Challenge of Cupriavidus gilardii infection in an immunocompromised child: a case report.

Background: Cupriavidus gilardii is a multidrug-resistant (MDR) pathogen found in soil and water. Human infection is extremely rare, with only two pediatric cases reported to date, and its clinical features and the antimicrobial strategies remain unclear. The pathogen's MDR nature often poses a therapeutic challenge. This case provides valuable clinical evidence regarding the management of C. gilardii infection in immunocompromised pediatric patients. Case Description: A 4-year-old boy with acute lymphoblastic leukemia developed severe immunosuppression after reinduction cyclophosphamide, cytarabine (Ara-C), mercaptopurine (CAM) chemotherapy according to the SCCCG-ALL-2023 protocol. The patient initially presented with recurrent fever, septic shock, and progressive respiratory distress. Despite an aggressive empirical antibiotic regimen including meropenem, imipenem, piperacillin-tazobactam, linezolid, and levofloxacin, his condition continued to worsen. Blood cultures and metagenomic next-generation sequencing (mNGS) subsequently confirmed C. gilardii infection. Based on susceptibility testing, therapy was adjusted to a combination of ceftazidime-avibactam (CAZ-AVI) and tigecycline. After this adjustment, the patient showed marked clinical improvement, with decreased inflammatory indicators and nearly completed clearance of the pathogen. Unfortunately, on hospital day 26, he developed sudden massive hemoptysis due to Aspergillus pulmonary artery invasion and died despite emergency treatment. Conclusions: This case demonstrates that CAZ-AVI may offer effective antimicrobial control for C. gilardii infection in immunocompromised pediatric patients. Although the patient succumbed to secondary fungal complications, successful microbiological control demonstrates that CAZ-AVI may serve as a potential salvage therapy for rare MDR Gram-negative bacteria and provides clinical insight into the management of uncommon pediatric infections.