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

Experimental Granulomatous Pulmonary Nocardiosis in BALB/C Mice

Pulmonary nocardiosis is a granulomatous disease with high mortality that affects both immunosuppressed and immunocompetent patients. The mechanisms leading to the establishment and progression of the infection are currently unknown. An animal model to study these mechanisms is sorely needed. We report the first in vivo model of granulomatous pulmonary nocardiosis that closely resembles human pathology. BALB/c mice infected intranasally with two different doses of GFP-expressing Nocardia brasiliensis ATCC700358 (NbGFP), develop weight loss and pulmonary granulomas. Mice infected with 10⁹ CFUs progressed towards death within a week while mice infected with 10⁸ CFUs died after five to six months. Histological examination of the lungs revealed that both the higher and lower doses of NbGFP induced granulomas with NbGFP clearly identifiable at the center of the lesions. Mice exposed to 10⁸ CFUs and subsequently to 10⁹ CFUs were not protected against disease severity but had less granulomas suggesting some degree of protection. Attempts to identify a cellular target for the infection were unsuccessful but we found that bacterial microcolonies in the suspension used to infect mice were responsible for the establishment of the disease. Small microcolonies of NbGFP, incompatible with nocardial doubling times starting from unicellular organisms, were identified in the lung as early as six hours after infection. Mice infected with highly purified unicellular preparations of NbGFP did not develop granulomas despite showing weight loss. Finally, intranasal delivery of nocardial microcolonies was enough for mice to develop granulomas with minimal weight loss. Taken together these results show that Nocardia brasiliensis microcolonies are both necessary and sufficient for the development of granulomatous pulmonary nocardiosis in mice.

Pulmonary nocardiosis in Chronic Obstructive Pulmonary Disease: A new clinical challenge

Pulmonary nocardiosis (PN) is a rare but severe disease caused by Nocardia spp. Despite the traditional description as opportunistic infection, case reports and case series of pulmonary nocardiosis have recently been reported in immunocompetent patients too, in particular among people with chronic pulmonary diseases such as advanced Chronic Obstructive Pulmonary Disease (COPD). PN is characterized by non-specific symptoms and radiological findings; bacteriological culture can be difficult. For the reasons above, diagnosis of PN is challenging, sometimes resulting in a misdiagnosis of tuberculosis. We report an interesting case of PN in a 75-year-old male with COPD. He complained a 3-months history of fatigue, evening rise in body temperature, night sweats, unexplained weight loss of 5 kg, worsening dyspnea, cough and mucopurulent sputum. The chest X-ray showed multiple nodules with cavitations bilaterally in the apical and subclavian regions. Nocardia cyriacigeorgica with 100% identity was identified in three sputum samples. Since the patient has never undergone a systemic and/or inhaled steroid therapy, and has no respiratory failure and comorbidities entailing immunodepression, it is conceivable that, in this immunocompetent patient, the COPD could represent an isolated risk factor for PN. Risk factors, clinical presentations, radiographic findings, differential diagnosis and review of the literature of PN cases in COPD, pointing out the similarities and differences, are also described.

Autochthonous Nocardia cerradoensis Infection in Humans, Spain, 2011 and 2014

Nocardia cerradoensis was first isolated in 2003 in the El Cerrado region of Brazil; since then, only 2 human infections, in France and Spain, have been reported. We describe 3 autochthonous cases in residents of Spain during 2011 and 2014. Together these cases support the idea of an emerging global pathogenic microorganism.

Pulmonary Nocardiosis in the Immunocompetent Host: Case Series

Pulmonary nocardiosis is commonly recognized as an opportunistic infection in patients with predisposing immunosuppressive conditions. However, reports of pulmonary nocardiosis in the immunocompetent host are rare. Here, we report a case series of four patients with pulmonary nocardiosis without a predisposing condition.

