Nocardia infections in solid organ transplantation: Guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation

Utility of clinical metagenomics in complex infections: Cryptococcal meningitis complicated by Nocardia brain abscess

Nocardia farcinica brain abscess (BA) is a rare yet life-threatening infection of the central nervous system (CNS) that predominantly affects immunocompromised patients. Its nonspecific symptoms often lead to delayed diagnosis and poor outcomes. Early diagnosis and precise treatment are essential to improve the prognosis of patients. We report the rare case of a 75-year-old man with IgG4-related disease undergoing long-term methylprednisolone therapy who presented with a N. farcinica brain abscess. The patient initially presented with cryptococcal meningitis but exhibited persistent symptoms despite standard antifungal treatment. Follow-up neuroimaging revealed new intracranial abscess formations. Metagenomic next-generation sequencing (mNGS) of brain tissue and cerebrospinal fluid (CSF) identified abundant N. farcinica-specific sequences, confirming a concurrent Nocardia brain abscess complicating the cryptococcal infection. The patient's condition gradually improved with timely antibiotic treatment and is currently in recovery. This case underscores the heightened risk of sequential opportunistic infections in immunocompromised individuals and exemplifies the clinical value of mNGS in detecting rare infectious diseases. We further conducted a systematic review of patients with Nocardia central nervous system infections confirmed by mNGS, analyzing their clinical presentations, laboratory parameters, therapeutic regimens, and prognostic outcomes. In summary, our study demonstrates that mNGS offers significant diagnostic advantages compared to conventional microbiological methods for uncommon infections. These findings provide clinically actionable, evidence-based guidance for the diagnosis and management of Nocardia brain abscesses.

Evaluation of the Incidence of Nocardia Infection in Solid Organ Transplant Recipients on Trimethoprim-Sulfamethoxazole for Opportunistic Infection Prophylaxis

BACKGROUND

Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred prophylactic agent for Pneumocystis jiroveci pneumonia (PJP) and toxoplasmosis after solid organ transplant (SOT). Compared with other agents, it has additional activity against Nocardia species.

OBJECTIVE

The purpose of this study was to evaluate the incidence of Nocardia infection in SOT patients receiving TMP-SMX or an alternative agent for opportunistic infection (OI) prophylaxis.

METHODS

This retrospective analysis included transplant recipients at a large urban medical center over a period of 4 years. All patients received either TMP-SMX or an alternative agent for PJP prophylaxis. The primary outcome was the incidence of Nocardia infection within 24 months posttransplant. Secondary outcomes included resistance rates of Nocardia isolates, usage rates of alternative prophylactic agents, reasons for using alternative agents, and rate of conversion from an alternative agent back to TMP-SMX.

RESULTS

A total of 791 adult SOT recipients who received PJP or toxoplasmosis prophylaxis were included. Mean age at transplantation was 60.9 years with the majority of patients being male (67.3%) lung transplant recipients (63.6%). TMP-SMX was the most commonly used initial prophylactic agent (84.6%), followed by atovaquone (15.4%). Of the 791 SOT recipients, 16 (2.0%) were diagnosed with nocardiosis within 24 months posttransplant. Patients receiving alternative agents had a higher incidence of infection compared with those receiving TMP-SMX prophylaxis (P < 0.001).

CONCLUSION AND RELEVANCE

Our findings suggest that OI prophylaxis with TMP-SMX may be protective against nocardiosis in SOT recipients. If possible, patients who are switched to an alternative agent due to TMP-SMX intolerance should be re-challenged when the adverse effect resolves. Most patients in our study were able to tolerate re-initiation, suggesting that the adverse effects associated with TMP-SMX may be temporary and may not warrant discontinuation.

Ultrasound-guided thoracentesis for diagnosing Nocardia beijingensis-related empyema in a patient with systemic lupus erythematosus: A rare case report

Infections caused by Nocardia species are relatively rare and primarily affect immunocompromised patients. There are few reported cases of Nocardia beijingensis causing empyema in patients with systemic lupus erythematosus (SLE). We present a case of a 49-year-old female patient with SLE on immunosuppressive therapy (corticosteroids and azathioprine), admitted with dyspnea and left-sided pleuritic chest pain. A diagnosis of large parapneumonic left pleural effusion was established based on blood tests, blind thoracentesis findings, and bronchoalveolar lavage results. The patient received empirical intravenous antibiotic therapy with imipenem/cilastatin and vancomycin without isolating the causative organism for 10 days. Three weeks postdischarge, the patient's left pleuritic chest pain worsened, prompting chest computed tomography that revealed multiple loculated pleural-abdominal wall fluid collections. Ultrasound-guided aspiration of these areas yielded pus cultured positive for N. beijingensis. The patient showed improvement following treatment with imipenem/cilastatin and trimethoprim/sulfamethoxazole. This case represents a rare manifestation of N. beijingensis causing pleural and abdominal wall empyema. Ultrasound-guided aspiration, targeting the loculated and encapsulated effusion, played a crucial role in confirming the diagnosis. Empirical treatment with imipenem/cilastatin combined with long-term oral trimethoprim/sulfamethoxazole was found to be effective.

State-of-the-Art Review: Modern Approach to Nocardiosis-Diagnosis, Management, and Uncertainties

Nocardiosis is an uncommon yet potentially devastating infection. Nocardia tends to affect individuals with chronic lung disease or immunocompromising conditions, 2 groups increasing in number. Incidence of nocardiosis is likely to increase as well, and it is vital to have an approach to this complex disease. Here, we aim to review the presentation, diagnosis, and management of Nocardia in the modern era. We will also highlight areas of uncertainty in our understanding of nocardiosis and propose a general approach to nocardiosis therapy, accounting for response and tolerance of Nocardia treatment.

Respiratory infections in lung transplant recipients

PURPOSE OF REVIEW

Morbidity and mortality rates after lung transplantation still remain higher than after other forms of solid organ transplantation, primarily due to a higher risk of infections and the development of chronic lung allograft dysfunction. Thus, a tiered approach highlighting the most significant respiratory pathogens including common opportunistic infections along with diagnostic, treatment and prevention strategies, including vaccination and prophylaxis is needed.

RECENT FINDINGS

The need for intense immunosuppressive therapy to prevent rejection, coupled with the transplanted lung's constant exposure to environment and impaired local defence mechanisms leads to frequent infections. Viral and bacterial infections are most frequent while fungal infections mainly involve the tracheobronchial tract but may be fatal in case of disseminated disease. Some infectious agents are known to trigger acute rejection or contribute to chronic allograft dysfunction. Invasive testing in the form of bronchoscopy with bronchoalveolar lavage is standard and increasing experience in point of care testing is gained to allow early preemptive therapy.

SUMMARY

Timely diagnosis, treatment, and ongoing monitoring are essential, but this can be difficult due to the wide variety of potential pathogens.

Disseminated Nocardiosis in Idiopathic CD4 Lymphocytopenia: A Rare Case and Literature Review

Nocardiosis typically affects immunocompromised patients; however, the clinical characteristics of idiopathic CD4 lymphocytopenia (ICL) remain poorly understood. A 64-year-old patient was diagnosed with ICL following disseminated nocardiosis, including bacteremia, pneumonia, knee arthritis, and brain abscess. The patient underwent trimethoprim-sulfamethoxazole therapy with frequent dose adjustments based on the renal function, ranging from 2 to 12 single-strength tablets daily over 5 months of hospitalization. While he had a 1-year uneventful course of lifelong prophylaxis, he experienced prolonged recovery in physical activity. A literature review highlighted the life-threatening nature of nocardiosis in ICL, underscoring the importance of a timely diagnosis and tailored management strategies.

