Application of Metagenomics Next-Generation Sequencing on Diagnosis of Disseminated Infection Caused by Rhizomucor pusillus in an Acute Lymphoblastic Leukemia Patient

Background: Rhizomucor pusillus is one of the major pathogens in mucormycosis. Infection due to R. pusillus is rare and has a high mortality rate, especially disseminated mucormycosis infections. Rapid and accurate pathogen identification is important for the development of targeted antifungal therapies. Case Presentation: We presented a case of disseminated R. pusillus infection, identified through metagenomics next-generation sequencing (mNGS), in a 4-year-old patient with acute lymphoblastic leukemia. On days 22, 23, and 28, R. pusillus was detected in bronchoalveolar lavage fluid, blood, and hydrothorax, respectively, through mNGS. The patient developed lung, pleural, and blood disseminated lesions caused by R. pusillus infection. Subsequently, the patient was treated with antifungal therapy, including posaconazole, amphotericin B, and isacconazole, with supportive treatment. However, with the continuous deterioration of symptoms, the patient's family decided to give up treatment. The patient eventually died of multiple-organ failure on day 34. Conclusion: mNGS facilitates prompt diagnosis of disseminated R. pusillus infections. The successful application of mNGS provided a new perspective for the clinician, underscoring the technique's potential for rapid diagnostic etiology. mNGS has the capability to identify pathogens at the species level, which is a significant asset in guiding clinical medication decisions.