Residency · Residency · Family Medicine

Pediatric Fever and Common Infections

Overview

Fever is the most common reason for pediatric emergency and urgent care visits. Family physicians must apply age-stratified approaches to febrile illness, identify serious bacterial infections, and manage common infections such as otitis media, pharyngitis, and upper respiratory infections with evidence-based antibiotic stewardship principles.

Fever: Definitions and Physiology

Fever is defined as a temperature of 38.0 degrees Celsius (100.4 degrees Fahrenheit) or above measured rectally. Rectal temperature is the gold standard in infants under 3 months. Temporal artery, tympanic, and axillary measurements are acceptable for older children but are less precise. Fever is a normal immune response, and the height of fever alone does not predict the severity of illness. Antipyretics improve comfort but do not prevent febrile seizures.

Age-Stratified Approach to Febrile Infants

Neonates (0-28 Days)

All febrile neonates are considered high risk regardless of clinical appearance. A full sepsis workup is required, including CBC, blood culture, urinalysis with culture, and lumbar puncture with CSF analysis and culture. Admission for empiric IV antibiotics with ampicillin plus gentamicin or ampicillin plus cefotaxime is standard. HSV testing with PCR from CSF and blood along with empiric acyclovir should be considered if risk factors are present, including maternal HSV, vesicles, seizures, or elevated liver function tests. Clinical appearance should not be relied upon to exclude serious infection, as neonates may appear well despite having a serious bacterial infection.

Young Infants (29-60 Days)

Risk stratification using validated criteria guides management in this age group. The AAP 2021 Clinical Practice Guideline for well-appearing febrile infants aged 8 to 60 days incorporates inflammatory markers such as procalcitonin, CRP, and ANC to stratify risk. Low-risk infants have a normal urinalysis, inflammatory markers below established thresholds, and appear well; they may be managed with close outpatient follow-up if the family is reliable and follow-up within 24 hours is arranged. Blood and urine cultures are sent, and lumbar puncture may be deferred in select low-risk infants aged 29 to 60 days. Infants not meeting low-risk criteria should be admitted for IV antibiotics pending cultures. Urinary tract infection is the most common serious bacterial infection in this age group, with a prevalence of 7 to 9%.

Infants 61-90 Days

Similar risk stratification applies, though the overall risk of serious bacterial infection is lower than in younger infants. UTI remains the most common serious bacterial infection. Lumbar puncture is generally not required if the infant is low risk by inflammatory markers and clinical appearance. Outpatient management is reasonable for low-risk infants with reliable follow-up.

Children 3 Months to 36 Months

The focus shifts to clinical appearance and identifiable sources of fever. A well-appearing child with an identifiable viral source needs only supportive care. An ill-appearing child or one without an identifiable source warrants urinalysis (especially in uncircumcised males under 12 months and females under 24 months) and consideration of CBC and blood culture. The risk of occult bacteremia has been greatly reduced in the era of PCV and Hib vaccines.

Children Over 36 Months

Evaluation focuses on clinical assessment and identifiable sources of infection, with laboratory testing guided by clinical findings.

Fever Without Source

Fever without an identifiable source is common in children under 36 months. Most cases (up to 90%) are viral. Evaluation must exclude UTI, occult bacteremia, occult pneumonia, and meningitis. Observation with close follow-up is appropriate for well-appearing, fully vaccinated children.

Febrile Seizures

Simple febrile seizures are generalized, last less than 15 minutes, involve a single episode in 24 hours, and occur in children aged 6 months to 5 years. Complex febrile seizures are focal, last more than 15 minutes, recur within 24 hours, or are followed by post-ictal Todd paralysis. Simple febrile seizures are benign, carry no increased risk of epilepsy, and require no treatment or workup beyond fever source evaluation. Complex febrile seizures warrant consideration of EEG and neurology referral, with lumbar puncture if meningitis is suspected. Parental reassurance is essential, as the recurrence risk is approximately 30%.

Acute Otitis Media (AOM)

Diagnosis

Diagnosing AOM requires all three of the following: acute onset of symptoms, middle ear effusion (bulging tympanic membrane, decreased mobility, or air-fluid level), and middle ear inflammation (erythema or otalgia). A bulging tympanic membrane is the most reliable finding. Erythema alone is insufficient because it can result from crying or fever. AOM must be distinguished from otitis media with effusion, which involves effusion without acute inflammation and does not require antibiotics.