Nocardia Isolation in People with Cystic Fibrosis and Non-CF Bronchiectasis: A Multicenter Italian Study

Background:Nocardia species are an emergent pathogen in people with CF (pwCF) or bronchiectasis. Their clinical role and management remain unclear, and their isolation is a challenge. In this paper, we describe four cases of Nocardia detection, in two pwCF and two patients with non-CF bronchiectasis or primary ciliary dyskinesia (PCD). Methods: We conducted a multicenter retrospective study, involving pwCF and non-CF people with bronchiectasis who presented with a Nocardia detection and were followed at three CF Italian centers (Florence, Verona, and Cerignola). Results:Nocardia detection was associated with clinical and radiological respiratory exacerbation and decline in lung function. In one CF patient, Nocardia was not detected in sputum cultures after starting Elexacaftor-Tezacaftor-Ivacaftor therapy. Conclusions: Managing Nocardia detection in patients with underlying lung diseases such as CF, PCD, or bronchiectasis presents significant challenges for clinicians.

Pulmonary Nocardiosis Due to Nocardia exalbida Infection Following Living-donor Liver Transplantation

Nocardia exalbida, an uncommon Nocardia, was first identified in 2006. We herein report a 70-year-old man with pulmonary nocardiosis caused by N. exalbida after living-donor liver transplantation. We also review 11 previously reported cases of N. exalbida infections. To our knowledge, there are no case reports available on nocardiosis consequent to N. exalbida infection following transplantation, thus highlighting the importance of identifying bacterial species for the successful management of infection.

Evaluation of Inborn Errors of Immunity Among Patients with Opportunistic Pulmonary Infection

This review of immunocompromised host pneumonia as the result of inborn errors of immunity (IEI) is organized by opportunistic pulmonary pathogen. The authors identify patients who warrant an evaluation for an IEI based on their clinical presentation. Their recommendations are guided by the immune defect(s) associated with each opportunistic pulmonary infection. Physicians without expertise in immunology may begin an evaluation for IEI using the guidance provided here. Comprehensive evaluation by an immunologist may also be warranted in many instances.

Nocardiosis in systemic lupus erythematosus patients treated with rituximab: Report of two cases and systematic review of literature

BackgroundThe relationship between systemic lupus erythematosus (SLE) patients treated with rituximab and nocardiosis remains unclear.Cases ReportA 55-year-old female with lupus nephritis II and smoking history, was treated with high-dose steroids, immunoglobulins, rituximab, and azathioprine. She developed infectious loci in the lungs, hip, and brain. N. farcinica was detected in bronchoalveolar lavage and abscess culture. She was treated with linezolid, trimethoprim/sulfamethoxazole (TMP/SMX), minocycline, and amoxicillin/clavulanic acid, achieving complete cure at 12 months. The second patient, a 73-year-old male with lupus nephritis V, autoimmune thrombocytopenia, antiphospholipid syndrome (APS), and alveolar hemorrhage, was treated with high-dose steroids, azathioprine, mycophenolate, and rituximab. He developed infections in the lungs, prostate, and possibly colon. N. farcinica was detected in blood cultures. Despite treatment with imipenem, linezolid, TMP/SMX, and moxifloxacin, he died from bronchoaspiration.MethodsA systematic review was conducted using PubMed, Embase, Web of Science, and Scopus. The search terms were (systemic lupus erythematosus OR SLE) AND (rituximab) AND (nocardia), with a timeframe up to 15 March 2024. Inclusion criteria were confirmed cases of Nocardia infection in SLE patients treated with rituximab in the previous year. Non-original studies and secondary research were excluded.ResultsOnly one article was included, describing a 34-year-old male with APS and lupus nephritis IV, treated with high-dose steroids, cyclophosphamide, and rituximab. He had infections in the lungs and brain, with N. farcinica detected in blood cultures. Despite treatment with TMP/SMX and fluoroquinolones, he died from thrombotic complications.ConclusionNocardiosis is more likely in SLE patients due to T lymphocyte immune dysfunction caused by the disease itself, rituximab, and other immunosuppressants. Diagnosis requires a high level of clinical suspicion, supported by long-time blood cultures and 16S rRNA. Beta-lactams and quinolones are reasonable alternatives to TMP/SMX and linezolid, which can worsen the hematological situation, and amikacin, which may worsen lupus nephritis.

Algorithmic Approach to an Abnormal Computed Tomography of the Chest in the Immunocompromised Host

The immunocompromised host is a patient who is at risk for life threatening complications. This article offers a structured approach to interpreting abnormal chest computed tomography (CT) scans in these patients. Immune defects are categorized as innate or adaptive and each is linked to specific infectious risks. CT scan findings are grouped into 5 categories: nodules and/or masses, consolidation or ground glass opacity, large airway abnormalities, pleural effusions, and lymphadenopathy. This algorithmic approach can guide clinicians in establishing a differential diagnosis for immunocompromised patients with abnormal chest CT scans and help them reach a faster and more accurate diagnosis.

Severe pneumonia caused by Nocardia otitidiscaviarum in a patient with bronchiectasis and IgA nephropathy: a case report

Background

Nocardia species are rare opportunistic pathogens in the clinic, with strong invasiveness and dissemination, that can cause serious pulmonary infection, especially in immunocompromised patients, chronic lung diseases and hormone use, and is easy to be missed and misdiagnosed, preventing patients from obtaining timely and effective treatment, resulting in a high mortality rate.

Case presentation

Here, we present a rare case of a patient with chronic bronchiectasis and IgA nephropathy who developed Nocardia otitidiscaviarum pneumonia shortly after hormone therapy. The patient presented with tongue and lip ulcers, chest distress, cough, expectoration, and fever as the initial symptoms, which were extremely similar to common bacterial pulmonary infections. The laboratory examination and pulmonary computer tomography results indicated pulmonary infection, but the blood and multiple sputum cultures failed to identify the pathogen. Empirical treatment with piperacillin/tazobactam sodium and ceftriaxone was ineffective, and the patient's condition worsened and progressed to respiratory failure. Subsequently, a bronchoscopy examination was performed, and the bronchoalveolar lavage fluid was collected for bacterial culture, which indicated Nocardia infection, however the treatment used of trimethoprim-sulfamethoxazole combined with imipenem was not effective. Finally, the patient was confirmed to have Nocardia otitidiscaviarum infection by mass spectrometry. According to the antibiotic sensitivity test and minimum inhibitory concentration (MIC) value results, Nocardia otitidiscaviarum was resistant to imipenem, so the treatment was changed to trimethoprim-sulfamethoxazole combined with linzolid. The patient's condition improved rapidly and he was discharged after his condition was stable.

Conclusion

This case reminded us that for patients with a history of chronic lung disease, when pulmonary infection occurs during hormone or immunosuppressive therapy for kidney disease, the possibility of Nocardia infection should be fully considered, and high-quality specimens should be collected as early as possible. Appropriate bacterial culture methods and efficient identification techniques should be adopted to promptly identify pathogens, and personalized treatment plans should be developed based on antibiotic sensitivity tests to save patients' lives.

Trimethoprim-sulfamethoxazole dosing and outcomes of pulmonary nocardiosis

BACKGROUND

Nocardia often causes pulmonary infection among those with chronic pulmonary disease or immunocompromising conditions. Trimethoprim-sulfamethoxazole (TMP-SMX) is recommended as first-line treatment, though little data exists regarding outcomes of different dosing regimens.

METHODS

We performed a multicenter retrospective cohort study of adult patients with non-disseminated pulmonary nocardiosis initially treated with TMP-SMX monotherapy. Patients' initial TMP-SMX dosing was categorized as high- (> 10 mg/kg/day), intermediate- (5-10 mg/kg/day) or low-dose (< 5 mg/kg/day). Outcomes included one-year mortality, post-treatment recurrence, and dose adjustment or early discontinuation of TMP-SMX. SMX serum concentrations and their effect on management were also assessed. Inverse probability of treatment weighting was applied to Cox regression analyses.

