Dan Li,1,* Qing Liu,2,* Xiaotong Xi,2 Zhen Huang,1 Chi Zhu,2 Ran Ding,2 Qi Zhang1 

1Department of Respiratory, Xuzhou Central Hospital, Xuzhou, Jiangsu, People’s Republic of China; 2Jiangsu Simcere Diagnostics Co., Ltd., Nanjing Simcere Medical Laboratory Science Co., Ltd., The State Key Laboratory of Neurology and Oncology Drug Development, Nanjing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Qi Zhang, Department of Respiratory, Xuzhou Central Hospital, Xuzhou, Jiangsu, People’s Republic of China, Email zhangqi1107@126.com

Purpose: Despite the increasing recognition of nocardiosis, there are still few reported cases of infections caused by Nocardia otitidiscaviarum (N. otitidiscaviarum). This particular strain is categorized as an opportunistic pathogen that predominantly affects individuals with compromised immune systems while seldom infecting immunocompetent individuals. The conventional diagnostic techniques for nocardiosis present difficulties due to their restricted effectiveness.
Case Description: We report on a case study of a 67-year-old male patient who was admitted to the hospital with a respiratory infection caused by N. otitidiscaviarum. Imaging and laboratory tests indicated lung infection, while conventional pathogenetic tests yielded negative results. Furthermore, bronchoalveolar lavage fluid (BALF) was subjected to nanopore sequencing (NS), which identified N. otitidiscaviarum infection after 4h of sequencing. Based on the combined findings from NS results and clinical symptoms, a diagnosis of pulmonary nocardiosis was established. The patient’s symptoms and signs showed improvement following treatment with imipenem cilastatin, linezolid and SMZ/TMP.
Conclusion: This case presents a pulmonary infection caused by N. otitidiscaviarum in an immunocompetent patient, where the pathogen was identified within 4 hours through NS. This rapid and accurate diagnostic approach offers significant advantages for the timely diagnosis of pulmonary nocardiosis.

Keywords: nanopore sequencing, Nocardia otitidiscaviarum, pulmonary nocardiosis, immunocompetent patients, case report