Nocardiosis has been believed to be caused by the members of the Nocardia asteroides complex and the Nocardia brasiliensis species. However, recent advances in genotypic identification have shown that the genus exhibits considerable taxonomic complexity and the phenotypic markers used in the past for its identification can be ambiguous. The aim of this study was to assess the species distribution of Nocardia isolates and to determine whether there are differences in pathogenicity or antimicrobial susceptibility between the different species identified. Nocardia isolates obtained over a 7 year period were retrospectively reviewed. The isolates were identified genotypically, their antibiotic susceptibility was tested and the clinical data of the 27 patients were retrieved. Eight different Nocardia species were identified: Nocardia farcinica (n59), Nocardia abscessus (n56), Nocardia cyriacigeorgica (n56), Nocardia otitidiscaviarum (n52), Nocardia nova (n51), N. nova complex (n51), Nocardia carnea (n51) and Nocardia transvalensis complex (n51). All species were susceptible to co-trimoxazole but different patterns of susceptibility to other agents were observed. All patients had active comorbidities at the time of infection. A total of 19 patients were immunosuppressed, due to human immunodeficiency virus infection, chronic corticosteroid therapy, immunosupressive therapy or haematological malignancies. Six patients displayed a Charlson comorbidity index score above 4. Global mortality was 50 % while attributable mortality was 34.6 %. Patients infected with N. farcinica -the most resistant species -had the highest Charlson index score and the highest mortality rate. Accurate identification of the species and susceptibility testing of Nocardia isolates may play an important role in diagnosis and treatment.

In this multicenter study, the reliability of two nonradiometric, fully automated systems, the MB/BacT and BACTEC MGIT 960 systems, for testing the susceptibilities of 82 Mycobacterium tuberculosis strains to isoniazid, rifampin, ethambutol, and streptomycin was evaluated in comparison with the radiometric BACTEC 460TB system. The arbitration of discrepant results was done by the reanalysis of the strain, the determination of the MIC, and the molecular characterization of some resistance determinants. The overall level of agreement with BACTEC 460TB results was 96% with the MB/BacT test and 97.2% with the BACTEC MGIT 960 system. With both methods, the level of agreement with BACTEC 460TB results was 96.3% for isoniazid, 98.8% for rifampin, and 98.8% for ethambutol. The level of agreement for streptomycin was 90.2% with MB/BacT and 97.5% with BACTEC MGIT 960. Overall, there were 11 very major errors and 2 major errors with the MB/BacT method and 5 very major errors and 2 major errors with the BACTEC MGIT 960 system. In general, the MB/BacT and BACTEC MGIT 960 systems showed good performance for susceptibility testing with first-line antituberculosis drugs.Tuberculosis (TB) is one of the most prevalent infectious diseases in the world. According to a recent report of the World Health Organization, in 2003 there were 8.8 million new TB cases and around 1.7 million deaths attributable to the disease (25). In addition, multidrug-resistant TB is becoming increasingly common and is a major health concern in many regions of the world, particularly in developing nations (24). Rapid, accurate diagnosis and the determination of drug susceptibility are crucial to optimize treatment and prevent transmission. The most widely used method for Mycobacterium tuberculosis drug susceptibility testing is the proportion method, either on solid medium or on liquid broth. The BACTEC 460TB system (Becton Dickinson Biosciences, Sparks, MD) has been widely validated for approximately 20 years for the reliable and rapid testing of the susceptibilities of M. tuberculosis isolates (9, 16, 21). The radiometric BACTEC 460TB test requires fewer than 14 days of incubation before results are available, but it is semiautomated and entails the disposal of a radioactive substance (16).New liquid medium-based systems have recently been introduced for the nonradiometric susceptibility testing of M. tuberculosis (4, 10, 17-19). These include the ESP Culture System II (AccuMed International, Westlake, OH), the MB Redox system (Biotest, Dreieich, Germany), the BACTEC MGIT 960 mycobacterial growth indicator tube system (Becton Dickinson Microbiology Systems, Sparks, MD), and the MB/BacT system (bioMérieux, Marcy l'Etoile, France).In the present multicenter study, we evaluated the reliability of the MB/BacT and BACTEC MGIT 960 systems for testing M. tuberculosis susceptibility to streptomycin, isoniazid, rifampin, and ethambutol (a combination known as SIRE) and compared the results obtained with these methods to those obtained with the radiometric BACTEC ...

The main advantage of the described method is the possibility of detecting rifampicin and isoniazid resistance within 48-72 h after sample collection, with a sensitivity of nearly 100% in smear-positive samples if the chosen target is responsible for the resistance.

The LCD array protocol takes 45 min (15 min 'hands-on' time) after prior PCR amplification. Only minimal laboratory equipment is required. LCD arrays provide a rapid and economical method to characterize mutations in codon 315 of the katG gene, in the mabA-inhA regulatory region and in the rpoB gene.

Twenty-five of 1423 isolates were found to display intermediate or full resistance to co-amoxiclav, cefotaxime or ceftazidime. Seventeen isolates had reduced susceptibility to co-amoxiclav; of these, seven produced TEM-110, eight produced the new TEM-159, one the new TEM-160 and one TEM-1. Five isolates producing TEM-110, TEM-159 or TEM-160 enzymes shared the same PFGE profile. Three isolates produced an ESBL, CTX-M-1, CTX-M-32 and the new variant, VEB-4. Finally, five isolates with an AmpC phenotype produced CMY-2, two with the same PFGE profile. Our data emphasize the diversity of beta-lactamases found in this species.