Status of First-Line Anti-TB drugs: An Audit of 84 Clinical Sputum AFB Isolates in Karachi

Objective: to evaluate the current incidence of multidrug-resistant tuberculosis (mdr-tb) among positive sputum culture isolates in two commercial laboratories in karachi, pakistan. methodology: in this laboratory-based study eighty four afb smear-positive sputum culture isolates grown on routine lowenstein-jensen (lj) medium in two separate diagnostic labs during 12 months ending august 2011 were identified and subjected to antimicrobial susceptibility testing using lj medium and anti-tb first-line drugs (fld). mics of the control h37rv-nctc strain 7416 were compared with the test strains inoculated with the batch tested. results were evaluated by the traditional resistance ratio method. results: the sputa expectorated by 45 females (53.57%) and 39 males (46.43%) aged 15-58 years yielded 84 m. tuberculosis isolates. the percentages of fld resistance were rifampicin (48.8%), streptomycin (28.57%), ethambutol (7.14%), and isoniazid (4.76%). kanamycin (28.57%) was also tested. only 12 (14.28%) of these were sensitive to all the flds, and 4 (4.76%) were mdr-tb strains (indifferent to rifampicin and isoniazid). conclusion: the sparse labs in karachi that do afb-cultures should periodically assess and publicize the frequency of mdr-tb isolates to guide empirical therapy. rifampicin, a consistent part of the initial drug regimen for empirical prescription, was currently least effective on the strains encountered.