LInezolid for the Treatment of Nocardia spp. Infections

The in vitro antimicrobial activity of linezolid against unconventional pathogens

Linezolid is an oxazolidinone antibiotic that is mainly permitted to treat Gram-positive bacterial infections. Recent studies have shown that linezolid also has antibacterial effects on several other bacteria outside the package insert, including Mycobacterium tuberculosis, non-tuberculous mycobacteria (NTM), Nocardia, Corynebacterium, and anaerobes, etc. Interestingly, linezolid also has an in vitro inhibitory effect on fungi. This review focuses on the in vitro antibacterial activity of linezolid against microorganisms outside its antibacterial spectrum. We mainly listed the number of the tested strains, the minimum inhibitory concentration (MIC) range, MIC50, and MIC90 of linezolid against those pathogens outside the package insert. The results showed that among these tested pathogens, linezolid displayed strong inhibitory effects against M. tuberculosis, Nocardia, and Corynebacterium, with an MIC range of ≤2 μg/mL. As for NTM, linezolid exhibited moderate to potent inhibitory effects against the strains of different species with an MIC range of 0.06-128 μg/mL. Moreover, linezolid was reported to have a species-dependent inhibitory effect on anaerobes at a concentration range of 0.003-16 μg/mL. Furthermore, linezolid could enhance azoles and amphotericin B's antifungal activity on Candida synergistically. It is hoped that this analysis can provide data for expanding the application of linezolid, make the off-label drug use have more compelling evidence, and provide clues for the development of new drugs.

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.

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.

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.

Nocardiosis: a single-center experience and literature review

INTRODUCTION

Nocardiosis is a rare bacterial infection caused by Nocardia spp. However, an increasing incidence has been described whereby data about epidemiology and prognosis are essential.

METHODS

A retrospective descriptive study was conducted among patients with positive Nocardia spp. culture, from January 2019 to January 2023, at a Terciary Hospital in Portugal.

RESULTS

Nocardiosis was considered in 18 cases with a median age of 63.8-years-old. At least one immunosuppressive cause was identified in 70% of patients. Five patients had Disseminated Nocardiosis (DN). The lung was the most common site of clinical disease (77.8%) and Nocardia was most commonly identified in respiratory tract samples. The most frequently isolated species were Nocardia nova/africana (n = 7) followed by Nocardia cyriacigeorgica (n = 3) and Nocardia pseudobrasiliensis (n = 3). The majority of the patients (94.4%) received antibiotic therapy, of whom as many as 55.6% were treated with monotherapy. The most frequently prescribed antibiotic was trimethoprim-sulfamethoxazole. Selected antimicrobial agents were generally effective, with linezolid and cotrimoxazole (100% Susceptibility [S]) and amikacin (94% S) having the most activity against Nocardia species. The median (IQR) duration of treatment was 24.2 (1‒51.4) weeks for DN; The overall one-year case fatality was 33.3% (n = 6) and was higher in the DN (66.7%). No recurrence was observed.

CONCLUSION

Nocardiosis is an emerging infectious disease with a poor prognosis, particularly in DN. This review offers essential epidemiological insights and underscores the importance of gaining a better understanding of the microbiology of nocardiosis. Such knowledge can lead to the optimization of antimicrobial therapy and, when necessary, guide appropriate surgical interventions to prevent unfavorable outcomes.

Linezolid: a safer and effective substitute to aminoglycoside in the treatment of actinomycetoma by Nocardia species

Actinomycetoma is chronic, suppurative, granulomatous infection caused by bacteria and requires prolonged antibiotic therapy preferrably in combinations. Nephrotoxicity is a common side effect of aminoglycosides used in the management of actinomycetoma. We report here two cases of actinomycetoma due to Nocardia species who received linezolid as a substitute to aminoglycosides after developing nephrotoxicity.

