A 10-week-old female presented to the emergency department of a community hospital in Alberta, Canada, with a 5-day history of increased work of breathing, cough, nasal congestion and poor feeding. She was the firstborn of twins conceived through in vitro fertilization (IVF), born at 30-weeks gestation by emergency caesarean section following premature rupture of membranes and suspected chorioamnionitis. The birth weight was 1350 g. Complications in the neonatal period included respiratory distress that required continuous positive airway pressure for 24 hours, apnea of prematurity, hyperbilirubinemia and slow growth. A chest radiograph on day 1 of life showed minor atelectasis in the perihilar regions bilaterally, with otherwise normal lung and pleural spaces. She was discharged from the neonatal nursery at 32 days of age but remained symptomatic with cough and nasal congestion in the subsequent weeks. A chest radiograph performed on day 50 of life showed coarse interstitial markings, cystic lucencies and confluent opacification in the upper lobes. These findings were attributed to chronic gastroesophageal reflux and aspiration, and she was treated as an outpatient with oral antibiotics (amoxicillin–clavulanate).
At presentation on day 72 of life, the patient had mild respiratory distress, with a temperature of 37.2°C, respiratory rate of 64 breaths/minute, heart rate of 160 beats/ minute, blood pressure of 68/32 mmHg and oxygen saturation of 93% in room air. Her weight was 2.64 kg. Physical examination was remarkable for bilateral chest retractions, decreased air entry to the lung apices without wheeze or crackles and a normal cardiac examination. The chest radiograph showed areas of consolidation bilaterally. Complete blood count revealed a hemoglobin count of 108 g/L, platelet count of 525 × 109/L and leukocyte count of 17.7 × 109/L (57% neutrophils, 30% lymphocytes, 10% monocytes, 1% eosinophils and 2% basophils). Glucose was 5.6 mmol/L. Electrolytes were sodium, 135 mmol/L; potassium, 5 mmol/L; chloride, 99 mmol/L and total carbon dioxide, 24 mmol/L. Creatinine was 13 μmol/L, and urea was 3.6 mmol/L.
Aspiration pneumonia was suspected, and she was treated with intravenous ampicillin and cefotaxime. She was transferred to a tertiary care facility on day 73 of life, where her clinical condition gradually deteriorated. Ten days later, she required intubation and admission to the pediatric intensive care unit (PICU). Despite conventional ventilatory support, she remained hypoxemic, necessitating escalation to high-frequency oscillation and then extracorporal membrane oxygenation the day after PICU admission. She was decannulated 6 days later but remained on conventional ventilatory support because of increasing bilateral chest radiographic consolidations and difficulties in weaning ventilation. Methicillin-susceptible Staphylococcus aureus was isolated from endotracheal secretions. A blood culture drawn on the day of admission grew Neisseria mucosa but subsequent cultures of blood were repeatedly negative. Antimicrobial therapy in the PICU consisted of piperacillin–tazobactam and azithromycin. Nasopharyngeal swab specimens were negative for influenza A and B, parainfluenza, respiratory syncytial virus, human coronavirus, enterovirus, rhinovirus, human metapneumovirus and adenovirus by direct fluorescent antibody and/or nucleic acid amplification tests. A diagnostic test was performed.
The authors thank Dr. Michelle Noga for assistance in preparing the radiographic images.