treatments often are difficult to obtain in those settings where drug-resistant TB takes its greatest toll. Other data also affect treatment regimens. For example, the degree of parenchymal damage should determine the duration and form of therapy; Russian physicians have demonstrated the importance in some cases of adjuvant surgery (see Chapter 3 and the further discussion of this approach later in this chapter). XDR TB is not a new genus or species, said Farmer. The disease is ultimately TB, and the issues that have been discussed for many years with regard to MDR TB apply also to XDR TB.
High-quality clinical care must keep pace not just with genetic mutations but also with social mutations, said Farmer. Social mutations in the Soviet Union, the United States, and other countries have been partially responsible for TB outbreaks in the past, which have consumed major resources before being brought under control. Yet the system of clinical care for drug-resistant TB has seen little innovation over the last 10 years. Most new drugs are really variants of old ones; no new class of drugs has made it through clinical trials and regulatory processes during this period. A few novel agents are in the drug development pipeline, but access to them for treatment is not yet close. Thus, as many workshop participants noted, MDR TB treatment must be provided with what is available today, tailored to the drug susceptibility patterns of patients.
Speakers addressed several topics related to treatment of drug-resistant TB: the need for tailored treatment regimens based on drug susceptibility testing, treatment of drug-resistant TB in the Russian Federation, treatment of patients coinfected with TB and HIV, and innovative research in MDR TB treatment.
M.tb. has developed resistance within a few years to every anti-TB drug introduced in the past, from streptomycin and isoniazid in the 1940s and 1950s, to rifampin in the 1960s and 1970s, to the quinolones in the 1990s. As a result, said Cegielski, the GLC was established with three goals: (1) increase access to effective treatment of MDR TB with quality-assured second-line drugs, (2) prevent increasing resistance to those same drugs, and (3) contribute to the evidence base for policy guidelines.
Evaluating the GLC’s impact on preventing drug resistance was the stimulus for the Preserving Effective TB Treatment Study (PETTS), which has the objective of determining the frequency of and risk factors for acquired resistance to second-line drugs in a diverse group of MDR TB programs. The study is examining the characteristics of programs (includ-
1 This section is based on the presentation of Dr. Cegielski.