[External control of drug sensitivity determination in mycobacteriologic laboratories in the Czech Republic]

In 1992 and 1993 an external control of sensitivity assessment of coded strains of M. tuberculosis to five basic antituberculotics was made: isoniazide, streptomycin, pyrazinamide, ethambutol and rifampicin. In 1992 from 11 participating laboratories an erroneous result was recorded in 9 (3 laboratories made two mistakes, 6 laboratories one mistake), two laboratories did not provide complete results. Unsatisfactory results were obtained during external controls in 1993. Of 15 participating laboratories four laboratories made one mistake, two laboratories two mistakes, four laboratories three mistakes. Five laboratories (i.e. one third) made more than three mistakes. Analysis of the results revealed a low reproductibility of results of drug sensitivity tests. To eliminate these shortcomings it will be necessary to make systematic external controls with subsequent solution of the shortcomings, restriction of the number of laboratories making these examinations to those who will systematically produce correct results. And it will be also necessary to test the sensitivity tests to antituberculotics in resistant strains in the National reference laboratory for mycobacteria.