Differential identification of pathogenic mycobacteria isolated from patients clinically diagnosed as pulmonary tuberculosis

ABSTRACT

By staining sputum samples from 121 patients diagnosed clinically to have pulmonary tuberculosis, before and after treating, sputum with digestion decontamination procedure [concentration], acid fast bacilli were detected in 10.7% and 22.36% of the cases respectively with statistically significant difference. By culture on L.J. agar, 38 strains [31.4%] were isolated. Comparing the results of staining, direct smear before and after concentration with that of culture, it was found that Z. N. staining of sputum after concentration is more sensitive and can be relied upon in diagnosing tuberculous infection. Applying the differential identification biochemical reactions, the 38 strains were 32 [84.2%] Mycobacterium tuberculosis, 2 [5.3%] M. avium, one [2.6%] M. Kansasii, one [2.6%] M. zenopi and 2 strains that could not be identified. All the strains were sensitive to rifampin, 28.9% were resistant to isoniazid, 13.1% were resistant to ethambutol, 7. 9% were resistant to streptomycin and 5.3 were resistant to kanamycin