RESULTS

Ninety-one patients were included with 24 (26.4%), 37 (40.7%), and 30 (33.0%) treated with high-, intermediate-, and low-dose TMP-SMX, respectively. Patients who initially received low-dose (HR 0.07, 95% CI 0.01-0.68) and intermediate-dose TMP-SMX (HR 0.27, 95% CI 0.07-1.04) had lower risk of one-year mortality than the high-dose group. Risk of recurrence was similar between groups. Nineteen patients had peak SMX serum concentrations measured which resulted in 7 (36.8%) dose changes and was not associated with one-year mortality or recurrence. However, 66.7% of the high-dose group required TMP-SMX dose adjustment/discontinuation compared to 24.3% of the intermediate-dose and 26.7% of the low-dose groups (p = 0.001).

CONCLUSIONS

Low- and intermediate-dose TMP-SMX for non-disseminated pulmonary nocardiosis were not associated with poor outcomes compared to high-dose therapy, which had a higher rate of dose adjustment/early discontinuation. Historically used high-dose TMP-SMX may not be necessary for management of isolated pulmonary nocardiosis.

Triple-drug antibiotic therapy for disseminated nocardial abscess in the mediastinum and brain of an immunocompetent patient: a case report

BACKGROUND

Nocardia are widely present in nature and considered opportunistic pathogens. They can result in hematogenous spread infection through the ruptured skin or respiratory tract when the host's immune system is compromised. Currently, 119 species of Nocardia have been identified, with 54 capable of causing infections in humans. Nocardial brain abscesses are a rare intracranial lesion that accounts for only 2% of all brain abscesses, but have a mortality rate of 20-55%. This article reports a successfully cured case of mediastinal Nocardia infection with disseminated brain abscess.

CASE PRESENTATION

The patient presented with intermittent chills, shivering, and fever, with the highest temperature of 39˚C, accompanied by shoulder and back pain, dizziness, and headaches. A chest-enhanced computed tomography (CT) revealed multiple enhanced nodulars in the bilateral hilum and mediastinum. A head-enhanced CT revealed scattered multiple ring-enhanced nodules in both cerebral hemispheres and the left cerebrum, accompanied by extensive surrounding edema. The mediastinal puncture tissue culture confirmed the growth of Nocardia. After twice discussions with multidisciplinary team (MDT) to rule out the possibility of mediastinal and intracranial metastatic tumors, we promptly initiated treatment with a triple-drug antibiotic regimen consisting of imipenem/cilastatin sodium, linezolid dextrose, and Trimethoprim-sulfamethoxazole (TMP-SMX). The patient ultimately achieved complete remission.

CONCLUSIONS

Mediastinal nocardiosis with disseminated brain abscesses is a rare condition that can be difficult to differentiate from brain metastases caused by lung cancer. Bacterial culture results, imaging features, and MDT discussions are crucial for accurate diagnosis and treatment. A triple-drug antibiotic regimen has been found to be effective in treatment with acceptable levels of toxicity.

Disseminated nocardiosis in a patient with AIDS and B-cell non-Hodgkin's lymphoma: a case report

BACKGROUND

Disseminated nocardiosis is a rare and potentially fatal disease, with a higher incidence in immunocompromised patients, such as those living with human immunodeficiency virus (HIV) or hematological malignancies, including lymphoma. Information on Nocardia spp. infection in Venezuela is limited.

CASE PRESENTATION

We present the case of a 62-year-old male patient, recently diagnosed with HIV, who exhibited prolonged fever and unintentional weight loss. Paraclinical tests revealed pancytopenia and a marked elevation of lactate dehydrogenase. Disseminated histoplasmosis was suspected, prompting a bone marrow (BM) aspirate. Culture and molecular studies for Histoplasma spp. and Mycobacterium tuberculosis in BM samples were negative. Antiretroviral therapy with tenofovir/lamivudine/dolutegravir was initiated, but the patient subsequently experienced clinical deterioration, including ascites, pericardial effusion, and respiratory failure. Post-mortem biopsy and immunohistochemistry identified non-Hodgkin's lymphoma of B-cell lineage, and mycological culture of BM isolated Nocardia farcinica.

CONCLUSION

Disseminated nocardiosis may mimic histoplasmosis. Nocardia spp. infection should be considered in HIV patients, particularly in advanced stages of infection.

Update on actinomycetoma treatment: linezolid in the treatment of actinomycetomas due to Nocardia spp and Actinomadura madurae resistant to conventional treatments

INTRODUCTION

Mycetoma is a chronic granulomatous infection, common throughout tropical regions, and is considered a neglected disease that mostly affects impoverished populations. Mycetoma is divided into eumycetoma, caused by fungi, and actinomycetoma, caused by filamentous bacteria. Clinical presentation is distinctive, and making the diagnosis is usually not difficult; however, access to safe and effective treatments is a major challenge. There is not a single best treatment, with the choice of treatment depending on etiology, severity and extent of disease, and patient comorbidities.

AREAS COVERED

The following topics regarding actinomycetoma are discussed. I) Background information on actinomycetoma, and etiology. II) Differences between actinomycetoma caused by Nocardia, and cutaneous nocardiosis. III) Review of the treatment options for actinomycetoma, caused by three species - Nocardia, Actinomadura, and Streptomyces. IV) Experience using linezolid in the treatment of mycetoma caused by Nocardia spp. and Actinomadura madurae.

EXPERT OPINION

Multiple treatment regimens for actinomycetoma were discussed according to the causative agent. Experience in using linezolid in combined therapy for actinomycetoma caused by Nocardia in which conventional treatment options failed was also presented. The first case report of treatment with linezolid for mycetoma caused by Actinomadura madurae is presented in this article.

Multicenter systematic review of clinical characteristics, diagnostic optimization, and personalized treatment for brain Nocardia infections

This study provides a systematic review of 512 reported cases of Nocardia brain infections from 2000 to mid-2024. It focuses on analyzing clinical manifestations, radiological findings, bacterial identification methods, and antibiotic resistance patterns. Special attention is given to the differences in outcomes between immunocompromised and non-immunocompromised patients. We also explored personalized treatment approaches by analyzing outcome-related factors through correlation analysis and linear discriminant analysis. Imaging findings commonly showed brain abscesses, lesions, and mass effects, with a high prevalence of antibiotic resistance. Diagnostic methods using conventional microbiological cultures were less effective compared to advanced molecular diagnostics, which enhanced detection accuracy and reduced time to diagnosis. This review also identifies key factors influencing treatment outcomes, including the timely initiation of appropriate antibiotics, particularly the combination of sulfonamides and β-lactams, as well as the importance of surgical intervention. These findings underscore the necessity of improving diagnostic and therapeutic strategies to achieve early diagnosis and personalized treatment.

Successful maintenance treatment of disseminated nocardiosis with cerebral abscess in a severely immunocompromised patient allergic to trimethoprim-sulfamethoxazole using moxifloxacin and high-dose minocycline: A case report

Nocardiosis in patients after allogeneic hematopoietic stem cell transplantation (HSCT) is rare, but is associated with a significant mortality risk. Although trimethoprim-sulfamethoxazole (TMP/SMX) remains the cornerstone of nocardiosis treatment, optimal alternative therapies for patients intolerant to TMP/SMX are not well-established. Herein, we report a case of disseminated nocardiosis with bacteremia and multiple lesions in the lungs and brain caused by Nocardia farcinica, in a 60-year-old man who had previously undergone allogeneic HSCT and was receiving immunosuppressants for severe chronic graft-versus-host disease. The patient received atovaquone for the prophylaxis of Pneumocystis pneumonia because of a previous serious allergic reaction to TMP/SMX. The patient was initially treated with imipenem/cilastatin and amikacin, which were later switched to ceftriaxone and amikacin based on the results of antimicrobial susceptibility testing. After switching to oral levofloxacin and a standard dose of minocycline, the patient experienced a single recurrence of brain abscesses. However, after switching to oral moxifloxacin and high-dose minocycline, the patient did not experience any relapses during the subsequent two years and seven months of treatment. In treating nocardiosis with brain abscesses, it is crucial to select oral antibiotics based on the antimicrobial susceptibility test results and pharmacokinetics, especially when TMP/SMX is contraindicated. A combination of oral moxifloxacin and high-dose minocycline could be a promising alternative therapy.

