ethambutol 11.8%, and to pyrazinamide 29.7%. Statistically significant difference was seen between primary and acquired resistances. When compared with the ...
Pak J Med Res Vol. 47, No. 1, 2008
ORIGINAL ARTICLE
Multidrug Resistance Tuberculosis in Lahore Rizwan Iqbal,* Iffat Shabbir,* Saulat Ullah Khan,** Shumaila Saleem,* Kashif Munir* PMRC TB Research Centre,* Institute of Chest Medicine King Edward Medical University/ Mayo Hospital* Lahore, Pakistan
ABSTRACT Objectives: To estimate drug resistance in TB patients and compare it with the previous studies to see if there is a changing trend. Settings: PMRC TB research centre Mayo hospital Lahore which is a specialized centre on research and diagnosis of tuberculosis. Patients and Methods: The centre receives sputum samples from all the leading hospitals of Lahore. This work was done from 2004 to 2006 where five first lines anti tuberculosis drugs were tested on LJ.medium using standard proportion method. Results: A total of 582 confirmed isolates of Mycobacterium tuberculosis were seen. Of the total 454 were pulmonary and 128 extra pulmonary specimens from 582 patients. These patients comprised of those with and without history of previous treatment. These sputa were subjected to drug susceptibility testing. Almost half of the patients had some resistance; multiple drug resistance (MDR) was seen in 12.8% and 27.0% cases without and with history of previous treatment respectively. Overall resistance to rifampicin was 26.6%, to isoniazid 23.5%, streptomycin 19.5%, ethambutol 11.8%, and to pyrazinamide 29.7%. Statistically significant difference was seen between primary and acquired resistances. When compared with the reports from previous studies from the same area, there was a trend of gradual increase of drug resistance in this area. Conclusion: Resistance to anti tuberculosis drugs is high in Lahore. The current approach may not be adequate and innovative approaches such as DOTS-Plus may have to be employed to effectively control MDR TB. Key Words: Multi Drug Resistant Tuberculosis, DOTS, PMRC TB Centre, Mycobacterium tuberculosis.
INTRODUCTION rug resistance in tuberculosis (TB) is a serious problem throughout the world.1 TB is the most common cause of death because it is one of the most serious infectious diseases with a considerable public health problem due to its high risk of person-to-person transmission, morbidity, and mortality in adults.2 World Health Organization (WHO) took an unprecedented step and declared TB to be a global emergency.3 According to the recent estimates, one third of the human population (about 1.86 billion people) was infected with Mycobacterium tuberculosis world wide in 1997.4 TB is principally a disease of poverty, with 95% cases and 98% of deaths occurring in developing countries. Of these, more than half the cases occur in five South East Asian countries.5
D
Corresponding Author:
Rizwan Iqbal Senior Medical Officer PMRC TB Research Centre King Edward Medical University/Mayo Hospital Lahore Phone: 92-042- 9211602
Though the disease was known since ancient times, the organism causing TB was described only a century ago by Robert Koch on 24th March 1882.6 With the availability of streptomycin, isoniazid and paraaminosalicylic acid (PAS), in the mid 1940s, predictable, curative treatment for TB became a reality.7 The introduction of rifampicin, pyrazinamide and ethambutol in the subsequent years ushered in the era of short course treatment and soon it was felt that TB could be easily contained and possibly eradicated. The advent of HIV infection, the acquired immunodeficiency syndrome (AIDS) pandemic in 1980 struck a blow to this optimism when there was a global resurgence of TB.8 Drug resistant strains simultaneously also created havoc. Strains of Mycobacterium tuberculosis which are resistant to both isoniazid and rifampicin with or without resistance to other drugs are called multidrug-resistant strains. Multidrug-resistant tuberculosis (MDR-TB) is posing a major threat to treatment as resistant cases have a high mortality.9 DOTS is the internationally recommended strategy for TB control and is based on eight months short course therapy which also prevents emergence of drug resistance.10 The present study is a part of the ongoing multidrug resistance study and trends in sensitivity are 22
Multidrug Resistance Tuberculosis in Lahore
compared to see the current status of MDR-TB in our setting.11-12
