Differential Diagnosis for the 4-week-old Male Neonate
- Single Most Likely Diagnosis
- Chlamydia trachomatis pneumonia: This is the most likely diagnosis given the neonate's history of conjunctivitis at 1 week of age, which is a common presentation of chlamydial infection in neonates. The lack of prenatal care and the mother's refusal of vaccinations increase the risk of undiagnosed and untreated chlamydial infection. The clinical presentation of a worsening cough without fever, bilateral rales, and the chest radiograph findings of hyperinflation with scant bilateral interstitial infiltrates are consistent with chlamydial pneumonia.
- Other Likely Diagnoses
- Respiratory syncytial virus (RSV) infection: Although the neonate does not have a fever, RSV infection can present with cough and bilateral interstitial infiltrates on chest radiograph. However, the lack of nasal congestion and the specific history of conjunctivitis at 1 week of age make chlamydial infection more likely.
- Influenza: The mother's refusal of vaccinations increases the risk of influenza exposure, but the lack of fever and the specific radiographic findings make this diagnosis less likely.
- Do Not Miss Diagnoses
- Congenital pneumonia due to group B streptococcus or other bacteria: Although the neonate does not have a fever, congenital pneumonia can present with cough and respiratory distress. It is essential to consider this diagnosis due to the potential for severe consequences if missed.
- Pertussis: The mother's refusal of vaccinations increases the risk of pertussis exposure. Although the neonate is young, pertussis can present with severe cough and respiratory distress, making it a critical diagnosis not to miss.
- Rare Diagnoses
- Cytomegalovirus (CMV) pneumonia: CMV infection can present with respiratory symptoms and bilateral interstitial infiltrates on chest radiograph. However, the lack of other systemic symptoms and the specific history of conjunctivitis at 1 week of age make this diagnosis less likely.
- Tuberculosis: Although the mother's lack of prenatal care and vaccination history increases the risk of undiagnosed infections, tuberculosis is a rare diagnosis in neonates, and the clinical presentation and radiographic findings are not typical for this age group.