Misdiagnosed tuberculosis being corrected as Nocardia farcinica infection by metagenomic sequencing: a case report

Lei Pan,Xiao-Bo Ji,Cai-Hong Wang,Xiao-Qing Huang,Min-Jie Mao,Jun-Ke Qiu,Yang Zhou,Xiao-Hong Pan,Jie-Kun Xu

doi:10.1186/s12879-021-06436-6

Abstract

BackgroundDisseminated nocardiosis is liable to be misdiagnosed owing to the non-specific clinical manifestations and laboratory/imaging findings. Metagenomic next-generation sequencing (mNGS) is a culture-independent and rapid method for direct identification of all microorganisms in clinical specimens.Case presentationA 72-year-old man was admitted to our hospital on February 20, 2019 with a history of recurrent cough, expectoration, fever, and diarrhea since 1 month, and unconsciousness since 1 week. Contrast-enhanced magnetic resonance imaging of head showed multiple lesions in the bilateral cerebral hemispheres, brainstem, and cerebellar hemispheres. The presumptive diagnosis was disseminated tuberculosis, although all tests for mycobacterium were negative. However, the patient did not benefit from antituberculosis treatment. Repeat MRI showed multiple abnormal signals in the brain and progression of meningeal thickening. Cerebrospinal fluid and bronchoalveolar lavage fluid specimens were subsequently sent for PMSeq metagenomics sequencing; the results indicated Nocardia. farcinica as the predominant pathogen. The anti-TB treatment was stopped and the patient was prescribed sulphamethoxazole in combination with linezolid and meropenem for nocardiosis. He showed gradual neurological improvement and was transferred to Huashan Hospital. He was discharged from the hospital on April 19, 2019, but died of persistent diarrhea on May 26, 2019.ConclusionsPatients with suspected nocardiosis do not always respond to conventional treatment; therefore, mNGS can facilitate diagnosis and timely treatment decision-making.

Highlights

Disseminated nocardiosis is liable to be misdiagnosed owing to the non-specific clinical manifestations and laboratory/imaging findings
The genus Nocardia includes at least 50 species, approximately half of which are pathogenic to humans or animals [1]
Owing to the non-specific clinical manifestations, Nocardia infection is liable to be misdiagnosed as tuberculosis, fungal pulmonary disease, or lung malignancy [16]

Summary

Introduction

Disseminated nocardiosis is liable to be misdiagnosed owing to the non-specific clinical manifestations and laboratory/imaging findings. The diagnosis of Nocardia infection is based on pathogen culture and biochemical identification [17]. Metagenomic next-generation sequencing (mNGS) is a culture-independent method that allows identification of all microorganisms in environmental or clinical samples by high-throughput sequencing and genomics analysis of total DNA [18,19,20].

Results

Conclusion