Clinical Analysis of Pulmonary Nocardiosis in Patients With Autoimmune Disease

Nocardiosis is an opportunistic infection that most commonly involves the lung; however, only a few case reports of autoimmune disease complicated by pulmonary nocardiosis exist in the literature. We conducted a retrospective analysis of 24 cases of both autoimmune disease and pulmonary nocardiosis at the Peking Union Medical College Hospital between 1990 and 2012. Fifty-two cases were hospitalized with nocardiosis, 24 of whom had at least 1 autoimmune disease before the diagnosis of pulmonary nocardiosis. The cohort patients consisted of 5 men and 19 women, with a mean age of 44.2 years. All were negative for human immunodeficiency virus. All but 1 patient had received immunosuppressants, including corticosteroids, cyclophosphamide, azathioprine, methotrexate, or hydroxychloroquine. Fever (87.5%), cough (83.3%), and sputum (79.2%) were the most common clinical manifestations. Ten cases were accompanied by subcutaneous nodules and/or cutaneous abscesses, and 4 had brain abscess. Half of them were lymphocytopenic. Thirteen of the 16 cases who underwent lymphocyte subtype analysis had decreased CD4+ T-cell counts. Nineteen cases had decreased serum albumin levels. Nocardia was isolated from sputum (13/24), bronchoalveolar lavage fluid (4/6), lung tissue (5/6), pleural effusions (3/5), skin or cutaneous pus (7/10), and brain tissue (1/1). The most common imaging findings were air-space opacities (83.3%), followed by nodules (62.5%), cavitations (45.8%), and masses (37.5%). Five were administered co-trimoxazole only, and the others were treated with 2 or more antibiotics. All 5 cases with skin abscesses and 2 of the 4 cases with brain abscesses were treated by surgical incision and drainage. None underwent thoracic surgery. Corticosteroid dosages were decreased in all cases, and cytotoxic agents were discontinued in some cases. Twenty-two cases recovered, and 2 died. Pulmonary nocardiosis associated with an underlying autoimmune disease showed a female predominance and presentation at younger age. Immunosuppressant therapy, lymphocytopenia, particularly low CD4+ T-lymphocyte counts, and low serum albumin levels may be disease susceptibility factors. Air-space opacities and nodules were the most common chest imaging features, and disseminated nocardiosis with lung and skin involvement was more common among them. Early diagnosis and anti-nocardial antibiotics with modulation of the basic immunosuppressive therapy were important for them.

Human Nocardia Infections: A Review of Pulmonary Nocardiosis

Human nocardiosis may present as an acute or a chronic infection. Although a saprophyte Nocardia spp are responsible for superficial skin infections, pulmonary infections, and disseminated nocardiosis usually involving patients who are immunosuppressed and debilitated. Infections in immunocompetent individuals are usually chronic and present non-specific symptoms. Invasive and disseminated nocardiosis is common among patients with weakened cellular immune systems. Clinical diagnosis of pulmonary nocardiosis is difficult owing to the similarity of its presentation with other respiratory pathogens that include Actinomycetes members and Mycobacteriumtuberculosis. Laboratory diagnosis of human nocardiosis is plagued by the fact that a culture of Nocardia spp requires prolonged incubation periods for isolation which most laboratories fail to follow. The lack of clinical, laboratory, and epidemiological data on the incidence of nocardiosis in humans undermines its significance as a potential pathogen. This review attempts to reexamine the pathogenic potential of Nocardia in human infections

A mimic's imitator: a cavitary pneumonia in a myasthenic patient with history of tuberculosis

A 77-year-old man with myasthenia gravis receiving prednisone and plasmapheresis was found to have right upper lobe cavitary pneumonia on radiological imaging studies after thymectomy. He had a remote history of treated pulmonary tuberculosis (TB) at the age of 19. On the basis of history of TB and current prednisone therapy, reactivation of pulmonary TB was highly suspected. Branching Gram-positive bacilli were identified on bronchoalveolar lavage (BAL). BAL Ziehl-Neelsen Acid-fast bacilli stain was negative, but a modified Kinyoun stain revealed branching, beaded, filamentous bacilli, suggestive of Nocardia spp. Nocardia cyriacigeorgica grew from the BAL culture. Cerebral MRI demonstrated a right frontal lobe lesion, clinically correlated to be nocardial brain abscess. The patient was treated with three-drug antimicrobial therapy (trimethoprim-sulfamethoxazole, meropenem, linezolid) for 2 months, followed by an additional 10 months of trimethoprim-sulfamethoxazole. Amikacin would have been included in the initial three-drug regimen, but its use was contraindicated in our myasthenic patient because aminoglycoside would trigger fatal myasthenic crisis by neuromuscular blockage. Follow-up imaging studies revealed resolution of the lung and brain lesions.

First report of Nocardia fusca isolated in humans

Nocardia fusca was first described in 1983; however, to date, no report of human infection has been done. In this work, we report the first case of N. fusca isolation during an episode of acute exacerbation in a patient with chronic obstructive pulmonary disease. The extent of the role of N. fusca as human pathogen still has to be determined.

Successful treatment of multifoci nocardial brain abscesses: a case report and literature review

Brain nocardiosis is a serious opportunistic infection with high mortality. It exists more common in the immunocompromised hosts than the immunocompetent patients. Trimethoprim-sulfamethoxazole (TMP-SMZ) has been mostly considered as the choice of the medical treatment. Linezolid is also newly found to be effective to avoid the invasive surgery. The authors reported a case of patient with multifoci nocardial brain abscesses who failed with the combination of linezolid and TMP-SMZ alone but recovered with the surgery intervention and sequential antibiotics for 2 years. The patient lived a high quality life without recurrence and complications during the 30 months follow-up.Through the literature review, we recommend earlier stereotactic aspiration for diagnosis, combination with surgery intervention and prolonged anti-infection therapy would improve the prognosis.