Brain abscess following solid organ transplantation: A 21-year retrospective study

BACKGROUND

Development of brain abscess following solid organ transplantation is associated with significant morbidity and mortality. We undertook a descriptive study to evaluate the etiology, clinical manifestations, diagnosis, management, and outcomes of brain abscess in solid organ transplant (SOT) recipients at three major transplant centers in the United States.

METHODS

This is a retrospective study of adults with brain abscess following SOT between January 2000 and June 2021 at Mayo Clinic sites in Arizona, Minnesota, and Florida.

RESULTS

A total of 39 patients were diagnosed with a brain abscess following SOT. The most common pathogens were Nocardia sp. (24 cases, 61.5% [Nocardia farcinica, 37.5%]), followed by fungi (12 cases, 30.7% [Aspergillus sp., 83.3%]). The majority were kidney transplant recipients (59%). Median time to brain abscess diagnosis was 1.3 years (range, 29 days-12 years) after SOT; 10 of 12 patients (83%) with fungal brain abscess were diagnosed within 1 year after SOT. Twelve patients underwent brain biopsy for diagnosis (25% Nocardia vs. 50% fungal), eight (20.5%) underwent surgical resection of the abscess, and 31 (79.5%) received antimicrobial therapy alone. Median time to brain abscess resolution was 166 days for Nocardia and 356 days for fungal pathogens. Eleven of 39 patients (28.2%) died as a result of their brain abscess, including four of 24 patients (16%) with Nocardia and six of 10 patients (60%) with Aspergillus brain abscess. All-cause mortality was 43.6%.

CONCLUSION

Brain abscess remains an uncommon infectious complication following SOT. Nocardia and fungi accounted for 92% of pathogens in our cohort. Fungal brain abscess portends a poor prognosis.

Shorter vs. standard-duration antibiotic therapy for nocardiosis: a multi-center retrospective cohort study

PURPOSE

The prolonged treatment recommended for nocardiosis does not rely on strong evidence. Consequently, some clinicians opt shorter therapy in certain circumstances. We assessed the effectiveness of shorter therapy.

METHODS

A multi-center retrospective cohort study comprising individuals diagnosed with nocardiosis between 2007 and 2022. We classified all patients who survived 90 days into three groups according to treatment duration: short (≤ 90 days), intermediate (91-180 days), and prolonged (> 180 days). We compared baseline characteristics (comorbidities, immune status) and nocardiosis manifestations across the unadjusted treatment groups, one-year all-cause mortality, disease relapse, and antibiotic-related adverse events to identify patients who may safely receive the short course.

RESULTS

We detected 176 patients with nocardiosis, their median age was 65 years; 74 (42%) were women. Forty-three (24%) patients died within 90 days. Of the remaining 133, 37 (28%) patients received short therapy, 40 (30%) intermediate, and 56 (42%) prolonged treatment duration. Longer courses were more likely to be administered to patients with immunosuppression, disseminated nocardiosis, and N. farcinica infection. Within a year, 20 (15%) individuals died and 2 (2%) relapsed. Treatment duration was not associated with either mortality (p = 0.945) or relapse (p = 0.509). Nocardiosis was the cause of death in only one patient, receiving a prolonged course. Of 73 patients with solitary pulmonary nocardiosis, 20 (27%) received short duration. None relapsed and 2 (10%) died, both immunocompromised. The rate of AE was similar across the groups.

CONCLUSIONS

With clinically guided case-by-case patient selection nocardiosis can be safely treated for durations significantly shorter than traditionally recommended.

Case report: Metagenomic next-generation sequencing for the diagnosis of rare Nocardia aobensis infection in a patient with immune thrombocytopenia

Background

Nocardiosis poses a diagnostic challenge due to its rarity in clinical practice, non-specific clinical symptoms and imaging features, and the limitations of traditional detection methods. Nocardia aobensis (N. aobensis) is rarely detected in clinical samples. Metagenomic next-generation sequencing (mNGS) offers significant advantages over traditional methods for rapid and accurate diagnosis of infectious diseases, especially for rare pathogens.

Case presentation

A 52-year-old woman with a history of immune thrombocytopenia for over 2 years was hospitalized for recurrent fever and cough lasting for 10 days. Her initial diagnosis on admission was community-acquired pneumonia, based on chest computed tomography findings of lung inflammation lesion. Empirical treatment with moxifloxacin and trimethoprim-sulfamethoxazole (TMP-SMZ) was initiated. However, her condition failed to improve significantly even after 1 week of treatment. Bronchoalveolar lavage fluid (BALF) subjected to mNGS revealed the presence of N. aobensis, resulting in a diagnosis of pulmonary nocardiosis caused by N. aobensis. This diagnosis was also supported by Sanger sequencing of the BALF. After adjusting the antibiotic regimen to include TMP-SMZ in combination with imipenem, the patient's condition significantly improved. She was finally discharged with instructions to continue oral treatment with TMP-SMZ and linezolid for 6 months. The patient's first follow-up 1 month after discharge showed good treatment outcomes but with obvious side effects of the drugs. Consequently, the antibiotic regimen was changed to doxycycline, and the patient continued to improve.

Conclusion

We report the first detailed case of pulmonary nocardiosis caused by N. aobensis diagnosed by mNGS. mNGS could be an effective method that facilitates early diagnosis and timely decision-making for the treatment of nocardiosis, especially in cases that involve rare pathogens.

Myasthenia gravis complicated with pulmonary infection by Nocardia cyriacigeorgica: a case report and literature review

Myasthenia gravis (MG) is an autoimmune disease. Patients with MG due to compromised autoimmune regulation, progressive muscle weakness, and prolonged use of immunosuppressants and glucocorticoid, often present with concomitant infections. However, cases of MG complicated by Nocardia infection are rare. In this case, we report MG complicated with pulmonary infection by Nocardia cyriacigeorgica. A 71-year-old male farmer who was admitted for management of MG. After 7 weeks of treatment of MG, the patient reported improvement. However, clinical presentation, inflammatory markers, and imaging findings supported a diagnosis of pulmonary infection. To further elucidate the etiology, Nocardia was identified in sputum smear microscopy and sputum culture, with 16S rRNA gene sequencing confirming N. cyriacigeorgica. The patient was prescribed trimethoprim-sulfamethoxazole. After 1 month of treatment, clinical symptoms of MG and pulmonary nocardiosis showed significant improvement. Additionally, we searched PubMed for case reports of Nocardia cyriacigeorgica pulmonary infection from 2010 to 2024 and conducted a statistical analysis of the case information. This report aims to highlights the increased risk of pulmonary Nocardia infection in MG patients after the use of steroids and immunosuppressants, thereby enhancing clinical awareness.

Nocardiosis in Renal Allograft Recipients

Introduction

The aim of the study was to study the clinical profile and outcomes of nocardiosis in renal allograft recipients.

Methods

This was a retrospective study of clinical outcomes in consecutive renal allograft recipients with Nocardia infection over a 22-year period (2000-2022) from a tertiary care center in Southern India. The clinical data were obtained from electronic medical records and patient files.

