Identification of medically relevant Nocardia species with an abbreviated battery of tests

Streptomyces yaizuensis sp. nov., a berninamycin C-producing actinomycete isolated from sponge

While screening for antibiotics in a marine sample, we discovered a berninamycin C-producing actinomycete, designated YSPA8T, isolated from a sponge. A polyphasic approach was used to determine the taxonomic position of the strain. Strain YSPA8T formed sympodially branched aerial mycelia that ultimately segment into chains of spores. Comparative and phylogenetic analyses of the 16S rRNA gene sequence showed that strain YSPA8T were closely related to Streptomyces clavuligerus ATCC 27064T (99.66%), Streptomyces amakusaensis NRRL B-3351T (98.69%), Streptomyces inusitatus NBRC 13601T (98.48%), and 'Streptomyces jumonjinensis' JCM 4947 (98.41%). The phylogenetic tree using the 16S rRNA gene sequences, and both phylogenomic trees suggested that the closest relative of strain YSPA8T was S. clavuligerus ATCC 27064T. The average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values between strain YSPA8T and S. clavuligerus ATCC 27064T were 84.1%, 28.9%, and 82.5%, respectively, which were below the thresholds of 95%, 70%, and 95% for a prokaryotic conspecific assignment. The G + C of the strain YSPA8T was 72.6%. Whole-cell hydrolysates of strain YSPA8T contained LL-diaminopimelic acid. The predominant menaquinones were MK-9(H6) (49%) and MK-9(H8) (48%), and the major fatty acids were C16:0 (26.8%), C16:1 ω7c/ω6c (17.2%), iso-C16:0 (16.0%), and iso-C15:0 (12.5%). The major phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, and other unidentified phospholipids. Based on the phenotypic, phylogenetic, genomic, and chemotaxonomic data, strain YSPA8T represents a novel species of the genus Streptomyces, and the proposed name for this species is Streptomyces yaizuensis sp. nov. The type strain is YSPA8T (=NBRC 115866T = TBRC 17196T).

A post-transplant infection by Nocardia cyriacigeorgica

Nocardia are Gram-positive, acid-fast, filamentous bacteria that cause opportunistic infections in susceptible populations. We describe a case of post-transplant infection of pulmonary nocardiosis caused by the rare strain Nocardia cyriacigeorgica and the challenges faced in reaching a definitive diagnosis. This case report emphasizes on keeping nocardiosis as a differential diagnosis in transplant recipients, as this disease is largely underdiagnosed and underreported.

Streptomyces pacificus sp. nov., a novel spongiicolazolicin-producing actinomycete isolated from a coastal sediment

A polyphasic approach was used to determine the taxonomic position of a marine actinomycete, designated isolate CWH03T, which we previously reported to produce new linear azole-containing peptides spongiicolazolicins A and B. Strain CWH03T is mesophilic, neutrophilic, and halotolerant streptomycete that forms spiral spore chains on aerial mycelium. Comparative 16S rRNA gene sequencing showed that CWH03T was most closely related to Streptomyces tirandamycinicus HNM0039T (99.7%), Streptomyces spongiicola HNM0071T (99.4%), 'Streptomyces marianii' ICN19T (99.1%) and Streptomyces wuyuanensis CGMCC4.7042T (99.0%). The phylogenetic tree prepared using the 16S rRNA gene, as well as the phylogenomic tree using the genome BLAST distance phylogeny method and 81 core housekeeping genes, respectively, showed that the closest relative of strain CWH03T was S. spongiicola HNM0071T. The average nucleotide identity and digital DNA-DNA hybridization values between strains CWH03T and S. spongiicola HNM0071T were 91.46% and 44.2%, respectively, which were below the thresholds of 96% and 70% for prokaryotic conspecific assignation. The G+C content of the genomic DNA of strain CWH03T was 72.3%. Whole-cell hydrolysates of strain CWH03T contained LL-diaminopimelic acid. The predominant menaquinone was MK-9(H8) (88.3%), and the major fatty acids were iso-C16:0 (28.4%), anteiso-C15:0 (15.0%) and iso-C15:0 (12.9%). The major phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. Based on data obtained from phenotypic, phylogenetic, genomic, and chemotaxonomic analyses, strain CWH03T represents a novel species of the genus Streptomyces, for which the proposed name is Streptomyces pacificus sp. nov. The type strain is CWH03T ( = NBRC 114659T = TBRC 15780T).

Clinical Presentation, Management, and Outcomes of Patients With Brain Abscess due to Nocardia Species

Background

Nocardial brain abscesses are rare, and published literature describing brain abscesses due to Nocardia species is limited to individual case reports or small series. We report one of the largest contemporary retrospective studies describing risk factors, diagnostic evaluation, management, and outcomes of nocardial brain abscess.

Methods

Retrospective review of all adults with brain abscess due to culture-confirmed Nocardia species at our institution between January 1, 2009, and June 30, 2020.

Results

Overall, 24 patients had nocardial brain abscesses during the study period. The median age at presentation was 64 years, and 62.5% were immunocompromised. Pulmonary and cutaneous infections were the most common primary sites of nocardial infection. All 24 patients had magnetic resonance imaging performed, and the frontal lobe was the most commonly involved. The most common organism isolated was Nocardia farcinica, followed by Nocardia wallacei and Nocardia cyriacigeorgica. Thirteen patients were managed with antimicrobial therapy alone, while 11 had both medical and surgical management. In all patients, dual therapy was recommended for the initial 6 weeks of treatment, and 22 patients received at least 1 oral agent as part of their final antibiotic regimen, predominantly trimethoprim-sulfamethoxazole and linezolid. Fourteen patients achieved complete clinical and radiographic resolution of infection.

Conclusions

Nocardia is an important cause of brain abscess in the immunocompromised host. Early diagnostic and therapeutic aspiration may help health care providers confirm the diagnosis, choose an appropriate antimicrobial regimen, and achieve source control.

