The detection of Mycobacterium tuberculosis DNA in peripheral blood mononuclear cells (PBMC) by PCR and non-isotopic hybridisation assay was evaluated for the laboratory diagnosis of pulmonary M. tuberculosis infection. The PCR technique was based on the presence of IS6120, a DNA sequence specific for M. tuberculosis, and performed on PBMC from 30 patients belonging to the fifth group of the American Thoracic Society (ATS) classification of tuberculosis. The identification of amplification products was confirmed after electrophoresis by hybridisation with a non-isotopic probe in a DNA enzyme immunoassay (DEIA). Of the 30 blood samples studied by the PCR-DEIA technique, 26 gave positive results and four gave negative results. Blood samples from 30 subjects in a control group were negative by this technique. The data suggest that PCR-DEIA of blood may provide a sensitive, specific and useful means of diagnosing mycobacterial infection.

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OBJECTIVE: To evaluate the new non-radioactive automated method BACTEC 9000 MB system for the rapid detection of mycobacteria in clinical specimens. METHODS: Ninety clinical specimens from 90 patients with a clinical diagnosis of tuberculosis were tested by both BACTEC 9000 and standard microbiological methods, and the results compared. RESULTS: The BACTEC 9000, in comparison with the standard method, showed significantly higher detection rates (45 of 90 positive versus 34), shorter time to culture positivity (mean time 18.8 versus 27.4 days) and lower contamination rate (2.2% versus 5.5%). CONCLUSIONS: These results encourage the use of this new system and suggest its use in microbiological laboratories involved in mycobacteriology.

Antibiotic resistant pneumococci have been reported from all continents. Because of the importance of pneumococci in the aetiology of life-threatening diseases, the screening for penicillin resistance with oxacillin disc on all clinically significant isolates is suggested. However, discrepancy between the determination of penicillin resistance by oxacillin disc diffusion and the determination of penicillin minimum inhibitory concentration (MIC) has been reported. On this basis we have examined seven strains of Streptococcus pneumoniae isolated from patients recovered for the exacerbation of chronic bronchitis which were oxacillin-resistant. The assay of penicillin MICs showed that three isolates were moderately resistant to this agent, while four isolates resulted sensitive to penicillin as well as to cefotaxime. These results suggest that a further evaluation of penicillin MIC should be performed on those strains of S. pneumoniae resulting oxacillin-resistant.