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Antibacterial therapy in infants and children presents many unique challenges not faced in other clinical specialties. A major problem is the paucity of pediatric data regarding efficacy, pharmacokinetics, and optimal dosages; pediatric recommendations are therefore often extrapolated from studies in adults. Age-appropriate antibiotic dosing and toxicities must also be considered, taking into account the developmental status and physiology of children. The clinician must consider important differences among various age groups with respect to the pathogenic bacterial species responsible for pediatric infections. Specific antibiotic therapy is optimally driven by a microbiologic diagnosis, predicated on isolation of the pathogenic organism from a normally sterile body site, and supported by antimicrobial susceptibility testing. Given the inherent difficulties that can arise in collecting specimens from pediatric patients and given the increased risk of serious bacterial infection in young infants, much of pediatric infectious diseases practice is based on clinical diagnosis with empirical use of antibacterial agents before or even without eventual identification of the specific pathogen.
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Several key considerations must be incorporated in decisions about the appropriate empirical use of antibacterial agents in infants and children. Recommendations for therapy often are dictated by the clinical syndrome and/or anatomic site of infection and the age of the child (Table 241-1). This information affects the choice of antimicrobial agent(s) and also the dose, dosing interval, route of administration (oral vs parenteral), and degree of urgency. The vaccination history may reflect reduced risk for some invasive infections but not necessarily elimination of risk of them. The risk of serious bacterial infection in pediatrics is also affected by the child’s immunologic status, which may be compromised by immaturity (neonates), underlying disease (immunodeficiency), or treatment of underlying diseases with chemotherapy (malignancy) or immune modulators (rheumatologic disease). Infections in immunocompromised children often result from bacteria that are not considered pathogenic in immunocompetent children. The possibility of central nervous system (CNS) involvement must be considered in pediatric patients, because some bacteremic infections in childhood carry a significant risk for hematogenous spread to the CNS including Haemophilus influenzae type b, pneumococcus, and meningococcus.
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