Disseminated nocardiosis in a patient with alcoholic liver cirrhosis: a case report

BACKGROUND

Nocardia are Gram-positive, aerobic, filamentous bacteria that can cause localized or disseminated infections. Immunocompromised patients are at a higher risk of developing Nocardia infection and further dissemination of the disease. To date, limited data have documented the relationship between nocardiosis and alcoholic liver disease.

CASE PRESENTATION

We report the case of a 47-year-old man with a known history of alcoholic liver cirrhosis. The patient presented to our emergency department with redness, swelling in the left eye, and diminished bilateral vision. Fundus examination of the left eye was obscured, while that of the right eye was consistent with subretinal abscess. Therefore, endogenous endophthalmitis was suspected. Imaging revealed two ring-enhancing lesions in the brain, and multiple bilateral small cystic and cavitary lung lesions. Unfortunately, the left eye eventually eviscerated due to the rapid progression of the disease. Cultures from the left eye were positive for Nocardia farcinica. The patient was started on imipenem, trimethoprim/sulfamethoxazole, and amikacin based on culture sensitivity. The patient's hospitalization course was complicated by his aggressive and advanced condition, which led to his death.

CONCLUSIONS

Although the patient's condition initially improved with the recommended antibiotic regimens, it led to death owing to the patient's advanced condition. Early detection of nocardial infection in patients with typical or atypical immunosuppressive conditions may improve overall mortality and morbidity. Liver cirrhosis disrupts cell-mediated immunity and may increase the risk of Nocardia infection.

Comparative Insights into the Antimicrobial, Antioxidant, and Nutritional Potential of the Solanum nigrum Complex

Solanum nigrum is a traditional medicinal plant renowned as a cure for many diseases due to the presence of bioactive compounds. The Solanum nigrum complex refers to a group of more than 30 closely related but morphologically distinct taxa. Five indigenous taxa of this complex were investigated for their medicinal potential by using methanolic extracts. The efficacy of each plant was different for each of the seven bacteria studied. On comparing the MIC values, S. americanum was found to be most potent against Bacillus licheniformis (34 µg/mL), S. chenopodioides against Escherichia coli (78 µg/mL), S. nigrum against Bacillus licheniformis (49 µg/mL) and Escherichia coli (49 µg/mL), S. retroflexum against Escherichia coli (30 µg/mL), and S. villosum against Proteus mirabilis (45 µg/mL). The extracts were also subjected to six antioxidant assays. Moderate scavenging activity was observed by all plants in the DPPH free radical assay, but S. chenopodioides was the most effective. The total phenolic contents of the five plants were comparable, but the gallic acid equivalents of S. americanum and S. nigrum were the highest (26.58 mg/100 g GAE). The highest Trolox equivalent antioxidant capacity was observed for S. retroflexum, with the ABTS assay giving a TEAC value of 33.88 mM/100 g of dry weight. Metal-chelating activity against Fe2+ was observed to be highest for S. chenopodioides (70.37%). The FRAP value of S. nigrum was the highest (8.5 mM FeSO4·7H2O) among all taxa. The lipid peroxidation trend was very similar for all five samples. The results suggest the specified medicinal use of different members of the Solanum nigrum complex, which will also have significant nutritional value.

A fatal case of disseminated nocardiosis due to Nocardia otitidiscaviarum resistant to trimethoprim-sulfamethoxazole: case report and literature review

Background

Disseminated nocardiosis still causes significant morbidity and mortality and is often caused by Nocardia asteroides, N. basiliensis, and N. farcinica and are often treated with trimethoprim–sulfamethoxazole (TMP–SMX). Nocardia otitidiscaviarum (N. otitidiscaviarum) rarely causes disseminated disease and resistance to TMP–SMX is even more rare.

