Fatal pulmonary Nocardia farcinica infection

Isolated Nocardiosis, an Unrecognized Primary Immunodeficiency?

Nocardiosis is an infectious disease caused by the gram-positive bacterium Nocardia spp. Although it is commonly accepted that exposure to Nocardia is almost universal, only a small fraction of exposed individuals develop the disease, while the vast majority remain healthy. Nocardiosis has been described as an "opportunistic" disease of immunocompromised patients, suggesting that exposure to the pathogen is necessary, but a host predisposition is also required. Interestingly, increasing numbers of nocardiosis cases in individuals without any detected risk factors, i.e., without overt immunodeficiency, are being reported. Furthermore, a growing body of evidence have shown that selective susceptibility to a specific pathogen can be caused by a primary immunodeficiency (PID). This raises the question of whether an undiagnosed PID may cause nocardiosis affecting otherwise healthy individuals. This review summarizes the specific clinical and microbiological characteristics of patients with isolated nocardiosis published during the past 30 years. Furthermore, it gives an overview of the known human immune mechanisms to fend off Nocardia spp. obtained from the study of PIDs and patients under immunomodulatory therapies.

Genomic Virulence Features of Two Novel Species Nocardia barduliensis sp. nov. and Nocardia gipuzkoensis sp. nov., Isolated from Patients with Chronic Pulmonary Diseases

Strains 335427^T and 234509^T, isolated from two 76-year-old patients with chronic pulmonary diseases, were the subject of polyphasic taxonomic studies and comparative genomic analyses for virulence factors. The 16 rRNA gene sequence similarity between strains 335427^T and 234509^T and their closest phylogenetic neighbors Nocardia asiatica NBRC 100129^T and Nocardia abscessus NBRC 100374^T were 99.5% and 100%, respectively. Digital DNA-DNA hybridization values between the aforementioned studied strains were well below the 70% threshold for assigning prokaryotic strains to a novel species. Strains 335427^T and 234509^T have genome sizes of 8.49 Mpb and 8.07 Mpb, respectively, with G + C content of 68.5%. Isolate 335427^T has C_16:0, C_18:1 ω₉c, C_18:0 and C_18:0 10 methyl as major fatty acids (>15%) and mycolic acids formed of 52-54 carbon atoms. However, only C_18:1 ω₉c was detected for isolate 234509^T, which had mycolic acids with 44-56 carbon. Based on phenotypic and genetic data, strains 335427^T (DSM 109819^T = CECT 9924^T) and 234509^T (DSM 111366^T = CECT 30129^T) merit recognition as novel species, which are named Nocardia barduliensis sp. nov. and Nocardia gipuzkoensis sp. nov., respectively. All the strains studied had homologous VF-associated genes to those described in M. tuberculosis, including experimentally verified virulence genes in humans related to tuberculosis. The narGHIJ (nitrate reduction pathway) and gvpAFGOJLMK (gas vesicles) genetic maps of strains 335427^T, 234509^T, NBRC 100129^T and NBRC 100374^T showed the same syntenic block and raise the question of whether their functions are interlinked during the infection of the human host. However, further research is required to decipher the role of the gas vesicle in the pathogenicity mechanism of Nocardia spp.

A Rare Presentation of Nocardia pericarditis Leading to Cardiac Tamponade in an Immunocompetent Patient

Nocardia can cause isolated disease in many parts of the body including the brain, skin, and lungs. It is also capable of causing disseminated disease. In almost all cases, Nocardia infections occur in immunocompromised hosts with depressed cell-mediated functions. We present a case of disseminated Nocardia farcinica leading to pericardial effusion and tamponade in an immunocompetent host with the only risk factor being heavy alcohol intake. Treatment relies on an accurate diagnosis. This case presentation highlights the importance of considering Nocardia infections in an alcoholic patient with a worsening clinical picture.

Detection of high serum levels of β-D-Glucan in disseminated nocardial infection: a case report

Background

β-D-glucan (BDG) is a helpful diagnostic marker for many invasive fungal infections, but not for nocardiosis. Here, we reported the first case of nocardial infection with high serum level of BDG.