Nocardiosis presenting as a lung mass in a kidney transplant recipient

Nocardiosis is a potentially life-threatening disease in renal transplant recipients. It is an uncommon infection with high lethality if left untreated. We report a case of a 67 year-old kidney transplant recipient who developed pulmonary nocardiosis and presented with pleural effusion along with an underlying lung mass, which was successfully treated with trimethoprim-sulphamethoxazole in conjunction with a reduction in immunosuppressive therapy. Five months later, graft function remains stable with complete regression of radiological abnormalities and absence of symptoms. Nocardiosis should be suspected in the presence of pulmonary symptoms in a transplant patient with unusual radiological presentation.

Pulmonary nocardiosis revisited: A case series

Pulmonary nocardiosis is a rising bacterial infection, with a high propensity for misdiagnosis. On account of a paucity of prospective studies, there is limited understanding on various aspects of its diagnosis and treatment. We present three patients with pulmonary nocardiosis, with emphasis on the predisposing factors, variable disease course, and treatment issues. There is a need to understand the basis of these discrepancies so as to rationalize the management of this potentially fatal infection.

Diversity and frequency of Nocardia spp. in the soil of Isfahan province, Iran

OBJECTIVE

To isolate and identify Nocardia spp. from soil in different regions of Isfahan province in the center of Iran.

METHODS

This study was conducted in 32 districts (16 cities and 16 villages) in Isfahan province during two years. A total of 800 soil samples from these regions were studied by using kanamycin. The isolated Nocardia species were examined by gram and acid-fast staining and were identified biochemically and morphologically. The frequency and distribution of Nocardia spp. were determined in relation to different factors such as soil pH and temperate climate.

RESULTS

From 153 (19.1%) Nocardia isolates identified, Nocardia asteroids (N. asteroids) complex (45.5%) and Nocardia brasiliensis (N. brasiliensis) (24.7%) were the most frequently isolated species, followed by Nocardia otitidiscaviarum (2.2%), Nocardiopsis dassonvillei, Actinomadura actinomadura (each 1.7%) and Nocardia transvalensis (1.1%) and also unknown spp. (23.0%). In this study, most species (54.4%) of Nocardia, especially N. asteroides complex were isolated from soils with pH: 7.01-8, whereas in pH: 8.01-9 more N. brasiliensis was isolated. The most Nocardia spp. was detected from regions with semi-nomadic and temperate climate (41.1%).

CONCLUSIONS

N. asteroids complex is more prevalent in Isfahan province and soil can be a potential source of nocardiosis infections. It is to be considering that climate and soil pH are involved in the frequency and diversity of aerobic Actinomycetes.

Nocardia co-infection in patients with pulmonary tuberculosis

Background:

Tuberculosis (TB) remains as one of the most serious infectious diseases in the world. Pulmonary tuberculosis can occur with other pulmonary diseases caused by opportunistic organisms such as Nocardia spp. particularly in immunocompromised patients. Therefore, diagnosis of co-infection at the early stage of the disease could be lifesaving.

Objectives:

The goal of this study was to detect Mycobacterium tuberculosis and Nocardia spp. in sputum specimens in order to assess the concomitant nocardiosis and tuberculosis in patients with suspected pulmonary tuberculosis.

Patients and Methods:

From March 2011 to April 2012, 189 sputum specimens were obtained from patients who were suspected of having pulmonary tuberculosis. Out of 189 samples, 32 of the samples belonged to hospitalized HIV-infected patients. Samples were examined by Gram and Ziehl-Nelsen staining, culture and PCR methods.

Results:

From 157 sputum specimens, positive samples by acid fast staining, culture and PCR for M. tuberculosis were reported for 7.6% (12/157), 10.1% (16/157) and 7% (11/157) of samples, respectively. No results were obtained by the described methods for Nocardia spp. Among 32 samples of HIV-infected patients, four (12.5%) had positive results for acid fast staining, culture and PCR detecting M. tuberculosis while only two samples had positive results for Nocardia spp. by PCR and no results were reported by culture, Gram and acid fast staining for this organism.

Conclusions:

Concurrent pulmonary nocardiosis and tuberculosis is frequent in HIV-infected patients. Rapid and sensitive methods such as PCR are recommended for detection of such co-infections.