Case presentation

A 37-year-old woman with metastatic breast cancer and right ear deafness with recent occupational gardening and manipulating soil, presented to the hospital with first time seizure and multiple skin nodules. Magnetic resonance imaging (MRI) showed ring enhancing lesions, biopsy of the skin and brain lesions grew N. otitidiscaviarum. She was empirically treated with TMP–SMX and Imipenem–Cilastatin, however, almost three weeks into therapy, susceptibility results revealed it to be resistant to both antimicrobials, she was subsequently changed to Amikacin, Linezolid, Moxifloxacin, and Doxycycline but ultimately died.

Conclusions

This case report highlights the importance of suspecting a rare Nocardia species in patients at risk with proper occupational exposure, moreover, TMP–SMX resistance should be suspected with lack of clinical response, this may have important implications on clinical practice when facing similar infections.

Brain abscess caused by Nocardia thailandica infection in systemic lupus erythematosus patient with steroid therapy

Background:

Nocardia is an aerobic Gram-negative bacillus belonging to actinomycetes and has been reported to be an infectious disease in healthy individuals. However, more than 60% have some underlying illnesses and are said to be opportunistic infections.

Case Description:

The case was a 69-year-old man who had been on long-term steroids for systemic lupus erythematosus. He developed with nausea and gait disturbance and was suspected of having a brain abscess by imaging. Abscess drainage detects actinomycetes that appear to belong to the genus Nocardia and brain abscess by Nocardia thailandica using matrix-assisted laser desorption/ionization time-of-flight mass analysis (MALDITOFMS) I was diagnosed. He died during the course of the treatment, and his organs did not detect his N. thailandica at necropsy, so he concluded that bacterial death from long-term administration of antibiotics was the cause of death.

Conclusion:

N. thailandica is a very rare bacterium belonging to Nocardia asteroides and is said to easily form brain lesions. In immunocompromised patients, prophylaxis with antibiotics and detailed examination of lung lesions for surveillance were considered necessary. This paper is the first report of a brain abscess caused by N. thailandica, including a review of the literature.

Therapeutic Drug Monitoring Can Improve Linezolid Dosing Regimens in Current Clinical Practice: A Review of Linezolid Pharmacokinetics and Pharmacodynamics

Linezolid is an antibiotic used to treat infections caused by drug-resistant gram-positive organisms, including vancomycin-resistant Enterococcus faecium, multi-drug resistant Streptococcus pneumoniae, and methicillin-resistant Staphylococcus aureus. The adverse effects of linezolid can include thrombocytopenia and neuropathy, which are more prevalent with higher exposures and longer treatment durations. Although linezolid is traditionally administered at a standard 600 mg dose every 12 hours, the resulting exposure can vary greatly between patients and can lead to treatment failure or toxicity. The efficacy and toxicity of linezolid are determined by the exposure achieved in the patient; numerous clinical and population pharmacokinetics (popPK) studies have identified threshold measurements for both parameters. Several special populations with an increased need for linezolid dose adjustments have also been identified. Therapeutic Drug Monitoring (TDM) is a clinical strategy that assesses the response of an individual patient and helps adjust the dosing regimen to maximize efficacy while minimizing toxicity. Adaptive feedback control and model-informed precision dosing are additional strategies that use Bayesian algorithms and PK models to predict patient-specific drug exposure. TDM is a very useful tool for patient populations with sparse clinical data or known alterations in pharmacokinetics, including children, patients with renal insufficiency or those receiving renal replacement therapy, and patients taking co-medications known to interact with linezolid. As part of the clinical workflow, clinicians can use TDM with the thresholds summarized from the current literature to improve linezolid dosing for patients and maximize the probability of treatment success.

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

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of Nocardia infections after solid organ transplantation (SOT). Nocardia infections have increased in the last two decades, likely due to improved detection and identification methods and an expanding immunocompromised population. The risk of developing nocardiosis after transplantation varies with the type of organ transplanted and the immunosuppression regimen used. Nocardia infection most commonly involves the lung. Disseminated infection can occur, with spread to the bloodstream, skin, or central nervous system. Early recognition of the infection and initial appropriate treatment is important to achieve good outcomes. Species identification and antimicrobial susceptibility testing are strongly recommended, as inter- and intraspecies susceptibility patterns can vary. Sulfonamide is the first-line treatment of Nocardia infections, and combination therapy with at least two antimicrobial agents should be used initially for disseminated or severe nocardiosis. Trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis may be helpful in preventing Nocardia infection after SOT.

