Table 2.

Global guidance on treating isoniazid resistant tuberculosis disease in adults

Issuer of guidance	Treatment regimen(s) recommended	Reference(s)
WHO	Two sets of guidance, one on the basis of background levels of INH resistance and non-availability of DST before the continuation phase of treatment, the other when individual-level DST is available.	5;103
	Where background levels are deemed ‘high’ among new TB patients and INH susceptibility testing results are not available before the continuation phase two months of INH, RMP, PZA and EMB followed by four months of INH, RMP and EMB are recommended. The threshold for ‘high’ levels is not defined.46
	In the presence of individual-level drug susceptibility results, recommendations are made depending upon the non-MDR INH resistance pattern found. For example, six to nine months of RIF, PZA and EMB (plus or minus a fluoroquinolone) for INH-monoresistant or INH and STM-resistant disease.
ATS	Six month regimen of RMP, PZA and EMB (plus a fluoroquinolone for extensive disease).	102
NICE	Nine month regimen (10 months where disease is extensive) of two months of RMP, PZA and EMB, then seven months of RMP and EMB.	87

ATS- American Thoracic Society, DST- drug sensitivity testing, EMB- ethambutol, INH-isoniazid, NICE- National Institute of Health and Care Excellence, UK, PZA- pyrazinamide, RMP-rifampicin, STM- streptomycin, WHO- World Health Organization