Nocardia infections

Nodular Cutaneous Lesions in Immune-Compromised Hosts as a Clue for the Diagnosis of Disseminated Nocardiosis: From Bedside to Microbiological Identification

BACKGROUND

Nocardia is a group of ubiquitous bacteria known to cause opportunistic infections in immunocompromised hosts, including those affected by malignancies and solid-organ or hematopoietic stem cell transplants. Pulmonary involvement, occurring in two-thirds of cases, is the most frequent presentation. Diagnosis might be challenging both because of microbiological technical issues, but also because of the variability of organ involvement and mimicry.

METHODS

We describe four cases of disseminated nocardiosis caused by N. farcinica observed between September 2021 and November 2021 in immune-compromised hosts presenting with nodular cutaneous lesions that had raised a high degree of clinical suspect and led to microbiological identification through MALDI-TOF MS.

RESULTS

Cutaneous involvement is typically reported in immunocompetent hosts with primary cutaneous nocardiosis with multiple forms of manifestation; nonetheless, disseminated nocardiosis rarely involves the skin and subcutaneous tissues, and this occurs as a result of metastatic spread. Our cases were disseminated nocardiosis in which the metastatic cutaneous involvement, even if rare, provided a clue for the diagnosis.

CONCLUSIONS

The pathomorphosis of disseminated nocardiosis may have changed in the current years with more rapid spread due to advanced immunosuppression. For this reason, after clinical suspicion, the prompt start of an active targeted therapy based on rapid microbiological identification might potentially open the way to hopeful results, even in the most immune-compromised patients.

Primary Nocardia Infection Causing a Fluorodeoxyglucose-Avid Right Renal Mass in a Redo Lung Transplant Recipient

Immunosuppression after lung transplantation may increase susceptibility to opportunistic infection and is associated with early and delayed deaths in lung transplant recipients. Factors that may predispose lung transplant recipients to opportunistic bacterial and fungal infections include prolonged corticosteroid use, renal impairment, treatment of acute rejection, and post-transplant diabetes mellitus. We present a unique case of a 63-year-old woman with diabetes mellitus who underwent redo lung transplantation. Three years after her right-sided single redo lung transplant, she presented with right-sided abdominal pain, nausea, and vomiting. Upon examination, computed tomography showed a 4.5 × 3.3 cm heterogeneous, enhancing right renal mass with a patent renal vein. Magnetic resonance imaging confirmed a T1/T2 hypointense, diffusion-restricting, right mid-renal mass that was fluorodeoxyglucose-avid on positron emission tomography. We initially suspected primary renal cell carcinoma. However, after a right nephrectomy, no evidence of neoplasia was observed; instead, a renal abscess containing filamentous bacteria was noted, raising suspicion for infection of the Nocardia species. Special stains confirmed a diagnosis of Nocardia renal abscess. Computed tomography of the chest and brain revealed no lesions consistent with infection. We initiated a long-term therapeutic regimen of anti-Nocardia therapy with imipenem and trimethoprim-sulfamethoxazole.

First reported case of disseminated Nocardia kroppenstedtii sp nov. infection presenting with brain abscess and endocarditis in an immunocompromised patient with mantle cell lymphoma: challenges in diagnosis and treatment

A 72-year-old man with a history of blastoid variant stage IV relapsed refractory mantle cell lymphoma presented with new central nervous system (CNS) symptoms. Brain imaging was positive for rim-enhancing lesions along with a mitral valve mass on the echocardiogram. It was a challenge to establish the exact aetiology of these lesions in this patient. He was empirically treated with chemotherapy on the presumption that the brain lesions were secondary to progressive malignancy. However, brain biopsy was negative for malignancy and blood cultures were found positive for Nocardia kroppenstedtii sp nov. He subsequently improved with antibiotic therapy. Disseminated Nocardia can present with multiorgan involvement. Clinical and microbiological diagnosis can be challenging. Antimicrobial treatment-related side effects require close monitoring, and dosage changes or therapy adjustments may be necessary.