Nocardia brasiliensis Infection Complicating Cryptogenic Organizing Pneumonia

Pulmonary nocardiosis is a severe and uncommon opportunistic infection caused by Nocardia species. We present a patient with cryptogenic organizing pneumonia who was receiving long-term immunosuppressive therapy, whose treatment course was complicated by cutaneous and pulmonary nocardiosis. Tissue cultures confirmed Nocardia brasiliensis. Nocardiosis should be a diagnostic consideration for patients treated with long-term immunosuppression who have worsening pulmonary symptoms and relapsing pustular skin lesions.

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.

Nocardiosis in the Tropical Northern Territory of Australia, 1997-2014

BACKGROUND

Nocardia is an opportunistic pathogen that can cause life-threatening disease. We aimed to characterize the epidemiological, microbiological, and clinical features of nocardiosis in the tropical north of Australia.

METHODS

We conducted a retrospective cohort study of nocardiosis diagnosed between 1997 and 2014. Population-based incidences were calculated using district population data.

RESULTS

Clinically significant nocardiosis was identified in 61 patients. The unadjusted population-based annual incidence of nocardiosis was 2.02 (95% confidence interval [CI], 1.55-2.60) per 100000 people and was 1.7 (95% CI, .96-2.90) fold higher in Indigenous compared with non-Indigenous persons (P = .027). Of 61 patients, 47 (77%) had chronic lung disease, diabetes, and/or hazardous alcohol consumption; 22 (36%) were immunocompromised; and 8 (13%) had no identified comorbidities. Disease presentations included pulmonary (69%; 42 of 61), cutaneous (13%; 8 of 61), and disseminated nocardiosis (15%; 9 of 61). The most commonly identified species were Nocardia asteroides and Nocardia cyriacigeorgica (each 11%). Linezolid was the only antimicrobial to which isolates were universally susceptible; 89% (48 of 54), 60% (32 of 53), and 48% (26 of 54) of isolates were susceptible to trimethoprim-sulfamethoxazole, ceftriaxone, and imipenem, respectively. Eighteen patients (30%) required intensive care unit (ICU) admission, and 1-year mortality was 31%.

CONCLUSIONS

The incidence of nocardiosis in tropical Australia is amongst the highest reported globally. Nocardiosis occurs in both immunocompromised and immunocompetent hosts, and it is associated with high rates of ICU admission, 1-year mortality, and resistance to commonly recommended antimicrobials. Diagnosis should be considered in patients with consistent clinical features, particularly if they are Indigenous or have chronic lung disease.

Nocardia farcinica abscess of the cerebellum in an immunocompetent patient: A case report and review of the literature

Nocardial brain abscesses are uncommon and rarely occur in patients without predisposing factors. They may be mistaken for gliomas or necrotic metastases, and surgical intervention may be required to make the diagnosis. We report the first case of Nocardia farcinica cerebellar abscess in a patient without immunosuppression. He presented to us with headache and instability beginning a week before. Brain magnetic resonance imaging (MRI) revealed a cystic lesion located at the right cerebellar hemisphere, hypointense in T1 and hyperintense in T2, with a fine wall that enhanced after injection of gadolinium. Image tests also showed a cavitated lesion at the upper lobule of the right lung. The patient underwent craniotomy and drainage of the cerebellar abscess. Initial post-operative treatment with linezolid produced a limited response. He was re-operated and vancomycin, imipenem and ciprofloxacin were added with an excellent outcome of the cerebellar and lung lesions.

