Antibiotics 101

Etiology & Treatment of Bacterial Infections in Children

Antibiotics 101

PreambleKeys to Prudent Antibiotic UseSpecific Recommendations

Keys to Prudent Antibiotic Use

Recognize the probable site of infectionKnow the usual pathogensKnow local pathogen sensitivitiesUnderstand drug kinetics Anticipate drug adverse effectsLimit your personal formulary

Specific InfectionsPharyngitisOtitis Media & SinusitisPneumoniaSepticemiaMeningitisCellulitis Bone & Joint InfectionsUrinary Tract InfectionsNeonatal Infections

Penicillin V 50 mg/kg/day; Q 6-8 hours

Benzathine Penicillin25,000 U/kg

Cephalexin50 mg/kg/day; Q 6-8 hours

Clindamycin30 mg/kg/day; Q 6 hours

Therapy of GAS Pharyngitis

Etiology of Acute Otitis Media

Streptococcus pneumoniae Nontypeable Haemophilus influenzae Moraxella catarrhalis

Spontaneous Bacteriologic Resolution of Acute Otitis Media

Pathogen % Resolved Day 5

MCAT 75%Haemophilus 50%Pneumococcus 16%

Categories of S. pneumoniae

Susceptible to penicillin ........... ≤ 0.06 ug/mlIntermediate to penicillin ........... 0.1-1.0 ug/mlResistant to penicillin ............ ≥ 2.0 ug/ml

Prevalence of “Beta-Lactam Challenged” Pneumococci

National average 51%

< 6 years of age 60%

DCC attendance 65%

Recent Antibiotic Rx 65%

Some US populations 80%

Oral Antibiotics vs. Penicillin-intermediate S. pneumoniae

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Bacteriologic Failure Rates in Acute Otitis Media

Antibiotic Haemophilus Pneumococcus

Amoxicillin 28% 5%Augmentin 22% 6%Cefaclor 38% 18%Cefuroxime 15% 8%Cefprozil 53% 8%Cefixime 3% 32%Azithromycin 80% 6%Placebo 25-50% 75-85%

Recommended Antibiotic Therapy of Acute Otitis Media

First Line Amoxicillin (80-90 mg/kg/day; Q 8-12 hours)

Second Line Augmentin (80-90 mg/kg/day; Q 8-12 hours)

Cefuroxime (30 mg/kg/day; Q 12 hours)

CDC Working Group on DRSP-AOM, 1998

Individualizing Therapy of Acute Otitis Media

5 days of therapy

Older childSummer monthsOtitis-free (or poor) pastMild episodePrompt improvement

10 days of therapy

Younger childWinter monthsOtitis-rich pastSevere episodeSlow improvement

The diagnosis of acute bacterial sinusitis should be based on clinical criteria in children who present with upper respiratory symptoms that are either persistent or severe.

Suspect Acute Bacterial SinusitisPersistent Symptoms

10 – 30 daysNasal discharge (any quality)Daytime cough (worse at night)Fever (variable)Headache & facial pain (variable)

Severe Symptoms Temperature > 39o

Purulent nasal discharge, 3-4 days

Etiology of Acute Sinusitis

Streptococcus pneumoniae Nontypable Haemophilus influenzae Moraxella catarrhalis

Therapy of Acute Sinusitis

Amoxicillin 45-90 mg/kg/day

Alternatives: cefuroxime, cefpodoxime, cefdinir, clarithromycin, azithromycin

Etiology of Pneumonia

Majority of cases are viralIf non-viral, etiology depends on age of patientIn neonate, consider causes of sepsisIn infant, also consider Staphylococcus aureusIn toddler *, consider Pneumococcus and HaemophilusIn school aged child, consider Mycoplasma

* If incompletely vaccinated

Determinants of Therapy of Pneumonia

Age of hostLaboratory investigationsSeverity of infection

Etiology of Septicemia

Neisseria meningitidisStreptococcus pneumoniae *Haemophilus influenzae type b *Staphylococcus aureus, if adolescent

* if incompletely vaccinated

Therapy of Septicemia

Cefotaxime150 mg/kg/day; Q 6 hours

if adolescent, Nafcillin

150 mg/kg/day; Q 6 hours

Etiology of Bacterial Meningitis

Neisseria meningitidisStreptococcus pneumoniae *Haemophilus influenzae type b *

* if incompletely vaccinated

Cefotaxime200 mg/kg/day; Q6 hours

Ceftriaxone100 mg/kg/day; Q12 hours

Vancomycin ± rifampin60 mg/kg/day; Q 6 hours20 mg/kg/day; Q12 hours

Therapy of Bacterial Meningitis

Etiology of Cellulitis

Streptococcus pyogenes Staphylococcus aureus

Therapy of Cellulitis

Nafcillin150 mg/kg/day; Q 6 hours

Penicillin100,000 Units/kg/day; Q 6 hours

± Clindamycin40 mg/kg/day; Q 6 hours

Etiology of Acute Hematogenous Osteomyelitis

Staphylococcus aureusHaemophilus influenzae *

* If incompletely vaccinated

Nafcillin150 mg/kg/day; Q 6 hours In young, “incompletely” vaccinated,

Cefuroxime150 mg/kg/day; Q 8 hours

Therapy of Acute Hematogenous Osteomyelitis

Etiology of Septic Arthritis

Staphylococcus aureusNeiserria meningitidisStreptococcus pneumoniae *Haemophilus influenzae type b *

* If “incompletely” vaccinated

Cefuroxime150 mg/kg/day; Q 8 hours

Therapy of Septic Arthritis

Etiology of Urinary Tract Infections

EnterobacteriaceaeGroup D streptococci

Sulfisoxazole150 mg/kg/day; Q 6 hours

If pyelonephritis:Ampicillin150 mg/kg/day; Q 6 hoursGentamicin6 mg/kg/day; Q 8 hours

Treatment of Urinary Tract Infections

Etiology of Early Onset Neonatal Sepsis

Group B streptococci Escherichia coli, et al. Listeria monocytogenes

Ampicillin50-200 mg/kg/day; Q 6-12 hours

Gentamicin2.5-7.5 mg/kg/day; Q 8-24 hours

Dose varies according to weight, gestational age, chronologic age, & site of infection

Therapy of Early Onset Neonatal Sepsis

Coagulase negative staphylococci Nosocomial enteric organisms Group B streptococci Listeria monocytogenes

Etiology of Late Onset Neonatal Sepsis

Vancomycin15-30 mg/kg/day; Q 8≥24 hours

Cefotaxime100-150 mg/kg/day; Q 8-12 hours

Dose varies according to weight, gestational age, chronologic age, & site of infection

Therapy of Late Onset Neonatal Sepsis