Mixed pulmonary infection in an immunocompromised patient: a rare case report

Patients who are immunocompromised are predisposed to a variety of common and uncommon pulmonary infections. We report a case of mixed pulmonary infection by drug resistant tuberculosis with a nocardiosis in a 49-year-old man who was a known case of chronic obstructive pulmonary disease, on prolonged corticosteroid use with diabetes mellitus. Chronic use of corticosteroids is a predisposing factor for opportunistic infections, such as nocardiosis or tuberculosis. Since such a mixed infection is rare, maybe a combined approach to therapy early in the course of disease would be effective in such cases.

First report of Nocardia beijingensis infection in an immunocompetent host in the United States

Here we describe the first reported case of Nocardia beijingensis infection in the United States, made rarer by its presence in an immunocompetent patient.

Pulmonary nocardiosis: a clinical analysis of 59 cases

BACKGROUND

Pulmonary nocardiosis is a rare but severe infection caused by Nocardia species. This study aimed at describing the clinical characteristics and prognosis of pulmonary nocardiosis.

METHODS

An observational, retrospective study was undertaken of patients diagnosed with pulmonary nocardiosis over a 13-year period at the Kinki-Chuo Chest Medical Center, Osaka, Japan.

RESULTS

Seven patients with airway nocardial colonization and 59 patients with pulmonary nocardiosis were identified, one of whom had disseminated nocardiosis. Patients with pulmonary nocardiosis were predominantly male patients (73%), with a mean age of 66 (range, 15-88) years. New-onset cough and dyspnea were the most common manifestations (76%). Although 52 (88%) patients had at least one underlying pulmonary disease, most patients did not appear to be systemically immunocompromised. The predominant abnormality on chest computed tomography in pulmonary nocardiosis was airspace consolidation (52%), sometimes associated with cavitation. Multivariate Cox proportional-hazards analysis revealed the following significant and independent risk factors for overall mortality: age >68 years (hazard ratio [HR], 4.7; 95% confidence interval [CI], 1.6-14; p=0.05), pulmonary aspergillosis (HR, 8.8; 95% CI, 2.4-33; p=0.01), and trimethoprim/sulfamethoxazole (TMP-SMZ) resistance (HR, 4.3; 95% CI, 1.6-11; p=0.04).

CONCLUSIONS

Clinicians should be aware that pulmonary nocardiosis can occur even in immunocompetent patients, especially those with an underlying pulmonary disease. In pulmonary nocardiosis, older age, pulmonary aspergillosis, and TMP-SMZ resistance are associated with increased risk of mortality.

Functional diversity of Nocardia in metabolism

Bacteria affiliated in the genus Nocardia are aerobic and Gram-positive actinomycetes that are widely found in aquatic and terrestrial habitats. As occasional pathogens, several of them cause infection diseases called 'nocardiosis' affecting lungs, central nervous system, cutaneous tissues and others. In addition, members of the genus Nocardia exhibit an enormous metabolic versatility. On one side, many secondary metabolites have been isolated from members of this genus that exhibit various biological activities such as antimicrobial, antitumor, antioxidative and immunosuppressive activities. On the other side, many species are capable of degrading or converting aliphatic and aromatic toxic hydrocarbons, natural or synthetic polymers, and other widespread environmental pollutants. Because of these valuable properties and the application potential, Nocardia species have attracted much interest in academia and industry in recent years. A solid basis of genetic tools including a set of shuttle vectors and an efficient electroporation method for further genetic and metabolic engineering studies has been established to conduct efficient research. Associated with the increasing data of nocardial genome sequences, the functional diversity of Nocardia will be much faster and better understood.

Lung transplant infection

Lung transplantation has become an accepted therapeutic procedure for the treatment of end‐stage pulmonary parenchymal and vascular disease. Despite improved survival rates over the decades, lung transplant recipients have lower survival rates than other solid organ transplant recipients. The morbidity and mortality following lung transplantation is largely due to infection‐ and rejection‐related complications. This article will review the common infections that develop in the lung transplant recipient, including the general risk factors for infection in this population, and the most frequent bacterial, viral, fungal and other less frequent opportunistic infections. The epidemiology, diagnosis, prophylaxis, treatment and outcomes for the different microbial pathogens will be reviewed. The effects of infection on lung transplant rejection will also be discussed.

Effects of inhaled corticosteroids on pneumonia severity and antimicrobial resistance

BACKGROUND

Limited information is available regarding the impact of prior use of inhaled corticosteroids (ICS) in patients subsequently developing community-acquired pneumonia (CAP). We assessed the effects of prior ICS use on severity of illness and microbiology in CAP hospitalized patients.

METHODS

A retrospective cohort study of subjects with CAP (by the International Classification of Diseases, 9th Revision, Clinical Modification) was conducted over a 4-year period at 2 tertiary teaching hospitals. Subjects were considered to be ICS users if they received ICS prior to admission. Primary outcomes were severity of illness and microbiology at admission.

