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A key element in the effective care
of immunocompromised patients with fever and infection is hypervigilance.
Not only are these patients at increased risk from a diverse range
of microorganisms, but also their resulting infections can present
with subtle or atypical symptoms and can progress to difficult-to-treat
chronic disease states, or to acute life-threatening clinical decompensations.
Given these facts, empiric anti-infective therapy is sometimes justified
before the definitive cause of a fever is elucidated. Yet, the same
facts also argue for the vital importance of making an accurate
and exact diagnosis, to guide definitive ongoing therapy.
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Toward this end, the general features of a thoughtful diagnostic
approach to fevers in immunocompetent patients remains valid for
immunocompromised patients, including a systematic consideration
of noninfectious diagnoses (see Chapter 228).
Likewise, a thorough exposure history remains essential and is expanded
to include microorganisms traditionally considered to be “environmental” or
of “low virulence.”
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Published guidelines for the use of antimicrobial agents in certain
sets of immunocompromised patients outline contemporary standards of
care and can provide useful algorithms to help improve outcomes
for these patients (for clinical practice guidelines, refer to www.idsociety.org/Content.aspx?id=9088).
However, a key first principle of such guidelines should be the
importance of frequent reevaluation of an immunocompromised patient’s
course and care, given his or her extreme medical vulnerability.
Furthermore, optimal care may require input from a physician with
expertise in treating immunocompromised patients infected with microorganisms
that are often difficult to treat, such as fungi or mycobacteria.
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Defined defects in particular immunologic functions (see Chapters 187 and 188) correspond with
increased patient risk for specific infections (Table
229-1). These immune defect–specific risks offer basic
principles and insights to influence diagnostic workup and empiric
therapy for children known to have a particular type of immunocompromise.
Conversely, certain infectious disease presentations provide clues
to trigger and guide an evaluation to first diagnose specific immune
defects in children.
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