PB1749 A CASE OF DIAGNOSIS OF BLOODSTREAM INFECTION OF M. MICROPHYLLA IN PATIENTS WITH HEMATOLOGIC MALIGNANCIES BY USING NGS
Authors: Song K. , tang B. , zhu X. , liu H. , sun Z. 
Published: June 2019

Background:

Rhizomucor pusillus Schipper is a very rare and serious opportunistic infection with very high mortality. Accurate and rapid pathogenic diagnosis is critical for early antifungal therapy and prognosis. At present, the second‐generation sequencing technology (NGS) can overcome the shortcomings of traditional methods, such as long time‐consuming and low sensitivity, and can directly detect pathogens of infectious diseases, and reports on the diagnosis of clinical infectious diseases are gradually increasing. We used NGS to detect mixed infections of Rhizopus oryzae and Candida tropicalis in the blood of a patient with refractory acute myeloid leukemia (NR), which played a key role in the successful treatment of fungal infection in patients.

Aims:

Second‐generation sequencing technology can be used as a complementary means of pathogen detection for sterile sites.

Methods:

The patient took the whole blood sample for NGS test 13 days after the operation, and extracted the fungal DNA primer sequence according to the kit requirements (reagent brand) as ITS1(F): 5’‐TCCGTAGGTGAACCTGCGG‐3 ’and ITS4(R): 5’ ‐ TCCTCCGCTTATTGATATGC‐3’. The sequence was sequenced with an illumina sequencer, and the sequence was compared with the existing sequence in GenBank. The sequence number of Rhizomucor pusillus was 1330 and the number of Candida tropicalis was 2265.

Results:

We reported that this patient quickly determined the mixed disseminated infection of Rhizomucor pneumoniae and Candida tropicalis using NGS on 13 days after transplantation. Using amphotericin B antifungal treatment, the whole body lesions quickly subsided after 24 hours. However, for elderly patients with refractory leukemia, especially those with basic diseases, cord blood transplantation provides a new choice, and the risk of transplantation is still huge. Even if the implantation is successful, the infection‐related complications and the infection before the immune function directly affect the prognosis.. The primary disease of this patient is malignant hematological disease, low immune function, and diabetes, and other basic diseases, which are in line with the high risk factors of mucor infection. During the treatment, the fungal hyphae were microscopically examined. The blood culture was Candida tropicalis infection. The invasive fungal infection was diagnosed clearly, but the treatment effect was not good. The possibility of combining two fungal infections was neglected, and the second generation sequencing technology was adopted. The application was carried out, and finally the neglected infection of M. oxysporum was found. After switching to liposomal amphotericin B in time, it quickly became effective. The blood flow and skin temperature were controlled within 24 hours.

Summary/Conclusion:

The high incidence of opportunistic infections in patients after allogeneic hematopoietic stem cell transplantation is essential for early detection of pathogens. Due to the presence of blood‐borne disseminated infection in patients with hematopoietic stem cell transplantation, the mortality rate is high and needs to be identified and treated as early as possible. Second‐generation sequencing technology can be used as a complementary means of pathogen detection for sterile sites.