Management

The observation option, with watchful waiting for 48 to 72 hours and provision of a safety-net prescription, is appropriate for children aged 6 months and older with unilateral AOM without severe symptoms or otorrhea, and for children aged 24 months and older with bilateral AOM without severe symptoms. Reliable follow-up is required, with parents instructed to fill the prescription if symptoms worsen. Immediate antibiotics are indicated for children under 6 months (always), severe symptoms (moderate to severe otalgia, otalgia lasting 48 hours or more, fever of 39 degrees Celsius or above), bilateral AOM in children aged 6 to 23 months, AOM with otorrhea, and recurrent AOM (3 or more episodes in 6 months or 4 or more in 12 months). First-line treatment is amoxicillin at 80 to 90 mg/kg/day divided twice daily for 10 days in children under 2 or 5 to 7 days in children 2 and older. If amoxicillin fails with no improvement in 48 to 72 hours, amoxicillin-clavulanate at 90 mg/kg/day is used. For penicillin allergy, options include cefdinir, cefuroxime, or ceftriaxone IM as a single dose or 3-day course. Second-line failure warrants tympanocentesis or ceftriaxone IM for 3 days.

Prevention

Preventive strategies include pneumococcal and influenza vaccination, breastfeeding (which is protective), avoiding bottle propping and secondhand smoke, and tympanostomy tubes for recurrent AOM (3 or more episodes in 6 months or 4 or more in 12 months with middle ear effusion).

Acute Pharyngitis

Diagnosis

Group A Streptococcus is the primary concern, accounting for 15 to 30% of pharyngitis in children aged 5 to 15 years and less than 5% in children under 3. The McIsaac/Modified Centor Score assigns points for fever above 38 degrees Celsius, absence of cough, tonsillar swelling or exudate, tender anterior cervical lymphadenopathy, and age (age 3 to 14 earns 1 point, age 15 to 44 earns 0, age 45 and above subtracts 1). A score of 2 to 3 warrants a rapid strep test, a score of 4 or above may justify empiric treatment while awaiting culture, and a score of 0 to 1 requires neither testing nor treatment.

Testing

Rapid antigen detection tests have high specificity (approximately 95%) and sensitivity of 70 to 90%. If the RADT is negative in a child, a confirmatory throat culture should be obtained due to the higher sensitivity of culture. In adults, culture is not required after a negative RADT because of lower GAS prevalence and lower rheumatic fever risk. Children under 3 should not be tested unless special circumstances exist, such as close GAS contact or high community prevalence. Test of cure after treatment is not indicated (except with a history of rheumatic fever), and asymptomatic carriers should not be tested or treated.

Treatment (If GAS Confirmed)

First-line treatment is penicillin V at 250 mg two to three times daily (or 500 mg twice daily for children 27 kg and above) for 10 days, or amoxicillin at 50 mg/kg once daily (maximum 1000 mg) for 10 days. For penicillin allergy, alternatives include cephalexin (if no anaphylaxis history), azithromycin, or clindamycin. Symptom relief includes acetaminophen, ibuprofen, and warm salt-water gargles. The child may return to school after 12 to 24 hours of antibiotics and once afebrile. The goals of treatment are prevention of rheumatic fever, reduction of suppurative complications (peritonsillar abscess), shortened symptom duration, and reduced transmission.

Complications

Suppurative complications include peritonsillar abscess (presenting with "hot potato voice," uvula deviation, and trismus), retropharyngeal abscess, and cervical lymphadenitis. Non-suppurative complications include rheumatic fever (prevented by antibiotics started within 9 days of symptom onset) and post-streptococcal glomerulonephritis (which is not prevented by antibiotics).

Upper Respiratory Infection (Common Cold)

The common cold has a viral etiology, with rhinovirus being the most common cause, and antibiotics are never indicated. Duration is typically 7 to 10 days, with residual cough potentially persisting 2 to 3 weeks. Supportive care includes nasal saline, honey (for children 1 year and older) for cough, and adequate hydration. Over-the-counter cough and cold medications should be avoided in children under 6 because they lack efficacy and carry potential for harm. Families should be educated about the viral illness course.

Acute Bacterial Sinusitis

Bacterial sinusitis is diagnosed clinically when URI symptoms persist 10 days or more without improvement, when severe onset occurs with fever of 39 degrees Celsius or above plus purulent discharge for 3 or more consecutive days, or when worsening after initial improvement ("double sickening") occurs. Most sinusitis in children is viral, with only approximately 6 to 7% of URIs leading to bacterial sinusitis. First-line treatment is amoxicillin-clavulanate at 45 mg/kg/day for 10 to 14 days, as amoxicillin alone is less effective due to beta-lactamase-producing organisms. Imaging is not indicated for uncomplicated acute sinusitis.

