the textbook Pediatric Critical Care.
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