Computed tomography diagnosis of pulmonary nocardiosis: A case report of a rare disease

Qiuyuan Yang; Ping Zhang; Xiaona Zhou; Xiao Chen; Haijun He; Zheng Miao; Zhengliang Li; Feng Zhang; Wenshuai Duan; Tengfei Ke; Bin Yang

doi:10.4103/RID.RID_13_21

CASE REPORT

Year : 2022 | Volume : 9 | Issue : 1 | Page : 31-33

Computed tomography diagnosis of pulmonary nocardiosis: A case report of a rare disease

Qiuyuan Yang¹, Ping Zhang², Xiaona Zhou¹, Xiao Chen¹, Haijun He¹, Zheng Miao³, Zhengliang Li⁴, Feng Zhang⁴, Wenshuai Duan⁴, Tengfei Ke⁵, Bin Yang⁶
¹ Department of Clinical Medicine, Dali University, Dali, China
² Department of Respiration, First Affiliated Hospital of Dali University, Dali, China
³ Department of Neurosurgery, First Affiliated Hospital of Dali University, Dali, China
⁴ Department of Medical Imaging, First Affiliated Hospital of Dali University, Dali, China
⁵ Department of Medical Imaging, Yunnan Cancer Hospital, Kunming, Yunnan, China
⁶ Medical Imaging Center, The First Hospital of Kunming, Kunming, Yunnan, China

Date of Submission	21-Oct-2021
Date of Acceptance	06-Feb-2022
Date of Web Publication	13-Oct-2022

Correspondence Address:
Bin Yang
Medical Iimaging Center,The First Hospital of Kunming, Kunming, Yunnan
China
Tengfei Ke
Department of Medical Imaging, Yunnan Cancer Hospital, Kunming, Yunnan
China
Wenshuai Duan
Department of Medical Imaging, First Affiliated Hospital of Dali University, Dali, Yunnan
China

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/RID.RID_13_21

Abstract

Nocardiosis, which is caused by the Nocardia bacterium, is an acute, subacute, or chronic purulent infection that mostly affects the lungs. The vast majority of these infections occur in people with impaired immune function. These infections are characterized by multiple areas of inflammation in both lungs. The initial examination of choice is chest computed tomography (CT), which can play an important role in early diagnosis and evaluation of the treatment's effectiveness. Since the disease is rare and lacks specific clinical manifestations, it is easily misdiagnosed or missed altogether, often resulting in poor patient outcomes, including death. Therefore, early diagnosis and evaluation of the effects of treatment by chest CT are essential to controlling disease progression and improving the prognosis.

Keywords: Computed tomography, imaging diagnosis, lung Nocardia, tomography

How to cite this article:
Yang Q, Zhang P, Zhou X, Chen X, He H, Miao Z, Li Z, Zhang F, Duan W, Ke T, Yang B. Computed tomography diagnosis of pulmonary nocardiosis: A case report of a rare disease. Radiol Infect Dis 2022;9:31-3

How to cite this URL:
Yang Q, Zhang P, Zhou X, Chen X, He H, Miao Z, Li Z, Zhang F, Duan W, Ke T, Yang B. Computed tomography diagnosis of pulmonary nocardiosis: A case report of a rare disease. Radiol Infect Dis [serial online] 2022 [cited 2023 Mar 23];9:31-3. Available from: http://www.ridiseases.org/text.asp?2022/9/1/31/358462

Introduction

Pulmonary nocardiosis, a rare disease caused by the Nocardia bacterium, presents as an acute, subacute, or chronic purulent lung infection.^[1] Nocardia organisms are widely present in the natural environment and can cause infection when inhaled into the respiratory tract. The main clinical manifestations include fever, cough, production of sputum, chest pain, shortness of breath, and hemoptysis. Rapid progression to respiratory failure, septic shock, and even death can occur in individuals with impaired immune function. Early diagnosis and evaluation of the effectiveness of treatment by chest computed tomography (CT) are essential to controlling disease progression and improving patient outcomes. We retrospectively analyzed the imaging and clinical data of a patient diagnosed with Nocardia pulmonary infection in our hospital to improve our understanding of this disease.

Case Report

The Institutional Review Board of the First Affiliated Hospital of Dali University approved this retrospective study and waived the need to obtain informed consent from the patient.

A 65-year-old woman was admitted to her local hospital because she had a fever for more than 10 days and cough and sputum for 3 days. Her maximum recorded body temperature was 39.9°C, this being accompanied by chills. She was given antibiotics, including ribavirin and other treatments (the specifics are unknown). However, her symptoms did not improve after diagnostic antituberculosis treatment with isoniazid and rifampicin. She had a heart rate of 101 beats/min and blood pressure of 102/63 mmHg. The results of relevant laboratory tests were as follows: fungi (−), acid-fast bacilli (−), WBC 13.01 × 10⁹/L (normal range 4–10 × 10⁹/L), and IgM 0.36 g/L (normal range 0.40–2.30 g/L). The patient had been diagnosed with nephrotic syndrome a year previously, for which she had undergone regular treatment with prednisone and cyclosporine. She also had a history of hypertension.