Specific clinical manifestations of Nocardia: A case report and literature review

Nocardiosis is a rare bacterial infection of either the lungs (pulmonary) or body (systemic) that usually affects immunocompromised individuals. It is caused by Gram-positive, aerobic actinomycetes of the Nocardia genus. Multiple high-density sheet shadows in both lungs along with nodules or cavities are the most common presentations of nocardiosis, whereas a large pulmonary mass is considered to be rare. However, there is no specificity in the clinical manifestation of the disease. Therefore, isolation and identification of Nocardia strains is the only reliable diagnostic method. The present study describes the cases of two male patients of Asian descent with nocardiosis. Chest computed tomography scans showed a suspected tumor mass in both patients. Microscopic analysis and culturing of tissue samples obtained using a bronchoscope detected the presence of Nocardia wallacei. Neither patient showed signs of immunosuppression. The present study aimed to improve the understanding of lung nocardiosis and demonstrated that pulmonary nocardiosis should be suspected in the case of non-immunocompromised patients with a large mass in the lung. Furthermore, a review of the literature on infection with Nocardia was conducted.

Nocardiosis in transplant recipients

Nocardiosis is a rare opportunistic infection caused by Nocardia spp., an aerobic actinomycete, that mainly affects patients with cell-mediated immunity defects, such as transplant recipients. Despite recent progress regarding Nocardia identification and changes in taxonomic assignment, many challenges remain for the diagnosis or management of nocardiosis. This opportunistic infection affects 0.04 to 3.5 % of patients with solid organ or hematopoietic stem cell transplantation, depending on the organ transplanted, cytomegalovirus (CMV) infection, corticosteroids dose and calcineurin inhibitors level. Nocardiosis diagnosis relies on appropriate clinical, radiological and microbiological workup that includes the sampling of an accessible involved site and molecular microbiology tools. In parallel, extensive clinical and radiological evaluations are mandatory, including brain imaging, even in the absence of neurological signs. In transplanted patients, differential diagnosis is challenging, with co-infections reported in 20 to 64 % of cases. As the antibiotic susceptibility pattern varies among species, the antimicrobial regimen before species identification should rely on the association of antibiotics active on all species of Nocardia. Bactericidal antibiotics are required in cases of severe or disseminated disease. Furthermore, in transplant recipients, combination therapy is difficult to manage because of cumulative toxicity and interactions with immunosuppressive agents. Because of a high recurrence rate, antibiotic therapy should be prescribed for 6 to 12 months.

Nocardia farcinica lung abscess presenting in the context of advanced HIV infection: Spontaneous resolution in response to highly active antiretroviral therapy alone

A 43-year-old man, known to be HIV-positive, presented with a six-week history of symptoms including cough, hemoptysis, anterior chest pain, fever and wasting. His CD4 cell count was 46 cells/muL, and his chest x-ray showed a cavitating lesion in the left upper lobe. Sputum culture was positive for Nocardia farcinica. His infection resolved following initiation of antiretroviral therapy. Nocardia is an uncommon opportunistic pathogen in patients with HIV infection and is usually associated with advanced CD4 depletion, cavitary pneumonia, metastatic infection and high mortality. The impact of antiretroviral therapy on Nocardia infection in the setting of HIV has not been clearly elucidated. The current report is the first to present a case in which a complete clinical cure of Nocardia pneumonia has been documented, primarily in response to highly active antiretroviral therapy alone.

Infection caused by Nocardia farcinica mimicking pulmonary metastasis in an adolescent girl

Nocardia farcinica infections are rare and potentially life threatening. Herein, we describe a case of pulmonary nocardiosis caused by N. farcinica. This 13-year-old girl admitted with 1-year history of cough, intermittent fever, and recurrent hemoptysis. She was examined for multiple pulmonary nodules mimicking pulmonary metastasis that were detected with chest radiography and computed tomography of the thorax. Eventually, N. farcinica was yielded in culture of sputum and aspiration material of pulmonary nodules. No predisposing factor could be shown for Nocardia infection. Although infections caused by N. farcinica have tendency to disseminate, and are mostly resistant to antibiotics, the patient was successfully treated with prolonged intravenous antibiotic therapy followed with oral amoxicillin-clavulanate.

Nocardiosis in a kidney-pancreas transplant

34-year-old man with chronic renal and pancreas failure in complicated diabetic disease received a kidney-pancreas transplantation. On the 32nd postoperative day, an acute kidney rejection occurred and resolved with OKT3 therapy. The patient also presented refractory urinary infection by E. Fecalis and M. Morganii, and a focal bronchopneumonia in the right-basal lobe resolved with elective chemotherapy. During the 50th post-operative day, an intense soft tissue inflammation localized in the first left metatarsal-phalangeal articulation occurred (Figure 1) followed by an abscess with a cutaneous fistula and extension to the almost totality of foot area. The radiological exam revealed a small osteo-lacunar image localized in the proximal phalanx head of the first finger foot. From the cultural examination of the purulent material, N. Asteroides was identified. An amoxicillin-based treatment was started and continued for three months, with the complete resolution of infection This case is reported for its rarity in our casuistry, and for its difficult differential diagnosis with other potentially serious infections.

