Ind. J. Tub., 1984, 31, 164 PREVALENCE OF INITIAL DRUG RESISTANCE AMONG PATIENTS ATTENDING THE CLINICS IN MADRAS CITY K.V. KRISHNASWAMI *, R. VENKATESAN ** AND R. PARTHASARATHY *** Summary: Sputum culture of 803 smear positive peases of pulmonary tuberculosis attending for the first time at the five Chest Clinics located in different parts of Madras, was positive m 750. These were further subjected to drug sensitivity tests’, 24.1% cultures were resistant to one drug, 17.6% to two drugs and 3.3% to three drugs, giving a total initial drug resistance of 45%. Total initial resistance to Isoniazid was 28.9 %, significantly higher than for any other drug. In the case of Ethambutol and Streptomycin, it was 18.7% and 17.9% respectively. Total initial resistance to Rifampicin was found to be the lowest as compared to all other drugs. Introduction Fairly large proportion of patients attending for the first time the Chest Clinics in India have had anti-tuberculosis chemotherapy for some time though irregularly. The assessment of the prevalence of Initial Drug Resistance (IDR) among these patients will be of great value in their management and also in formulating general policies of treatment in the Chest Clinics under the National Tuberculosis Control Programme. Material and Methods Chest symptomatics attending for the first time at the five Chest Clinics located in different parts of Madras City, over a period of three months, from 1st March 1982 till the end of May 1982, were investigated, irrespective of whether they had previous chemotherapy or not. A preliminary skiagram of the chest was taken and those with suggestive pulmonary shadows were subjected to detailed bacterio- logical investigations commencing with sputum smears. Two spot and one overnight sputum specimens were examined for Acid Fast Bacilli by Ziehl Neelsen procedure. For all the sputum smear positive cases, culture for M. Tuber- culosis and drug sensitivity tests were carried out. Culture The technique adopted for culture of M. Tuberculosis was described by Tuberculosis Chemotherapy Centre (1959). Two sputum specimens, one spot and one overnight, were used. The following identification tests for M. Tuberculosis were done: (a) Niacin production test (Medveczky 1960); (b) Qualitative test for catalase activity (Selkon and Mitchison 1959); (c) Pigmentation and Morphology of growth after incubation at 37°C for 6 weeks in the dark and exposed to .light. Drug Sensitivity Tests One positive culture from each patient was subjected to drug sensitivity tests. The drugs and their concentrations used for the tests were as follows: Drug Concentration 1,2,4,16,32, & 64 0,2,1,5, 1,1.4,2,2.8,4,5.6,8,11.2 & 16 5,10,20,28.5,40,57,80, 114 Drug Streptomycin Isoniazid Ethambutol Ethionamide Rifampicin 1,2,4,8,16,32,64,128. A standard (approx. 3 mm) loopful of the appropriate suspension was inoculated on Lowenstein-Jensen slopes containing the drug concentrations and simultaneously on a drug free slope as control. The standard strain of H 37 Rv was also set up with each batch of tests. The results were read at the end of 6 weeks of incubation at 37°C. The results for Isoniazid, Ethambutol, Ethionamide and Rifampicin were expressed as minimum inhibitory concentration (MIC) of the drugs inhibiting growth while those of Streptomycin was expressed as resistance ratio (RR). *Formerly Professor of TB & Chest Diseases, Madras Medical College and Director, Institute of TB & Chest Diseases, Madras. **Non-medical Tutor in Microbiology ‘“Statistician PREVALENCE OF INITIAL DRUG RESISTANCE AMONG PATIENTS ATTENDING THE CLINICS IN MADRAS 165 The MIC and RR indicative of Drug Resi- tance are detailed in Table-I. TABLE 1 Criteria for Drug Resistance Results Seven hundred and fifty specimens of sputa yielded positive cultures (93%4%) from among the 803 smear positives investigated. The culture was negative in 19 smears and contaminated in 23. • TABLE 2 Pattern of Drug Resistance No. Percentage Sensitive cases 412 54.9 Resistance to one Drug 181 24.1 Resistance to two Drugs 132 17.6 Resistance to three Drugs 25 3.3 Total 750 99.9 Eleven specimens showed unclassified mycobacteria. Analysis of the pattern