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Evaluation of partial 16S ribosomal DNA sequencing for identification of nocardia species by using the MicroSeq 500 system with an expanded database.

Identification of clinically significant nocardiae to the species level is important in patient diagnosis and treatment. A study was performed to evaluate Nocardia species identification obtained by partial 16S ribosomal DNA (rDNA) sequencing by the MicroSeq 500 system with an expanded database. The expanded portion of the database was developed from partial 5' 16S rDNA sequences derived from 28 reference strains (from the American Type Culture Collection and the Japanese Collection of Microorganisms). The expanded MicroSeq 500 system was compared to (i). conventional identification obtained from a combination of growth characteristics with biochemical and drug susceptibility tests; (ii). molecular techniques involving restriction enzyme analysis (REA) of portions of the 16S rRNA and 65-kDa heat shock protein genes; and (iii). when necessary, sequencing of a 999-bp fragment of the 16S rRNA gene. An unknown isolate was identified as a particular species if the sequence obtained by partial 16S rDNA sequencing by the expanded MicroSeq 500 system was 99.0% similar to that of the reference strain. Ninety-four nocardiae representing 10 separate species were isolated from patient specimens and examined by using the three different methods. Sequencing of partial 16S rDNA by the expanded MicroSeq 500 system resulted in only 72% agreement with conventional methods for species identification and 90% agreement with the alternative molecular methods. Molecular methods for identification of Nocardia species provide more accurate and rapid results than the conventional methods using biochemical and susceptibility testing. With an expanded database, the MicroSeq 500 system for partial 16S rDNA was able to correctly identify the human pathogens N. brasiliensis, N. cyriacigeorgica, N. farcinica, N. nova, N. otitidiscaviarum, and N. veterana.

DNA, Ribosomal↗

Primary cerebral abscess due to nocardia presenting as 'ghost tumor'. Clinical and pathological study.

We report a case of a primary cerebral abscess due to Nocardia asteroides in a nonimmunocompromised patient with a particular clinical course. The first symptom (right subacute brachial palsy) and the lesion in a computed tomographic (CT) scan (left parietofrontal edema suggestive of brain tumor) disappeared after corticosteroid treatment and the patient was discharged with total recovery. After 2 months she complained of headache and visual disturbance. A new CT scan showed an annular lesion in the left occipital lobe. A cerebral biopsy was diagnosed of nocardia infection. The patient died 2 weeks after this biopsy. A postmortem study showed an occipital brain abscess but not structural abnormalities were seen in the left parietofrontal area. We believe that the first episode could be a local inflammatory response to cerebral implantation of nocardia which disappeared clinically in the CT scan and in the postmortem study after corticosteroid treatment. Then the nocardia could have displaced by the hematological route to the second and definitive cerebral lesion.

Aged↗

Changes in host resistance caused by Nocardia brasiliensis in mice: cross-protection against Listeria monocytogenes.

Listeria monocytogenes was used to study the rate of development, magnitude, and persistence of the antimicrobial resistance engendered by Nocardia brasiliensis infection in mice. The growth of Listeria in the liver and spleen was more effectively restricted in Nocardia-infected mice than in noninfected animals. The development of delayed-type hypersensitivity to the Nocardia antigen was closely correlated to the increased resistance to Listeria, suggesting that both properties are the consequence of a single immunological event. The antibacterial resistance was also demonstrated in vitro. The results of the foregoing studies indicate that the microbicidal ability of macrophages, very likely activated by cell-mediated immunity, in enhanced in mice infected with Nocardia.

Animals↗

Nocardia keratitis: a case report.

