False-positive result with BinaxNOW Legionella Antigen immunochromatographic (ICT) assay: response to Helbig et al. (2001).
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A 65-year-old Japanese woman with nocardial mycetoma which developed five years after a compound bone fracture of the left foot due to a traffic accident was reported. During this accident, two small pieces of gravel had entered her foot. Nocardia asteroides, which had been attached to the gravel, was probably inserted 5 years previously during the trauma. The lesion did not respond to oral minocycline and trimethoprim-sulfamethoxazole and was finally removed surgically; she has been free from recurrences for one year, of follow-up.
The genera Nocardia and Rhodococcus were clearly differentiated in the present study. Eleven characteristics were shown to be useful for differentiation between these two genera. Nocardia asteroides sunsu stricto previously defined by Tsukamura was divided into two taxa. One contained the type strain and was considered to retain the name Nocardia asteroides in a new sense. Another was named in the present study as Nocardia nova sp. nov. Tsukamura. The type strain of this species is ATCC 33726. The following seven characters were useful for differentiating N. nova from newly defined N. asteroides: 1) arylsulfatase activity after 14 days; 2) catalase activity (semiquantitative); 3) beta-esterase activity; 4) pyrazinamidase activity; 5) utilization of citrate as a sole source of carbon; 6) utilization of 2,3-butylene glycol as a sole carbon source; and 7) resistance to 5-fluorouracil (20 micrograms/ml). The name Nocardia farcinica for Tsukamura's Kyoto-I group should be rejected. This taxon has been named Nocardia paratuberculosis sp. nov. Tsukamura. The type strain is ATCC 23826. Three new species of the genus Rhodococcus were proposed: Rhodococcus aichiensis sp. nov. Tsukamura (type strain, ATCC 33611); Rhodococcus chubuensis sp. nov. Tsukamura (type strain, ATCC 33609); Rhodococcus obuensis sp. nov. Tsukamura (type strain, ATCC 33610).
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Nocardia asteroides complex organisms derived from human specimens between 1979 and 1992 were identified to the species level. Of 117 N. asteroides complex organisms, 34 (29%) were N. farcinica, 28 (24%) were N. nova, and 55 (47%) were N. asteroides sensu stricto. An analysis of the specimen sites from which the organisms were derived showed that isolates derived from blood, brain, or bone marrow were more likely to be N. farcinica than the other two species. A study of the virulence of ten strains of each species was undertaken, using a mouse model with intravenous inoculation. The 50% lethal doses (LD50) for N. farcinica were significantly lower than those of the other two species. LD50 values for N. nova and N. asteroides were not significantly different. The above data confirming the greater virulence of N. farcinica support the identification of species within the N. asteroides complex.
Pulmonary nocardiosis is a rare disease. We reported a case of pulmonary nocardiosis associated with middle lobe atelectasis. A 66-year-old female was admitted to Saga Medical School Hospital with complaints of fever, productive cough and hemosputum. Nocardia asteroides was isolated from her sputum and bronchial lavage fluid. Administration of sulfamethoxazole-trimethoprim (ST) improved her symptoms and Nocardia asteroides were rapidly eliminated from her sputum. However, she had severe side effects of ST: toxic dermatitis, granulocytopenia and liver dysfunction, whereupon administration of ST was stopped. About two weeks later, Nocardia asteroides appeared again in her sputum. Either netilmicin (NTL) or minocycline (MINO) given consecutively could not eliminate Nocardia asteroides from her sputa. Subsequently a combination therapy of OFLX administration and gentamicin inhalation was tried. This treatment improved her symptoms and eradicated Nocardia asteroides from her sputa completely. In vitro study, ST, MINO and aminoglycosides showed good susceptibility against Nocardia asteroides. In this case, it was revealed that GM inhalation therapy is also very useful for pulmonary Nocardiosis.