Croup (Laryngotracheobronchitis)

Croup is the most common cause of acute stridor in children aged 6 months to 3 years, with parainfluenza virus as the most common etiology. It presents with a barking cough, inspiratory stridor, and hoarse voice, typically worse at night. The Westley Croup Score classifies severity. Mild croup is treated with a single dose of dexamethasone at 0.6 mg/kg orally (or 0.15 mg/kg for mild cases) with observation. Moderate to severe croup requires dexamethasone plus nebulized racemic epinephrine, with observation for 3 to 4 hours after epinephrine to monitor for rebound stridor. A single dose of dexamethasone reduces symptoms, return visits, and hospital admissions. Red flags including drooling, toxic appearance, and high fever should prompt consideration of epiglottitis or bacterial tracheitis.

Bronchiolitis

Bronchiolitis is the most common lower respiratory infection in infants under 12 months, peaking between 2 and 6 months of age. RSV is the most common cause. It is a clinical diagnosis based on rhinorrhea, cough, tachypnea, wheezing, crackles, and increased work of breathing. Management is entirely supportive and includes nasal suctioning, maintaining hydration through small frequent feeds with nasogastric or IV fluids if oral intake is not tolerated, supplemental oxygen if oxygen saturation is consistently below 90%, and high-flow nasal cannula for moderate to severe respiratory distress. Bronchodilators (albuterol), systemic steroids, antibiotics, chest physiotherapy, and routine chest X-ray are not recommended. Palivizumab (Synagis) provides RSV prophylaxis for high-risk infants including those born before 29 weeks, those with chronic lung disease, and those with hemodynamically significant heart disease, administered monthly during RSV season. Nirsevimab (Beyfortus) is a single-dose monoclonal antibody for RSV prevention in all infants under 8 months entering RSV season, approved in 2023.

<image>An age-stratified algorithm for evaluating the febrile infant showing the workup and disposition pathway for neonates (0-28 days, always admit with full sepsis workup), young infants (29-60 days, risk-stratified using inflammatory markers and clinical appearance), and older infants (61 days to 36 months, source-directed evaluation), with decision points for LP, empiric antibiotics, and safe outpatient management.</image>

<image>A diagnostic comparison of acute otitis media versus otitis media with effusion showing tympanic membrane appearance (bulging, erythematous, decreased mobility in AOM versus retracted or neutral, amber fluid, air-fluid level in OME), clinical features, and management differences emphasizing that OME does not require antibiotics.</image>

<image>A clinical decision pathway for pediatric pharyngitis showing McIsaac score calculation, testing strategy (RADT with culture backup for scores 2-3, empiric treatment for score 4+, no testing for scores 0-1), first-line and alternative antibiotic choices, and management of complications including peritonsillar abscess warning signs.</image>

Clinical Pearls

In neonates aged 0 to 28 days, all febrile infants require a full sepsis workup and empiric IV antibiotics regardless of clinical appearance; a well-appearing neonate should not provide false reassurance. The most reliable finding for diagnosing AOM is a bulging tympanic membrane; erythema alone is insufficient and commonly results from crying. Observation with watchful waiting for AOM is appropriate and guideline-endorsed for children 6 months and older with unilateral non-severe AOM, and this strategy reduces unnecessary antibiotic use by approximately 60%. Antibiotics should not be prescribed for bronchiolitis, viral URI, or non-specific cough; families should be educated that most respiratory infections are viral and self-limited. Over-the-counter cough and cold medications should be avoided in children under 6 because of lack of efficacy and potential for serious adverse effects. A single dose of oral dexamethasone is the cornerstone of croup management and benefits even mild cases. For GAS pharyngitis, amoxicillin once daily for 10 days is equivalent to divided dosing and improves adherence. Honey for children 1 year and older has better evidence for nocturnal cough relief than most over-the-counter cough suppressants. Nirsevimab is now recommended for all infants under 8 months entering their first RSV season, representing a paradigm shift from targeted prophylaxis to universal prevention.

References

• Pantell RH et al. AAP Clinical Practice Guideline: Evaluation and Management of Well-Appearing Febrile Infants 8-60 Days Old. Pediatrics. 2021
• Lieberthal AS et al. AAP Clinical Practice Guideline: Diagnosis and Management of AOM. Pediatrics. 2013
• Shulman ST et al. IDSA Clinical Practice Guideline for GAS Pharyngitis. Clin Infect Dis. 2012
• Ralston SL et al. AAP Clinical Practice Guideline: Bronchiolitis. Pediatrics. 2014 (affirmed 2023)
• Gates A et al. Interventions for Acute Pharyngitis in Children. Cochrane Database Syst Rev. 2023

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