Case presentation

A 73-year-old man was hospitalized because of fever, headache, and appetite loss after 10 months of steroid and immunosuppressive therapy for cryptogenic organizing pneumonia. With a diagnosis of bacterial pneumonia, treatment with ampicillin/sulbactam was initiated. There was improvement on chest radiograph, but fever persisted. Further work-up revealed multiple brain abscesses on cranial magnetic resonance imaging (MRI). Serum galactomannan and BDG were elevated at 0.6 index and 94.7 pg/ml, respectively. Voriconazole was initiated for presumed aspergillus brain abscess. However, fever persisted and consciousness level deteriorated. Drainage of brain abscess was performed; based on the Gram stain and Kinyoun acid-fast stain, disseminated nocardiosis was diagnosed. Voriconazole was then shifter to trimethoprim/sulfamethoxazole. The presence of Nocardia farcinica was confirmed by the 16S rRNA gene sequence. Treatment course was continued; BDG level normalized after 1 month and cranial MRI showed almost complete improvement after 2 months.

Conclusion

BDG assay is widely used to diagnose invasive fungal infection; therefore, clinicians should be aware that Nocardia species may show cross-reactivity with BDG assay on serum.

The role of oral co-trimoxazole in treating Nocardia farcinica keratitis-a case report

BACKGROUND

Nocardia farcinica is one of the more recently identified species of the Nocardia genus. Nocardia farcinica keratitis is a rare occurrence, with only eight previously reported cases. Semi-permeable rigid contact lens use was associated with one of these reported cases. We report the first case of extended wear soft contact-lens-related Nocardia farcinica keratitis and recommend a new treatment regime.

FINDINGS

A 47-year-old lady presented with a right eye keratitis after wearing her extended wear soft contact lenses for five continuous weeks. There was no history of trauma or swimming with contact lenses in. Empirical ciprofloxacin and tobramycin eye drops were not tolerated due to ocular surface irritation on application; and instead, empirical treatment was with chloramphenicol and fortified gentamicin 1.5 % eye drops. Corneal scrapings grew Nocardia farcinica after 3 weeks-sensitive to amikacin and co-trimoxazole. Treatment was changed to amikacin 2.5 % eye drops, resulting in partial resolution of the corneal infiltrates. Oral co-trimoxazole 160/800 mg BD was added, due to cultured drug sensitivity and its high ocular penetration, with good results and a final right eye best-corrected visual acuity of 6/5.

CONCLUSION

Nocardia farcinica keratitis should be considered in the differential diagnosis of contact-lens-related keratitis. We report the first case occurring in association with extended wear soft contact lenses. Nocardia species can mimic fungal and Acanthamoeba keratitis. Treatment with oral co-trimoxazole has not been previously reported. This case demonstrates a role for co-trimoxazole in treating Nocardia farcinica keratitis based on cultured drug sensitivities.

The role of oral co-trimoxazole in treating Nocardia farcinica keratitis: a case report

Nocardia farcinica is one of the more recently identified species of the Nocardia genus. Nocardia farcinica keratitis is a rare occurrence, with only eight previously reported cases. Semi-permeable rigid contact lens use was associated with one of these reported cases. We report the first case of an extended wear soft contact lens-related Nocardia farcinica keratitis and recommend a new treatment regime. A 47-year-old lady presented with a right eye keratitis after wearing her extended wear soft contact lenses for five continuous weeks. There was no history of trauma or swimming with contact lenses in. Empirical ciprofloxacin and tobramycin eye drops were not tolerated due to ocular surface irritation on application, and instead, empirical treatment was with chloramphenicol and fortified gentamicin 1.5 % eye drops. Corneal scrapings grew Nocardia farcinica after 3 weeks-sensitive to amikacin and co-trimoxazole. Treatment was changed to amikacin 2.5 % eye drops, resulting in partial resolution of the corneal infiltrates. Oral co-trimoxazole 160 mg/800 mg BD was added, due to cultured drug sensitivity and its high ocular penetration, with good results and a final right eye best-corrected visual acuity of 6/5. Nocardia farcinica keratitis should be considered in the differential diagnosis of contact lens-related keratitis. We report the first case occurring in association with extended wear soft contact lenses. Nocardia species can mimic fungal and acanthamoeba keratitis. Treatment with oral co-trimoxazole has not been previously reported. This case demonstrates the role of co-trimoxazole in treating Nocardia farcinica keratitis based on cultured drug sensitivities.

