What are the most common infections in children in primary care and their treatment options?

Most Common Infections in Children in Primary Care

Respiratory tract infections (particularly upper respiratory infections including otitis media, pharyngitis, and sinusitis) and urinary tract infections are the most common infections seen in children in primary care, with acute otitis media being the single most frequent reason parents bring children to the primary care physician's office. 1

Respiratory Tract Infections

Upper Respiratory Tract Infections

Acute otitis media (AOM) is the most common infection requiring primary care visits in children. 1, 2

• The primary bacterial pathogens causing AOM are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. 3, 4
• First-line treatment is amoxicillin for uncomplicated cases. 1, 2
• If treatment failure occurs within 48-72 hours, switch to ceftriaxone or amoxicillin-clavulanate. 2
• Observation without immediate antibiotics may be considered for selected uncomplicated cases in children older than 2 years when adequate follow-up is ensured. 2

Acute pharyngitis is another common upper respiratory infection in children. 5, 2

• Group A Streptococcus (Streptococcus pyogenes) is the most common bacterial cause requiring antibiotic treatment. 3, 4
• Clinical criteria alone cannot distinguish bacterial from viral pharyngitis—microbiological confirmation via throat culture or rapid antigen detection test is required before prescribing antibiotics. 2
• Amoxicillin or amoxicillin-clavulanate remains first-line treatment for confirmed streptococcal pharyngitis. 2

Acute rhinosinusitis (ARS) shares similar pathogenesis and microbiology with otitis media. 3

• Diagnosis requires persistence of purulent nasal or post-nasal drainage lasting at least 10 days. 2
• Amoxicillin is first-choice for mild ARS; if symptoms persist or worsen, use amoxicillin-clavulanate, cefpodoxime proxetil, or ceftriaxone. 2

Lower Respiratory Tract Infections

Community-acquired pneumonia is a significant cause of morbidity, with cough being the second most common reason for emergency department visits. 6

• Viruses are the most common causative agents in younger children, while Streptococcus pneumoniae is the most common bacterial cause across all pediatric age groups. 7
• Mixed viral-bacterial infections occur in 8-40% of cases. 7
• In older children (>3 years), when bacterial causes are identified, S. pneumoniae predominates, followed by Mycoplasma pneumoniae and Chlamydia pneumoniae. 6, 7

Treatment approach for pneumonia is age-dependent:

• For children <3 years: Amoxicillin 80-100 mg/kg/day in three divided doses is the reference treatment for pneumococcal pneumonia. 6
• For children >3 years: If clinical and radiological findings suggest pneumococcal infection, use amoxicillin; if atypical bacteria (M. pneumoniae or C. pneumoniae) are suspected, macrolides are reasonable first-line. 6
• Treatment duration: 10 days for pneumococcal pneumonia (beta-lactam) and at least 14 days for atypical pneumonia (macrolide). 6
• Reassess after 48-72 hours; if amoxicillin fails, consider macrolide monotherapy for atypical bacteria. 6

Acute bronchiolitis in young children typically does not require antibiotic therapy due to low risk of invasive bacterial infection. 6

• Antibiotics (amoxicillin-clavulanate, cefuroxime-axetil, or cefpodoxime-proxetil) are only indicated if fever ≥38.5°C persists >3 days, purulent acute otitis media is present, or pneumonia/atelectasis is confirmed on chest X-ray. 6

Urinary Tract Infections

UTIs are the most common serious bacterial infection in febrile infants and young children, particularly in the post-vaccine era. 6

• UTI prevalence in children aged 2 months to 2 years with fever of unknown source is 5-7%, with higher rates (up to 20%) in uncircumcised male infants. 6
• In the current era, UTI has replaced occult bacteremia as the most common serious bacterial infection, accounting for 92% of occult infections in febrile infants <24 months. 6
• Escherichia coli is the leading cause, responsible for 87.4% of UTIs, 60% of bacteremia, and 43.7% of bacterial meningitis in this age group. 6
• Girls <1 year have a UTI prevalence of 6.5%; uncircumcised males have significantly higher rates than circumcised males. 7

Gastroenteritis

Acute gastroenteritis is a frequent cause of outpatient visits and hospitalizations. 6

• Norovirus is the leading pathogen overall (58% of cases), while Salmonella enterica subspecies is second (11% of cases). 6
• In children <5 years, norovirus has become the most common pathogen since rotavirus vaccine introduction, causing nearly 1 million ambulatory care visits and 14,000 hospitalizations annually. 6
• The most common bacterial pathogens in young children are Salmonella enterica subspecies (42%), Campylobacter (28%), Shigella (21%), Yersinia (5%), and E. coli O157 (3%). 6
• Most acute diarrhea episodes are viral or of unknown etiology, self-limited, and do not warrant laboratory investigation or antibiotic treatment. 6

Important Clinical Caveats

Common pitfalls to avoid:

• Do not prescribe antibiotics for viral pharyngitis—always confirm Group A streptococcal infection before treatment. 2
• Most respiratory infections in children are viral and self-limited; indiscriminate antibiotic use drives resistance. 5, 4
• In febrile infants <24 months without obvious source, always consider UTI as it is now the most common serious bacterial infection. 6
• Antibiotic resistance is increasing in respiratory pathogens, particularly penicillin resistance in S. pneumoniae and beta-lactamase production in H. influenzae. 4