PURPOSE: To describe a case of Nocardia keratitis resistant to 2% amikacin, with a toxic-allergic reaction to fortified topical 5% amikacin, and recurrence of the infection with topical corticosteroids. METHODS: Nocardia was diagnosed from a smear and positive culture and identified as Nocardia asteroides by gas chromatography and quantitative fatty acid analysis using the Microbial Identification System. Treatment was started with topical 2% amikacin, which was subsequently raised to 5% because of clinical resistance. RESULTS: A toxic-allergic reaction was observed after 5% amikacin so the drug was discontinued and commercially available drugs combining 1% chloramphenicol, 0.5% tetracycline, and 18 mil IU colistin with 0.3% ofloxacin were given. These were well tolerated and the infection improved quickly. After 1 month the antibiotics were discontinued and topical 0.1% clobetasone was given to reduce scar formation. The infection recurred after 1 week but responded to 3 months of the previous antibiotic combination and its sensitivity was checked with the Epsilometer test. CONCLUSIONS: Nocardia keratitis may not respond to 2% topical amikacin and fortified topical 5% amikacin may cause a strong toxic-allergic reaction. A commercially available combination of chloramphenicol, tetracycline, and colistin, with ofloxacin, may be effective but the treatment must be continued for several months. Topical steroids should only be used with considerable caution since they can lead to relapse of the infection.

Adult↗

Nocardia keratitis after traumatic detachment of a laser in situ keratomileusis flap.

PURPOSE: Nocardia are gram-positive bacteria existing ubiquitously in the environment; they can cause keratitis. Nocardia asteroides keratitis occurred in the interface between the stromal bed and flap after traumatic detachment of the flap 4 months after an initially uncomplicated laser in situ keratomileusis (LASIK) procedure. METHODS: Nocardia asteroides keratitis was confirmed by culture. Therapy included topical and oral trimethoprim-sulfamethoxazole. RESULTS: Thirteen months after the trauma, the patient's spectacle-corrected visual acuity was 20/20 with a manifest refraction of -2.25 -1.00 x 30 degrees. CONCLUSIONS: The immediate steps of management consisting of surgically lifting the corneal flap, rapid microbial identification, and proper treatment with specific antibiotics resulted in the successful treatment of Nocardia asteroides keratitis in a traumatized eye after LASIK.

Adult↗

[Nodular lymphangitis caused by Nocardia asteroides].

BACKGROUND: Nocardia species are typically found in soil and decaying organic matter. The lymphocutaneous type or nodular lymphangitis is unusual. This is acquired in most of cases by a traumatic inoculation through the skin of a person who is immunocompetent, and is generally caused by Nocardia brasiliensis. METHODS: We report two cases of nodular lymphangitis caused by Nocardia asteroides, that have been admitted in our hospital during one year period. RESULTS: The two healthy persons of 26 and 56 years old suffered from a cutaneous puncture in their arms caused by a plant's pricke while they were gardening. The symptoms they showed at the area of the puncture were ulcerative lesion and inflammatory nodules through the lymphatic tract that were abscessed. There were not any systemic involvement. Cultures of the purulent drainage and skin biopsy revealed Nocardia asteroides. Treatment with oral trimethoprim-sulfamethoxazole for 8 weeks and surgical debridement resulted in a cure without relapse. CONCLUSION: Nodular lymphangitis has specific symptoms and clinical signs. A detailed clinical and occupational history, accompanied by microbiology identification at the cutaneous biopsy and exudation, should allow specific treatment. Trimethoprim-sulfamethoxazole continues being the selected antibiotic.

Adult↗

Nocardia asteroides sclerokeratitis in a contact lens wearer.

