ELSEVIER Mutation Research 334 (1995) 175-183 Environmental Mutagenesis Cytogenetic study of tuberculosis patients before and after tuberculostatic drug treatment Abdullah Ekmek§i *, Ay~e ~ayli Department of Medical Biology and Genetics, Faculty of Medicine, Gazi University, 06510 Besevler, Ankara, Turkey Received 21 September 1993; revision received 7 June 1994; accepted 8 August 1994 Abstract Cytogenetic analyses were carried out in lymphocytes of 15 untreated tuberculosis (tb) patients and 15 other tb patients who had received combined tuberculostatic chemotherapy HRZ (isoniazid + rifampicin + pyrazinamide) for 2 months. The frequency of chromosomal aberrations and sister-chromatid exchanges (SCEs) did not show any statistically significant differences in the patients before treatment and after exposure to combined HRZ therapy as compared to controls (p > 0.05). However, we observed that the mitotic index was significantly decreased in both groups (p < 0.05). Based on the results of the present study, we believe there is no indication for a chromosome damaging effect of HRZ and their metabolites in human lymphocytes in vivo after treatment of tuberculosis patients with optimum doses. Keywords: Tuberculosis chemotherapy; Cytogenetic effects 1. Introduction Despite availability of highly effective chemotherapy, the tubercle bacillus continues to cause devastating illness in the world with wide socio-economic implications even a century after its first identification (WHO, 1983). In the treat- ment of tuberculosis, drugs are usually prescribed in certain combinations. It is well known that in combination drugs may act synergistically, antag- onistically or additively. Therefore, the combined effects of different drugs need to be the same as * Corresponding author. Fax 90 312 213 4338. their individual genetic effects, and some of these have been tested by various research groups. However, there are some contradictory cytoge- netic findings about the endo/exotoxins released by Mycobacterium tuberculosis in untreated pa- tients (Gapol Rao et al., 1990) and some com- monly used antitubercular drugs individually (Stott et al., 1976; Bauchinger et al., 1978) or in combination with others (Bauchinger et al., 1978; Jaju et al., 1981, 1983; Roman et al., 1983). More- over, chromosome damage induced by tubercle bacilli (Gapol Rao et al., 1990) and by antituber- cular drugs (Gapol Rao et al., 1991) was reported by the same research group in different times. This study was designed to compare the chro- 0165-1161/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI 0165-1 161(94)00074-3