RESULTS

Data were abstracted on 664 subjects: 89 prior ICS users (13.4%) and 575 non-users (86.6%). Prior ICS users had higher severity of illness at admission: mean ± SD Pneumonia Severity Index 100.8 ± 31.4 vs 68.8 ± 33.4, P = .001, and CURB-65 (confusion, urea nitrogen, respiratory rate, blood pressure, ≥ 65 years of age) score 1.56 ± 1.02 vs 1.19 ± 1.02, P = .002. Prior ICS use was independently associated with antimicrobial-resistant pathogens: 11.2% vs 5.9%, odds ratio 2.6, 95% CI 1.1-6.1, P = .04.

CONCLUSIONS

Prior ICS use was associated with higher severity of illness at admission and higher incidence of antimicrobial-resistant pathogens in CAP hospitalized patients.

Pulmonary nocardiosis in southern Taiwan

BACKGROUND/PURPOSE

Nocardiosis mainly affects immunocompromised patients. The objectives of this study were to better understand the epidemiologic, demographic, clinical, and laboratory information in patients with pulmonary nocardiosis in southern Taiwan.

METHODS

Retrospective analyzing patients aged ≥18 years with culture-proven pulmonary nocardiosis received treatment at KCGMH between January 2004 and June 2010. Nocardiae were identified by 16S rRNA gene sequence analysis. Patients with pulmonary nocardiosis caused by the mostly commonly encountered Nocardia sp. were compared with those with pulmonary nocardiosis due to other Nocardia spp.

RESULTS

Among the 20 patients included, cough (80%) and fever (50%) were the 2 leading symptoms/signs, while lobar consolidation (50%) and pleural effusion (40%) were the most frequent radiographic manifestations. Eighteen patients (90%) had at least one underlying disease/condition. Nocardia cyriacigeorgica was most commonly found. Compared with those whose pathogens were other Nocardia spp., patients with pulmonary nocardiosis caused by N cyriacigeorgica experienced higher clinical severity as measured by APACHE II score (19.8 ± 7.0 vs. 12.8 ± 6.7; p = 0.04) and ICU admission rate (100% vs. 25%; p < 0.01). Thirteen patients (65%) turned out to be fatal. The severity (APACHE II score, 18 ± 6 vs. 10 ± 8; p = 0.02) and the proportion of acute and subacute pulmonary nocardiosis (76% vs. 0%, p = 0.03) between fatal and survived patients differed significantly.

CONCLUSIONS

N cyriacigeorgica was the most common pathogen in southern Taiwan. Higher mortality rate in patients with pulmonary nocardiosis was related to disease severity and acute and subacute infection.

Nocardia brasiliensis cell wall lipids modulate macrophage and dendritic responses that favor development of experimental actinomycetoma in BALB/c mice

Nocardia brasiliensis is a Gram-positive facultative intracellular bacterium frequently isolated from human actinomycetoma. However, the pathogenesis of this infection remains unknown. Here, we used a model of bacterial delipidation with benzine to investigate the role of N. brasiliensis cell wall-associated lipids in experimental actinomycetoma. Delipidation of N. brasiliensis with benzine resulted in complete abolition of actinomycetoma without affecting bacterial viability. Chemical analyses revealed that trehalose dimycolate and an unidentified hydrophobic compound were the principal compounds extracted from N. brasiliensis with benzine. By electron microscopy, the extracted lipids were found to be located in the outermost membrane layer of the N. brasiliensis cell wall. They also appeared to confer acid-fastness. In vitro, the extractable lipids from the N. brasiliensis cell wall induced the production of the proinflammatory cytokines interleukin-1β (IL-1β), IL-6, and CCL-2 in macrophages. The N. brasiliensis cell wall extractable lipids inhibited important macrophage microbicidal effects, such as tumor necrosis factor alpha (TNF-α) and nitric oxide (NO) production, phagocytosis, bacterial killing, and major histocompatibility complex class II (MHC-II) expression in response to gamma interferon (IFN-γ). In dendritic cells (DCs), N. brasiliensis cell wall-associated extractable lipids suppressed MHC-II, CD80, and CD40 expression while inducing tumor growth factor β (TGF-β) production. Immunization with delipidated N. brasiliensis induced partial protection preventing actinomycetoma. These findings suggest that N. brasiliensis cell wall-associated lipids are important for actinomycetoma development by inducing inflammation and modulating the responses of macrophages and DCs to N. brasiliensis.