PATIENTS AND METHODS The patients were selected from tuberculosis ward/OPD of Mayo and other major hospitals of Lahore. Total of 582 cases were seen; of which 476 were pulmonary and 106 extra pulmonary (lymph nodes and pus 62, pleural fluid 26, urine 7, CSF 2, gastric aspirate 8, endometrial tissue 1). All cases showed positive culture for M.tuberculosis. Patients between the ages of 15 to 60 were included in the study. Previous history of treatment was investigated through medical records and by interviewing the patient. And treatment with rifampicin, isoniazid, streptomycin, ethambutol and pyrazinamide was investigated. The patients were divided into two groups, one who had no history of taking treatment in the past and the other who had received prior treatment for 4 weeks or more. The treatment regimens usually followed these days are rifampicin (RIF), isoniazid (INH), ethambutol (EMB), and pyrazinamide (PZA) for initial two months followed by RIF, INH and EMB for continuation phase for seven months, in selected cases streptomycin (STM) is also used. Culture and drug susceptibility testing were carried out at PMRC TB Research Center, Mayo Hospital, King Edward Medical University, Lahore. Total of 582 isolates of M.tuberculosis, grown from various specimens, mostly sputum were tested for drug susceptibility. Only one isolate per patient was included. Primary isolation of mycobacterium was performed on Lowenstein Jensen (LJ) medium. Cultures grown on LJ medium with pH 6.8 were subjected for drug susceptibility testing on LJ medium containing drugs with the following concentrations using standard proportion method. RIF 40.0 μg/ml medium, INH 0.2 μg/ml, STM 4.0 μg/ml, EMB 2.0 μg/ml and PZA 100.0 μg/ml. Stock solutions of drugs and drug containing medium were made aseptically and added to the medium with pH 6.8 to achieve the desired concentration. Pyrazinamide containing medium was acidified with 1N HCL and pH of the medium was kept at 5.5. A small portion of several colonies was scraped from a culture on LJ slant and was homogenized using glass beads and vortex mixer. The turbidity of the suspension was adjusted to the McFarland No. 1 turbidity standard. Two dilutions of homogenized bacterial suspension, 103 and 105 were inoculated on each of the drug-containing medium, and on drug free medium which serve as a positive growth control. H37RV strain of M.tuberculosis known to be susceptible to all drugs was used as negative control.
All the tubes were incubated at 37o C ± 10 C for a minimum of four weeks. The growth was checked and colonies were counted both on drug containing as well as on control media. The number of colonies on drugcontaining medium was compared with those on drugfree medium. The ratio of two was calculated and expressed as percentage. This semi quantitative analysis gave the proportion of mycobacterium population resistant to each drug tested. Any isolate giving more than 1% growth on the medium containing isoniazid, ethambutol and rifampicin as compared with control was labeled as resistant strain. The critical proportion for resistance of streptomycin and pyrazinamide was 10%. Data was further analyzed on the basis of patient’s history of previous anti tuberculosis treatment. One group of patients who had no treatment history, and other group who had definite history of treatment for four weeks or more or returned to treatment after having interrupted treatment for two months or more. To determine the level of significance between the two groups, chi square ( χ2) was applied.
RESULTS Total of 582 culture-positive cases with M.tuberculosis infection had a complete record of susceptibility results. Table 1 shows resistance to five first line anti tuberculosis drugs i.e., rifampicin, isoniazid, streptomycin, ethambutol and pyrazinamide. Multidrug resistance was seen in about 16% cases. The drug resistance pattern from patients with and without history of treatment for various anti tuberculosis drugs showed statistically significant difference in MDR for RIF, PZA, INH and STM. Almost 6% TB patients were resistant to four drugs. Table 2 shows the percentage of isolates resistant to one or more anti tuberculosis drugs. The quality control susceptible strain which was run simultaneously with the routine testing yielded satisfactory results. Table 1: Pattern of resistance to individual primary anti tuberculosis drugs among tuberculosis cases. Drugs
All Patients
No. history of Treatment N = 382
With history of Treatment N = 200
97 16.6 %
49 12.8 %
48 27 %
< 0.001
157 26.9 % 137 23.53 % 115 19.5% 69 11.8% 173 29.7%
57 14.9 % 68 17.8 % 61 15.9 % 38 9.9 % 68 17.8 %
100 50 % 69 34.5 % 54 27 % 31 15.5 % 80 40%