Coniochaeta fungus benefits from its intracellular bacteria to form biofilm and defend against other fungi

During cultivation of a gastric fungus, Coniochaeta polymorpha, growth of Nocardia colonies on top of the fungal culture raised the question whether bacteria originated from inside of fungus. In this study, the likelihood of intracellular origin of bacteria as well as interaction of two microorganisms was assessed. Fluorescence and electron microscopy showed occurrence of several bacterial cells in fungal cytoplasm. A thick biofilm was observed on the surface of co-culture compared with thin one on bacterial and none on fungal monocultures. Field emission scanning electron microscopy (FESEM) micrographs of co-culture showed a dense network of fungal and bacterial cells embedded in a slime-like layer. Dual cultures revealed antagonistic activity of both fungus and bacteria against three Candida species. These findings indicate that Nocardia isolate identified in this study originated from the inside of fungus C. polymorpha. Intracellular bacteria could benefit the fungal host by producing a rigid biofilm and an antifungal compound.

Nocardia Infections: Ten Years Experience from a Tertiary Health Care Center in North India (2007-2016)

BACKGROUND

Nocardia species are important cause of infections in humans but are underreported due to missed diagnosis as well as misdiagnosis. Majority of the literature on these infections consists of case reports or series with few articles describing high number of cases.

OBJECTIVE

To study the epidemiology of Nocardia infections in a tertiary care center.

MATERIALS AND METHODS

This retrospective observational study was done in a tertiary care centre of North India over a period of 10 years (2007-2016). The detection of Nocardia spp. from clinical specimens was done by conventional methods viz. direct microscopy (Gram's stain, modified Ziehl -Neelsen stain [1%], KOH examination) and culture.

RESULTS

A total of 25 cases of nocardiosis were diagnosed during the study period. The mean age of the patients was 50.9 years (range 30-72 years) with a male:female ratio of 3:2. The site of disease in these patients included pulmonary (n=18), cutaneous (n=4), perinephric abscess (n=1), ocular (n=1) and bone (n=1). Risk factors associated were underlying lung disease (n=11), smoking (n=7), diabetes (n=5) and steroid therapy (n=4) in pulmonary nocardiosis, iatrogenic (n=1) and leprosy (n=1) in cutaneous nocardiosis, diabetes in perinephric abscess and cataract surgery in ocular nocardiosis. Culture was positive in 12/25 (48%) patients for Nocardia spp. Direct microscopy was positive in 22 patients. We wish to highlight that meticulous observation of KOH wet mount examination helped in clinching the diagnosis of Nocardiosis in 3 cases which were earlier missed by other methods.

CONCLUSION

Good communication with the clinician alongside a meticulous effort in the laboratory is essential for appropriate diagnosis and management of these cases.

Revisiting nocardiosis at a tertiary care institution: Any change in recent years?

OBJECTIVE

To analyse relevant changes in incidence, clinical and microbiological characteristics of nocardiosis over the last 24 years at the current institution.

MATERIALS AND METHODS

The clinical records of patients with nocardiosis (2006-2018) were reviewed and then compared with a previous cohort (1995-2006). Nocardia isolates were identified by 5'-end-16S-rRNA-gene-PCR targeting the first 500 bp of the gene and sequencing. Susceptibility tests were determined by broth microdilution (CLSI guidelines).

RESULTS

Forty-two patients (64.3% male) with nocardiosis were evaluated in the recent cohort: 51.2% had COPD, 43.9% were on corticosteroid therapy and 31.7% had cancer. The incidence of nocardiosis varied from 6.3 to 7.1/100,000 admissions (p = 0.62). There was a decrease in HIV patients (27% vs. 4.9%, p = 0.01) and solid organ transplantation (SOT) recipients (18.9% vs. 2 .4%, p = 0.01). Cases with pulmonary involvement had increased (70.3% vs. 90.5%, p = 0.04). Nocardia species were similar but the most common were N. cyriacigeorgica (32.4% vs. 40.5%, p = 0.49) and N. farcinica (24.3% vs. 14.3%, p = 0.39). Antibiotic resistance remained stable: cotrimoxazole (10.8% vs. 5.7%, p = 0.68), imipenem (5.4% vs. 5.6%, p = 1.0); amikacin and linezolid were 100% active. No differences were found in breakthrough nocardiosis (21.6% vs. 9.8%, p = 0.21) or related mortality (21.6% vs. 21.4%, p = 1.0). The multivariate analysis confirmed that nocardiosis caused by N. farcinica is a risk factor for poor outcome (p = 0.045).

CONCLUSIONS

Nocardiosis incidence has remained stable. It mainly affected elderly patients with chronic respiratory conditions and those on corticosteroid treatment. Infections in HIV and SOT patients have practically disappeared. Pulmonary involvement remains the most common area to be affected. Nocardiosis caused by N. farcinica is apparently a risk factor for poor clinical outcome.

Retrospective Analysis of Antimicrobial Susceptibility Profiles of Nocardia Species from a Tertiary Hospital and Reference Laboratory, 2011 to 2017

Nocardia species are found worldwide and are opportunistic pathogens of both immunocompromised and immunocompetent hosts. Recent updates to the taxonomy of this genus have indicated that there are more than 90 recognized species of Nocardia with 54 species reported to be clinically relevant. In this paper, we report the species distribution, specimen source distribution, and antimicrobial susceptibility profiles of 2,091 clinical isolates recovered for the years 2011 to 2017 using the updated taxonomy. The most commonly isolated species included Nocardia nova complex, Nocardia cyriacigeorgica, and Nocardia farcinica complex, with an additional 25 species or species complexes recovered from clinical specimens. The antimicrobial susceptibility profile was highly variable between the species, but in general, amikacin, linezolid, and trimethoprim-sulfamethoxazole demonstrated good in vitro activity against most species.