Experience with linezolid for the treatment of nocardiosis in organ transplant recipients

OBJECTIVES

Combination therapy with amikacin is recommended for treatment of nocardiosis in severely ill solid organ transplant recipients (SOT), but its use is complicated by nephrotoxicity. Linezolid has shown promise as an alternative in the empiric therapy of nocardiosis, but little is known about its effectiveness and safety in this setting. We describe the experience with linezolid for nocardiosis in SOT.

METHODS

Retrospective review of cases of nocardiosis in SOT at a large center from 2006 to 2012.

RESULTS

Nineteen cases were identified, 15/19 in lung transplant recipients. Median creatinine clearance at diagnosis was 56 ml/min. Eighteen patients were treated: 17/18 (94%) received trimethoprim/sulfamethoxazole and 15/18 (83%) received linezolid. Median duration of linezolid treatment was 21 days and it was discontinued in 10/15 (67%) due to side effects. Thrombocytopenia and anemia occurred in 14/15 (93%) and 9/15 (60%) of patients on linezolid, respectively, and were not different from patients not on linezolid. Cure was observed in 16/19 (84%), 33% of deaths were related to nocardiosis.

CONCLUSIONS

Linezolid was acceptable as initial empiric therapy for nocardiosis. Myelosuppression was a limiting factor, but not exclusive to patients on linezolid and could have been aggravated by concomitant use of other myelosuppressive drugs.

Successful treatment of Nocardia pneumonia with cytomegalovirus retinitis coinfection in a renal transplant recipient

Nocardiosis is a rare opportunistic infection, especially seen in immunocompromised patients, including renal allograft recipients. Primary pulmonary infection is the most common clinical pattern and can easily result in disseminated Nocardia infection if treatment therapy is not adequate at the beginning. We report a case of pulmonary nocardiosis associated with cytomegalovirus retinitis in a renal transplant recipient, followed by chronic allograft dysfunction. Our patient was a 50-year-old male renal allograft recipient, with diabetes mellitus and hypertension, who was diagnosed with pneumonia and cytomegalovirus retinitis. High-resolution computed tomography scan of the thorax and bronchoscopy revealed nocardial pneumonia. The patient responded well to ceftriaxone and was later switched to oral minocycline. To our knowledge, this is the first report of a successful treatment of co-infection with Nocardia pneumonia and cytomegalovirus retinitis in a renal transplant patient, with early diagnosis and prompt treatment.

Disseminated Nocardia farcinica: literature review and fatal outcome in an immunocompetent patient

BACKGROUND

Nocardia farcinica is a gram-positive, partially acid-fast, methenamine silver-positive aerobic actinomycete. Nocardia spp. are opportunistic pathogens, and N. farcinica is the least common species of clinical importance.

METHODS

Review of the recent literature and description of a immunocompetent patient with no known risk factors who contracted fatal N. farcinica sepsis.

RESULTS

Positive pre-mortem and post-mortem cultures from the lung and synovium correlated with acute bronchopneumonia and synovitis at autopsy. Colonies of filamentous bacteria, which were not apparent in conventional hematoxylin and eosin-stained sections, were observed with gram and methenamine silver stains, but acid-fast stains were negative. A literature review revealed that disseminated N. farcinica often is associated with an underlying malignant tumor or autoimmune disease (88% of patients). Chemotherapy or corticosteroid treatments are additional risk factors.

CONCLUSIONS

Trimethoprim-sulfamethoxazole typically is the first-line therapy for N. farcinica; treatment with amikacin and imipenem-cilastatin is used less often (7% of patients). Despite aggressive therapy, we observed that the death rate (39%) associated with N. farcinica in recent publications was eight percentage points higher than reported in a review from 2000.

Successful long-term treatment of cerebral nocardiosis with unexpectedly low doses of linezolid in an immunocompromised patient receiving complex polytherapy

Cerebral nocardiosis is a severe infection that carries the highest mortality rate among all bacterial cerebral abscesses. We report on a case in an immunocompromised patient which was successfully treated with unexpectedly low doses of linezolid. Therapeutic drug monitoring was very helpful in highlighting issues of poor compliance and of drug-drug interactions.

