DisseminatedNocardia farcinica infection in an AIDS patient

This report describes an AIDS patient presenting with disseminatedNocardia farcinica infection diagnosed by percutaneous kidney biopsy. The isolate was initially identified asNocardia asteroides. ThoughNocardia asteroides remains sensitive to most antimicrobial agents,Nocardia farcinica is resistant to gentamicin, tobramycin and cephalosporins and is indistinguishable fromNocardia asteroides by regular laboratory methods. In view of the rising incidence of infections withNocardia farcinica, third-generation cephalosporins should not be used in the initial management ofNocardia infections, and all isolates should be submitted for antibiotic susceptibility testing.     

Primary Nocardia osteomyelitis as a presentation of AIDS

Human infection with Nocardia species presents as a wide range of clinical syndromes. Nocardia is an important opportunistic pathogen in immunocom-promised patients. We report a case of primary Nocardia asteroides osteomyelitis as the initial clinical presentation of AIDS. The infection was successfully treated with a prolonged course of trimethoprim-sulfamethoxazole in conjunction with HAART. Nocardia osteomyelitis should be recognized as an unusual but important and treatable opportunistic infection in patients living with HIV infection.     

Nocardia anaemiae sp. nov. isolated from an immunocompromised patient and the first isolation report of Nocardia vinacea from humans.

Two actinomycete strains that were isolated from patients in Japan were assigned provisionally to the genus Nocardia based on their morphological characteristics. The two isolates were further studied to determine their specific taxonomic status. Detailed chemotaxonomic characterization and 16S rDNA sequence data for the strains showed that they are most similar to Nocardia vinacea. DNA-DNA hybridization experiments indicated that strain IFM 0344 should be identified as N. vinacea, and that strain IFM 0323T is classifiable as a new species. This report describes the first isolation of N. vinacea from clinical samples. A new species of the genus Nocardia is proposed based on their phenotypic and phylogenetic characteristics: Nocardia anaemiae for IFM 0323T (=NBRC 100462T=JCM 12396T=DSM 44821T).     

Taxonomy and phylogenetic analysis of infectious Nocardia strains isolated from clinical samples]

Following recent advances in medical technology, the increased number of immunocompromised patients such as those with organ transplants has led to an increase in opportunistic infections due to Nocardia. Although nocardiosis has been considered to be rare, recent reports indicate that the incidence of the infection is increasing. The Nocardia asteroides group is the principal source of infectious species, but the definition of species in Nocardia is problematic because species identification of N. asteroides has been based on mainly morphological and biochemical properties. Additionally, it was assumed that a clinical strain with properties that did not fully coincide with existing species was N. asteroides sensu lato. This caused problems in both clinical and taxonomical fields, and reclassification of N. asteroides sensu lato was necessary. Therefore, determination of the appropriate taxonomic position of N. asteroides sensu lato that is now classified as N. asteroides sensu stricto was conducted using a molecular phylogenetic method. From 1965 to 2001, twenty-two strains of N. asteroides sensu lato were isolated from clinical samples. The phylogenetic tree using 16S rDNA sequences and detailed biochemical characters on the 22 isolates was determined. Results revealed that nine strains should be reclassified into species other than N. asteroides sensu stricto, and we proposed nine new species of the genus Nocardia. In addition, we proposed eight other new species of the genus Nocardia from other samples; hence seventeen new species were proposed in total. We also reported the first infectious cases due to Nocardia beijingensis, Nocardia transvalensis and Nocardia pseudobrasiliensis in Japan.     

Disseminated Nocardia asteroides diagnosed by blood culture in a patient with disseminated histoplasmosis.

We describe herein a provocative case involving an immunosuppressed patient with disseminated Histoplasma capsulatum and also disseminated Nocardia asteroides, which was documented by multiple routine blood culture samples. Nocardia asteroides was isolated from 15 routine blood cultures using the nonradiometric blood culture system (Bactec NR-660, Becton Dickinson, Towson, Md). Several different species of the genus Nocardia proved to thrive in blood culture bottles (Bactec) when experimental inoculations were performed. The paucity of reports in the literature of disseminated nocardiosis with positive blood cultures has led us to consider cause for the apparent poor recovery of these organisms from blood culture media. We suggest that the media (Bactec) can successfully support growth of Nocardia species and that other variables, such as incubation times and subculture, should be considered to optimize isolation of this pathogen in blood culture systems.     

