Review of Respiratory Medicine - Volumen 25, Número 1 - March 2025

Case Reports

Disseminated Nocardiosis in Immunocompetent Patient: A Case Report

Nocardiosis diseminada en paciente inmunocompetente a propósito de un caso

ABSTRACT

Nocardiosis is a rare infection caused by bacteria of the Nocardia genus, widely dis­tributed saprophytic germs. Its transmission occurs by inhalation or direct inoculation. Pulmonary and disseminated presentation predominantly affect immunocompromised patients.

The pulmonary form is the most common, and it can be localized or disseminated. Risk factors are immunosuppression and pre-existing lung pathology. Disseminated forms with central nervous system (CNS) involvement are rare in immunocompetent patients.

We present the case of an immunocompetent patient diagnosed with disseminated nocardiosis (lung and CNS involvement).

Key words:

Disseminated nocardiosis, Pulmonary nocardiosis, Immunocompetent

RESUMEN

La nocardiosis es una infección poco frecuente causada por bacterias del género No­cardia, gérmenes saprófitos de distribución mundial, su transmisión se da por inhalación o inoculación directa. La presentación pulmonar y la diseminada afectan predominante­mente a pacientes inmunocomprometidos.

La forma pulmonar es la más frecuente; puede ser localizada o diseminarse. Los factores de riesgo son la inmunosupresión y la patología pulmonar previa. Las formas diseminadas con afectación del sistema nervioso central (SNC) son poco frecuentes en pacientes inmunocompetentes.

Presentamos un caso de paciente inmunocompetente con diagnóstico de nocardiosis diseminada (afección pulmonar y del SNC).

Palabras claves: Nocardiosis diseminada, Nocardiosis pulmonar, Inmunocompetente

Received: 09/09/2024

Accepted: 10/17/2024

INTRODUCTION

The species that affect humans are Nocardia as­teroides (80% of cases) and Nocardia brasiliensis. Nocardia cyriacigeorgica (an emerging species) has been implicated in severe pulmonary infections. Inhalation and cutaneous inoculation are the most common routes of infection. The pulmonary form is the most common, and it can be localized or disseminated. Risk factors are immunosuppression and pre-existing lung pathology. Disseminated forms with CNS involvement are rare in immu­nocompetent patients.

We present a case of disseminated nocardiosis with lung, pleural, and CNS involvement in an immunocompetent patient.

CASE REPORT

59-year-old male with a medical history of arterial hyper­tension (AHT) and solitary plasmacytoma (in remission).

The patient reports having experienced mucopurulent cough, asthenia, adynamia, profuse sweating and weight loss for 3 weeks. Physical examination: 93% oxygen saturation, hypoventilation, and dullness in the left lung field. Chest X-ray: blunting of the left costophrenic angle and radiopaque lesion in the left lung field. Laboratory re­sults: leukocyte count, 14,400 (leukocyte differential?); hemoglobin, 7.8; hematocrit, 24%; platelets, 265,000. Thoracentesis: macroscopic appearance consistent with empyema. A pleural drainage tube was placed. Empiric antibiotic therapy with ampicillin-sulbactam (AMS) was initiated. Chest CT scan: left-sided hydropneumothorax with pleural drainage tube, right-sided loculated pleu­ral effusion with organized appearance, and bilateral pulmonary consolidations, predominantly on the right side (Fig. 1). Pleural fluid cultures (left side): positive for nocardia cyriacigeorgica. Right-sided pleural fluid: negative. Antibiotic regimen was changed to imipenem + trimethoprim–sulfamethoxazole (TMP-SMX). Brain MRI (magnetic resonance imaging): the left subcortical temporal region shows hyperintense 10 mm nodular lesion with ring enhancement and restricted diffusion, consistent with an abscess (Fig. 2).

The case is interpreted as disseminated nocardia infection, with involvement of the pleura, lungs, and CNS.

DISCUSSION

Nocardiosis is a rare disease, generally opportu­nistic, with an incidence of 0.87 cases per 100,000 individuals per year.¹ It is caused by a bacterium.

Nocardia species are saprophytic organisms with worldwide distribution and are an important component of the normal soil and water microflora.