In vitro activity of TP-271 against Mycobacterium abscessus, Mycobacterium fortuitum, and Nocardia species

The in vitro activities of TP-271, a novel fluorocycline antimicrobial, against 22 isolates of Mycobacterium abscessus, 22 isolates of Mycobacterium fortuitum, and 19 isolates of Nocardia spp. were studied by a microtiter broth dilution method. The MIC(90)s for M. abscessus, M. fortuitum, and Nocardia spp. were 0.5 μg/ml, 0.03 μg/ml, and 8 μg/ml, respectively. TP-271 was significantly more active than the respective control drug in virtually all tests.

Opportunistic and fungal infections of the lung

Opportunistic infections are a major cause of morbidity and mortality in severely immunocompromised patients, such as those receiving chemotherapy or with haematological malignancy, aplastic anaemia or HIV infection, or recipients of solid-organ or stem cell transplants. In addition, the increasing use of biological therapies will result in more patients at risk of opportunistic infections, albeit to a lesser degree than classic causes of immunocompromise. The type and degree of immune defect dictates the profile of potential opportunistic pathogens; T-cell mediated defects increase the risk of viral (cytomegalovirus and respiratory viruses) and Pneumocystis jirovecii infections, whereas neutrophil defects are associated with bacterial pneumonia and invasive aspergillosis. However, patients often have combinations of immune defects and a wide range of other opportunistic infections can cause pneumonia. The radiological pattern of disease (best assessed by CT scan) and speed of onset also help identify the likely pathogen(s), which can then be supported by targeted investigation including early use of bronchoscopy in selected patients. Rapid and expert clinical assessment can identify the most likely pathogens, which can then be treated aggressively and so provide the best opportunity for a positive outcome.

Nocardiosis: updates and clinical overview

Nocardia, a gram-positive bacillus with the microscopic appearance of branching hyphae, can produce considerable disease in the appropriate host. The taxonomy of Nocardia continues to evolve; more than 50 species have been described. Early recognition and effective therapy are imperative to achieve successful outcomes. Although nocardiosis typically occurs in patients with cell-mediated immunosuppressive conditions, infection may occasionally develop in immunocompetent patients as well. This review addresses the microbiology of Nocardia, risk factors for infection, clinical presentations, and management strategies.

Sulfonamide resistance in isolates of Nocardia spp. from a US multicenter survey

Recent reports of increasing in vitro sulfonamide resistance in Nocardia prompted us to investigate the findings. Despite the reports, there is a paucity of clinical reports of sulfonamide failure in treatment of nocardia disease. We reviewed 552 recent susceptibilities of clinical isolates of Nocardia from six major laboratories in the United States, and only 2% of the isolates were found to have resistant MICs of trimethoprim-sulfamethoxazole and/or sulfamethoxazole. We hypothesize that the discrepancies in the apparent sulfonamide resistance between our study and the previous findings may be associated with difficulty in the laboratory interpretation of in vitro MICs for trimethoprim-sulfamethoxazole and sulfamethoxazole and the lack of quality controls for Nocardia for these agents.

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.

Infections in Leukemia and Hematopoietic Stem Cell Transplantation

Infections are one of the most common complications in patients diagnosed with leukemia and serve as a major obstacle to treatment. Through the early 1970s, infections were the most common cause of death in patients diagnosed with acute leukemia, but improvement in treatment and supportive care over the past few decades, coupled with expanded prophylaxis and prevention regimens, have led to reduction in both the frequency and severity of infections. Regardless, due in part to an aging cancer population and the diversity of cancer treatments and procedures, infectious diseases remain a major cause of morbidity and mortality in patients with leukemia.

Nocardiosis complicated with Addison's disease

A 77-year-old woman presented with subacute respiratory symptoms which were demonstrated to be due to nocardiosis. After initial improvement with antimicrobial therapy, new symptoms appeared, consisting of persistent vomits, abdominal pain and hypotension, which led to the diagnosis of Addison's disease.

Nocardiosis in a tertiary care hospital in saudi arabia

BACKGROUND

Nocardiosis is an uncommon bacterial infection that is caused by aerobic actinomycetes of the genus Nocardia. This pathogen has emerged as an important cause of mortality and morbidity among both immunocompetent and (more commonly) immunocompromised hosts. The prevalence of nocardiosis is unknown in Saudi Arabia. Only sporadic cases of cutaneous nocardiosis have been reported. In this study, we performed a 10-year retrospective review of all cases of nocardiosis identified at the King Fahad National Guard Hospital in Riyadh. Clinical presentation, risk factors, site of disease involvement, radiological features, and outcomes of 30 patients with pulmonary and disseminated nocardiosis are presented.

MATERIALS AND METHODS

A retrospective chart review of all cases of nocardiosis over the last ten years.