Results

A total of 1970 patients underwent renal transplantation at Christian Medical College, Vellore, India, between January 1, 2000, and December 31, 2022. During this period, 26 patients were diagnosed to have Nocardia infection. Half (50%) of the patients had fever and cough as their initial presentation, 7 (26.9%) patients presented with cutaneous abscesses, 2 (7.6%) patients were incidentally detected to have lung nodules during routine follow-up, 2 (7.6%) patients presented with headache accompanied by fever, and 3.8% had graft abscess. The diagnosis was made by isolating the organism in culture from one or more of the following samples: sputum, blood, pus, or lung biopsy (either computed tomography [CT]-guided or bronchoscopic aspirate culture). Eight patients required bronchoscopy and two patients required CT-guided biopsy for obtaining samples for diagnosis. All patients were similarly managed initially with a reduction of immunosuppression and appropriate antibiotics as per culture sensitivity. All 26 patients responded to induction treatment with meropenem (or imipenem) and trimethoprim-sulfamethoxazole (co-trimoxazole) followed by maintenance treatment with co-trimoxazole. Five (19.2%) out of 26 patients received Minocycline in induction and maintenance treatment regimens as in four patients isolates were resistant and one patient had allergic reaction to Cotrimoxazole. All patients had stable graft function. Two patients succumbed after 2 months of diagnosis with Gram-negative sepsis.

Conclusions

At present, there exists no single serological test to diagnose Nocardia infection in patients. Multiple initially obtained cultures may be negative because of the slow growth of the organism and variable colony morphology. Hence, infected specimens should be obtained by aggressive approaches if the index of suspicion is high. Procedures such as bronchoscopic lavage and aspiration of abscess are invaluable toward making a diagnosis. In our study, eight patients required invasive diagnostic procedures such as bronchoalveolar lavage and CT-guided lung biopsy since initial Gram stain and sputum culture were negative. In conclusion, it is crucial to maintain a high level of suspicion and conduct thorough investigations among post renal transplant recipients. This approach facilitates early diagnosis, prompt initiation of appropriate treatment which helps prevent the spread of disease.

Clinical characteristics and outcome analysis of pulmonary nocardiosis in southern China: a two-center retrospective study

BACKGROUND

Pulmonary nocardiosis (PN) is a rare and opportunistic infection. This study aimed to analyze clinical, radiological, and microbiological features, treatment and outcome of PN in southern china.

METHODS

Clinical, laboratory, imaging, treatment and outcome data of PN patients at two tertiary hospitals from January 1, 2018, to January 1, 2024 were collected. Factors associated with clinical outcomes were determined by multivariate logistic regression analysis.

RESULTS

67 PN patients including 53 with clinical improvement and 14 with treatment failure were enrolled. Bronchiectasis was the most common respiratory disease in patients with PN (31.3%). The major symptoms of PN were cough (89.6%) and sputum (79.1%). Lung nodules, bronchiectasis, consolidation, pleural involvement, mass, cavity, and lymph node enlargement were the frequent computed tomography findings of PN. Among the Nocardia species detected, N. farcinica was the most common pathogen. Neutrophil-to-lymphocyte ratio (OR = 1.052, p = 0.010), concurrent bacterial infection (OR = 7.706, p = 0.016), and the use of carbapenems (OR = 9.345, p = 0.023) were independently associated with poor prognosis in patients with PN.

CONCLUSIONS

This study provides important insights into the clinical features of PN in southern china. neutrophil-to-lymphocyte ratio, concurrent bacterial infection, and the use of carbapenems were independently associated with poor prognosis in patients with PN.

Musculoskeletal infections associated with Nocardia species: a case series

Background: Nocardia is an uncommon pathogen that has been reported to infect musculoskeletal structures. However, studies are largely limited to case reports, and little is known regarding management and outcomes of these infections. Methods: We performed a multicenter retrospective cohort study of adults with culture-confirmed musculoskeletal Nocardia infections at three Mayo Clinic centers in Arizona, Florida, and Minnesota from November 2011 through April 2022. Results: Nine cases of Nocardia musculoskeletal infection were identified. Seven (78 %) occurred in men, and the median age was 57.3 years (range 32.6-79.0). Specific infections included native joint septic arthritis with or without associated osteomyelitis ( N = 3 ), hardware-associated infection ( N = 1 ), sternal osteomyelitis ( N = 1 ), pyomyositis ( N = 2 ), bursitis ( N = 1 ), and tenosynovitis ( N = 1 ). Three cases (33 %) were associated with disseminated disease, all three occurring in solid organ transplant recipients. Surgical intervention was performed in all but the bursitis case. Length of treatment varied from 21 d for tenosynovitis to 467 d for osteomyelitis. The 1-year mortality was 22 %, and all fatal cases involved disseminated disease. Conclusion: Patients with localized nocardiosis affecting musculoskeletal structures generally have good outcomes, as opposed to those with disseminated infection. Management often required operative intervention, with one patient experiencing recurrence within 1 year.

Infection route influence the consequences of Nocardia farcinica infection in BALB/c mice

BACKGROUND

Nocardia, a rare but potentially fatal pathogen, can induce systemic infections with diverse manifestations. This study aimed to investigate the tissue and organ damage caused by Nocardia farcinica (N. farcinica) in mice via different infection routes, evaluate the resulting host immune responses, and assess its invasiveness in brain tissue.

METHODS

BALB/c mice were infected with N. farcinica through intranasal, intraperitoneal, and intravenous routes (doses: 1 × 10^8, 1 × 10^7, 1 × 10^7 CFU in 50 µl PBS). Over a 7-day period, body temperature, weight, and mortality were monitored, and samples were collected for histopathological analysis and bacterial load assessment. Serum was isolated for cytokine detection via ELISA. For RNA-seq analysis, mice were infected with 1 × 107 CFU through three infection routes, after which brain tissue was harvested.

RESULTS

Intraperitoneal and intravenous N. farcinica infections caused significant clinical symptoms, mortality, and neural disruption in mice, resulting in severe systemic infection. Conversely, intranasal infection primarily affected the lungs without causing significant damage to other organs. Intraperitoneal and intravenous infections significantly increased serum cytokines, particularly TNF-α and IFN-γ. RNA-seq analysis of brains from intravenously infected mice revealed significant differential gene expression, whereas the intranasal and intraperitoneal routes showed limited differences (only three genes). The enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in the intravenous group were primarily related to immune processes.

CONCLUSION

The study demonstrated that intravenous N. farcinica infection induces significant clinical symptoms, triggers an inflammatory response, damages multiple organs, and leads to systemic infections.

Challenging Case of Postoperative Nocardia Endophthalmitis

Purpose: To describe a case of postoperative Nocardia endophthalmitis that proved to be challenging. Methods: A 64-year-old woman presented with a clinical picture of postoperative endophthalmitis, which was managed by vitrectomy with intraocular lens explantation. Nocardia puris, sensitive to amikacin, cotrimoxazole (trimethoprim-sulfamethoxazole), and ciprofloxacin, was isolated in culture. The patient received intracameral and intravenous amikacin. On the sixth postoperative day, the infection appeared controlled; however, a macular infarction developed. One month later, the patient presented with recurrent infection (iris nodule and vitritis). After consultation with an infectious disease specialist, oral trimethoprim-sulfamethoxazole and oral moxifloxacin were started. Treatment continued for 6 months. Results: At the 3-month and 6-month follow-ups, the iris nodules had regressed in size with no new visible lesions. The vitreous cavity was clear, and the retina was attached; however, the best-corrected visual acuity was poor because of the macular infarction. Conclusions: This case highlights the importance of obtaining a microbiological diagnosis with sensitivity in cases of Nocardia endophthalmitis and its use in the aggressive management of the infection, including frequent monitoring for recurrences.

Guidelines for Antibiotics Prescription in Critically Ill Patients

How to cite this article: Khilnani GC, Tiwari P, Mittal S, Kulkarni AP, Chaudhry D, Zirpe KG, et al. Guidelines for Antibiotics Prescription in Critically Ill Patients. Indian J Crit Care Med 2024;28(S2):S104-S216.