Cellulomonas algicola sp. nov., an actinobacterium isolated from a freshwater alga

An actinomycete strain, TKZ-21^T, was isolated from a freshwater alga (Chetophoraceae) collected from the Takizawa River, Yamanashi, Japan, and examined using a polyphasic taxonomic approach. Cells were Gram-stain positive, aerobic, non-sporulating, motile, and coccoid or short rod-shaped. The strain grew in the presence of 0-4 % (w/v) NaCl, between pH 6-9.4, and over a temperature range of 15-40 °C, with optimum growth at 30 °C. The peptidoglycan type of strain TKZ-21^T was A4β, containing l-ornithine as diagnostic diamino acid and d-glutamic acid as the interpeptide bridge. The predominant menaquinone was MK-9(H₄). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, ninhydrin-positive glycolipid, and unidentified phospholipids. The major cellular fatty acids were anteiso-C_15 : 0 and anteiso-C_17 : 0, and the DNA G+C content was 75.6 mol%. On the basis of 16S rRNA gene sequence analysis, strain TKZ-21^T was closely related to Cellulomonas fimi (98.5 % sequence similarity) and Cellulomonas biazotea (98.3 %). The genome orthoANI value between strain TKZ-21^T and C. biazotea and C. fimi were 84.7 and 84.2 %, respectively. On the basis of fatty acid and MALDI-TOF MS profile analysis, phylogenetic analyses, genomic analysis, and phenotypic data, it is proposed that the isolate be classified as a representative of a novel species of the genus Cellulomonas, with the name Cellulomonas algicola sp. nov. The type strain is TKZ-21^T (=NBRC 112905^T=TBRC 8129^T).

Evaluation of the Vitek MS v3.0 Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry System for Identification of Mycobacterium and Nocardia Species

This multicenter study was designed to assess the accuracy and reproducibility of the Vitek MS v3.0 matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry system for identification of Mycobacterium and Nocardia species compared to DNA sequencing. A total of 963 clinical isolates representing 51 taxa were evaluated. In all, 663 isolates were correctly identified to the species level (69%), with another 231 (24%) correctly identified to the complex or group level. Fifty-five isolates (6%) could not be identified despite repeat testing. All of the tuberculous mycobacteria (45/45; 100%) and most of the nontuberculous mycobacteria (569/606; 94%) were correctly identified at least to the group or complex level. However, not all species or subspecies within the M. tuberculosis, M. abscessus, and M. avium complexes and within the M. fortuitum and M. mucogenicum groups could be differentiated. Among the 312 Nocardia isolates tested, 236 (76%) were correctly identified to the species level, with an additional 44 (14%) correctly identified to the complex level. Species within the N. nova and N. transvalensis complexes could not always be differentiated. Eleven percent of the isolates (103/963) underwent repeat testing in order to get a final result. Identification of a representative set of Mycobacterium and Nocardia species was highly reproducible, with 297 of 300 (99%) replicates correctly identified using multiple kit lots, instruments, analysts, and sites. These findings demonstrate that the system is robust and has utility for the routine identification of mycobacteria and Nocardia in clinical practice.

Culturable rare actinomycetes from Indian forest soils: Molecular and physicochemical screening for biosynthetic genes

BACKGROUND AND OBJECTIVES

Rare actinomycetes are a promising source of novel metabolites of pharmaceutical importance. The current study focussed on selective isolation of specific genera of rare actinomycetes and screening the isolates for biosynthetic genes particularly polyketide synthases (PKS) and non ribosomal peptide synthetases (NRPS).

MATERIALS AND METHODS

The soil samples were subjected to various pre-treatments like 1.5% phenol treatment, 0.3% chloramine T treatment, benzethonium chloride treatment, etc. and plated on selective media supplemented with specific antibiotics targeting rare genera of actinomycetes. The putative rare actinomycete isolates were screened for bioactivity using agar cross streak method and agar well diffusion method. The ability of the isolates to produce anti-quorum sensing compounds was tested against Serratia marcescens. The isolates were also screened for the presence of biosynthetic gene clusters associated with PKS-I, PKS-II and NRPS pathways using the degenerate primer sets K1F-M6R, KSα/KSβ and A3FA7R, respectively. The expression of these gene clusters was tracked by physicochemical screening of the extracts of isolates using spectroscopic and chromatographic techniques.

RESULTS

In this study, 1.5% phenol treatment was found to be the most promising followed by heat treatment and chloramine treatment. Our studies showed that ISP5 agar was the best for isolation of rare genera followed by ISP7, Starch Caesin agar and ISP2 supplemented with antibiotics like gentamicin, nalidixic acid and streptomycin. Micromonospora was the most abundant genus followed by Dactylosporangium. Actinomadura, Nocardiopsis and Actinoplanes were almost equal in number. Primary screening showed that 92% of the isolates were active against one of the test organisms. Thirty seven isolates were found to produce anti-quorum sensing (QS) compounds. NRPS sequences were detected in thirty nine isolates (42.8%), whereas PKS-I and PKS-II sequences were detected in seventeen and twenty eight strains (18.6% and 30.7%), respectively.

CONCLUSION

Nine type I and type II polyketide-producing isolates as well as six peptide-producing isolates were found. The peptide extract of isolate KCR3 and a polyketide extract of isolate NCD10 were found to possess anti-tumor activity exhibiting an IC₅₀ value of 3 μg/ml and 2.5 μg/ml against HeLa cells.

Nocardiosis from 1888 to 2017

The genus Nocardia is an aerobic bacterium, Gram-positive and catalase positive that is in Nocardiaceae family. This bacterium first described by Edmond Nocard in 1888 and is not in human commensal bacteria. To date, nocardiosis incidence is increasing due to increase population growth rate, increase in patients with immune disorder diseases and immunocompromised patients. We surveyed taxonomic position, isolation methods, phenotypic and molecular identification at the genus and species levels, antibiogram, treatment and epidemiology in the world from 1888 to 2017.

Nocardia farcinica Brain Abscess: Report of 3 Cases

BACKGROUND

Central nervous system nocardial infection is a rarely reported disease that usually affects patients with predisposing and debilitating conditions but also the immunocompetent population. The most common variant affecting the brain is Nocardia farcinica. Management of brain nocardiosis is troublesome and requires consideration of the severity of the underlying systemic disease, the difficulties in identifying the bacterium, and the frequent delay in initiating adequate therapy.

CASE DESCRIPTION

We present 3 cases of N. farcinica brain abscess (single, multiloculated, and multifocal) diagnosed in 3 patients with predisposing factors that could be successfully cured. The patients underwent craniotomy, evacuation of the purulent collection, and partial resection of the abscesses' walls. Confirmation of N. farcinica species was achieved using specific polymerase chain reaction sequencing of the 16S ribosome RNA gene. Antibiotic therapy was selected on susceptibility tests and was maintained for 10 months (1 case) and 12 months (2 cases).