A fatal case of pulmonary nocardiosis

Pulmonary nocardiosis is a serious, most often considered an opportunistic infection affecting the respiratory tract. Even though it is more common in immunocompromised hosts, it is not infrequently seen in immunocompetent patients as well. The aerosol route is the main portal of entry in to the body. Molecular techniques have revolutionised the identification of Nocardia species. However such tests are limited to referral laboratories. The radiographic appearances of Nocardia infection vary from a small nodule to bilateral infiltrates with cavitation. Traditionally sulphonamides have been considered the treatment of choice. However, resistance to sulphonamides is increasingly recognised. Carbapenems and linezolid have been found to be uniformly active against all the pathogenic species of Nocardia that affect human beings. The authors report a case of pulmonary nocardiosis in an immunocompetent patient, in whom the infection relentlessly progressed to florid sepsis despite prompt institution of right antibiotics. Florid sepsis relating to pulmonary nocardiosis is rare.

Disseminated Nocardiosis caused by Nocardia concava with acute respiratory failure and central nervous system involvement treated with linezolid

Nocardia concava was identified as a new species in 2005; however, the clinical manifestations of Nocardia concava infection have yet to be clarified. We herein present the case of an immunosuppressed patient who developed disseminated nocardiosis caused by N. concava with multiple abscesses in the lungs, cutis, subcutaneous tissue, skeletal muscles and kidneys accompanied by central nervous system involvement, including meningitis and ventriculitis. The patient was cured with appropriate treatment including linezolid after testing for susceptibility. Linezolid should be considered as an alternative agent for treating disseminated nocardiosis because of its effective distribution to multiple sites.

Nocardia infection in kidney transplant recipients: case report and analysis of 66 published cases

Nocardiosis is a rare but life-threatening opportunistic infection, especially in immune compromised patients, including kidney transplant recipients. Primary pulmonary infection is the most common clinical pattern, and can easily result in disseminated Nocardia infection if treatment therapy is not adequate at the beginning. In this article, we report a new case of disseminated nocardiosis (lungs, skin, and pericardium) after renal allograft transplantation. We also review the English literature published from 1980 to 2010 and analyze the clinical characteristics of nocardiosis in kidney transplant recipients.

Nocardiosis: updated clinical review and experience at a tertiary center

Nocardiosis is a rare opportunistic disease that affects mainly patients with deficient cell-mediated immunity, such as those with acquired immunodeficiency syndrome (AIDS) or transplant recipients. Pulmonary disease is the most common presentation in immunosuppressed patients and approximately one-third have a disseminated disease. Primary cutaneous nocardiosis is more frequently observed in immunocompetent patients with direct inoculation of the organism through professional exposure. The diagnosis can be challenging, as signs and symptoms are not specific and a high index of clinical of suspicion is necessary. Although gram stain, modified acid-fast stain, and cultures remain as the standard diagnostic tools, novel molecular techniques have changed the taxonomy of these organisms and, in some instances, have facilitated their identification. The disease has a marked tendency to recur and a high morbidity and mortality rate in immunosuppressed patients. Treatment is usually prolonged and an associated antibiotic treatment is preferred for severe disease. Although sulfonamides in combination with other antibiotics are still the treatment of choice, other associations such as imipenem plus amikacin are preferred in some centers. Linezolid is a useful alternative therapeutic agent due to its oral availability and activity against most of the isolates studied. Twenty-eight cases of nocardiosis were diagnosed at our center between January 1989 and April 2009. We report the epidemiologic characteristics of Nocardia spp. observed in our institution and discuss the risk factors, clinical features, diagnosis, and management of the disease.