PURPOSE: To report a case of sclerokeratitis caused by Nocardia asteroides in a soft contact lens wearer. CASE REPORT: A 65-year-old male presented with a 2-month history of a corneal ulcer in the left eye. He wore two weekly disposable soft contact lenses on an extended basis. He revealed his history of gardening before the onset of symptoms. On examination, his best-corrected visual acuity was 20/30 in the right eye and 20/400 in the left eye. In the left eye, there was conjunctival injection. His cornea showed multiple patchy infiltrates, with a feathery border that was raised and involved up to the midstroma. There was a 3+ anterior chamber reaction. Corneal scrapings were performed for smears and cultures. Topical 2% amikacin sulfate every half hour along with oral clarithromycin therapy was initiated. On follow-up, the sclera lesions worsened. RESULTS: Smears of corneal scrapings revealed gram-positive filamentous bacteria in Gram's stain. The cultures grew Nocardia asteroides. The patient was switched to trimethoprim-sulfamethoxazole (Bactrim DS, Roche Laboratories, Nutley, NJ) as the sclera was involved. The patient responded to treatment, and the infection resolved. When last seen, approximately 4 months after his initial presentation to us, his visual acuity was 20/40 in the affected eye. There was corneal scarring, and the adjacent sclera showed thinning. CONCLUSIONS: Nocardia sclerokeratitis can be associated with contact lens wear. Nocardia should be considered in the differential diagnosis of a corneal ulcer with an indolent progressive course with feathery infiltrates. Topical amikacin and systemic trimethoprim-sulfamethoxazole are effective drugs in the treatment of nocardial corneal infection with scleral involvement.

Aged↗

[Nocardia isolated from the respiratory tract].

Twelve strains of Nocardia isolated from sputa, bronchial washings and pleural fluids, were studied. The classification was based on the following characteristics: a) acid-fastness; 2) ability to disolve crystals of tyrosine and xantine; 3) hydrolysis of casein; 4) growth in dilute gelatin medium (0.4%) and 5) galactose acidification. Direct cultivation of the clinical material in Czapek liquid culture medium without carbon source and containing a paraffin rod (pariffin-bait technic), as well as the routin T.B. sputum digestion and concentration with NaOH solution followed by its cultivation in Loewenstein's medium, were employed for the isolation of Nocardia. The sensitivity of the strains to tuberculostatic drugs was investigated using the Canetti's method, as was the ability to growth in Sabouraud and lactrimel culture media supplemented with 100 mug/ml of rifamycin. Finally the pathogenicity test was carried out by intraperitoneal and intramuscular inoculation in guinea-pigs. All the strains were classified as Nocardia asteroides. Seven starins were isolated from patiens with lung conditions of no nocardial etiology. The diagnosis of nocardiosis of the lung was demonstrated in the remaining five patiens by microscopical observation of Nocardia in clinical specimens, by the repeated cultures obtained from these materials and, finally, by the fact that an improvement of the clinical symptomatology was obtained by sulfa administration.

Anti-Bacterial Agents↗

Nocardia farcinica arthritis of the knee. A case report.

Nocardia is a gram positive, aerobic branched actinomycete; it is an ubiquitous soil saprophyte. As an infecting agent it has been increasingly identified in humans, especially in immuno-suppressed hosts. Nocardia as a cause of septic arthritis is very unusual. The described genus was Nocardia asteroides in nearly all previously reported cases. We report an unusual case of spontaneous Nocardia farcinica septic arthritis of the left knee in a 68-year-old man, who was under systemic corticosteroids for chronic obstructive pulmonary disease. The diagnosis was rapidly made by Gram and acid-fast stains and later confirmed by culture. PCR was used to identify the subtype. The patient was treated successfully with sulphametaxazole-trimethoprim for six months. Our case re-emphasises, especially in the immuno-compromised patient, the importance of performing fungal and acid-fast bacilli cultures, besides the most common bacterial cultures for aerobic and anaerobic organisms, in order to identify less common organisms and to initiate early and adequate treatment.

Aged↗

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.

Aged↗

Disseminated Nocardia caviae with positive blood cultures.

Disseminated Nocardia caviae infection with multiple positive blood cultures occurred in a bone marrow transplant recipient. Positive blood cultures are unusual in disseminated Nocardia infections and N caviea is an unusual species of Nocardia to cause infections in man, although its virulence in laboratory animals is similar to N asteroides. Multiple positive blood cultures in this case suggest a continuous or recurrent bacteremia rather than a transient bacteremia as previously has been thought to occur in disseminated Nocardia infections. The marked immunosuppressed state of the patient and an indwelling venous line could also have accounted for the recurrent bacteremia.