of Initial Drug Resistance (IDR) among the 750 positive cultures (Table 2) shows that 181 (24.1 %) were resistant to a single drug and 132 (17.6%) were resistant to two drugs, the difference being statistically significant (P<0.01). A small number of patients (3.3%) were found to be resistant to three drugs, the differance again being significant (P<0.01) in comparison to both for single and two drugs. Of the 750 cases identified as Drug Resistant cases, a high proportion of 28.9% (Table 3) were found to be resistant to Isoniazid, which is significantly higher than the propor- tions of resistance to any other drug (P<0.01) in all instances. The proportions of resistance to Ethambutol and Streptomycin were 18.7% and 17.9% respectively, the difference between which was not found to be statistically signifi- cant. But these proportions were significantly higher than those for Ethionamide and Rifampicin. Resistance to Ethionamide and Rifampicin were found to be of the order of 2.8% and 1.1% respectively with a signifi- cant difference (P<0.01). IDR for all the four drugs was found to be significantly higher than Rifampicin (P<0.01) in all instances). But still it is to be noted that 8 cases showed IDR to Rifampicin, a sheet anchor for Short Course Chemotherapy. TABLE 3 Drug Resistance to Individual Drugs Drug Resistant Cases No. Percentage Isoniazid 217 28.9 Ethambutol 140 18.7 Streptomycin 134 17.9 Ethionamide 21 2.8 Rifampicin 8 1.1 Single drug resistance was seen only for Isoniazid, Ethambutol & Streptomycin (Table 4) and not for the other two drugs, viz. Ethiona- mide and Rifampicin. Among those with single drug resistance, IDR to Isoniazid was signifi- cantly higher (P<0.01) than that for Etham- butol and Streptomycin. The difference between the proportions of cases resistant to Ethambutol and Streptomycin is not statistically signifi- cant. Among the 132 patients who were identified as being resistant to two drugs initially, the proportions of resistance to Ethambutol & INH and Streptomycin & INH were the highest viz. 40.9% and 34.9% respectively (Table 5). Name of Drug Minimum Inhi- bitary concent- ration Resistant Ratio Streptomycin — 8 & more Isoniazid 5 & more Ethambutol 8 & more Ethionamide 80 & more Rifampicin 128 & more 166 K.V. KRISHNASWAMI, R. VENKATESAN AND R. PARTHASARATHY TABLE 4 Single Drug Resistance Drug No. Resistant Percentage Isoniazid 96 53.0 Ethambutol 45 24.9 Streptomycin 40 22.1 Total 181 100.00 Of the 25 cases who had been found resis- tant initially to three anti-TB drugs. (Table 6) 8 cases (32 %) were resistant to the three drugs Streptomycin, Ethambutol and Ethionamide and 6 cases (24%) to Streptomycin, Isoniazid and Ethambutol. Discussion Initial drug resistance includes (a) naturally occurring drug resistant mutants, a small insigni- ficant group, (b) primary drug resistance, i.e. those infected with drug resistant bacilli, while not having had the particular drugs themselves and (c) Acquired resistance in those who have had chemotherapy knowingly or unknowingly I do not admit it. Assessment of IDR will TABLE 5 Two-Drug Resistance Drugs No. Resistant Percentage Ethambutol & Isoniazid 54 40.9 Streptomycin & Isonizid 46 34.9 Streptomycin & Ethambutol 22 16.7 Streptomycin & Ethionamide 6 4.6 Rifampicin & Isoniazid 4 3.0 Total 132 100.0 TABLE 6 Three-Drug Resistance Drugs No. Resistant Percentage Streptomycin, Ethambutol & Ethionamide 8 32.0 Streptomycin, Isoniazid & Ethambutol 6 24.0 Isoniazid, Ethambutol & Ethionamide 4 16.0 Streptomycin, Isoniazid & Rifampicin 3 12.0 Streptomycin, Isoniazid & Ethionamide 3 12.0 Ethambutol, Isoniazid & Rifampicin 1 4.0 Total 25 100.0 PREVALENCE OF INITIAL DRUG RESISTANCE AMONG PATIENTS ATTENDING CLINICS IN MADRAS 167 therefore give good indication of the prevalent practice of chemotherapy and the extent of patients compliance and consequent possible reduction in the therapeutic effectiveness of the drugs routinely used for the treatment of patients under the National Tuberculosis Programme. The W:H.O. Expert Committee on Tuberculosis (IX Report) opined that failure to respond to the standard regimen of chemo- therapy because of I.D.R.is more likely to occur in patients