皮肤型奴卡菌病二例并文献分析

目的探讨皮肤型奴卡菌感染的临床表现、诊断、治疗及预后，提高对奴卡菌的认识。 方法选取2016年6月至2017年5月解放军总医院第四医学中心烧伤整形科收治的皮肤型奴卡菌病患者2例，患者入院后积极进行外科清创，清创术后行负压封闭引流治疗，细菌培养结果明确为奴卡菌后，使用敏感抗生素结合口服复方磺胺甲口恶唑治疗。分析患者的临床资料、治疗过程，并结合检索、查阅奴卡菌相关文献，对奴卡菌病进行系统性陈述。 结果2例患者最终均治愈。皮肤型奴卡菌病临床表现及影像学检查无特异性，易误诊。 结论皮肤型奴卡菌病少见，病原菌培养为奴卡菌是诊断本病的主要依据，伴有脓肿需行外科手术切开引流，并结合磺胺类药物治疗。     

Nocardia mexicana sp. nov., a new pathogen isolated from human mycetomas

Three isolates collected from human mycetomas and showing an unusual brownish purple pigmentation on Bennett agar plates were analyzed by a polyphasic taxonomic approach, including morphological, biochemical, physiological, and chemotaxonomic properties coupled with genomic and phylogenetic analysis. It clearly appeared that these microorganisms were distinct from their closest phenotypic and genetic match, the most related species according to 16S rRNA gene sequence analysis being Nocardia pseudobrasiliensis. The data obtained indicated that the three clinical strains should be recognized as a new species for which the name Nocardia mexicana sp. nov. is proposed.     

Pulmonary nocardiosis in human immunodeficiency virus infection: a tuberculosis mimic

Patients with human immunodeficiency virus (HIV) infection are prone to develop pulmonary infections like nocardiosis. It is often misdiagnosed as pulmonary tuberculosis since the manifestations are similar. A twenty-seven years old male presented with fever, cough with expectoration and weight loss for two months. Chest radiograph showed opacity in the right mid zones. Sputum smears were negative for acid fast bacilli (AFB) and revealed gram positive branching filamentous organisms resembling Nocardia species. Subsequently, Nocardia was grown on sputum culture. HIV antibody was positive by ELISA test. He was treated with co-trimoxazole. If sputum is repeatedly tested negative for AFB in the setting of radiological suspicion of tuberculosis, testing for Nocardia species should be considered in the HIV-infected patients.     

Determination of antimicrobial susceptibility patterns of Nocardia spp. from clinical specimens by Etest

Susceptibilities to 11 antimicrobial agents were determined by Etest for 93 Nocardia isolates from clinical specimens and 15 type strains belonging to different Nocardia spp. All isolates were susceptible to trimethoprim-sulphamethoxazole, amikacin and linezolid, but susceptibilities of the various Nocardia spp. to beta-lactams, aminoglycosides, ciprofloxacin and clarithromycin varied markedly. Overall, there was a good correlation between the drug resistance patterns and the species identification established by conventional phenotypic tests and 16S rDNA sequencing. Among the different species encountered, Nocardia farcinica and Nocardia brasiliensis displayed the most multiresistant profiles, with resistance to imipenem occurring mainly among isolates of N. brasiliensis and Nocardia abscessus. The species variability in susceptibility profiles and the numerous recent taxonomic changes means that in-vitro susceptibility tests may be a complementary tool for the identification of Nocardia isolates from human clinical specimens. Further studies on a larger number of species from more diverse geographical sources, including species that are found less commonly among clinical isolates, are required to validate and extend the results.     

Review of nocardial infections in France 1987 to 1990

On the basis of the numbers ofNocardia strains referred to the National Reference Center for Mycoses and Antifungal Agents (NRC), Institut Pasteur, Paris, in the period from 1987 to 1990, it was estimated that between 150 and 250 cases of nocardiosis are diagnosed in France each year. A total of 63 clinical isolates were referred to the NRC and identified asNocardia asteroides (66.7 %),Nocardia farcinica (23.8 %),Nocardia brasiliensis (3.2 %),Nocardia otitidiscaviarum (4.8 %) andNocardia carnea (1.5 %).Nocardia asteroides accounted for 71.4 % of pulmonary infections, 80.0 % of central nervous system infections and 80.0 % of systemic infections. Patients infected withNocardia farcinica died in 57.1 % of cases, compared with 17.6 % of patients infected withNocardia asteroides. Corticosteroid therapy represented a significant factor in mortality. Isolates ofNocardia asteroides revealed variable resistance, whereas isolates ofNocardia farcinica were resistant to most antimicrobial agents. Only amoxicillin/clavulanic acid, imipenem, cefoxitin, kanamycin, amikacin, minocycline and vancomycin showed activity against both species. Nocardiosis caused byNocardia farcinica may be a growing problem because of the relatively high incidence in AIDS patients and the resistance of this species to most antimicrobial agents.     

Modified Thayer-Martin medium for recovery of Nocardia species from contaminated specimens.

Specimens submitted for isolation of Nocardia species are frequently contaminated with other bacteria. Although decontamination with sodium hydroxide or benzalkonium chloride can remove these bacteria, this treatment is also toxic for Nocardia species. We demonstrate that modified Thayer-Martin medium can be used for selective isolation of Nocardia species.     