Adult↗

Immunologically specific direct T lymphocyte-mediated killing of Nocardia asteroides.

Macrophage-depleted populations of splenic lymphocytes obtained from immunized and nonimmunized BALB/c mice were tested to determine their ability to kill Nocardia asteroides GUH-2 in vitro. Nocardia-primed lymphocytes, but not normal lymphocytes, killed N. asteroides. The ability of these lymphocytes to kill N. asteroides could be further enhanced by in vitro activation of the lymphocytes with nocardial cell wall fragments 12 to 48 hr before challenge. The nocardicidal activity of the lymphocytes was greater in populations enriched in T cells and was eliminated by lysing the lymphocytes with anti-Thy-1.2 plus C. N. asteroides-primed T cells were unable to kill a distantly related actinomycete, Rothia dentocariosa, and killed other species of Nocardia (N. brasiliensis and N. caviae) poorly or not at all, indicating that the microbicidal activity was immunologically specific. Light microscopy and electron microscopy revealed a close association between the T cell membrane and the cell wall of N. asteroides, with possible damage to the latter structure. The ability of immunologically specific T cells to recognize, bind, and kill Nocardia may be an important mechanism of host defense, because these microorganisms often are able to escape intracellular killing by macrophages.

Animals↗

Characterisation of Nocardia farcinica isolated from cattle with bovine farcy.

Twenty-one strains of Nocardia farcinica isolated from cattle with bovine farcy in the Sudan were examined to determine their taxonomic relationships. The strains had morphological, cultural and physiological properties of Nocardia, but exhibited some variations of minor taxonomic importance. All strains contained lipids characteristic of nocardiae (LCN-As) and all except two were found by immunodiffusion tests to be serologically related to each other, to N asteroides but not to Mycobacterium tuberculosis nor M bovis. Consequently, these organisms were regarded as true members of the genus Nocardia.

Animals↗

Isolation and characterisation of nocardia from clinical specimens.

Sixteen isolations of nocardia of which 12 were from pulmonary infections, one from wound infection, one from mycetoma and 2 from eye infections were studied from June, 1989 to May, 1990. The importance of Gram's stain findings of primary smear is being highlighted. The nocardia species were identified utilising the morphological characters including acid fastness and cultural and biochemical characters. Notable among the isolates were Nocardia brasiliensis, one each from mycetoma and pulmonary infection, which are rare in South India and Nocardia asteroides from a case of endophthalmitis probably of endogenous origin.

Aged↗

Nocardia fractions, NLD and NWSM, induce tumor necrosis factor-alpha secretion in human monocytes: role of protein kinase C.

Nocardia lysozyme digest (NLD) and Nocardia water-soluble mitogen (NWSM) are two fractions derived from Nocardia opaca. In this report, we demonstrated that both fractions elicited significant secretion of tumor necrosis factor-alpha (TNF-alpha) in human monocytes. Supernatants from monocytes stimulated with NWSM and low concentrations of NLD displayed a cytotoxic activity against TNF-alpha-sensitive L929 cells, but supernatants from monocytes stimulated with high concentrations of NLD failed to lyse L929 cells. This latter phenomenon might be related to the secretion of an inactive form of TNF-alpha or the release of an inhibitor of TNF-alpha cytotoxic activity. Since it is well established that protein kinase C (PKC) plays a major role in the signaling of several monocyte activators, we investigated the putative role of PKC in cytokine synthesis induced by NLD and NWSM fractions. TNF-alpha secretion in response to both Nocardia fractions was inhibited by sphingosine, staurosporine and calphostin C, known PKC inhibitors, as well as by a PKC depletion procedure. In addition, NLD and NWSM induced a transient increase in [3H]phorbol dibutyrate binding, which assessed the activation of PKC. The data suggest the involvement of PKC in the signaling of NLD and NWSM fractions leading to the synthesis and the secretion of TNF-alpha by human monocytes.