Comparison of Clinical Characteristics and Treatment Outcome Between Localized and Disseminated Nocardiosis in a Tertiary Hospital in China

Background

In China, due to the large population, infections caused by Nocardia may not be as rare. Unfortunately, there is still inadequate knowledge of the clinical impact caused by Nocardia. This study aimed to compare the clinical characteristics and treatment of localized and disseminated nocardiosis.

Methods

The clinical and microbiological data of patients diagnosed with nocardiosis in a tertiary hospital in Beijing from July 2011 to July 2021 were collected and retrospectively analyzed.

Results

Among the 54 nocardiosis cases, 34 cases were in the localized infection group, while 20 cases in the disseminated infection group. The proportion of patients with chronic structural lung disease was higher in the localized group (P=0.010). In contrast, patients with disseminated infections were more prone to receive long-term glucocorticoids and/or immunosuppressants (P=0.027). Pulmonary nodules were prominent features of imaging changes in patients with disseminated infections (P=0.027) whereas bronchial dilatation was more common in patients with localized infections (P=0.025). In addition, the disseminated group had longer average hospitalization days relative to the localized group (P=0.016), but there was no significant difference in mortality between them (P=0.942).

Conclusion

There were differences in the clinical profiles between patients with localized and disseminated nocardiosis in terms of clinical presentation, infection site, radiological features, treatment, and prognosis. These findings may provide references for the management and treatment of patients with nocardiosis.

Nocardiosis in Solid Organ Transplant Recipients: 10-Year Single Center Experience and Review of Literature

Solid organ transplant recipients (SOTRs) are at an increased risk of nocardiosis, a rare but life-threatening opportunistic infection. Universal PCP prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) is used at our center, which is active in vitro against most species of the Nocardia genus and may have a role in preventing early infections. This is a single-center retrospective cohort study of nocardiosis in adult SOTRs at a large transplant center between January 2012 and June 2022, with comprehensive review of literature. Out of 6179 consecutive cases, 13 (0.2%) were diagnosed with nocardiosis. The patients were predominantly male (76.9%) and kidney transplant recipients (62%). Infection was diagnosed at median of 8.8 months (range, 3.7-98) after transplant. Patients were followed for a median of 457 days (range 8-3367). Overall mortality within one year after diagnosis was 46% (6/13), of which 17% (1/6) of deaths was attributable to Nocardia infection. No recurrence was reported. Nocardia infections were noted in a small proportion of our SOTRs and carried significant morbidity and mortality. TMP-SMX prophylaxis may be protective in some cases given low incidence of cases.

Nocardiosis in kidney transplant recipients: A tertiary care center experience

INTRODUCTION

Kidney transplant recipients are at increased risk of opportunistic infections, including Nocardia. The incidence of nocardiosis in kidney transplant recipients is 0.4-1.3%. The data regarding its epidemiology and outcomes is limited.

METHODS

This was a 10-year retrospective observational study from January 2012 to December 2021 at a tertiary care center in northern India, in which all kidney transplant recipients with Nocardia infection were included and followed.

RESULTS

12 (1.1%) patients had a Nocardia infection among the 1108 kidney transplant recipients. All were living donor kidney transplant recipients, and the mean age at diagnosis was 48.67 ± 12.60 years. Nocardia infection occurred at a median of 26 months (range 4-235) post-transplantation, with 4 (33.1%) of the cases occurring within a year of transplant. Breakthrough infection occurred in 7 (58.3%) patients on cotrimoxazole prophylaxis. 41.7% (n = 5) cases had an episode of rejection in the preceding year of Nocardia diagnosis. Concurrent cytomegalovirus (CMV) infection was present in one (8.3%) case. The lung was the most frequently involved organ. Microscopy was positive in all the cases; while culture was positive in 10 cases, and antimicrobial susceptibility testing (AST) were performed for these isolates. The majority (60%) of isolates were resistant to cotrimoxazole. All tested isolates remained susceptible to Amikacin, Imipenem, and Linezolid. No patients experienced Nocardia recurrence after completion of antibiotic therapy. The mortality at 12 months was 66.7% (n = 4), and only one death was Nocardia-related.

CONCLUSION

Nocardia may cause a late-manifesting infection beyond the traditional window. The cotrimoxazole prophylaxis may not be sufficient for Nocardia prevention.

Risk factors for Nocardia infection among allogeneic hematopoietic cell transplant recipients: A case-control study of the Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

OBJECTIVES

Nocardiosis is a rare but life-threatening infection after hematopoietic cell transplantation (HCT). We aimed at identifying risk factors for nocardiosis after allogeneic HCT and clarifying the effect of trimethoprim-sulfamethoxazole prophylaxis on its occurrence.

METHODS

We performed a retrospective multicenter case-control study of patients diagnosed with nocardiosis after allogeneic HCT between January 2000 and December 2018. For each case, two controls were matched by center, transplant date, and age group. Multivariable analysis was conducted using conditional logistic regression to identify potential risk factors for nocardiosis. Kaplan-Meier survival curves of cases and controls were compared using log-rank tests.

RESULTS

Sixty-four cases and 128 controls were included. Nocardiosis occurred at a median of 9 months after allogeneic HCT (interquartile range: 5-18). After adjustment for potential confounders in a multivariable model, Nocardia infection was associated with tacrolimus use (adjusted odds ratio [aOR] 9.9, 95 % confidence interval [95 % CI]: 1.6-62.7), lymphocyte count < 500/µL (aOR 8.9, 95 % CI: 2.3-34.7), male sex (aOR 8.1, 95 % CI: 2.1-31.5), recent use of systemic corticosteroids (aOR 7.9, 95 % CI: 2.2-28.2), and recent CMV infection (aOR 4.3, 95 % CI: 1.2-15.9). Conversely, use of trimethoprim-sulfamethoxazole prophylaxis was associated with a significantly decreased risk of nocardiosis (aOR 0.2, 95 % CI: 0.1-0.8). HCT recipients who developed nocardiosis had a significantly decreased survival, as compared with controls (12-month survival: 58 % and 90 %, respectively; p < 0.0001).

CONCLUSIONS

We identified six factors independently associated with the occurrence of nocardiosis among allogeneic HCT recipients. In particular, trimethoprim-sulfamethoxazole prophylaxis was found to protect against nocardiosis.

In vitro activity of omadacycline against clinical isolates of Nocardia

Nocardiosis typically requires a prolonged treatment duration of ≥6 months and initial combination therapy with 2-3 antibiotics. First-line regimens for nocardiosis are associated with considerable toxicity; therefore, alternative therapies are needed. Omadacycline is an aminomethylcycline with broad antimicrobial activity whose in vitro activity against Nocardia species has not been formally assessed. The in vitro potency of omadacycline was evaluated against 300 Nocardia clinical isolates by broth microdilution. The most common Nocardia species tested were N. cyriacigeorgica (21%), N. nova (20%), and N. farcinica (12%). The most common specimens were respiratory (178 isolates, 59%) and wound (57 isolates, 19%). Omadacycline minimum inhibitory concentrations (MICs) across all Nocardia species ranged from 0.06 µg/mL to 8 µg/mL, with an MIC50 of 2 µg/mL and MIC90 of 4 µg/mL. The lowest MICs were found among N. paucivorans (MIC50 = 0.25 µg/mL, MIC90 = 0.25 µg/mL), N. asiatica (MIC50 = 0.25 µg/mL, MIC90 = 1 µg/mL), N. abscessus complex (MIC50 = 0.5 µg/mL, MIC90 = 1 µg/mL), N. beijingensis (MIC50 = 0.5 µg/mL, MIC90 = 2 µg/mL), and N. otitidiscaviarum (MIC50 = 1 µg/mL, MIC90 = 2 µg/mL). The highest MICs were found among N. farcinica (MIC50 = 4 µg/mL, MIC90 = 8 µg/mL). In vitro potency differed by species among Nocardia clinical isolates. Further studies are warranted to evaluate the potential clinical utility of omadacycline for nocardiosis.

