Successful management of highly drug resistant tuberculosis with individualised drug susceptibility testing

Abstract

Introduction: Many tuberculosis (TB) patients have resistance patterns intermediate between multidrug-resistant (MDR) and extensively drug-resistant (XDR). We defined MDR+ as resistance to rifampin (RMP), isoniazid (INH) and at least one more drug other than fluoroquinolone (FQ) and second-line injectable agent (IA); and Pre-XDR as MDR with additional resistance to either FQ or IA. Such patients too, have compromised treatment options that require various combinations of second line drugs (SLD). The aim of our study was to assess the clinical outcome of patients having such resistance patterns, managed on the basis of prior drug exposure and drug susceptibility testing (DST).

Methodology: 52 consecutive patients were studied. Treatment regimen was devised as per DST and predominantly consisted of a second-line injectable agent (IA), para-aminosalicylic acid (PAS) and clofazimine. Additionally, cycloserine, linezolid, co-amoxiclav and clarithromycin were used to complete a regimen of four to five drugs. Clinical and radiological outcome was evaluated at follow-up and at the end of treatment.

Results: 49/52 (94%) patients had good outcome. However, 34 different regimens had to be used, as options for individual patients were limited.

Conclusion: Management on the basis of prior drug exposure and individualised DST led to good clinical outcomes. No single regimen emerged as having a wide applicability. This study supports the clinical relevance of DST of oral second line drugs.