The species that affect humans are Nocardia asteroides (80% of cases) and Nocardia brasiliensis. The incidence of infections caused by Nocardia cyriacigeorgica has increased in recent years and it has been more and more implicated in severe pulmonary infections.²

Nocardiosis is usually an opportunistic infec­tion, which can be either localized or disseminated. Immunocompetent hosts can also succumb to nocardiosis (10%–50% of cases).³ The most com­mon route of infection is through inhalation, while direct percutaneous inoculation (in healthy individuals) is less common.

It has a generally chronic course and tends to relapse (5%), which prompts the use of secondary prophylaxis in patients considered high risk.⁴

Predisposing factors include immunosuppres­sion and/or pre-existing lung disease, for example bronchiectasis.^5,6,7,8

The most common forms of presentation are pulmonary, cerebral, cutaneous, or disseminated.²

In a review of 16 patients with nocardiosis admitted to the Banner Good Samaritan Medical Center in Phoenix, Arizona, over a one-year period, nearly 75% had an underlying chronic pulmonary condition. Other predisposing conditions included diabetes mellitus, hematologic and other types of neoplasms, transplants, autoimmune disease, and HIV/AIDS. The authors estimated that less than 10% of patients with nocardiosis had no identifi­able underlying predisposing factor.⁹

Symptoms are usually varied, including fever, cough, dyspnea, hemoptysis, and weight loss. Neu­rological symptoms, such as hemiparesis, visual field disturbances, altered consciousness, headache, or sei­zures may appear when the central nervous system is affected. However, it’s important to remember that neurological symptoms may not develop.

The most common radiological pattern consists of bilateral pulmonary nodules in 50% of the cases and infiltrates in 35%, often associated with areas of consolidation, cavitation, and loculated pleural effusion. Pulmonary masses have also been de­scribed, though less frequently.

The isolation and identification of the organ­ism from clinical samples are essential to make a diagnosis. These bacteria grow slowly and show varying degrees of acid resistance, complicating microbiological confirmation. Therefore, they are visualized using a modified Ziehl-Neelsen stain that uses 1% sulfuric acid.^9,10

The differential diagnosis of the pulmonary form includes tuberculosis or community-acquired pneumonia; it can also mimic fungal pneumonia, antineutrophil cytoplasmic antibody (ANCA)- associated vasculitis, or lung cancer.¹⁰

Central nervous system nocardiosis in immu­nocompetent patients is usually rare. The most frequently found lesions are meningitis, cerebritis, granulomas, and classic brain abscesses.¹¹

Patients with acute disease (symptoms lasting for less than one month) may have a worse progno­sis than those with a chronic course (mortality rate of 66% vs. 18%, respectively).¹² Mortality increases when two or more contiguous organs are affected, or when there is chronic pulmonary comorbidity, active neoplasia, if the patient had received prior corticosteroid therapy, or if they had been given empirical antibiotic treatment within the previous 3 months, reaching rates between 44% and 85%.¹³ When the central nervous system is affected, mor­tality can range from 40% to 87%.¹⁴

The first-line treatment is trimethoprim-sul­famethoxazole (TMS). In severe or immunocom­promised patients, prolonged triple therapy is recommended: TMS, imipenem, and amikacin. The total duration of treatment is recommended to be six to twelve months, which may be extended in immunocompromised patients.^15,16

Prevention of recurrence with TMS is 4 to 6 months in localized pulmonary disease and 6 to 12 months in systemic or CNS nocardiosis.¹⁷

CONCLUSIONS

Nocardiosis remains an opportunistic infection and should always be considered in the differential diagnosis of pneumonia—not only in immunocom­promised individuals but also in immunocompe­tent patients, especially when there is no response to standard therapy.

Once diagnosed, it is recommended that all pa­tients undergo neuroimaging, even in the absence of neurological symptoms. Early recognition and appropriate individualized treatment are key to a successful outcome.

The treatment with sulfonamides is usually effective. In severely ill or immunocompromised patients, prolonged triple therapy is recommended: TMS, imipenem, and amikacin. The total duration of treatment is recommended to be six to twelve months, which may be extended in immunocom­promised patients. For recurrence prevention: TMS from 4 to 6 months in localized pulmonary disease and 6 to 12 months in systemic or CNS nocardiosis.

Conflict of interest

The authors have no conflicts of interest to declare.

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