Demonstration of synergism between trimethoprim and sulfamethoxazole against 10 Nocardia isolates was found to be critically dependent upon the isolate, the duration of incubation, and the trimethoprim-sulfamethoxazole ratio. Inoculum effect was not significant. The trimethoprim-sulfamethoxazole ratio in the commercial, fixed-dose combination was found to contain too little trimethoprim to be optimal for Nocardia.
A retroperitoneal Nocardia asteroides abscess was diagnosed in a 76-year-old patient. Trimethoprimsulfamethoxazole treatment for 6.5 weeks failed after surgical drainage of the abscess, and superinfection occurred. Subsequent treatment with amikacin resulted in a cure after 7 weeks. Amikacin might significantly shorten the duration of treatment in disseminated nocardiosis.
A mouse model of cerebral nocardiosis was used to determine relative antibiotic efficacy by reducing bacterial colony counts per gram of brain tissue. The antimicrobial agents employed were demonstrated in vitro to be inhibitory to most strains of Nocardia asteroides at very low concentrations. The agents used in this study were imipenem-cilastatin, amikacin, trimethoprim-sulfamethoxazole, and minocycline. Antibiotics were administered every 4 h for 72 h before animal sacrifice. Bacterial colony counts were assayed at various time points before the completion of therapy. Imipenem-cilastatin and amikacin were the most effective agents tested. Trimethoprim-sulfamethoxazole was less effective than imipenem and amikacin but more effective than minocycline. Minocycline did not eradicate intracerebral organisms and was similar to saline (control) in its effects.
Testing of the susceptibility to 12 antimicrobial agents, including beta-lactams, aminoglycosides, ciprofloxacin, and erythromycin, was performed by broth microdilution on 78 consecutive clinical isolates of Nocardia asteroides. Surprisingly, a limited number of patterns of susceptibility were identified that included all drug classes, with 95% of isolates exhibiting one of five patterns. One group (17%) exhibited resistance to the broad-spectrum cephalosporins, one group (18%) was susceptible to both ampicillin and erythromycin, one group (17%) was susceptible to ampicillin and carbenicillin but intermediate in susceptibility to imipenem, and the most common group (35%) was resistant to ampicillin but susceptible to the broad-spectrum cephalosporins and imipenem. The most active parenteral agents were amikacin (95%), imipenem (88%), ceftriaxone (82%), and cefotaxime (82%), while the most active oral agents were the sulfonamides (100%), minocycline (100%), and ampicillin (40%). Additional studies are needed to determine whether differences in beta-lactamases relate to varying beta-lactam resistance and whether taxonomic differences that correlate with the different susceptibility groups can be identified.
Thirteen isolates of Nocardia asteroides from both soils and aquatic samples (lake and moat sediments, as well as scum from activated sludge), together with a type strain and two known clinical isolates of this species, were characterized by repetitive extragenic palindromic-PCR fingerprinting with the BOX-A1R primer. The resulting DNA fingerprint patterns proved to be strain specific, and cluster analysis distinguished the soil isolates, the aquatic isolates, and the known strains as being in separate groups.
Guinea pigs immunized with ribonucleic acid protein fraction from Nocardia asteroides developed high cell-mediated immunity within 2 weeks, as shown by increased macrophage microbicidal activity and macrophage migration inhibition. This immunity protected against intravenous and subcutaneous challenge with N. asteroides and persisted for at least 70 days.
Cells of Nocardia asteroides undergo structural and chemical changes, especially in the cell wall, during growth in brain heart infusion broth. Experiments were devised to determine whether these changes affected the virulence of Nocardia for mice. It took, on the average, 1,380 times the number of colony-forming units at the stationary phase to achieve the same mortality induced by the log-phase cells. Cells in either the lag phase or early stationary phase of growth were intermediate in the numbers of colony forming units required to kill mice. Dry-weight determinations at different stages of growth demonstrated that the log-phase organisms were approximately 10 times heavier than stationary-phase cells. Thus, on the basis of dry-weight (micrograms) values, the average colony-forming unit of log phase is approximately 130 times more virulent than in stationary-phase cultures. Therefore, the stage of growth affects greatly the virulence of N. asteroides.