RESULTS

Thirty cases of nocardiosis were identified. The disease was more common in males. Fever and cough was the most common presentation. Most of the patients had an underlying pulmonary disease. Consolidation was the most prevalent radiological feature. Pleural effusion was common. Unfortunately, none of the isolates were sub-speciated. Cure was possible in 40% of the cases. Ten percent of patients died, while follow-up on the rest of the patients was lost.

CONCLUSION

Nocardiosis is not uncommon in Saudi Arabia. Cases are not restricted to the classical immunocompromised host. A database is urgently needed to better evaluate the prevalence of the illness among the Saudi population.

Pulmonary nocardiosis due to Nocardia otitidiscaviarum in an immunocompetent host- a rare case report

Nocardiosis is a localized or disseminated infection caused by soil-borne aerobic actinomycetes. Pulmonary nocardiosis is a rare infection mostly occurring in immunocompromised patients. We reported a case of 36 year old immunocompetent non-smoker female patient with no premorbid illness who presented with fever, cough with scanty sputum, hemoptysis, left sided chest pain and exertional dyspnea for two weeks. There was no past history of tuberculosis, diabetes mellitus or steroid therapy. Chest X-ray showed homogenous peripherally based opacity in the left upper zone. Bronchoscopy was done and brushing sent for culture, which showed colonies with features of Nocardia species after 48 hours. Further phenotypic characterization revealed it to be Nocardia otitidiscaviarum. Patient was treated with cotrimaxazole for six months after which complete recovery was evidenced symptomatically and radiologically. We report this case to emphasize the fact that among the Nocardia species, Nocardia otitidiscaviarum as causative agent of pulmonary disease is rarely reported even in immunocompromised individuals.

Susceptibility of 186 Nocardia sp. isolates to 20 antimicrobial agents

This study determined the antimicrobial susceptibilities of 186 clinical isolates of Nocardia spp. isolated in Gipuzkoa, northern Spain, between 1998 and 2009. Most isolates were recovered from respiratory samples, Nocardia nova, N. farcinica, N. cyriacigeorgica, N. abscessus, and N. carnea being the species most frequently isolated. Linezolid and amikacin were the only two antimicrobials to which all isolates were susceptible. The majority of N. flavorosea, N. carnea, and N. farcinica isolates were trimethoprim-sulfamethoxazole resistant.

Nocardiosis in a patient with rheumatoid arthritis treated with rituximab and a summary of reported cases

Rituximab is a B-cell-depleting monoclonal anti-CD20 antibody. It is widely used in haematology and rheumatology. However, usage of rituximab in immunosupressed patient has been associated with various opportunistic infections. The authors reported a case of refractory rheumatoid arthritis treated with rituximab, which later presented with non-resolving pneumonia with pulmonary nodule. Percutaneous computer tomogram guided lung biopsy was arranged to confirm the suspicion of tuberculosis, but did not yield conclusive results. Later, she presented left-chest abscess and underwent incision and drainage. The pus culture and sensitivity confirmed pulmonary nocardiosis with chest wall dissemination. She was treated with 2-week course of trimethoprim sulfamethoxazole and responded. The authors also reviewed published cases of nocardiosis post-rituximab.

Phylogeny and identification of Nocardia species on the basis of multilocus sequence analysis

Nocardia species identification is difficult due to a complex and rapidly changing taxonomy, the failure of 16S rRNA and cellular fatty acid analysis to discriminate many species, and the unreliability of biochemical testing. Here, Nocardia species identification was achieved through multilocus sequence analysis (MLSA) of gyrase B of the β subunit of DNA topoisomerase (gyrB), 16S rRNA (16S), subunit A of SecA preprotein translocase (secA1), the 65-kDa heat shock protein (hsp65), and RNA polymerase (rpoB) applied to 190 clinical, 36 type, and 11 reference strains. Phylogenetic analysis resolved 30 sequence clusters with high (>85%) bootstrap support. Since most clusters contained a single type strain and the analysis corroborated current knowledge of Nocardia taxonomy, the sequence clusters were equated with species clusters and MLSA was deemed appropriate for species identification. By comparison, single-locus analysis was inadequate because it failed to resolve species clusters, partly due to the presence of foreign alleles in 22.1% of isolates. While MLSA identified the species of the majority (71.3%) of strains, it also identified clusters that may correspond to new species. The correlation of the identities by MLSA with those determined on the basis of microscopic examination, biochemical testing, and fatty acid analysis was 95%; however, MLSA was more discriminatory. Nocardia cyriacigeorgica (21.58%) and N. farcinica (14.74%) were the most frequently encountered species among clinical isolates. In summary, five-locus MLSA is a reliable method of elucidating taxonomic data to inform Nocardia species identification; however, three-locus (gyrB-16S-secA1) or four-locus (gyrB-16S-secA1-hsp65) MLSA was nearly as reliable, correctly identifying 98.5% and 99.5% of isolates, respectively, and would be more feasible for routine use in a clinical reference microbiology laboratory.