Infections in lung transplanted patients: A review

Lung transplantation can improve the survival of patients with severe chronic pulmonary disorders. However, the short- and long-term risk of infections can increase morbidity and mortality rates. A non-systematic review was performed to provide the most updated information on pathogen, host, and environment-related factors associated with the occurrence of bacterial, fungal, and viral infections as well as the most appropriate therapeutic options. Bacterial infections account for about 50% of all infectious diseases in lung transplanted patients, while viruses represent the second cause of infection accounting for one third of all infections. Almost 10% of patients develop invasive fungal infections during the first year after lung transplant. Pre-transplantation comorbidities, disruption of physical barriers during the surgery, and exposure to nosocomial pathogens during the hospital stay are directly associated with the occurrence of life-threatening infections. Empiric antimicrobial treatment after the assessment of individual risk factors, local epidemiology of drug-resistant pathogens and possible drug-drug interactions can improve the clinical outcomes.

Interesting case from Argentina: Kidney transplant recipient with skin lesions-A Latin American perspective

This is a case of a kidney transplant recipient who presented with skin lesions, low-grade fevers, and pancytopenia 2 months after his transplant.

Epidemiology, Timing, and Secondary Prophylaxis of Recurrent Nocardiosis

Background

Nocardia tends to cause infection in immunocompromised patients or those with chronic pulmonary disease. Nocardia is known to recur, prompting the practice of secondary prophylaxis in patients perceived at high risk. However, few data exist regarding the epidemiology of recurrent nocardiosis or the effectiveness of secondary prophylaxis.

Methods

We performed a multicenter, retrospective cohort study of adults diagnosed with nocardiosis from November 2011 to April 2022, including patients who completed primary treatment and had at least 30 days of posttreatment follow-up. Propensity score matching was used to analyze the effect of secondary prophylaxis on Nocardia recurrence.

Results

Fifteen of 303 (5.0%) patients developed recurrent nocardiosis after primary treatment. Most recurrences were diagnosed either within 60 days (N = 6/15, 40.0%) or between 2 to 3 years (N = 4/15, 26.7%). Patients with primary disseminated infection tended to recur within 1 year, whereas later recurrences were often nondisseminated pulmonary infection. Seventy-eight (25.7%) patients were prescribed secondary prophylaxis, mostly trimethoprim-sulfamethoxazole (N = 67/78). After propensity-matching, secondary prophylaxis was not associated with reduced risk of recurrence (hazard ratio, 0.96; 95% confidence interval, .24-3.83), including in multiple subgroups. Eight (53.3%) patients with recurrent nocardiosis required hospitalization and no patients died from recurrent infection.

Conclusions

Recurrent nocardiosis tends to occur either within months because of the same Nocardia species or after several years with a new species. Although we did not find evidence for the effectiveness of secondary prophylaxis, the confidence intervals were wide. However, outcomes of recurrent nocardiosis are generally favorable and may not justify long-term antibiotic prophylaxis for this indication alone.

Comparative Analysis of CT Findings and Clinical Outcomes in Adult Patients With Disseminated and Localized Pulmonary Nocardiosis

BACKGROUND

Pulmonary nocardiosis is a rare opportunistic infection with occasional systemic dissemination. This study aimed to investigate the computed tomography (CT) findings and prognosis of pulmonary nocardiosis associated with dissemination.

METHODS

We conducted a retrospective analysis of patients diagnosed with pulmonary nocardiosis between March 2001 and September 2023. We reviewed the chest CT findings and categorized them based on the dominant CT findings as consolidation, nodules and/or masses, consolidation with multiple nodules, and nodular bronchiectasis. We compared chest CT findings between localized and disseminated pulmonary nocardiosis and identified significant prognostic factors associated with 12-month mortality using multivariate Cox regression analysis.

RESULTS

Pulmonary nocardiosis was diagnosed in 75 patients, of whom 14 (18.7%) had dissemination, including involvement of the brain in 9 (64.3%) cases, soft tissue in 3 (21.4%) cases and positive blood cultures in 3 (21.4%) cases. Disseminated pulmonary nocardiosis showed a higher frequency of cavitation (64.3% vs. 32.8%, P = 0.029) and pleural effusion (64.3% vs. 29.5%, P = 0.014) compared to localized infection. The 12-month mortality rate was 25.3%. The presence of dissemination was not a significant prognostic factor (hazard ratio [HR], 0.80; confidence interval [CI], 0.23-2.75; P = 0.724). Malignancy (HR, 9.73; CI, 2.32-40.72; P = 0.002), use of steroid medication (HR, 3.72; CI, 1.33-10.38; P = 0.012), and a CT pattern of consolidation with multiple nodules (HR, 4.99; CI, 1.41-17.70; P = 0.013) were associated with higher mortality rates.

CONCLUSION

Pulmonary nocardiosis with dissemination showed more frequent cavitation and pleural effusion compared to cases without dissemination, but dissemination alone did not affect the mortality rate of pulmonary nocardiosis.

Trimethoprim-sulfamethoxazole significantly reduces the risk of nocardiosis in solid organ transplant recipients: systematic review and individual patient data meta-analysis

BACKGROUND

Whether trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis prevents nocardiosis in solid organ transplant (SOT) recipients is controversial.

OBJECTIVES

To assess the effect of TMP-SMX in the prevention of nocardiosis after SOT, its dose-response relationship, its effect on preventing disseminated nocardiosis, and the risk of TMP-SMX resistance in case of breakthrough infection.

METHODS

A systematic review and individual patient data meta-analysis.

DATA SOURCES

MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Web of Science Core Collection, and Scopus up to 19 September 2023.

STUDY ELIGIBILITY CRITERIA

(a) Risk of nocardiosis between SOT recipients with and without TMP-SMX prophylaxis, or (b) sufficient details to determine the rate of TMP-SMX resistance in breakthrough nocardiosis.

PARTICIPANTS

SOT recipients.

INTERVENTION

TMP-SMX prophylaxis versus no prophylaxis.

ASSESSMENT OF RISK OF BIAS

Risk Of Bias In Non-randomized Studies-of Exposure (ROBINS-E) for comparative studies; dedicated tool for non-comparative studies.

METHODS OF DATA SYNTHESIS

For our primary outcome (i.e. to determine the effect of TMP-SMX on the risk of nocardiosis), a one-step mixed-effects regression model was used to estimate the association between the outcome and the exposure. Univariate and multivariable unconditional regression models were used to adjust for the potential confounding effects. Certainty of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Individual data from three case-control studies were obtained (260 SOT recipients with nocardiosis and 519 uninfected controls). TMP-SMX prophylaxis was independently associated with a significantly decreased risk of nocardiosis (adjusted OR = 0.3, 95% CI 0.18-0.52, moderate certainty of evidence). Variables independently associated with an increased risk of nocardiosis were older age, current use of corticosteroids, high calcineurin inhibitor concentration, recent acute rejection, lower lymphocyte count, and heart transplant. Breakthrough infections (66/260, 25%) were generally susceptible to TMP-SMX (pooled proportion 98%, 95% CI 92-100).

CONCLUSIONS

In SOT recipients, TMP-SMX prophylaxis likely reduces the risk of nocardiosis. Resistance appears uncommon in case of breakthrough infection.

