treatment of multi drug resistant tuberculosis
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In 2013, out of the reported 136,000 MDR-TB patients, just over 71% (97,000) started on treatment. This is a three-fold increase compared with 2009 (1).
Access to quality-assured drug susceptibility testing (DST) is a critical component of TB treatment. Furthermore it is important that drug resistant TB programmes to have knowledge about:
- the prevalence of drug resistance in new patients, as well as in different groups of retreatment cases
- which and with what frequency second-line anti-TB drugs have been used within a given area served by a programmatic strategy
Treatment strategies for MDR-TB can be
- standardised
- data on historical resistance patterns and drugs which have been used in that region are used as the basis for regimen design
- all patients in a defined group or category receive the same regimen
- suspected MDR-TB should be confirmed by DST whenever possible
- individualized
- each regimen is designed based on the patient's past history of TB treatment and individual DST results (1,2)
Current recommendation requires 18-24 months of treatment for MDR-TB (2).
- empiric standardized regimens often need to be adjusted based on patient clinical history, once additional history or when DST results becomes available
- individual regimens are designed based on DST of the infecting strain, patient's history of TB treatment and contact history.
The following steps can be uses to build a regimen for drug-resistant TB treatment.
- step 1 - choose an injectable agent such as amikacin, kanamycin, or capreomycin
- Streptomycin is generally not used because of high rates of resistance in patients with MDR-TB
- step 2 - choose a higher generation fluoroquinolone
- use a later generation fluoroquinolone. If levofloxacin (or ofloxacin) resistance is documented, use moxifloxacin
- avoid moxifloxacin if possible when using bedaquiline or delamanid
- step3 - choose two or more oral bacteriostatic second-line anti-TB drugs
- e.g. - Cycloserine/terizidone, Para-aminosalicylic acid (PAS), Ethionamide/prothionamide
- Ethionamide/prothionamide is considered the most effective
- DST is not considered reliable for the drugs in this group
- step 4 - Add Group 1 drugs. Pyrazinamide, Ethambutol
- Pyrazinamide is routinely added in most regimens
- step 5 - consider adding a new antituberculosis drug
- e.g. - Bedaquiline, Delamanid, Linezolid, Clofazimine
- consider if four second-line anti-TB drugs are not likely to be effective
- if drugs are needed from this group, it is recommended to add two or more
Treatment of MDR-TB can be divided into:
- intensive phase
- consist of at least four second-line anti-TB drugs that are likely to be effective (including an injectable anti-TB drug), as well as pyrazinamide
- lasts at least eight months in total, but the duration can be modified according to the patient's response to treatment
- continuation phase
- continuation of treatment with other drugs
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