Multi-drug resistant tuberculosis in Northern Pakistan.

OBJECTIVE: To determine the resistance pattern of Mycobacterium tuberculosis isolates in Rawalpindi-Islamabad. METHODS: The study was carried out at the Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi between September 2000 and August 2002. We examined 1359 pulmonary and extra-pulmonary specimens from suspected cases of tuberculosis. The radiometric Bactec 460 TB system was used for culture and antimicrobial susceptibility testing. RESULTS: Mycobacterium tuberculosis was isolated from 325 clinical specimens. Antimicrobial susceptibility of the isolates was tested against the four first-line anti-tuberculous drugs (rifampicin, isoniazid, streptomycin and ethambutol). Fifteen percent of the isolates were resistant to a single drug, 28% were multi-drug resistant including 7% which were resistant to all the four drugs. The overall resistance against individual drugs was rifampicin 32%, isoniazid 37%, streptomycin 19% and ethambutol 17%. CONCLUSIONS: The increasing level of drug resistance among mycobacterial isolates in our population is most alarming. Strict implementation of control measures is required to combat this unfolding crisis.

Characterization of type I procollagen N-proteinase from fetal bovine tendon and skin. Purification of the 500-kilodalton form of the enzyme from bovine tendon.

Procollagen N-proteinase (EC 3.4.24.14) is the enzyme that specifically cleaves the NH2-terminal propeptides from type I procollagen. Two forms of N-proteinase with apparent molecular sizes of 300 and 500 kDa were found in partially purified preparations from fetal bovine tendon extracts. The 500-kDa form of enzyme was purified 16,000-fold with a recovery of 8% from the extracts of the tendons by six purification steps. The purified enzyme was a neutral, Ca(2+)-dependent proteinase (5-10 mM) that was inhibited by metal chelators. The 500-kDa enzyme contained unreduced polypeptides of 58, 125, 170, and 190 kDa which were separated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Electron microscopic study indicated that the enzyme molecules were generally globular and had diameters of 33 +/- 4 nm. Other properties of the 500-kDa enzyme were: 1) the Km for type I procollagen is 35 nM at pH 7.5 and 35 degrees C, and the kcat is 290 h-1; 2) the activation energy for reaction with type I procollagen is 10,050 cal mol-1; 3) the isoelectric point is 3.8; 4) the enzyme cleaves the NH2-terminal propeptides of type II procollagen as well as type I procollagen but not of type III procollagen; and 5) the enzyme specifically cleaves a -Pro-Gln- bond in the pro-alpha 1(I) chain and an -Ala-Gln- bond in the pro-alpha 2(I) chain. The bovine N-proteinase with a mass of 300 kDa was found to be similar to the 500-kDa enzyme and appeared to be a degraded form of the 500-kDa enzyme generated during purification. The N-proteinase from fetal bovine skin extracts also contained 300-kDa and 500-kDa enzyme forms.