Fatal Nocardia farcinica Bacteremia Diagnosed by Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry in a Patient with Myelodysplastic Syndrome Treated with Corticosteroids

Nocardia farcinica is a Gram-positive weakly acid-fast filamentous saprophytic bacterium, an uncommon cause of human infections, acquired usually through the respiratory tract, often life-threatening, and associated with different clinical presentations. Predisposing conditions for N. farcinica infections include hematologic malignancies, treatment with corticosteroids, and any other condition of immunosuppression. Clinical and microbiological diagnoses of N. farcinica infections are troublesome, and the isolation and identification of the etiologic agent are difficult and time-consuming processes. We describe a case of fatal disseminated infection in a patient with myelodysplastic syndrome, treated with corticosteroids, in which N. farcinica has been isolated from blood culture and identified by Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry. The patient died after 18 days of hospitalization in spite of triple antimicrobial therapy. Nocardia farcinica infection should be suspected in patients with history of malignancy, under corticosteroid therapy, suffering from subacute pulmonary infection,and who do not respond to conventional antimicrobial therapy. Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry can be a valuable tool for rapid diagnosis of nocardiosis.

Mycobacterium tuberculosis volatiles for diagnosis of tuberculosis by Cricetomys rats

Tuberculosis (TB) diagnosis in regions with limited resources depends on microscopy with insufficient sensitivity. Rapid diagnostic tests of low cost but high sensitivity and specificity are needed for better point-of-care management of TB. Trained African giant pouched rats (Cricetomys sp.) can diagnose pulmonary TB in sputum but the relevant Mycobacterium tuberculosis (Mtb)-specific volatile compounds remain unknown. We investigated the odour volatiles of Mtb detected by rats in reference Mtb, nontuberculous mycobacteria, Nocardia sp., Streptomyces sp., Rhodococcus sp., and other respiratory tract microorganisms spiked into Mtb-negative sputum. Thirteen compounds were specific to Mtb and 13 were shared with other microorganisms. Rats discriminated a blend of Mtb-specific volatiles from individual, and blends of shared, compounds (P = 0.001). The rats' sensitivity for typical TB-positive sputa was 99.15% with 92.23% specificity and 93.14% accuracy. These findings underline the potential of trained Cricetomys rats for rapid TB diagnosis in resource-limited settings, particularly in Africa where Cricetomys rats occur widely and the burden of TB is high.

Characterization of Nocardia farcinica, a filamentous bacterium isolated from foaming activated sludge samples

The identification and characterization of filamentous bacteria and their association with specific plant operating conditions and influent characteristics has been hampered because of morphological variations and differences between process configurations. A study was conducted to isolate and characterize the predominant filamentous bacteria observed in a foaming activated sludge treatment plant. The predominant foam-forming filament was isolated and characterized using microscopic, biochemical and molecular techniques. The phylogenetic analysis of the 16S rRNA gene confirmed that it was Nocardia farcinica, a typical filamentous foam-foaming pathogenic bacterium which is not widely reported outside of South Africa. The bacterium used a variety of substrates for its growth and showed greater affinity to larger and slowly biodegradable compounds. The N. farcinica grew well at temperatures ranging from 12 to 30 degrees C in R2A medium and with a pH ranging from 5.5 to 8.0 and an NaCl concentration of 1 to 5%. This range of conditions shows that N. farcinica can withstand extreme conditions, which results in its proliferation in foaming samples.