CONCLUSIONS

Brain nocardiosis needs to be suspected primarily (though not exclusively) in immunocompromised patients presenting with neurologic deficit and harboring intracerebral lesions resembling brain tumors. Early identification of the specific species is paramount in order to initiate long-term antibiotic therapy, acknowledging the inherent resistance of N. farcinica to third-generation cefalosporins and its susceptibility to trimethoprim-sulphamethoxazole. According to the literature, surgical excision or aspiration of the brain abscess seems to provide good chances of eradication of the disease. In our experience, successful outcome was achieved with subtotal resection and prolonged and adequate antibiotic therapy.

Aerobic Actinomycetes of Clinical Significance

The group of Gram-positive bacillary organisms broadly known as "aerobic actinomycetes" consists of heterogeneous and taxonomically divergent genera. They are found in a wide variety of natural and man-made environments but are rarely considered a part of the normal human flora, with infections normally originating from exogenous sources. An extensive number of genera have been described, but only a minority of these has been associated with human or veterinary health. The association with human disease is usually of an opportunistic nature, either through accidental means of inoculation or through involvement with immunocompromising conditions in the host. They cause a wide spectrum of diseases in humans, which may differ greatly between the genera and even between species, but which also may have a great amount of overlap. The occurrence of such infections is probably greater than appreciated, since many may go unrecognized. Etiologic prevalence of specific genera and species varies geographically within the United States and worldwide. Traditional phenotypic identification methods for separation of the many genera and species of aerobic actinomycetes have found great difficulties. Recent use of chemotaxonomic analyses and emerging technologies such as molecular analysis of nucleic acids, and more recently proteomics for identification to the genus/species level, has provided a far more robust technique to understand the organisms' relatedness, distribution, epidemiology, and pathogenicity in humans.

Identification of mycobacterium spp. and nocardia spp. from solid and liquid cultures by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)

Identification of microorganisms by MALDI-TOF MS has been widely accepted in clinical microbiology. However, for Mycobacterium spp. and Nocardia spp. such identification has not yet reached the optimal level of routine testing. Here we describe the development of an identification tool for 49 and 15 species of Mycobacterium spp. and Nocardia spp., respectively. During database construction, a number of ambiguous reference identifications were revealed and corrected via molecular analyses. Eventually, more than 2000 individual mass spectra acquired from 494 strains were included in a reference database and subjected to bio-statistical analyses. This led to correct species identification and correct combination of species into several complexes or groups, such as the Mycobacterium tuberculosis complex. With the Advanced Spectrum Classifier algorithm, class-specific bin weights were determined and tested by cross-validation experiments with good results. When challenged with independent isolates, overall identification performance was 90% for identification of Mycobacterium spp. and 88% for Nocardia spp. However, for a number of Mycobacterium sp. isolates, no identification could be achieved and in most cases, this could be attributed to the production of polymers that masked the species-specific protein peak patterns. For the species where >20 isolates were tested, correct identification reached 95% or higher. With the current spectral database, the identification of Mycobacterium spp. and Nocardia spp. by MALDI-TOF MS can be performed in routine clinical diagnostics although in some complicated cases verification by sequencing remains mandatory.

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.

Creation of an In-House Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Corynebacterineae Database Overcomes Difficulties in Identification of Nocardia farcinica Clinical Isolates

Nocardiosis is a rare disease that is caused by Gram-positive actinobacteria of the Nocardia genus and affects predominantly immunocompromised patients. In its disseminated form, it has a predilection for the central nervous system and is associated with high mortality rates. Therefore, prompt identification of the pathogen is critical. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is a relatively novel technique used for identification of microorganisms. In this work, an upgraded MALDI-TOF Biotyper database containing Corynebacterineae representatives of strains deposited in the Polish Collection of Microorganisms was created and used for identification of the strain isolated from a nocardial brain abscess, mimicking a brain tumor, in an immunocompetent patient. Testing with the API Coryne system initially incorrectly identified Rhodococcus sp., while chemotaxonomic tests, especially mycolic acid analysis, enabled correct Nocardia identification only at the genus level. Subsequent sequence analysis of 16S rRNA and secA1 genes confirmed the identification. To improve the accuracy of the results, an in-house database was constructed using optimized parameters; with the use of the database, the strain was eventually identified as Nocardia farcinica. Clinical laboratories processing various clinical strains can upgrade a commercial database to improve and to accelerate the results obtained. This is especially important in the case of Nocardia, for which valid microbial diagnosis remains challenging; reference laboratories are often required to identify and to survey these rare actinobacteria.

Nocardiosis in 132 patients with cancer: microbiological and clinical analyses

OBJECTIVES

To correlate the microbiological and clinical features of infections caused by Nocardia species.

METHODS

We determined the species and drug susceptibility of 138 Nocardia strains isolated from 132 patients at the University of Texas M. D. Anderson Cancer Center (Houston, TX) from 2002 through 2012 and analyzed the clinical features.

RESULTS

The 132 patients included 82 men and 50 women with a mean age of 59.1 years. All except two had underlying cancer, and 47 (35.6%) also received a stem cell transplant. These patients experienced 136 episodes of Nocardia infection, including pulmonary infection, abscess of deep skin and soft tissue, bacteremia and dissemination, and brain abscess. The 138 Nocardia strains involved 27 species, of which 20 species have been described since 2000. Common species included Nocardia nova, Nocardia cyriacigeorgica, Nocardia farcinica, and Nocardia abscessus, together accounting for 59.4%. N nova caused most bacteremia cases, whereas N farcinica caused most of the skin and brain infections. Infections with a few recent species likely represented first confirmation or report of human infections. Antimicrobial susceptibility tests of 117 strains showed that they were all susceptible to trimethoprim-sulfamethoxazole and linezolid but variably susceptible to other drugs depending on species. Most patients who were treated for the infection showed improvement or resolution.

CONCLUSIONS

Diverse Nocardia species can cause secondary infections in patients with cancer. Timely species identification and antimicrobial susceptibility tests may guide treatment.