Pulmonary and cutaneous nocardiosis in a patient treated with corticosteroids

Nocardiosis is a localized or disseminated infection caused by gram-positive bacteria of the genus Nocardia. The infection most commonly affects the lungs, skin and central nervous system. Nocardiosis principally occurs in individuals with cellular immunodeficiency and should be considered in the differential diagnosis when such individuals present respiratory, cutaneous or neurological alterations. Herein, we report a case of pulmonary and cutaneous nocardiosis in a patient receiving oral corticosteroids to treat bronchiolitis obliterans accompanied by organizing pneumonia of unknown origin. After long-term treatment with sulfamethoxazole-trimethoprim, the clinical and radiological profile improved.

Risk factors, clinical characteristics, and outcome of Nocardia infection in organ transplant recipients: a matched case-control study

BACKGROUND

Risk factors for Nocardia infection in organ transplant recipients have not been formally assessed in the current era of transplantation.

METHODS

We performed a matched case-control study (1:2 ratio) between January 1995 and December 2005. Control subjects were matched for transplant type and timing. Univariate matched odds ratios were determined and conditional logistic regression was performed to identify independent risk factors. Clinical and microbiological characteristics of all case patients were reviewed.

RESULTS

Among 5126 organ transplant recipients, 35 (0.6%) were identified as having cases of Nocardia infection. The highest frequency was among recipients of lung transplants (18 [3.5%] of 521 patients), followed by recipients of heart (10 [2.5%] of 392), intestinal (2 [1.3%] of 155), kidney (3 [0.2%] of 1717), and liver (2 [0.1%] of 1840) transplants. In a comparison of case patients with 70 matched control subjects, receipt of high-dose steroids (odds ratio, 27; 95% confidence interval, 3.2-235; P=.003) and cytomegalovirus disease (odds ratio, 6.9; 95% confidence interval, 1.02-46; P=.047) in the preceding 6 months and a high median calcineurin inhibitor level in the preceding 30 days (odds ratio, 5.8; 95% confidence interval, 1.5-22; P=.012) were found to be independent risk factors for Nocardia infection. The majority of case patients (27 [77%] of 35) had pulmonary disease only. Seven transplant recipients (20%) had disseminated disease. Nocardia nova was the most common species (found in 17 [49%] of the patients), followed by Nocardia farcinica (9 [28%]), Nocardia asteroides (8 [23%]), and Nocardia brasiliensis (1 [3%]). Of the 35 case patients, 24 (69%) were receiving trimethoprim-sulfamethoxazole for Pneumocystis jirovecii pneumonia prophylaxis. Thirty-one case patients (89%) experienced cure of their Nocardia infection.

CONCLUSIONS

Receipt of high-dose steroids, history of cytomegalovirus disease, and high levels of calcineurin inhibitors are independent risk factors for Nocardia infection in organ transplant recipients. Our study provides insights into the epidemiology of Nocardia infection in the current era, a period in which immunosuppressive and prophylactic regimens have greatly evolved.

Nocardiosis following solid organ transplantation: a single-centre experience

Nocardiosis is a localized or disseminated bacterial infection caused by aerobic Actinomyces that commonly affects immunocompromised hosts. The aim of this study was to retrospectively review clinical course and outcome of nocardiosis in solid organ recipients at our centre. Five cases of nocardiosis were identified in a series of more than 4000 consecutive solid organ transplants performed at Innsbruck university hospital during a 25-year period. Of the five patients with nocardiosis, two had undergone multivisceral, one liver, one kidney and one lung transplantation. Three patients with Nocardia asteroides infection were treated successfully and recovered from their infectious disease, however, one lost his renal graft following withdrawal of immunosuppression. The lung recipient recovered from nocardiosis but died later on from Pseudomonas pneumonia. One multivisceral recipient died from Nocardia farcinica-disseminated infection. Nocardiosis is a rare, difficult-to-diagnose-and-treat complication following solid organ transplantation. Intestinal recipients might be at increased risk to develop this infection.