with strains resistant to 2 or all three drugs in the regimen than those with resistant to one drug only. The Indian Council of Medical Research Second Drug Resistance Investigation (1969) estimated the prevalence of drug resistance in patients with Pulmonary Tuberculosis present- ing for the first time with symptoms at urban chest clinics in India with or without history of previous chemotherapy. Madras was one of the 9 centres participating in this study. Considering all the centres, 25 % of the patients had resistance to Isoniazid and 22.9% to Streptomycin; 15.8% were resistant to both the drugs. In other words, 32 % of the patients had resistance to either one or both of these potent drugs. At the Madras Center (The Institute of Tuberculosis and Chest Diseases), the IDR findings were 18% for Isoniazid, 15% for Streptomycin and 10% for both and 23% for either or both the drugs in ICMR study. In the present study it was observed that 28.9% of the patients were resistant to Isonia- zid, 17.9% to Streptomycin and 7.7% to both the drugs and 25.7 % for either one or both the drugs. Subbammal (1975) reported IDR of 9.1% for Isoniazid and 4.3 % for both Streptomycin and Isoniazid from among the cases selected for chemotherapy trials during 1973-74. The patients comprised largely of those who had not had previous chemotherapy and the prevalence figures were therefore close to those of Primary Drug Resistance. In a previous study (Krishnaswamy, and Abdul Rahim, 1976) prevalence of Primary Drug Resistance was reported to be 10.6% for Isoniazid, 9.5% for Streptomycin and 4.7% for both, which proportions were more or less similar to those reported by the Tuber- culosis Chemotherapy Centre (Subbammal, 1975). The salient findings in the present study arc: 1. A sizeable proportion (17.6%) of bacillary resistance to two drugs was observed among the freshly reporting bacillary cases; 2. Total resistance to Ethambutol (18.7%) and Streptomycin (17.9%) was almost similar. 3. Total Resistance to Rifampicin was 1.1%. The above findings call for similar studies in other centres in the country. Acknowledgements We thank the Director of Medical Edu- cation, Tamilnadu, Smt. K. Rukmani, Steno- typist and the staff of the Laboratory of the Institute of Tuberculosis and Chest Diseases. REFERENCES Indian Council of Medical Research: Prevalence of Drug Resistance in patients with Pulmonary Tuber- culosis presenting for the first time with symptom at chest clinics in India Part; II, Findings in Urban clinics among all patients with or without history of previous chemotherapy; Ind. Jour. Med. Research 1969, 57, 823-835. Krishnaswamy, K.V. and Abdul Rahim, M: Primary Drug Resistance in Pulmonary Tuberculosis. Ind. Jour. Chest Diseases, 1976,18, 233-237. Medveczky, E: A micro method for the routine differentia- tion of human tubercle bacilli from other mycobac- terin in primary cultures: Am. Rev. Resp. Dis.; I960, 81, 757. Selkon, J.B. and Mitchison, D.A. : Atypical myco- bacteria and drug resistant tubercle bacilli isolated during a survey of untreated patients with pulmonary tuberculosis; Tubercle; 1959, 40, 141. Subbammal, S: Prevalence of Initial Drug Resistance in patients attending the Tuberculosis Chemotherapy Centre: Paper presented at the 30th National Con- ference on Tuberculosis and Chest Diseases; 1975. Tuberculosis Chemotherapy Centre—Concurrent com- parison of home and sanatorium treatment of Pulmonary Tuberculosis in South India; Wld. Hlth. Org. 1959, 21-51. W.H.O. Expert Committee in Report, Technical Report 204.2.10. Tuberculosis, Ninth Series 1974 , 552 , . assessment of the prevalence of Initial Drug Resistance (IDR) among these patients will be of great value in their management and also in formulating general policies of treatment in the Chest Clinics. Diseases, Madras. **Non-medical Tutor in Microbiology ‘“Statistician PREVALENCE OF INITIAL DRUG RESISTANCE AMONG PATIENTS ATTENDING THE CLINICS IN MADRAS 165 The MIC and RR indicative of Drug. PREVALENCE OF INITIAL DRUG RESISTANCE AMONG PATIENTS ATTENDING CLINICS IN MADRAS 167 therefore give good indication of the prevalent practice of chemotherapy and the extent of patients compliance