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.

Abscess of adrenal gland caused by disseminated subacute Nocardia farcinica pneumonia. A case report and mini-review of the literature

Background

Infections caused by Nocardia farcinica are uncommon and show a great variety of clinical manifestations in immunocompetent and immunocompromised patients. Because of its unspecific symptoms and tendency to disseminate it may mimic the clinical symptoms and radiologic findings of a tumour disease and the diagnosis of nocardiosis can easily be missed, because there are no characteristic symptoms.

Case presentation

We present a case of an adrenal gland abscess caused by subacute disseminated N. farcinica pneumonia.

Conclusion

An infection with N. farcinica is potentially lethal because of its tendency to disseminate -particularly in the brain- and its high resistance to antibiotics. Awareness of this differential diagnosis allows early and appropriate treatment to be administered.

The biocontaminants and complexity of damp indoor spaces: more than what meets the eyes

Nine types of biocontaminants in damp indoor environments from microbial growth are discussed: (1) indicator molds; (2) Gram negative and positive bacteria; (3) microbial particulates; (4) mycotoxins; (5) volatile organic compounds, both microbial (MVOCs) and non-microbial (VOCs); (6) proteins; (7) galactomannans; (8) 1-3-β-D-glucans (glucans) and (9) lipopolysaccharides (LPS — endotoxins). When mold species exceed those outdoors contamination is deduced. Gram negative bacterial endotoxins, LPS in indoor environments, synergize with mycotoxins. The gram positive Bacillus species, Actinomycetes (Streptomyces, Nocardia and Mycobacterium), produce exotoxins. The Actinomycetes are associated with hypersensitivity pneumonitis, lung and invasive infections. Mycobacterial mycobacterium infections not from M. tuberculosis are increasing in immunocompetent individuals. In animal models, LPS enhance the toxicity of roridin A, satratoxins G and aflatoxin B1 to damage the olfactory epithelium, tract and bulbs (roridin A, satratoxin G) and liver (aflatoxin B1). Aflatoxin B1 and probably trichothecenes are transported along the olfactory tract to the temporal lobe. Co-cultured Streptomyces californicus and Stachybotrys chartarum produce a cytotoxin similar to doxorubicin and actinomycin D (chemotherapeutic agents). Trichothecenes, aflatoxins, gliotoxin and other mycotoxins are found in dust, bulk samples, air and ventilation systems of infested buildings. Macrocyclic trichothecenes are present in airborne particles <2 μm. Trichothecenes and stachylysin are present in the sera of individuals exposed to S. chartarum in contaminated indoor environments. Haemolysins are produced by S. chartarum, Memnoniella echinata and several species of Aspergillus and Penicillium. Galactomannans, glucans and LPS are upper and lower respiratory tract irritants. Gliotoxin, an immunosuppressive mycotoxin, was identified in the lung secretions and sera of cancer patients with aspergillosis produced by A. fumigatus, A. terreus, A. niger and A. flavus.

[60-year old woman with round lesion of the right upper lobe of the lung after heart transplantation]

We report on a woman presenting with fever and novel round lesion in the lung four months after heart transplantation. Microbiologic assessment of bronchial lavage and operative specimen revealed pulmonary nocardiosis. Furthermore, cerebral involvement has been observed. Antibiotic treatment according to the microbiological sensitivity test for eleven months resulted in complete remission of pulmonary and cerebral nocardiosis. Immunosuppressive treatment increases the risk for opportunistic infections early after transplantation as well as malignancies during the late course.

Respiratory infections in immunocompromised patients

PURPOSE OF REVIEW

Immunosuppressive states and therapies are becoming common in clinical practice. Recent advances and trends in bacterial, fungal, viral and parasitic pulmonary infections in immunosuppressed patients are described.

RECENT FINDINGS

Pulmonary infections can jeopardize the prognosis of immunosuppressed patients. The number of patients infected with multidrug-resistant bacteria or opportunistic pathogens like rapid-growing environmental mycobacteria, Strongyloides stercoralis or Rhodococcus equi is increasing with the increased numbers of immunosuppressed patients due to HIV/AIDS and the potent immunosuppressive therapies used in solid-organ and haematopoietic transplantations, cancer and systemic illnesses. The slow development of more effective antibiotics underlines the necessity of preventive measures, development of rapid detection tests for pathogens and appropriate treatment regimens to avoid development of further resistance.

SUMMARY

Adequate prophylaxis, clinical suspicion, microbiological and molecular investigations, drug susceptibility-based antibiotic treatment and new drug development are strategies required to face up to the challenge of pulmonary infections in immunodepressed patients.