[Kinetics of the killing of Staphylococcus aureus with formaldehyde].
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Biomedical subjects
Publications and source records attributed to M Salfinger.
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The adequate diagnosis and treatment of tuberculosis depends on many events, including rapid pathogen detection, patient isolation, species identification, and drug susceptibility testing. Well trained staff, using state-of-the-art technology, are necessary in the mycobacteriology laboratory to produce timely results that are necessary for the patients' care and public health measures. Mycobacteriology laboratories still play a pivotal role in the control of tuberculosis, which is especially true in view of the spread of multidrug-resistant tuberculosis. One way to optimize diagnostic efforts in spite of limited financial resources might be to sort and allocate specimens according to a system of priorities, e.g., diagnostic versus follow-up specimens. A "fast track" program for tuberculosis testing, which should be established as part of a dynamic diagnostic network, should focus on the highly infectious patient population. Collaboration between clinicians and mycobacteriologists remains the basis of dynamic diagnostic teamwork. Immediate screening of smears for acid-fast-bacilli in patients suspected of tuberculosis, followed by immediate processing of smear-positive specimens using modern mycobacteriological technology, should be given high priority. Diagnosis of disease due to nontuberculous mycobacteria can be difficult. Nontuberculous mycobacteria are commonly found in nature, and assessment as to whether a nontuberculous mycobacterium isolate is clinically significant can be a difficult task.
Pyrazinamide (PZA) is one of the most important drugs in modern chemotherapy of tuberculosis. Since PZA is active only at an acid pH, testing the susceptibility of Mycobacterium tuberculosis to PZA is difficult and timeconsuming. Therefore, we evaluated the BACTEC system for rapid testing of PZA susceptibility at pH 6. A total of 91 M. tuberculosis strains and 2 different strains of M. bovis BCG were screened for susceptibility to PZA. Each strain was tested in special 7H12 broth supplemented with polyoxyethylene stearate containing 25, 50 and 100 micrograms PZA/ml. Strains resistant to 100 micrograms/ml were retested against 25-100 micrograms/ml and at an extended range of PZA concentrations from 200-6,400 micrograms/ml. The MIC was determined with all strains within 4-20 (mean 7) days. Of the 77 susceptible strains, based on the pyrazinamidase test, MIC were less than or equal to 25 micrograms/ml for 34 strains, 50 for 38 and 100 for 2 strains. Three pyrazinamidase-positive strains had still higher MIC, 1 at 800 and 2 at 3,200 micrograms/ml. PZA-resistant strains had MIC of 800 or greater. Monoresistance to PZA has not been detected to date. The clear bimodal distribution of MIC in this method could enable the routine clinical microbiology laboratory to perform PZA susceptibility testing as easily as the 4 drugs now tested in the BACTEC system.