A plain CT scan of the lungs showed multiple patchy and cloud-like lesions and increased density in the right middle lobe and lower lobe. Air bronchograms and multiple small exudates with blurred margins were also noted [Figure 1]a and [Figure 1]b. The mediastinal window showed partial consolidation of the lower lobe of the left lung [Figure 1]c. There was no obvious enhancement on an enhanced scan [Figure 1]d. The anterior, outer basal, and posterior basal segments of the left lower lobe were brushed with sterile brushes through an electronic bronchoscope. Examination of the alveolar lavage fluid thus obtained (next-generation sequencing technology) resulted in a diagnosis of Nocardia nova infection. After being treated with compound sulfamethoxazole for 1 month, repeat chest CT showed almost complete resolution of the pulmonary lesions [Figure 2]a and [Figure 2]b.

Figure 1: (a−c) Lung computed tomography images. (a and b) Lung windows showing multiple patchy and cloud-like high-density shadows in the lower lobes of both lungs. (c) Mediastinal window: there is consolidation in part of the lung lobes. (d) Enhanced computed tomography image of the lung showing absence of obvious enhancement in the left lower lobe lesion

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Figure 2: (a and b) Follow-up imaging. Chest computed tomography plain scan after 1 month showing that the lung lesions have almost completely resolved

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Discussion

Nocardia, Gram-positive aerobic bacteria with weak acid resistance, are widely found in soil, freshwater, air, and decaying plants. They can enter the body through the respiratory tract or damaged skin. The main pathogenic species are N. nova (the most common), Nippostrongylus brasiliensis, Nocardia caviae, and Nocardia farcinica.^[2],[3] The lung is the most common site of infection by Nocardia; however, other organs, such as the brain, liver, and skin, can also be infected.^[4] These organisms can cause severe lung infections, particularly in patients with weakened immune systems. Long-term use of prednisone, other immunosuppressants, and organ transplantation are common causes of increased susceptibility. Our patient had been treated with prednisone for nephrotic syndrome for a year; this is consistent with published reports.^[5] There are also some reports of pulmonary nocardiosis in patients with apparently normal immune function. Ozgenç et al.^[6] have reported one such patient. Compound sulfamethoxazole is considered optimal first-line treatment because Nocardia is characteristically sensitive.^[7] Since Nocardia infection tends to recur, long-term treatment is required. Our patient had early-stage infection and responded to compound sulfamethoxazole taken continuously for 1 month, after which a repeat chest CT showed complete resolution of her pulmonary lesions.

Pulmonary nocardiosis has diverse imaging presentations. The main CT manifestations include punctate or patchy lesions, isolated or multiple nodules, inflammation-associated cavities, lung consolidation, masses, subpleural infiltration, pleural exudation, ground-glass opacities, and evidence of exudation. The most common presenting features are patchy lesions and masses. Because of the absence of any specific symptoms, clinical findings, or imaging manifestations, it is important to distinguish pulmonary nocardiosis from other lung infections. Patchy lesions with peripheral exudation on plain CT need to be differentiated from infiltrating tuberculosis. Nocardia-related lesions can occur in any part of the lung, whereas tuberculosis is mostly located in the posterior part of the tips of the upper and lower lobes of both lungs. Dorsal lung involvement combined with other manifestations of tuberculosis can be used to distinguish it from nocardial infection. Furthermore, thick-walled, cavitated, lung lesions on CT can occur with both nocardial lesions and abscesses caused by other bacteria. However, nocardial lung cavities rarely contain gas and fluid, whereas lung abscesses caused by other bacteria are often accompanied by air-fluid levels; the latter respond favorably to conventional antibiotics. Other lung diseases such as pneumonia, fungal diseases, and atelectasis need to be differentiated from nocardial infection. In addition, single or multiple masses on CT of the lungs need to be distinguished from tumors. In the case of nocardial infection, enhanced CT scans characteristically show purulent lung lesions with no enhancement, whereas lung tumors generally have strong enhancement, indicating a rich blood supply.

Conclusion

Pulmonary nocardiosis is rarely encountered in clinical practice. Because of the lack of typical symptoms, clinical findings, and imaging manifestations, together with the lack of knowledge among clinicians, this infection is easily misdiagnosed, resulting in poor patient outcomes, including death. Therefore, promoting awareness of this disease among clinicians is essential for preventing its progression and improving its prognosis. In patients with impaired immune function, especially those on long-term corticosteroids or other immunosuppressants, for whom lung CT shows multiple patchy lesions and nodules, the possibility of nocardial infection and treatment with sulfamethoxazole and trimethoprim should be considered.

Acknowledgment

We thank Dr. Trish Reynolds, MBBS, FRACP, from Liwen Bianji (Edanz) (http://www.liwenbianji.cn/), for editing the English text of a draft of this manuscript.

Author contributions

QY-Y conceived the idea of this report. WSh-D, XN-Zh, XCh, HJ-He, PZh, ZhM, ZhL-L, FZh and TF-Ke collected the data. QY-Y wrote the manuscript. BY edited and reviewed the manuscript. All authors discussed the results and commented on the manuscript.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This work was supported by the Program for Cultivating Reserve Talents in Medical Disciplines from the Health Committee of Yunnan Province (H-2018008 for B.Y) and the National Natural Science Foundation of China (NSFC) (82160348 for Y.B).

Conflicts of interest

There are no conflicts of interest.

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