Merits and pitfalls of currently used diagnostic tools in mycetoma

Treatment of mycetoma depends on the causative organism and since many organisms, both actinomycetes (actinomycetoma) and fungi (eumycetoma), are capable of producing mycetoma, an accurate diagnosis is crucial. Currently, multiple diagnostic tools are used to determine the extent of infections and to identify the causative agents of mycetoma. These include various imaging, cytological, histopathological, serological, and culture techniques; phenotypic characterisation; and molecular diagnostics. In this review, we summarize these techniques and identify their merits and pitfalls in the identification of the causative agents of mycetoma and the extent of the disease. We also emphasize the fact that there is no ideal diagnostic tool available to identify the causative agents and that future research should focus on the development of new and reliable diagnostic tools.

Case report: nocardia infection associated with ectopic cushings

BACKGROUND

Cushing's syndrome results from exposure to excess glucocorticoids. Ectopic Cushings is endogenous ACTH dependant form of Cushing's associated with markedly raised ACTH and cortisol levels. This leads to an impaired immune response, setting the stage for occurrence of opportunistic infections. Nocardiosis is a gram positive bacterial infection caused by aerobic actinomycetes in genus Nocardia. We report a series of patients diagnosed with ectopic Cushings, having pneumonia with Nocardia spp. In one of these cases, the manifestations of Cushing's disappeared with treatment for Nocardia.

CASE PRESENTATION

Two middle aged men of Asian descent presented to the Endocrine clinic: the first with history of exertional shortness of breath, and weight loss for 1 year, the other with facial swelling, disturbed sleep and lethargy for a month. The third case was a young Asian male who presented with progressive weakness & weight loss for 2 months. All three patients had uncontrolled hypertension, high blood sugars & were hypokalemic (K: 2.52, 2.9, 1.5 mmol/l); 24 hour urine cortisol was elevated at 2000, 27216 and 9088 (32-243 ug/24 hours); ACTH 68.5, 159, 255 [0-48 pg/ml), respectively. Their MRI pituitary was normal, inferior petrosal sinus sampling revealed no central peripheral gradient. CT chest of these subjects demonstrated cavitatory lung lesions; microscopic analysis of respiratory samples was suggestive of infection with Nocardia spp. Histopathology of bronchoscopic-guided biopsy revealed no malignancy. Antihypertensives, insulin, potassium replacement, ketoconazole & trimethoprim-sulphamethoxazole (TS) were initiated. The patients' symptomatology improved & cavitatory lesions resolved with treatment. The primary source for the ectopic cushings remained unknown. The first case required bilateral adrenalectomy. The second case followed a progressively downhill course leading to death. In the third case, we were able to completely taper off ketoconazole, potassium, insulin & antihypertensives, after starting TS.

CONCLUSION

Opportunistic infections are known to be associated with Cushing's syndrome, and higher levels of glucocorticoid secretion are found in patients with ectopically produced ACTH. Pulmonary nocardiosis is important differential to consider. This series includes the first case reported in which signs and symptoms of cushings subsided after treatment of Nocardia.

Soil-acquired cutaneous nocardiosis on the forearm of a healthy male contracted in a swamp in rural eastern Virginia

A 45-year-old man complained of pain and swelling on his right wrist after receiving a scratch while playing paintball in a swampy area of eastern Virginia. Two weeks later, he noticed a pimple-like lesion developing, which quickly grew in size and then ulcerated. Because of the severity of his condition, the patient was taken to the emergency room where surgical drainage of the abscess was carried out and the pus was sent for culture and sensitivity testing. Enlarged and tender lymph nodes were palpable going up the arm and surrounding the right axillary area. Three days following culture of pus from his lesion, colonies of Nocardia brasiliensis were isolated. He was successfully treated with an extended regimen of trimethoprim-sulfamethoxazole. Because of its low incidence, nocardiosis is usually not considered in the initial diagnosis. The rapidity with which his infection developed from a pimple-like lesion into an extensive ulcerated area, the involvement of his lymphatic system, the extended time needed to successfully treat his infection, and the potential for infection to rapidly disseminate, reinforces the necessity for laboratory identification and immediate treatment of severe pyogenic cutaneous lesions.

Molecular identification of nocardia isolates from clinical samples and an overview of human nocardiosis in Brazil

BACKGROUND

Nocardia sp. causes a variety of clinical presentations. The incidence of nocardiosis varies geographically according to several factors, such as the prevalence of HIV infections, transplants, neoplastic and rheumatic diseases, as well as climate, socio-economic conditions and laboratory procedures for Nocardia detection and identification. In Brazil the paucity of clinical reports of Nocardia infections suggests that this genus may be underestimated as a cause of human diseases and/or either neglected or misidentified in laboratory specimens. Accurate identification of Nocardia species has become increasingly important for clinical and epidemiological investigations. In this study, seven clinical Nocardia isolates were identified by multilocus sequence analysis (MLSA) and their antimicrobial susceptibility was also determined. Most Nocardia isolates were associated to pulmonary disease.

METHODOLOGY/PRINCIPAL FINDINGS

The majority of Brazilian human isolates in cases reported in literature were identified as Nocardia sp. Molecular characterization was used for species identification of Nocardia nova, Nocardia cyriacigeorgica, Nocardia asiatica and Nocardia exalbida/gamkensis. Data indicated that molecular analysis provided a different Nocardia speciation than the initial biochemical identification for most Brazilian isolates. All Nocardia isolates showed susceptibility to trimethoprim-sulfamethoxazole, the antimicrobial of choice in the treatment nocardiosis. N. nova isolated from different clinical specimens from one patient showed identical antimicrobial susceptibility patterns and two distinct clones.

CONCLUSIONS/SIGNIFICANCE

Although Brazil is the world's fifth-largest country in terms of land mass and population, pulmonary, extrapulmonary and systemic forms of nocardiosis were reported in only 6 of the 26 Brazilian states from 1970 to 2013. A least 33.8% of these 46 cases of nocardiosis proved fatal. Interestingly, coinfection by two clones may occur in patients presenting nocardiosis. Nocardia infection may be more common throughout the Brazilian territory and in other developing tropical countries than is currently recognized and MLSA should be used more extensively as an effective method for Nocardia identification.

Co-infection with Nocardia asteroides complex and Strongyloides stercoralis in a patient with autoimmune hemolytic anemia

We describe an unusual case of pulmonary nocardiosis co-existing with Strongyloides stercoralis hyperinfection syndrome in a patient with autoimmune hemolytic anemia who was being treated with corticosteroids. This case highlights the importance of being aware of the possibility that infections can co-exist in immunosuppressed patients. To the best of our knowledge, this is the first report of co-infection with Nocardia asteroides and S. stercoralis.