Cerebellar nocardiosis and myopathy from long-term corticosteroids for idiopathic thrombocytopenia

Infection of the central nervous system with Nocardia sp. usually manifests as supratentorial abscesses. Supratentorial and cerebellar abscesses from infection with Nocardia sp. following immunosuppression with long-term corticosteroids for idiopathic thrombocytopenia (ITP) have not been reported. An 83 years-old, human immunodeficiency virus (HIV)-negative, polymorbid male with ITP for which he required corticosteroids since age 53 years developed tiredness, dyspnoea, hemoptysis, abdominal pain, and progressive gait disturbance. Imaging studies of the lung revealed an enhancing tumour in the right upper lobe with central and peripheral necrosis, multiple irregularly contoured hyperdensities over both lungs, and right-sided pleural effusions. Sputum culture grew Nocardia sp. Neurological diagnostic work-up revealed dysarthria, dysphagia, ptosis, hypoacusis, tremor, dysdiadochokinesia, proximal weakness of the lower limbs, diffuse wasting, and stocking-type sensory disturbances. The neurological deficits were attributed to an abscess in the upper cerebellar vermis, myopathy from corticosteroids, and polyneuropathy. Meropenem for 37 days and trimethoprime-sulfamethoxazole for 3 months resulted in a reduction of the pulmonary, but not the cerebral lesions. Therefore, sultamicillin was begun, but without success. Long-term therapy with corticosteroids for ITP may induce not only steroid myopathy but also immune-incompetence with the development of pulmonary and cerebral nocardiosis. Cerebral nocardiosis may not sufficiently respond to long-term antibiotic therapy why switching to alternative antibiotics or surgery may be necessary.

Pulmonary nocardiosis: risk factors, clinical features, diagnosis and prognosis

PURPOSE OF REVIEW

Pulmonary infection by Nocardia spp. has been recognized for the past 100 years. The number of cases of pulmonary nocardiosis reported in the literature is increasing, and in some cases, a diagnosis is reached even postmortem. This increase is partly due to the growing number of patients with depressed cellular immunity. The diagnosis of this infection, which has a high rate of mortality, is usually delayed, due to a nonspecific clinical-radiological presentation and the difficulties in cultivating the bacteria. This review analyzes the current situation, in order to better understand this infection and enhance awareness and clinical suspicion that would lead to further specific microbiological studies and treatment.

RECENT FINDINGS

The number of case series in the literature is increasing. This development may be due to an absolute increase in the number of immunocompromised patients, but also to improvements in laboratory techniques and molecular methods to detect nocardiosis.

SUMMARY

It is important to keep in mind, and suspect the presence of pulmonary nocardiosis in the immunodepressed patients with clinical pulmonary infection. Furthermore, the laboratory should be notified when Nocardia is suspected in a clinical specimen so that measures can be taken to optimize recognition and recovery of the organism.

Efficacy of DA-7218, a new oxazolidinone prodrug, in the treatment of experimental actinomycetoma produced by Nocardia brasiliensis

Two recently synthesized oxazolidinones: (R)-3-(4-(2-(2-methyltetrazol-5-yl)-pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one (DA-7157) and its corresponding pro-drug (R)-3-(4-(2-(2-methyltetrazol-5-yl)-pyridin-5-yl)-3-fluorophenyl)-2-oxo-5-oxazolidinyl) methyl disodium phosphate (DA-7218), have shown very good activity against several Gram positive bacteria, including Nocardia and Mycobacterium. In the present work we evaluated the therapeutic in vivo effects of DA-7218 on Nocardia brasiliensis. We first determined the plasma concentration of the prodrug in BALB/c mice using several doses and then tested its activity in an in vivo experimental actinomycetoma murine model. At the end of treatment, there was a statistically significant difference between the three drug receiving groups (25, 12.5 and 5 mg/kg) and the control group(saline solution) (p=0.001), proving that DA-7218 is effective for the treatment of experimental murine actinomycetoma. This compound could be a potential option for patients affected with mycetoma by Nocardia brasiliensis.