Case report: Nocardia asteroides mycetoma

Primary cutaneous infections with Nocardia asteroides are rare and have been reported in immunocompromised patients. Herein, we report a case of primary cutaneous Nocardia asteroides mycetoma of the skin in an immunocompetent individual. The infection was treated successfully with trimethoprim-sulfamethoxazole. Because a prolonged incubation time is required for the cultures and since additional biochemical tests are necessary for identification of this species, the clinician should alert the microbiology laboratory when such an infection is suspected clinically.     

Use of PCR-restriction enzyme pattern analysis and sequencing database for hsp65 gene-based identification of Nocardia species

Nocardia identification required laborious and time-consuming phenotypic and chemotaxonomic methods until molecular methods were developed in the mid-1990s. Here we reassessed the capacity of PCR-restriction enzyme pattern analysis (PRA) of the hsp65 gene to differentiate Nocardia species, including 36 new species. Our results confirm that hsp65 PRA must no longer be used for Nocardia species identification, as many species have the same restriction pattern. We then compared sequencing-based strategies using an hsp65 database and a 16S rRNA database and found that the hsp65 region contained sufficient polymorphisms for comprehensive Nocardia species identification.     

Nocardia wallacei sp. nov. and Nocardia blacklockiae sp. nov., human pathogens and members of the "Nocardia transvalensis Complex"

Nocardia isolates that share the property of in vitro amikacin resistance are grouped together by some authors in the Nocardia transvalensis complex. Our examination of 13 isolates that are amikacin resistant has revealed the existence of three distinct species. Sequence analysis of the 16S rRNA, 65-kDa heat shock protein, and secA1 genes, coupled with DNA-DNA hybridization, indicated that "N. asteroides drug pattern IV," "N. transvalensis new taxon 1," and N. transvalensis sensu stricto should each be considered a distinct species. The phenotypic and molecular characteristics of the proposed new species Nocardia wallacei (N. asteroides drug pattern IV) and N. blacklockiae (N. transvalensis new taxon 1) are presented and compared with those of N. transvalensis sensu stricto. The relative genetic diversity of isolates best placed with the species N. blacklockiae is also discussed. Case studies demonstrating the pathogenicity of N. wallacei and N. blacklockiae are presented. The type strain of N. wallacei is ATCC 49873 (DSM 45136), and that of N. blacklockiae is ATCC 700035 (DSM 45135).     

Analysis of multiple differing copies of the 16S rRNA gene in five clinical isolates and three type strains of Nocardia species and implications for species assignment

Five clinical isolates of Nocardia that showed ambiguous bases within the variable region of the 16S rRNA gene sequence were evaluated for the presence of multiple copies of this gene. The type strains of three Nocardia species, Nocardia concava, Nocardia ignorata, and Nocardia yamanashiensis, which also showed ambiguous bases in the variable region, were also examined. Cloning experiments using an amplified region of the 16S rRNA that contains the variable region showed that each isolate possessed 16S rRNA genes with at least two different sequences. In addition, hybridization studies using a 16S rRNA gene-specific probe and extracted genomic DNA of the patient isolates and of the type strain of N. ignorata showed that each isolate possessed at least three copies of the gene. These multiple differing copies of the 16S rRNA gene and the results of DNA-DNA hybridization studies indicate problems of species definition and identification for such isolates. A broader species concept than that currently in vogue may be required to accommodate such organisms.     

A method for determining in-vitro drug susceptibilities of some Nocardiae and Actinomadurae: results with 17 antimicrobial agents.

A simple timesaving method for determining drug susceptibilities in vitro of isolates of Nocardia and Actinomadura is reported. An isolate is considered "susceptible" when the quantity of drug required for inhibition of growth is that concentration which might be obtained in serum by conventional therapy. Sulfonamides remain the drugs of choice for treating disease due to Nocardia species. Although doxycycline and minocycline appear to be very effective against Nocardia species, susceptibility testing may be desirable when a physician is considering substitution of an antibiotic for a sulfonamide. Susceptibility testing also may be desired before a drug is selected for treating disease due to Actinomadura madurae.     

Isolation of Nocardia asteroides from respiratory specimens by using selective buffered charcoal-yeast extract agar.

Nocardiosis is difficult to diagnose clinically and by laboratory methods. A patient presented with disease compatible with pulmonary malignancy, but Nocardia asteroides was isolated on buffered charcoal-yeast extract agar. Investigation revealed that this medium may be a suitable selective primary isolation medium for Nocardia species from respiratory specimens.     

Brain abscess caused by Nocardia cyriacigeorgica in a patient with human immunodeficiency virus infection

Nocardia cyriacigeorgica is a recently characterized species within the genus of Nocardia. We report a brain abscess, following a primary pulmonary colonization, due to this species in a human immunodeficiency virus-infected patient. This case confirms that isolation of Nocardia in sputum is associated with a high risk of disseminated infection in immunocompromised patients.