showed that risk for MDR-TB is three times higher among recreational drug users than non-users. Shin et al.s study demonstrated that alcohol usage was linked to poorer outcomes in MDR-TB treatment; they also noted that a majority of subjects within their study (many of whom regularly used alcohol) were nevertheless cured by their aggressive treatment regimen.Non-compliance with treatment plans is often cited as a contributor to MDR-TB transmission and mortality. Indeed, of the 80 newly released TB-infected inmates in Fry et al.s study, 73.8% did not report visiting a community dispensary for further treatment. Ruddy et al. cite release from facilities as one of the main causes of interruption in prisoners TB treatment, in addition to non-compliance within the prison and upon reintegration into civilian life. Fry et al.s study also listed side effects of TB treatment medications (especially in HIV positive individuals), financial worries, housing insecurities, family problems, and fear of arrest as factors that prevented some prisoners from properly adhering to TB treatment. They also note that some researchers have argued that the short-term gains TB-positive prisoners receive, such as better food or work exclusion, may dis-incentivize becoming cured. In their World Health Organization article, Gelmanova et al. posit that non-adherence to TB treatment indirectly contributes to bacterial resistance. Although ineffective or inconsistent treatment does not "create" resistant strains, mutations within the high bacterial load in non-adherent prisoners can cause resistance. Nachega & Chaisson argue that inadequate TB control programs are the strongest driver of MDR-TB incidence.
This serves as a useful marker for MDR-TB, because isolated RMP resistance is rare (except when patients have a history of being treated with rifampicin alone). If the results of a gene probe (rpoB) are known to be positive, then it is reasonable to omit RMP and to use SHEZ+MXF+cycloserine. The reason for maintaining the patient on INH is that INH is so potent in treating TB that it is foolish to omit it until there is microbiological proof that it is ineffective (even though isoniazid resistance so commonly occurs with rifampicin resistance). For treatment of RR- and MDT-TB, WHO treatment guidelines are as follows: "a regimen with at least five effective TB medicines during the intensive phase is recommended, including pyrazinamide and four core second-line TB medicines – one chosen from Group A, one from Group B, and at least two from Group C3 (conditional recommendation, very low certainty in the evidence). If the minimum number of effective TB medicines cannot be composed as given above, an agent from Group D2 and other agents from Group D3 may be added to bring the total to five. It is recommended that the regimen be further strengthened with high-dose isoniazid and/or ethambutol (conditional recommendation, very low certainty in the evidence)."