Bacteraemia caused by Sciscionella marina in a lymphoma patient: phenotypically mimicking Nocardia

A 55-year-old female patient with malignant lymphoma after induction chemotherapy developed fever. Blood culture yielded an organism biochemically identified as representing Nocardia spp., but molecular identification (16S rRNA gene sequencing) later identified it as representing Sciscionella marina. This is the first report, to the best of our knowledge, of Sciscionella being isolated from a human sample.

First report of Nocardia asiatica olecranon bursitis in an immunocompetent traveler returning to Austria

Nocardia spp. are rarely isolated in extrapulmonary clinical specimens. We describe the first case of olecranon bursitis caused by Nocardia asiatica. The patient, a traveler returning from Thailand, was successfully treated with linezolid.

The first Korean case of disseminated mycetoma caused by Nocardia pseudobrasiliensis in a patient on long-term corticosteroid therapy for the treatment of microscopic polyangiitis

Nocardia pseudobrasiliensis is predominantly associated with invasive infections in immunocompromised patients. We report a case of disseminated mycetoma caused by N. pseudobrasiliensis in a 57-yr-old woman with microscopic polyangiitis, who was treated for 3 months with corticosteroids. The same organism was isolated from mycetoma cultures on the patient's scalp, right arm, and right leg. The phenotypic characteristics of the isolate were consistent with both Nocardia brasiliensis and N. pseudobrasiliensis, i.e., catalase and urease positivity, hydrolysis of esculin, gelatin, casein, hypoxanthine, and tyrosine, but no hydrolysis of xanthine. The isolate was identified as N. pseudobrasiliensis based on 16S rRNA and hsp65 gene sequencing. The patient was treated for 5 days with intravenous ampicillin/sulbactam, at which time both the mycetomas and fever had subsided and discharged on amoxicillin/clavulanate. This case highlights a very rare presentation of mainly cutaneous mycetoma caused by N. pseudobrasiliensis. This is the first reported case of N. pseudobrasiliensis infection in Korea.

Uncommon mandibular osteomyelitis in a cat caused by Nocardia africana

BACKGROUND

Nocardiosis is an unusual infection in companion animals characterized by suppurative to pyogranulomatous lesions, localized or disseminated. Cutaneous-subcutaneous, pulmonary and systemic signs are observed in feline nocardiosis. However, osteomyelitis is a rare clinical manifestation in cats. Nocardia cyriacigeorgica (formerly N. asteroides sensu stricto), Nocardia brasiliensis, Nocardia otitidiscaviarum, and Nocardia nova are the most common pathogenic species identified in cats, based on recent molecular classification (16S rRNA gene). The present report is, to our knowledge, the first case of mandibular osteomyelitis in a cat caused by Nocardia africana, diagnosed based upon a combination of methods, including molecular techniques.

CASE PRESENTATION

A one-year-old non-neutered female cat, raised in a rural area, was admitted to the Companion Animal Hospital-PUCPR, São José dos Pinhais, State of Paraná, Brazil, with a history a progressive facial lesion, difficulty apprehending food, loss of appetite, apathy and emaciation. Clinical examination showed fever, submandibular lymphadenitis, and a painless, 8 cm diameter mass, which was irregularly-shaped, of firm consistency, and located in the region of the left mandible. The skin around the lesion was friable, with diffuse inflammation (cellulitis), multiple draining sinuses, and exudation of serosanguinous material containing whitish "sulfur" granules.Diagnosis was based initially in clinical signs, microbiological culture, cytological, and histopathological findings, and radiographic images. Molecular sequencing of 16S rRNA of isolate allowed diagnosis of Nocardia africana. Despite supportive care and antimicrobial therapy based on in vitro susceptibility testing the animal died.

CONCLUSION

The present report describes a rare clinical case of feline osteomyelitis caused by Nocardia africana, diagnosed based upon a combination of clinical signs, microbiological culture, cytological and histopathological findings, radiographic images, and molecular methods. The use of modern molecular techniques constitutes a quick and reliable method for Nocardia species identification, and may contribute to identification to new species of Nocardia that are virulent in cats.

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.

Pulmonary nocardiosis: a comparative analysis of Nocardia asteroides and non-asteroides species

Our study compares the risk factors, clinical presentations and outcomes of pulmonary infections caused by Nocardia asteroides and non-asteroides species. We performed a retrospective cohort study comparing pulmonary infections by both species in patients presenting to a tertiary care hospital in Karachi, Pakistan. Forty-one patients were identified with pulmonary nocardiosis, with 58.5% belonging to the N. asteroids complex. The most common clinical findings were fever and a cough for both groups, with lobar infiltrates being the most common finding on chest radiographs. In vitro testing showed a sensitivity of all species to trimethoprim-sulfamethoxazole (TMP-SMZ), aminoglycosides, ceftriaxone and imipenem. The majority of the patients were treated with TMP-SMZ in combination with other drugs. The results of our study suggest that there is no significant difference in the risk factors, presentations and outcomes of pulmonary infections by N. asteroides and non-asteroides species. Immunocompromised patients are more likely to have unfavorable outcomes.

Nocardia artemisiae sp. nov., an endophytic actinobacterium isolated from a surface-sterilized stem of Artemisia annua L

A novel actinobacterium, designated YIM 65623T, was isolated from a surface-sterilized stem of Artemisia annua L. Strain YIM 65623T had morphological, biochemical, physiological and chemotaxonomic properties that were consistent with its classification in the genus Nocardia. Growth occurred with 0–7 % (w/v) NaCl (optimum 0–3 %), at pH 5.0–9.0 (optimum pH 6.0) and at 10–37 °C (optimum 20–28 °C). Comparative 16S rRNA gene sequence analysis showed that strain YIM 65623T constituted a distinct sublineage within the genus Nocardia and displayed 94.1–98.2 % sequence similarity to members of established species in the genus Nocardia. However, DNA–DNA relatedness and physiological and biochemical characteristics showed that strain YIM 65623T could be differentiated from its closest phylogenetic relatives. The G+C content of the genomic DNA was 69.6 mol%. It is proposed that strain YIM 65623T be classified as a representative of a novel species, Nocardia artemisiae sp. nov. The type strain is YIM 65623T ( = DSM 45379T  = CCTCC AA 209038T).