Nocardia brasiliensis Pyomyositis in an Immunocompetent Patient Following Gardening Activity

Nocardia pyomyositis in immunocompetent patients is a rare occurrence. The diagnosis may be missed or delayed with the risk of progressive infection and suboptimal or inappropriate treatment. We present the case of a 48-year-old immunocompetent firefighter diagnosed with pyomyositis caused by Nocardia brasiliensis acquired by direct skin inoculation from gardening activity. The patient developed a painful swelling on his right forearm that rapidly progressed proximally and deeper into the underlying muscle layer. Ultrasound imaging of his right forearm showed a 7-mm subcutaneous fluid collection with surrounding edema. Microbiologic analysis of the draining pus was confirmed to be N brasiliensis by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry. After incision and drainage deep to the muscle layer to evacuate the abscess and a few ineffective antibiotic options, the patient was treated with intravenous ceftriaxone and oral linezolid for 6 weeks. He was then de-escalated to oral moxifloxacin for an additional 4 months to complete a total antibiotic treatment duration of 6 months. The wound healed satisfactorily and was completely closed by the fourth month of antibiotic therapy. Six months after discontinuation of antibiotics, the patient continued to do well with complete resolution of the infection. In this article, we discussed the risk factors for Nocardia in immunocompetent settings, the occupational risks for Nocardia in our index patient, and the challenges encountered with diagnosis and treatment. Nocardia should be included in the differential diagnosis of cutaneous infections, particularly if there is no improvement of "cellulitis" with traditional antimicrobial regimens and the infection extends into the deeper muscle tissues.

Clinical and Radiological Characterization of Central Nervous System Involvement in Nocardiosis: A 20-Year Experience

Background This study aimed to present the clinical and radiological characteristics and the outcomes of patients with Nocardia infection of the central nervous system (CNS). Methodology We conducted a retrospective review of patients aged 18 and older admitted between August 1998 and November 2018 with culture-proven nocardiosis and CNS involvement. Results Out of 110 patients with nocardiosis, 14 (12.7%) patients had CNS involvement. The median age was 54.5 (27, 86) years, and 12 (85.7%) patients were male. Overall, 12 (85.7%) patients were immunosuppressed on high doses of glucocorticoids; seven (50%) patients were solid organ transplant recipients. Only eight (57.1%) patients had neurological symptoms at presentation, and the rest were diagnosed with CNS involvement after imaging surveillance. Three distinct radiologic patterns were identified, namely, single or multiple abscesses, focal cerebritis, and small, septic embolic infarcts. All isolates of Nocardia were susceptible to trimethoprim/sulfamethoxazole and amikacin, with susceptibility to linezolid and carbapenems being 90.9% and 79.5%, respectively. Despite receiving antibiotic therapy, six (42.8%) patients died, most of them within weeks of initial admission. All surviving patients underwent prolonged antimicrobial therapy until the resolution of MRI abnormalities. All solid organ transplant recipients recovered. Conclusions Nocardia CNS infection was a rare condition, even among a large, immunosuppressed patient population. CNS imaging surveillance is paramount for immunosuppressed patients with nocardiosis, as CNS involvement influences the choice and duration of therapy. Nocardia antibiotic susceptibility varied widely between strains and the empiric therapy should consist of multiple classes of antimicrobials with CNS penetration. Mortality was high, but all solid organ transplant recipients recovered.

Bacterial Infections in Patients Living with HIV

Pneumonia, as well as other types of acute and chronic lung injuries, remain the leading causes of death in individuals living with HIV. Individuals with HIV who are on antiretroviral therapy continue to have a greater risk for pneumonia, including bacterial and mycobacterial infections. Alveolar macrophages and lung epithelial cells constitute the first line of host defense against invading pathogens. The predisposition of individuals living with HIV to infections despite ante-retroviral therapy is mechanistically related to HIV pro-viruses integrating into host cells, including airway epithelial cells and alveolar macrophages. Alveolar macrophages harbor latent HIV even when individuals appear to have complete suppression on ART. In parallel, pneumonia can irreversibly impair lung function in HIV-infected individuals. Cells that Macrophages exposed to HIV or HIV-related proteins have been shown to secrete exosomes that contain miRNAs. These exosomes can regulate several innate and acquired immune functions by stimulating cytokine production and inflammatory responses. Furthermore, these secreted exosomal miRNAs can shuttle between cells, causing cellular dysfunction in the case of epithelial cells; they disrupt lung epithelial barrier dysfunction, which leads to a predisposition to bacterial infections. We discuss the common bacterial infections that occur in patients living with HIV and provide mechanistic insights into how the intercellular communication of miRNAs results in cellular dysfunction.

Successful treatment with amoxicillin-clavulanic acid: cutaneous nocardiosis caused by Nocardia brasiliensis

AIM

To emphasize the role of non-sulfonamides in the treatment of Nocardia infection and reduce the adverse reactions caused by sulfonamides.

METHODS

We retrospectively analyzed a case of cutaneous nocardiosis in an immunocompetent individual. The colonies obtained by staining the pus in the lesion with antacid and culturing the agar plates were identified by flight mass spectrometry. The pathogenic identification showed Nocardia brasiliensis infection and the patient was treated with amoxicillin-clavulanic acid.

RESULTS

After treatment with amoxicillin and clavulanic acid, the ulcer gradually peeled and crusted, leaving dark pigmentation. The patient has finally recovered.

CONCLUSION

Sulfonamides are the first-line antibacterial agents for years in treatment of nocardiosis but are of great toxicity and side effects. This patient was successfully treated with amoxicillin-clavulanic acid and it provided a reference protocol for patients with sulfonamide-resistant Nocardia or sulfonamides intolerance.

Invasive Nocardia Infections across Distinct Geographic Regions, United States

We reviewed invasive Nocardia infections in 3 noncontiguous geographic areas in the United States during 2011–2018. Among 268 patients with invasive nocardiosis, 48.2% were from Minnesota, 32.4% from Arizona, and 19.4% from Florida. Predominant species were N. nova complex in Minnesota (33.4%), N. cyriacigeorgica in Arizona (41.4%), and N. brasiliensis in Florida (17.3%). Transplant recipients accounted for 82/268 (30.6%) patients overall: 14 (10.9%) in Minnesota, 35 (40.2%) in Arizona, and 33 (63.5%) in Florida. Manifestations included isolated pulmonary nocardiosis among 73.2% of transplant and 84.4% of non–transplant patients and central nervous system involvement among 12.2% of transplant and 3.2% of non–transplant patients. N. farcinica (20.7%) and N. cyriacigeorgica (19.5%) were the most common isolates among transplant recipients and N. cyriacigeorgica (38.0%), N. nova complex (23.7%), and N. farcinica (16.1%) among non–transplant patients. Overall antimicrobial susceptibilities were similar across the 3 study sites.

A Clinical Model to Predict the Occurrence of Select High-risk Infections in the First Year Following Heart Transplantation

Background

Invasive infection remains a dangerous complication of heart transplantation (HT). No objectively defined set of clinical risk factors has been established to reliably predict infection in HT. The aim of this study was to develop a clinical prediction model for use at 1 mo post-HT to predict serious infection by 1 y.

Methods

A retrospective cohort study of HT recipients (2000-2018) was performed. The composite endpoint included cytomegalovirus (CMV), herpes simplex or varicella zoster virus infection, blood stream infection, invasive fungal, or nocardial infection occurring 1 mo to 1 y post-HT. A least absolute shrinkage and selection operator regression model was constructed using 10 candidate variables. A concordance statistic, calibration curve, and mean calibration error were calculated. A scoring system was derived for ease of clinical application.

Results

Three hundred seventy-five patients were analyzed; 93 patients experienced an outcome event. All variables remained in the final model: aged 55 y or above, history of diabetes, need for renal replacement therapy in first month, CMV risk derived from donor and recipient serology, use of induction and/or early lymphodepleting therapy in the first month, use of trimethoprim-sulfamethoxazole prophylaxis at 1 mo, lymphocyte count under 0.75 × 103cells/µL at 1 mo, and inpatient status at 1 mo. Good discrimination (C-index 0.80) and calibration (mean absolute calibration error 3.6%) were demonstrated.

Conclusion

This model synthesizes multiple highly relevant clinical parameters, available at 1 mo post-HT, into a unified, objective, and clinically useful prediction tool for occurrence of serious infection by 1 y post-HT.