Adjuvants, Immunologic↗

Disseminated infection due to Nocardia transvalensis coincident with Cryptococcus neoformans variety gattii meningitis.

A case of meningitis due to Cryptococcus neoformans var. gattii coincident with disseminated Nocardia transvalensis infection is reported. Nocardia infection initially progressed despite high-dose antimicrobial therapy. Although a specific immunologic defect could not be defined, in vitro lymphocyte proliferation in response to stimulation with the Nocardia isolate was reduced. It is proposed that coinfection with Cryptococcus neoformans may have contributed to the observed impairment of lymphocyte function, leading to disseminated Nocardia disease and a suboptimal treatment response.

Anti-Bacterial Agents↗

Comparative evaluation of the E test for susceptibility testing of Nocardia species.

The E Test (PDM Epsilometer; AB Biodisk, Solna, Sweden) was compared with microbroth dilution and disk diffusion for antimicrobial susceptibility testing of Nocardia as a collaborative study by two geographically separate laboratories. A total of 52 clinical isolates and five species of Nocardia were used in this comparative evaluation. Susceptibility testing was performed with Mueller-Hinton media and eight antimicrobial agents. Growth of the test strains with Mueller-Hinton medium was generally satisfactory, with the majority of isolates producing adequate growth within 24-36 h. Growth inhibition ellipses were generally well delineated and uniform for most drugs, and the points of intersection with the E Test strip were generally easy to determine. An inoculum size of approximately 2.0 x 10(7) CFU/ml was optimal for performance of the E Test method with the Nocardiae. Comparison of E Test and microbroth dilution MICs revealed 89.4% agreement for all drugs within +/- 1 log2 dilution. Using NCCLS interpretive criteria for susceptible and resistant results, complete agreement between E Test and disk diffusion results was 93.3%, and between E Test and microbroth dilution results was 96.2%. Interpretive category errors occurred at rates of 18.2% (risk corrected), 0, and 4.1% for very major, major, and minor errors, respectively, when E Test results were compared with disk diffusion results, and 0, 0, and 3.8%, respectively, when E Test was compared with microbroth dilution. Inter- and intra-laboratory reproducibility, within +/- 1 log2 dilution for all drugs, was 95% and 98%, respectively. Results from this study suggest that E Test may be suited for use as an alternative method for antimicrobial susceptibility testing of Nocardia species.

Culture Media↗

Differentiation of Nocardia from rapidly growing Mycobacterium species by PCR-RFLP analysis.

The nucleotide sequences from a region of the groEL gene from one Nocardia asteroides and from several species of Mycobacterium were determined and found to be highly homologous. Based on these homologies, we developed a rapid method capable of differentiating between these two genera. The method is based on restriction fragment-length polymorphism (RFLP) analysis of DNA amplified from the groEL gene that is highly conserved between mycobacteria and nocardiae. When the groEL gene from species of these genera is enzymatically amplified by the polymerase chain reaction (PCR), a 422-bp fragment is generated. Correlation of the restriction endonuclease digestion patterns of the amplification products with reference and/or biochemically characterized clinical samples enabled us to establish RFLP profiles for ten species of Mycobacterium and five species of Nocardia. When a portion of the groEL gene from each of these organisms is digested with the restriction endonuclease Hae III, that organism is readily assigned to one of these two genera on the basis of the derived RFLP patterns. The utility of this approach was examined by testing 105 pure cultures from samples previously identified by routine culture techniques for the presence of groEL DNA sequences of mycobacterial or nocardial origin. This analysis correctly identified the organism in all samples tested. In summary, PCR-RFLP analysis provides a rapid and sensitive method for the differentiation of Nocardia species from rapidly growing Mycobacterium species.

Bacterial Proteins↗