Nocardiosis: An Essential Diagnostic Challenge in Suspected Pulmonary Tuberculosis
Introduction: Nocardiosis is a globally recognized opportunistic infection that predominantly affects immunocompromised individuals, leading to a diverse range of clinical manifestations, from cutaneous to severe systemic forms. The similarity of pulmonary nocardiosis symptoms to those of pulmon...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Pasteur Institute of Iran
2024-09-01
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| Series: | Journal of Medical Microbiology and Infectious Diseases |
| Subjects: | |
| Online Access: | https://jommid.pasteur.ac.ir/article-1-666-en.html |
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| Summary: | Introduction: Nocardiosis is a globally recognized opportunistic infection
that predominantly affects immunocompromised individuals, leading to a
diverse range of clinical manifestations, from cutaneous to severe systemic
forms. The similarity of pulmonary nocardiosis symptoms to those of
pulmonary tuberculosis often leads to misdiagnosis, presenting a significant
diagnostic challenge for clinicians. We present an illustrative case of a 48-
year-old male, newly diagnosed with HIV, who exhibited symptoms initially
suggestive of pulmonary tuberculosis but was subsequently diagnosed with
pulmonary nocardiosis. Methods: Bronchoalveolar lavage (BAL) fluid
samples were obtained and subjected to microbiological culture, Gram
staining, and modified acid-fast (Ziehl-Neelsen) staining for the
identification of Nocardia species. Results: Gram staining of BAL fluid
revealed thin, branched, beaded, filamentous, Gram-positive bacilli.
Modified acid-fast staining identified branching acid-fast bacilli (1-2
organisms per high-power field (HPF)), consistent with Nocardia. Diagnosis
of Nocardia is crucial as it necessitates targeted therapy, particularly in
immunocompromised hosts. Nocardia was cultured after one week,
highlighting its slow growth characteristic, which can delay diagnosis and
treatment. The patient was commenced on trimethoprim-sulfamethoxazole
(800/160 mg four times daily), showing significant clinical improvement
within two weeks. After 12 months of treatment, there was complete
resolution of symptoms, radiological improvement, and normalization of
laboratory parameters, indicating successful treatment of pulmonary
nocardiosis. Conclusion: Pulmonary nocardiosis must be considered in
immunocompromised patients with persistent respiratory symptoms.
Comprehensive imaging and bronchoscopy with BAL are pivotal for
effective sample collection and accurate laboratory diagnosis. Modified
Ziehl-Neelsen staining is critical for the definitive identification of Nocardia
infection. Early and proactive screening in high-risk groups, such as HIV
patients, cancer patients, or organ transplant recipients, is crucial for the
prompt initiation of targeted therapy, typically with trimethoprimsulfamethoxazole,
to improve outcomes. |
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| ISSN: | 2345-5349 2345-5330 |