A fatal case of empyema thoracis by Nocardia farcinica in an immunocompromised patient

Empyema thoracis by Nocardia farcinica infection is uncommon. Here we report a rare and fatal infection in a 27-year-old HIV- seropositive male who presented with cough, expectoration, and breathlessness. Nocardia farcinica was isolated from sputum and pus from the pleural cavity. Confirmation of the isolate and minimum inhibitory concentrations (MIC) for various antibiotics was done at the Aerobic Actinomycetes Reference Laboratory, Centres for Disease Control and Prevention (CDC), Atlanta. Patient was treated with suitable antibiotics and antiretroviral drugs in spite of which he eventually succumbed to the disease.

Nocardia farcinica lung infection in a patient with cystic fibrosis: a case report

INTRODUCTION

Respiratory tract infections are the major causes of morbidity and mortality in patients with cystic fibrosis. Nocardia are rarely implicated in these infections and few reports of the involvement of this species are found in the literature.

CASE PRESENTATION

We describe a case of lung infection followed by chronic colonization of trimethoprim and sulfamethoxazole resistant Nocardia farcinica in a patient with cystic fibrosis. The chronic colonization of this uncommon bacterium in patients with cystic fibrosis was proved using a newly developed real-time polymerase chain reaction assay, which indicates that this bacterium, despite treatment, is difficult to eradicate.

CONCLUSION

Our case report confirms that this organism can be recovered in persons with cystic fibrosis. Its eradication is necessary especially if the patient is to undergo lung transplantation.

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.

Molecular diagnosis of fatal Nocardia farcinica pneumonia in an HIV-negative patient

Nocardiosis is a rare and potentially life-threatening infection caused by several species of the Nocardia genus. Most cases occur in immunocompromised patients, and a delay in establishing the diagnosis is common due to the non-specific clinical presentations and the difficulty in cultivating Nocardia. Although the majority of pulmonary nocardiosis cases are caused by Nocardia asteroides, cases of human infection due to N. farcinica are increasingly diagnosed due to recent developments in taxonomy and diagnostic methods. N. farcinica is a separate species from N. asteroides and appears to be more virulent and resistant to antibiotics. Herein, we describe the case of a 65-year-old HIV-negative immunocompromised patient with a fulminant bilateral pulmonary nocardiosis while on empirical treatment with trimethoprim/sulfamethoxazole and imipenem. Post-mortem diagnosis of N. farcinica infection was performed by means of DNA amplification and sequencing of the 65-kDa bacterial heat shock protein.

Nocardiosis y bronquiectasias. ¿Una asociación infrecuente?

OBJECTIVE

Nocardiosis is difficult to diagnose and infrequently associated with bronchiectasis or cystic fibrosis. This study analyzes the clinical and microbiological characteristics of 40 patients in whom microorganisms belonging to the Nocardia asteroides complex were isolated.

METHODS

We studied 27 males and 13 females, with a mean age of 45 years (8-82). Nocardia spp. were isolated in 129 samples. Cultures were performed with conventional methods; additionally, when branching Gram-positive bacilli were visualized on microscopic examination, modified BCYE-alpha (m) medium was used.

RESULTS

In 77.5% of the cases, investigation for Nocardia spp. was based on microscopy findings, in six patients it was a fortuitous finding in BCYE-alpha (m) medium, and in only three patients nocardiosis was clinically suspected. Twenty-five patients had nocardiosis (5 disseminated infection and 20 lung infection) and the remaining 15 were colonized. The most frequent risk factor in the infections, whether disseminated or not, was systemic glucocorticoid use (P 5 .001). The most frequent underlying pathology was bronchiectasis (80%), associated or not with cystic fibrosis. There were seven deaths and two patients had neurological sequelae.

CONCLUSIONS

Bronchiectasis was an important risk factor for colonization by Nocardia spp. (P 5 0.01) in all the patients studied, and for infection (P 5 0.05) in patients without cystic fibrosis. The use of BCYE-alpha (m) medium in processing respiratory secretions highly facilitated the isolation of Nocardia spp.