[Process of acquiring drug resistance: retrospective review of records of MDR TB].

PURPOSE

To investigate the reasons of acquiring drug resistance among MDR TB cases and to learn lessons for the prevention of acquiring of drug resistance.

METHOD

Retrospective review of 159 MDR TB cases who were treated at Fukujuji Hospital from 1990 January to 2003 August.

RESULT

We found that among 159 cases, 48 cases were infected with multidrug resistant M. tuberculosis bacilli, 35 cases acquired drug resistance, 7 cases were with the history of tuberculosis treatment before 1970 only, and that remaining 69 cases were difficult to evaluate because of the lack of informations on previous drug susceptibility tests. Among 35 cases that acquired drug resistance, the drug susceptibility test patterns before becoming MDR TB were categorized as follows: 12 HR susceptible, 18 H resistant R susceptible, 3 R susceptible (H unknown), and 2 H susceptible R resistant. The factors that may have influenced to acquire MDR were lack of modification of the regimen after knowing drug resistance among H resistant R susceptible cases, and defaulting among cases that were not evaluated (15/69) and H resistant R susceptible cases (3/18).

DISCUSSION

Control of MDR TB needs to be strengthened. Proper drug susceptibility test, proper choice of drugs at the beginning of treatment and modification of treatment after knowing drug susceptibility test results are important for the prevention of MDR TB. Ensuring patient adherence to treatment is important in the medical institutions where drug susceptibility test is not properly done, in particular, for H resistant R susceptible cases, and guidance to these institutions by the public health centers should be intensified.