Tuberc Respir Dis.  1974 Jun;21(2):85-95. 10.4046/trd.1974.21.2.85.

Drug Resistance of M. tuberculosis Isolated from Patients Discovered In The Second National Tuberculosis Prevalence Survey

• KMID: 2529021
• DOI: http://doi.org/10.4046/trd.1974.21.2.85

Abstract

Sensitivity tests to anti-tuberculosis standard and second line drugs were carried out on a total of 132 cultures of M. t u tuberculosis which were obtained from patients discovered in the Second National Tuberculosis Survey (1970) in Korea. Using the British MRC-Standard Method with the following concentrations (μg/ml) for both test strains and standard sensitive strain H₃₇Rv: And sensitivity tests of second-line drugs (except pyrazinamide) were done: critical concentrations (μg/ml) for Tbl, EB, TH, RFP, CPM, KM, VM, and CS were 1, 1. 25, 40, 10, 20, 10, 40 and 20 μg /ml respectively. The results were read at the end of four weeks of incubation. The term ‘ growth’ has been used to mean the presence of 20 or more colonies on any drug-containing slope. The results of the isoniazid-sensitivity test s were expressed as ‘resistant ’ in the presence of growth on the slope containing 0.2μg isoniazid per ml. The PAS and streptomycin sensitivity test results were expressed as ‘resistance ratio’, namely, the MIC of the test strain divided by the MIC of strain H ₃₇ Rv. The sensitivity of second line drugs was determined upon the presence or absence of growth on critical concentration of each drug.
Results
obtained were as follows: 1. Of the total of 132 patients, 92(69. 7% ) had no history of previous chemotherapy and the remaining 40 (30.3%) had a history of previous chemotherapy. 37.9% of the total of 132 had resistance to one or more standard drugs. items 2-6 refer to resistance to standard drugs only. 2. Of the 92 patients with no history of previous chemotherapy, 23.9% had resistance to one or more drugs: 16.9% had resistance to 1 drug only, 6.5% to 2 drugs and 6.5% to all 3 drugs 19.5% of the total patients showed resistance to isoniazid, 10.9% to PAS and 13.0% to streptomycin. 3. Of the 40 patients with a history of previous chemotherapy, 70% bad drug resistance to one or more drugs; 27.5% had resistance to 1 drug only, 15.0% to 2 drugs, and 27.5% to all 3 drugs. 70.0% of the total patients showed resistance to isoniazid, 40.0% to PAS and 30.0% to streptomycin. streptomycin. 4. Resistance to one or more drugs was found to increase with the diagnosed extent of disease, that is: 51.2% in the group ‘Far Advance' were found to be drug-resistant while only 31. 8% in the ‘Moderately Advanced' group and 26.8% in the ‘Minimal’ showed resistance. 5. The resistance to one or more drugs of patients in urban areas was found to be double that of patients in rural areas; 49.3% to 22.8% and the Urban patients also showed considerably higher resistance to all 3 drugs; 18. 7% to 5.3 %. 6. Referring to the drug resistance according to duration of previous chemotherapy, 16.7%, 55.5%, 60.0%, 100.0%, and 92. 8% in the groups treated during 1-6, 7-12, 13-18, 19-24, and over 25 months respectively, showed resistance to one or more drugs. 7. The great majority of strains showed noticeably higher sensitivity to second line drugs. Thiacçtazone showed appreciable resistance (46.9%). 8. An overall statistical comparison of drug resistance to standard drugs shown in the First and Second Surveys has revealed no particular difference in prevalence of drug resistance to one or more drugs but there was a marked increase in multi-drug resistance to isoniazid, PAS and streptomycin in the Second Survey as compared to the First. (table 8)