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|Year : 2003 | Volume
| Issue : 2 | Page : 127--128
Resistance of mycobacterium tuberculosis to the first line anti tubercular drugs - A twenty year review
MV Jesudason, U Mukundan, R Saaya, K Vanitha, MK Lalitha
Department of Clinical Microbiology, Christian Medical College, Vellore - 632 004, Tamil Nadu, India
M V Jesudason
Department of Clinical Microbiology, Christian Medical College, Vellore - 632 004, Tamil Nadu
Tuberculosis and more so the multi drug resistant variety has been thrust into the forefront as a serious and life threatening illness in recent years. The advent of AIDS contributes to this substantially, especially in the developed world where it had become practically non- existent. We reviewed our data over the past 20 years with a view to determine when drug resistance began to manifest in the strains.
|How to cite this article:|
Jesudason M V, Mukundan U, Saaya R, Vanitha K, Lalitha M K. Resistance of mycobacterium tuberculosis to the first line anti tubercular drugs - A twenty year review.Indian J Med Microbiol 2003;21:127-128
|How to cite this URL:|
Jesudason M V, Mukundan U, Saaya R, Vanitha K, Lalitha M K. Resistance of mycobacterium tuberculosis to the first line anti tubercular drugs - A twenty year review. Indian J Med Microbiol [serial online] 2003 [cited 2020 Aug 6 ];21:127-128
Available from: http://www.ijmm.org/text.asp?2003/21/2/127/7991
Multi drug resistant tuberculosis (MDR-TB) has been a matter of growing concern in the last decade and it continues to be so. MDR TB has been described as the third epidemic, complicating the epidemic of HIV and the re-emergence of TB in the west. Although pulmonary tuberculosis is the most commonly encountered form, tuberculosis affecting other sites is not uncommon. At the department of microbiology, Christian Medical College and Hospital, Vellore, which is a tertiary care center, this is the experience (unpublished) and we present here the antibiotic susceptibility pattern of M.tuberculosis strains isolated from all specimens. Ideally, the resistance to anti tuberculous drugs can be classified into primary and secondary based on whether a patient has had prior treatment. Unfortunately this information could not be retrieved for all. We have compiled the data at two yearly intervals, namely 1980, 82, 84, 86 ….. 2000, to give an overview of the prevalence of drug resistance over a twenty year period and to have an idea of the present trend.
The term MDR TB is used to signify disease due to M.tuberculosis that is resistant to the two currently most extensively used anti TB drugs, isoniazid and rifampicin, with or without resistance to other drugs. The difference in perception arose because, while previously isoniazid and streptomycin resistant tuberculosis could still be effectively treated with the then available drugs, rifampicin and ethambutol, the outcome of treatment of isoniazid and rifampicin resistant tuberculosis is not so favourable.
Materials and Methods
The study sample consisted of strains of M.tuberculosis, isolated from clinical samples from both pulmonary and extra pulmonary cases, over a period of 20 years, from January 1980 to December 2000. It included samples from both inpatients and out-patients. Being a tertiary care center, these strains were isolated from patients who came to our hospital from all over India; hence the results do not reflect the prevalence of resistance only in Vellore. As such, no clear distinction between primary and acquired resistance was possible to determine.
Standard procedures were followed for the isolation and identification of M.tuberculosis from clinical specimens. Lowenstein Jensen (LJ) medium was used. Indirect antibiotic susceptibility test was carried out by Resistance Ratio method for streptomycin (SM) and MIC determination for INH and rifampicin (R) using LJ medium incorporated with different concentration of the drugs (4). For SM, a resistance ratio of 4 or more was considered resistant. In the case of INH and R, an MIC of 0.4 µg/mL and 64 µg/mL respectively were taken as resistant. Since the susceptibility testing with rifampicin was introduced only in 1983, the results for the previous years could not be included. H37 Rv was used as the control strain.
Results and Discussion
Results of only three important anti tubercular drugs viz. streptomycin (SM), isoniazid (INH), and rifampicin (R) are included for analysis.
Our observations [figure:1] indicate that there has been an increased isolation of MDR strains in the 1990s. There has been a spurt in 2000 in resistance to INH alone and to some extent, SM alone and R alone.
It helps to monitor antibiotic susceptibility test results and document them so that we are aware of any change in resistance pattern as and when it occurs. Moreover our documentation is a useful reference for physicians in smaller hospitals and health care centers who do not have the facilities to do this for themselves.
The commonest risk factors for MDR-TB are said to be either inadequate anti tubercular treatment in the past or exposure to patients with MDR-TB. A monitoring of drug resistance in tuberculosis, distinguishing primary and acquired resistance is under way.
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