On the basis of the numbers of Nocardia 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 as Nocardia asteroides (66.7%), Nocardia farcinica (23.8%), Nocardia brasiliensis (3.2%), Nocardia otitidiscaviarum (4.8%) and Nocardia 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 with Nocardia farcinica died in 57.1% of cases, compared with 17.6% of patients infected with Nocardia asteroides. Corticosteroid therapy represented a significant factor in mortality. Isolates of Nocardia asteroides revealed variable resistance, whereas isolates of Nocardia 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 by Nocardia 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.

Nocardia farcinica is a rare Nocardia species causing localised and disseminated infections. A case of Nocardia farcinica infection is presented, and 52 cases previously reported in the literature are reviewed. The hosts usually had predisposing conditions (85%), and acquired the infection through the respiratory tract or skin; the infection then often spread to the brain, kidney, joints, bones and eyes. Pulmonary or pleural infections (43%), brain abscesses (30%) and wound infections (15%) which failed to respond to conventional antimicrobial therapy were the more frequent forms of infection. Nocardia farcinica was frequently isolated from pus (100% of samples), bronchial secretions (41%) and biopsy specimens (63%), but isolation from blood and urine, as in the case presented here, is rare. Antibiotic therapy was adequate in 61% of the patients in whom it was specified, the agents most frequently given being trimethoprim-sulfamethoxazole (54%), amikacin combined with imipenem (7%) and amoxicillin-clavulanate (7%). The high mortality (31%) can be attributed to the severe underlying diseases present, difficulties encountered in identifying the pathogen, inappropriate therapy and late initiation of therapy. Although an infrequent pathogen, Nocardia farcinica should be kept in mind as a cause of infection especially in immunosuppressed patients with indolent infections not responding to third-generation cephalosporins.

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.