Possible impact of the standardized Category IV regimen on multidrug-resistant tuberculosis patients in Mumbai

Treatment of multidrug-resistant tuberculosis (MDR-TB) in the Programmatic Management of Drug-resistant TB program involves a standard regimen with a 6-month intensive phase and an 18-month continuation phase. However, the local drug resistance patterns in high MDR regions such as Mumbai may not be adequately reflected in the design of the regimen for that particular area.

The study was carried out at a private Tertiary Level Hospital in Mumbai in a mycobacteriology laboratory equipped to perform the second-line drug susceptibility testing (DST).

We attempted to analyze the impact of prescribing the standardized Category IV regimen to all patients receiving a DST at our mycobacteriology laboratory.

All samples confirmed to be MDR-TB and tested for the second-line drugs at Hinduja Hospital's Mycobacteriology Laboratory in the year 2012 were analyzed.

A total of 1539 samples were analyzed. Of these, 464 (30.14%) were MDR-TB, 867 (56.33%) were MDR with fluoroquinolone resistance, and 198 (12.8%) were extensively drug-resistant TB. The average number of susceptible drugs per sample was 3.07 ± 1.29 (assuming 100% cycloserine susceptibility). Taking 4 effective drugs to be the cut or an effective regimen, the number of patients receiving 4 or more effective drugs from the standardized directly observed treatment, short-course plus regimen would be 516 (33.5%) while 66.5% of cases would receive 3 or less effective drugs.

Our study shows that a high proportion of patients will have resistance to a number of the first- and second-line drugs. Local epidemiology must be factored in to avoid amplification of resistance.