Linezolid combined with trimethoprim-sulfamethoxazole therapy for the treatment of disseminated nocardiosis

We describe a case of disseminated nocardiosis in a 45-year-old male with a history of chronic glomerular nephritis and allograft renal transplantation both treated with immunosuppressive drugs. Clinical symptoms included fever, chest distress, breathlessness, subcutaneous nodules and pustules. Pulmonary computed tomography scans revealed areas of consolidation in both lung fields, pleural effusion and massive pericardial effusion. Bacterial culture of the pus in the subcutaneous abscesses and pericardial effusion showed growth of Nocardia asteroides sensitive to linezolid and trimethoprim-sulfamethoxazole (TMP-SMZ) for both. Treatment with linezolid combined with TMP-SMZ resulted in a clear clinical improvement and bacterial clearance.

Unusual infections: Femoral abscess due to Nocardia abscessus in a patient suffering from metastatic peripheral bronchial carcinoma and hygienic consequences

During the course of a peripheral bronchial carcinoma with pulmonary and cerebral metastases a femoral abscess developed in a 49 year-old patient after radio- and chemotherapy. A bacterial strain, which was isolated four times from a deep wound of the left thigh was tentatively identified as a member of the genus Nocardia on the basis of selected phenotypic and chemotaxonomic characteristics. The isolate was confirmed to belong to Nocardia abscessus by 16S rRNA gene sequencing. This species had previously been described as the causative agent of soft tissue infections. Although rare, nocardia soft tissue infections as complication of systemic nocardiosis are typical air born infections of immuncompromised patients and need specific attention. Infection prevention can be realized by restriction of soil and aerosol (builder's dust) together with antibiotic intervention (oral administration of trimethoprim/sulfamethoxazole).

Cutaneous Nocardia brasiliensis infection in an immunocompetent host after ovarian cystectomy: A case study

Nocardia brasiliensis is a rare human pathogen that is usually associated with localised cutaneous infections. We report a case of primary cutaneous Nocardia brasiliensis infection causing delayed wound healing that developed after ovarian cystectomy in an otherwise healthy 32-year-old woman. The patient was initially treated with cotrimoxazole, however due to intolerance intravenous amikacin was given and gradually the wound healed. The diagnosis was confirmed by demonstrating the causative organism in exudates, and cultures. Early diagnosis as well as early institution of chemotherapy is effective in most patients, and antimicrobial susceptibility testing of the isolate should be performed to identify the best treatment options.

Bovine abortion associated with Nocardia farcinica

Nocardia spp. are recognized as a cause of bovine mastitis, cutaneous or subcutaneous abscesses, pneumonia, and disseminated disease. Abortion caused by Nocardia spp. is uncommon, and only a few sporadic cases have been reported in horses, pigs, and cattle. In all previous reports, of nocardial abortion, the causative agent was identified as Nocardia asteroides. The current report describes an aborted bovine fetus that was infected with Nocardia farcinica. Placenta, abomasal fluid, lung, liver, and kidney specimens from a late-term bovine abortion were submitted to the Kansas State Veterinary Diagnostic Laboratory. The gross findings included purulent exudate in the placenta and numerous abscesses in lung. Histologically, there was necrotizing and suppurative placentitis, pyogranulomatous pneumonia, and nephritis with numerous intralesional branching and filamentous, Gram-positive bacteria. Nocardia farcinica was isolated by bacteriology, and the bacteriology result was confirmed by 2 established polymerase chain reaction protocols and by DNA sequencing.

Nocardiosis at the turn of the century

Nocardia species is an uncommon pathogen that affects both immunosuppressed and immunocompetent patients. The clinical and microbiologic spectrum of nocardiosis has changed recently due to the widespread use of cotrimoxazole prophylaxis, the emergence of new types of immunosuppressed patients, and the improved identification of isolates using molecular techniques. Nocardia asteroides was traditionally considered the predominant organism, and prophylaxis with cotrimoxazole was considered almost universally protective. We conducted the current study to determine the incidence of nocardiosis and its microbiologic and clinical characteristics in a general hospital over the last 12 years. We reviewed the clinical records of all patients in whom Nocardia species was isolated from clinical specimens between 1995 and 2006. Nocardia isolates were identified by standard procedures and by 5' end 16S rRNA gene polymerase chain reaction (PCR) and sequencing. Susceptibility to cotrimoxazole, minocycline, imipenem, linezolid, and amikacin was determined by the broth microdilution method following the guidelines of the Clinical and Laboratory Standards Institute.The incidence of Nocardia infections did not increase significantly during the study period (0.39/100,000 inhabitants in 1995-1998 and 0.55/100,000 inhabitants in 2003-2006). Nocardia was recovered from 43 patients. Six were considered to be colonized. The colonizing species were N. farcinica, N. nova, and N. asteroides. All colonized patients had severe underlying pulmonary conditions and were treated with antimicrobials (6 patients) or corticosteroids (4 patients). Invasive nocardiosis was diagnosed in 37 patients (86.5% were men, and their mean age was 55.8 +/- 17.3 yr). The most common underlying condition in our institution was human immunodeficiency virus (HIV) infection (10 patients; 27%), followed by chronic obstructive pulmonary disease (8 patients; 21.6%), autoimmune diseases (8 patients; 21.6%), solid organ transplantation (7 patients; 18.9%), and cancer (4 patients; 10.8%). The most important risk factor for nocardiosis was corticosteroid administration (23 patients; 62.2%). Nocardiosis affected the lungs in 26 cases (70.3%), the skin in 3 cases (8.1%), and the central nervous system in 2 cases (5.4%). It was disseminated in 5 cases (13.5%) and caused otomastoiditis in 1 (2.7%). The species identified were N. cyriacigeorgica (32.4%), N. farcinica (24.3%), N. otitidiscaviarum (10.8%), N. veterana (8.1%), N. nova (5.4%), N. abscessus (5.4%), N. asiatica (2.7%), N. beijingensis (2.7%), N. brasiliensis (2.7%), N. carnea (2.7%), and Nocardia species (2.7%).Linezolid and amikacin were uniformly active against all the isolates, whereas 29.7% of isolates showed intermediate susceptibility to minocycline (minimum inhibitory concentration = 2 mg/L), 10.8% were resistant to cotrimoxazole, and 5.4% were resistant to imipenem. Nocardiosis occurred while the patients were on cotrimoxazole prophylaxis in 8 cases (21.6%). The strains isolated from these patients were susceptible to cotrimoxazole in 5 cases (62.5%) and resistant in 3 (37.5%). Overall, 13 patients died (35.1%); related mortality was 21.6% (8 patients). We conclude that HIV infection has become the most common underlying condition for invasive nocardiosis in our institution, followed by chronic lung disease. Previous use of corticosteroids was the main risk factor and was present in more than half the patients. New species of Nocardia have been identified, and administration of cotrimoxazole prophylaxis should no longer be considered highly reliable protection against nocardiosis. Larger studies of nocardiosis are required to better identify risk factors associated with mortality, and alternative and more effective methods of prevention must be developed.

