RESUMO
Background: Prompt and accurate diagnosis of multi drug resistant tuberculosis is essential to avoid unnecessary delay in treatment. The conventional methods for testing drug susceptibility requires 4-6 weeks for isolation of Mycobacterium tuberculosis and another 4-5 weeks for testing susceptibility thus delaying the diagnosis and treatment
Objectives: To validate the drug susceptibility testing of isoniazid and rifampicin with Genotype MTBDRplus kit and comparing with the conventional standard drug proportion method. Study type, settings and duration: This cross sectional study was carried out in PMRC TB Research Centre, King Edward Medical University Mayo Hospital Lahore in collaboration with Shaukat Khanum Memorial Cancer Hospital and the Research Centre from November 2008 to October 2009
Materials and Methods: A total of 77 AFB smear positive and negative specimens from adult patients suffering from pulmonary and extra pulmonary TB were included in this study. Samples were processed for drug sensitivity testing by drug proportion method using Lowenstein Jensen medium and also on Genotype MTBDRplus assay
Results: Out of 77 specimens 74% were pulmonary and 26% extra pulmonary. There were 29 females and 48 males with a mean age was 30 years. Culture positivity on LJ medium was 69% while that on MTB PCR was 79%. Out of 53 culture positive specimens, 8[15%] were MDR while out of 61 MTB PCR positive specimens 9[14.7%] were MDR
Conclusion: Genotype MTBDRplus assay, is a highly sensitive technique for diagnosis of MDR TB in smear positive and smear negative complicated suspects; but it requires expensive instruments and skilled personnel
RESUMO
Tuberculosis is as old as mankind. One third of the world's population carries the bacillus. Tuberculosis remains the single greatest contributor to the world's morbidity and mortality. Zheil Neelsen stained smears for acid-fast bacilli and culture on Lowenstein Jensen media are the methods being used for the diagnosis of Mycobacterium tuberculosis in most developing countries. Zheil Neelsen smear is rapid but less sensitive and culture is more sensitive and specific but results in delay in definitive diagnosis. Polymerase chain reaction test for the diagnosis of tuberculosis is not well evaluated in developing countries. To compare the ability of polymerase chain reaction to diagnose Mycobacterium tuberculosis rapidly in pulmonary and extra-pulmonary clinical specimens, and compare it with the yield of smear positivity and culture. This was a comparative study which was carried out at PMRC TB Research Center, King Edward Medical University, Mayo Hospital Lahore in collaboration with Shaukat Khanum Memorial Cancer Hospital from November 2008 to October 2009. Clinically suspected cases of pulmonary and extra-pulmonary patients with symptoms of fever, fatigue, anorexia and weight loss were asked to submit their sputum or respective samples for the diagnosis of tuberculosis. Direct and concentrated smears were prepared and stained by Zheil Neelsen method and were subjected to culture on Lowenstein Jensen media. Decontaminated specimens were checked for mycobacteria using polymerase chain reaction where amplicons were used for detection to membrane bound probes on the strips. A total of 98 specimens were processed for acid-fast bacilli smear, culture and polymerase chain reaction. These included 67 specimens from cases having strong clinical suspicion of tuberculosis while, 31 sputum specimens from non-tuberculosis subjects served as negative controls. Over all polymerase chain reaction positivity was 62.2%, culture positivity was 52% and smear positivity was 35.7%. Polymerase chain reaction testing was the most specific, rapid and sensitive method for the diagnosis of tuberculosis while culture is specific but it takes 4 to 6 weeks to provide results and smear testing is the cheapest but least sensitive test. Early diagnosis of TB is cornerstone for proper treatment and control of this deadly disease. PCR testing is specific, rapid and sensitive method for diagnosis of TB especially in complicated cases