The first cases of drug resistant tuberculosis were discovered as early as in the 1950s after the introduction of streptomycin as mono-therapy. Therefore, tuberculosis must always be treated with standardized combinations of various drugs. Due to the slow growth of the bacteria and the low potential for mutations, the likelihood of developing resistance in connection with combined treatment, is limited. Tuberculosis sensitive to all first-line drugs, is treated with a standardized treatment regimen for six months. Choice of treatment regimen for resistant tuberculosis depends on the drug susceptibility results. Generally, the treatment regimen will contain as many first-line drugs as possible followed by second-line and possibly third-line drugs chosen according to the drug susceptibility pattern.
As it can take several weeks to obtain the drug susceptibility result, many patients have already started the treatment with four drugs" standard regimen before test results are available. If the isolate shows sensitivity to all first-line drugs, ethambutol can be considered discontinued. If drug resistance is detected, interruption of the tuberculosis treatment can be considered depending on clinical criteria, until additional drug susceptibility results are available and a tailored treatment can be prescribed. Alternatively, a preliminary treatment regimen based on empirical considerations can be prescribed until complete drug susceptibility results are available.
If the doctor suspects resistant tuberculosis at the time of diagnosis either because of the patients medical history, known exposure to a case with resistant tuberculosis or the patient originates from a country with a high incidence of resistant tuberculosis, it may be considered to postpone start of treatment until drug susceptibility results are available, at least for rifampicin and isoniazid.
Globally, the cure rate for patients treated for multi-drug-resistant tuberculosis is lower than for patients treated for tuberculosis sensitive to first-line drugs (1). Most of the patients with multi-drug-resistant tuberculosis in Norway receive adequate treatment as we have favourable routines for drug susceptibility testing, high quality diagnostic services and access to all types of drugs. Monitoring of treatment outcome for patients with multi-drug-resistant tuberculosis in Norway from 1996 until 2006, show that 67 % of patients are currently receiving correct treatment or have completed such treatment. The most important cause of discontinuation of treatment is loss to follow-up. This is very unfortunate and can constitute a serious threat to public health. Treatment options for drug resistant tuberculosis are already reduced and additional resistance will limit the treatment possibilities even more. It is adamant to establish a good collaboration with the patient as early as possible. As the treatment takes so long, and the drugs partly have serious side effects (3, 12), the patient faces multiple challenges in practical, medical and emotional terms. The reasons for tuberculosis patients abandoning their treatment can comprise language problems, cultural differences, poor communication between various officials and levels in the health service, drug abuse, and lack of residence permit, a place to live or work (13). Collaboration between the Norwegian Directorate of Immigration and the Immigration Appeals Board ensures that patients applying for political asylum during an ongoing tuberculosis treatment are granted a temporary residence permit until the treatment is complete.