Nocardiosis: an overview and additional report of 28 cases in cattle and dogs

Phenotypic characteristics, antimicrobial susceptibility profile, and clinical-epidemiological features of 28 Nocardia strains isolated from 19 cases of bovine mastitis, eight cutaneous-subcutaneous lesions and one case of pneumonia in dogs were evaluated. Microbiological, biochemical, cytological and scanning electron microscopy methods were used in diagnosis. Nocardia asteroides type IV, Nocardia otitidiscaviarum,Nocardia nova (type III) and Nocardia farcinica (type V) were isolated from bovine milk, bronchial lavage and/or cutaneous-subcutaneous abscesses in dogs. Nocardial bovine mastitis was diagnosed predominantly in clinical cases, in dairy herds with poor environmental hygienic conditions between milking and inappropriate intramammary therapy. Canine nocardiosis was observed commonly in animals co-infected with distemper virus. Sulphamethoxazole-trimethoprim (92.8%), amikacin (92.8%) and ceftiofur (92.8%) were the most effective drugs in 28 isolates. Multiple drug resistance to three or more and five or more antimicrobials was observed in ten (35.7%) and three (10.7%) strains, respectively, predominantly with use of cloxaxillin, cefoperazone and ampicillin. The species (type) classification, clinical-epidemiological characteristics, diagnosis, multiple-drug resistance and public health considerations in Nocardia strains isolated from cattle and dogs in Brazil are discussed, with special reference to report of bovine mastitis by N. otitidiscaviarum by first time in Brazil and the similarity between Nocardia species isolated from human and animal origin.

Nocardia infections in cats: a retrospective multi-institutional study of 17 cases

OBJECTIVE

To record 17 cases of nocardiosis in cats from eastern Australia and to compare this series with cases previously reported.

DESIGN

Retrospective/prospective study.

RESULTS

Nocardia spp infections were diagnosed in 17 cats over 14 years from the three eastern states of Australia. There were no isolates from dogs during this period, but one isolate from a koala and two from dairy cows. The majority of cats presented with spreading lesions of the subcutis and skin associated with draining sinus tract(s). Early cutaneous lesions consisted of circumscribed abscesses. Infections spread at a variable rate, generally by extension to adjacent tissues. Lesions were generally located in regions subjected to cat bite or scratch injuries, including limbs, body wall, inguinal panniculus and nasal bridge. In some other cases, lesions were situated on distal extremities. The clinical course was variable, from chronic, indolent, initially localised infections to acute fulminating disease. Of the 17 cats, 14 were domestic crossbreds and three were purebreds. There was a preponderance of male cats (12 castrated, 1 entire young adult, 1 entire kitten). Nine of 17 cats were 10 years or older. Interestingly, the majority of infections were attributable to N nova. Immediate and/or predisposing causes could be identified in all cases, and included: renal transplantation [one cat]; chronic corticosteroid administration [three cats]; catabolic state following chylothorax surgery [one cat]; fight injuries [seven cats]; FIV infections [three of seven cats tested]. Of the 17 cats, three were apparently cured. Four were thought to be cured, but infection recurred after several months. Three cats responded partially but were euthanased, while another was improving when it died of unrelated complications. Two died despite treatment and two were euthanased without an attempt at therapy. For two cats there were either insufficient records or the patient was lost to follow up.

CONCLUSION

Nocardiosis is a rare, serious disease. Currently it is more common in cats than dogs. Nocardial panniculitis may be clinically indistinguishable from the syndrome caused by rapidly growing mycobacteria. Although the prognosis is guarded, patients with localised infections caused by N nova often respond to appropriate therapy. If definitive treatment is delayed because of misdiagnosis, the disease tends to become chronic, extensive and refractory. Insufficient duration of therapy leads to disease recurrence.

Actinomycoses and Nocardia pulmonary infections

PURPOSE OF REVIEW

Actinomycosis and nocardiosis are uncommon pulmonary infections with distinct morphologic features. Both infections most commonly present as chronic, debilitating illnesses with radiographic manifestations simulating lung cancer or tuberculosis. Immunocompromised hosts, however, may develop fulminant disease resembling acute bacterial pneumonia. The purpose of this review is primarily to review the clinical features, diagnosis, and management of actinomycosis and nocardiosis.

RECENT FINDINGS

Treatment of actinomycosis is usually simple, requiring long-term, high-dose intravenous penicillin. Short-course chemotherapy, however, has recently been reported to be successful. Pulmonary nocardiosis is an important cause of opportunistic infection in immunosuppressed patients, and the incidence of this infection is increasing. The sulfonamides are still first-line agents in the management of nocardiosis, but resistance is most common among N. farcinica and N. otitidiscaviarum isolates. Carbapenems should be used as an alternative treatment for severely ill patients. Broth microdilution, E-test (AB Biodisk, Solna, Sweden) and BACTEC (Becton Dickinson, Sparks, Maryland, USA) radiometric method may be more useful in the routine clinical laboratory for antimicrobial testing of aerobic actinomycetes.

SUMMARY

The practical distinction between the two diseases is in the matter of therapy. Diagnosis depends on a high degree of suspicion so as to alert the microbiology and pathology laboratories to employ special methods to identify the organisms. Early recognition and prompt treatment usually results in complete cure.