Prevalence of XDR TB cases--a retrospective study from a tertiary care TB hospital

The emergence of XDR -TB strains is a major roadblock in the successful implementation of TB control programmes. This further leads to high morbidity and mortality, especially in immuno-compromised patients. Identification and observation of resistance patterns of XDR-TB strains may help clinicians manage MDR-TB cases, the treatment line of which is expensive, time-taking and involves intake of toxic drugs with many side-effects. Our study is aimed to find out the prevalence of XDR-TB among the MDR-TB strains isolated in a tertiary care hospital.

The study population consisted of 223 patients of tuberculosis who were culture positive and Mycobacterium tuberculosis was resistant to Rifampicin and Isoniazid during January 2007 to December 2009. Each patient had submitted two sputum samples i.e. spot and morning. The identified Mycobacterium tuberculosis complex was subjected to drug sensitivity testing by first and second line drugs by proportion and absolute concentration methods as per standard procedure.

The results showed that 20.17% strains (45/223) were XDR-TB strains. Most of these strains showed resistance to four drug combination viz. KM, ETH, OFX & PAS (5.82%), KM & OFX (3.13%), OFX, KM and ETH (1.79%), 1.34% strains showed resistance to all the drugs i.e. pan resistance and other combinations in the remaining strains. Nearly 80% of the XDR-TB strains showed resistance to three or more drugs combination pattern.

The multidrug resistant TB cases need urgent and timely sensitivity report for second line ATT drugs to help clinicians start proper drug combinations to treat MDR-TB patients.