Please reduce the following text to 450 words or less without significant changes in content. Case presentation
A 5-year-old boy presented with a 4-day history of fever and respiratory distress. His medical history revealed severe neonatal asphyxia and gastroesophageal reflux, which were treated with Nissen fundoplication. His current medications included triclofos sodium, eperisone hydrochloride, and phenobarbital, and a vaccination history of PCV13 (administered four times). On admission, his body temperature (36.3 °C), heart rate (134 beats/min), respiratory rate (50 breaths/min), SpO2 (88%; ambient air), blood pressure (82/62 mmHg), and Glasgow coma scale (E1V1M1) were measured. Physical examination revealed retractive breathing of the suprasternal fossa and subcostal arch with large respiratory secretions, seesaw breathing, rhonchi, and peripheral cyanosis in the upper and lower extremities (capillary refill time of > 3 s). On admission, the blood test results showed leukopenia (white blood cell count 1200/μL) and elevated C-reactive protein 9.82 mg/dL (Table 1). Chest radiography revealed bilateral infiltration in the middle lung field.
After admission, intensive care management was initiated, with the use of mechanical ventilation and vasoactive agents. P. aeruginosa was detected in previous sputum cultures, and intravenous cefepime (CFPM; 100 mg/kg/day) was initiated. Lumbar puncture was not performed due to unstable circulation. Four sets of blood cultures were collected. Gram-positive diplococcus was detected in three blood culture sets taken on admission (day 1). Intravenous vancomycin (45 mg/kg/day) was therefore administered. Based on the susceptibility test results, the treatment was switched to ampicillin (200 mg/kg/day; day 3). The final blood culture results revealed S. pneumoniae serotype 35 B. On day 4, his fever resolved and his general condition and laboratory results improved. On day 7, the patient developed fever again, and on day 8 his sputum culture was positive for P. aeruginosa (Table 2). The antibacterial agent was replaced with CFPM; however, his condition did not improve. Contrast-enhanced chest computed tomography (CT) was performed (day 11), which revealed a cavitary lesion in the right upper lobe with infiltration and bilateral air bronchograms in each lobe (Figure 2 a, b). A. fumigatus grew (day 11) from sputum cultures obtained on day 8 (Figure 3). Therefore, treatment with voriconazole was initiated. P. aeruginosa was clinically decided to be a carrier alone because CFPM did not improve the symptoms, and the treatment was switched to sulbactam/ampicillin. Bronchoalveolar lavage was performed (day 12), and tests for Aspergillus antigens and bacteria and fungi cultures were negative. After a trend of improvement, clinical symptoms and laboratory findings stabilized. Contrast-enhanced chest CT displayed fluid formation in a cavitary lesion in the right lung with surrounding inflammation (day 20), leading to the diagnosis of a lung abscess (Figure 2 c, d). Surgical intervention was planned; however, a large amount of bloody and purulent sputum appeared (day 21), suggesting fistula formation between the abscess cavity and bronchus. After bronchoscopy, Gram staining of an abscess cavity specimen revealed a high count of P. aeruginosa (day 23); therefore, the antimicrobial agent was changed to CFPM. On day 27, chest CT showed that the abscess had shrunk but persisted, and antimicrobial therapy was continued. The clinical symptoms and laboratory findings normalized on day 30. It was difficult to extubate the patient because of long-term intubation management, and a tracheostomy was performed on day 33. On day 52, chest CT showed that the fluid level formation of the cavitary lesion had disappeared, and the surrounding infiltrate had improved. On day 53, the treatment was switched to oral ciprofloxacin (30 mg/kg/day) and voriconazole (12 mg/kg/day). Contrast-enhanced chest CT (day 79) showed a reduction in the cavity lesion with a small amount of fluid retention (Figure 2 e, f). The patient was discharged without home oxygen therapy (day 84). One month after discharge, immunodeficiency screening revealed no abnormalities. Outpatient contrast-enhanced chest CT displayed that the cavitary lesion in the right upper lobe had almost disappeared, and antimicrobial therapy was completed after 18 weeks.