Case Report: Washed microbiota transplantation for the treatment of malnutrition with multidrug-resistant Klebsiella pneumoniae and Candida tropicalis coinfection in a child

Background: and fungal coinfection in children with severe malnutrition are difficult to control with antibiotics alone. This report describes an 8-year-old boy whose pulmonary infection remained uncontrolled and whose nutritional status progressively deteriorated. Washed microbiota transplantation (WMT) was introduced as part of a multimodal salvage treatment strategy, after which the patient showed gradual improvement during continued antimicrobial therapy, respiratory support, and nutritional rehabilitation. Case presentation: . Despite broad-spectrum antimicrobial therapy, respiratory support, bronchoscopy/bronchoalveolar lavage, and enteral nutrition through a nasojejunal tube, infection control remained poor and nutritional status continued to deteriorate, complicated by sepsis and antibiotic-associated diarrhea. In this context, WMT was introduced through a nasojejunal tube as part of a multimodal salvage treatment strategy and was administered in two treatment courses. Thereafter, during continued antimicrobial treatment, respiratory support, and nutritional rehabilitation, the patient showed progressive clinical improvement, with subsequent negative sputum culture results, gradual radiographic resolution of pulmonary inflammation, weight gain from 14.0 to 22.5 kg, and marked functional recovery. Conclusion: This case suggests that, in severely malnourished children with refractory multidrug-resistant pulmonary bacterial and fungal infections, WMT may have potential adjunctive value as part of comprehensive management. However, because multiple interventions were implemented concurrently and no pre- and post-WMT microbiome sequencing was performed, the observed clinical improvement could not be attributed exclusively to WMT. Therefore, this case should be interpreted only as an exploratory clinical observation rather than confirmatory evidence, and future prospective studies under strict ethical oversight need to be conducted.