Received Date: May 24, 2014; Accepted Date: August 27, 2014; Published Date: August 29, 2014
Citation: Therese KL. (2014) A Pilot Study on the Detection of Multidrug Resistant Tuberculosis in Hospital Based Population of Chennai, India.J Med Microb Diagn 3:153. doi: 10.4172/2161-0703.1000153
Copyright: © 2014 Therese KL, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Background: Community-acquired pneumonia (CAP) is associated with high mortality. Drug resistance is common in countries where the alternative treatments are limited and available drugs are misused. In resource limited countries like Ethiopia; it is wise to determine antimicrobial susceptibility pattern of common bacterial pathogens of CAP. The objective of our study was to determine antimicrobial susceptibility pattern of common bacterial pathogens of CAP among adult patients visiting Arba Minch Hospital.
Methods: A cross sectional study conducted at Arba Minch Hospital, Southern Ethiopia from February to May 2013. Sputum specimens were collected; microbiological investigations and antimicrobial susceptibility testing were performed using standard procedures. Data was processed and analyzed with SPSS version16.0. Results: Out of 170 cases, only 73 (42.9%) were culture positive. Majority of tested bacterial isolates (>86%) were sensitive to Ceftriaxone and Ciprofloxacin. Most S. pneumoniae isolates (60%) were resistant to Oxacillin. Most of S. aureus and gram negative bacterial isolates were resistance to Tetracycline (100%), Penicillin (83.3%), Ampicillin (50-100%), Doxycycline (50-100%), and Trimethoprim-sulfamethoxazole (83.3-100%). Multidrug resistance (MDR) was observed to most (60.3%) bacterial isolates.
Conclusion: Antimicrobial resistance including MDR was observed to a number of commonly used antibiotics, such as trimethoprim- sulfamethoxazole, penicillin groups and doxycycline. Hence, periodic monitoring of drug resistant pattern is essential for better management of CAP.
Tuberculosis (TB) is the leading cause of death from a curable infectious disease. Globally more than 1.3 million people die of the disease every year. Nearly one third of the world’s population is infected with tubercle bacilli; approximately 10% of them have a life time risk of developing the disease . The incidence rate is highest among young adults, and most cases are due to recent infection or reinfection. As transmission falls, the caseload shifts to older adults, and a higher proportion of cases are attributable to the reactivation of latent infection. The emergence of drug resistant TB, and particularly MDR-TB, has become a significant public health problem in a number of countries and an obstacle to effective TB control.
India has more new TB cases annually than any other country. In 2008, out of the estimated global annual incidence of 9.4 million TB cases, 1.98 million were estimated to have occurred in India, of whom 0.87 million were infectious cases, thus catering to a fifth of the global burden of TB . About 40% of Indian population is infected with TB bacillus. The present study was carried out in Chennai, India to find out the prevalence of MDR-TB in the local population using BACTEC microMGIT culture system.
The study was carried out after getting the approval from Institutional Research Ethics committee. An informed consent from the patients was obtained after explaining the purpose of the study. The patients were recruited after thorough examination by the Chest clinicians from 3 centres: Institute of Thoracic Medicine, Chetpet, Chennai, Stanley Medical College, Chennai and Madras Medical College, Chennai. The patients were categorized into new [patients without any previous history of anti-tuberculous treatment (ATT)] and control (patients with malignancy and without radiological evidence of tuberculosis). 961 clinical specimens including 801 new cases and 160 control cases were collected during the period December 2009 to September 2011. The specimen and categorywise distribution of the 961 clinical specimens is given in table 1. The mean age of the patients was 37.3 (age range: 18-81) and the male female ratio was 1.5:1 (491- male and 310-female). The specimen was processed for direct smear by Ziehl-Neelsen method and culture for M. tuberculosis by BACTEC MicroMGIT culture system as per the manufacturer’s instruction.
Table 1: Specimen and category wise distribution of 961 clinical specimens
Mycobacterial culture was performed by BACTEC microMGIT culture system after standard decontamination procedure using NALC-NaOH . The isolates were confirmed as M. tuberculosis by performing PCR targeting MPB64 gene  and IS6110 region . After the confirmation of isolate as M. tuberculosis, phenotypic drug susceptibility testing (DST) for the first line drugs streptomycin (S), isoniazid (H), rifampicin (R), ethambutol (E) and pyrazinamide (Z) was performed by BACTEC microMGIT culture system. Antibiotic stock solutions for S, H, R, E and Z were prepared and kept in aliquots in -20°C until use. The final concentrations used for performing DST were 0.8µg/ml, 0.1µg/ml, 2.0µg/ml, 100µg/ml and 100µg/ml of S, H, R, E and Z respectively.
Out of the 801 new cases, 322 (41.3%) were culture positive for the isolation of M. tuberculosis by BACTEC microMGIT culture system. The specimen wise distribution of 322 M. tuberculosis isolates was given in table 2. The isolation rate among the new patients was 40.1% (322/801). None of the control was culture positive.
*FNAB from Cervical lymphnode-27, Right neck-4, Axillary lymph node-2, one each from fore head, Right ear and Right supraclavicular node-1
$Pus aspirates cervical lymphnode-3, one each from right axillary lymphnode,cold abscess sternal region and right wrist joint
Table 2: Specimen wise distribution of 322 M. tuberculosis isolates
First Line Drug Susceptibility Testing Results
Among the 322 M. tuberculosis isolates, 194 (60.2%) were sensitive to all the five first line drugs, 13 (4.03%) were MDR (resistant to H and R with or without resistance to other first line drugs), 62 (19.25%) were polyresistant (resistant to more than two drugs) and 53 (16.45%) were monoresistant. Among the 53 monoresistant strains, 22 were resistant to Z, 19 to S, 9 to H and 3 to E (Table 3). Majority of the resistant strains were from Sputum – 104 followed by FNAB - 13, Bronchial wash – 6, Pleural fluid – 3, and pus aspirates - 2 (Table 4).
|Susceptible to all the first line drugs||Monoresistant
|Resistant to two or more drugs
N= 62 (19.25%)
HEZ - 2
S -Streptomycin, H- Isoniazid, R- Rifampicin, E- Ethambutol, Z- Pyrazinamide
Table 3: Phenotypic drug susceptibility testing results of 322 M.tuberculosis by BACTEC MicroMGIT system
|Clinical specimen (n=322)||All sensitive||MDR-TB||MR||PR|
|Bronchial wash (18)||12||2||3||1|
|Pleural Fluid (6)||3||0||1||2|
MR- Monoresistant, PR- Polyresistant, MDR-TB: Multidrug resistant tuberculosis
Table 4: Clinical specimenwise of results of phenotypic drug
susceptibility testing for First line anti-TB drugs
MDR-TB among new cases
Out of the 13 MDR-TB patients, 9 were male and 4 were female and mean age was 34.8 (age range: 22-60). The 13 MDR-TB was isolated from 10 sputum, 2 bronchial wash and 1 FNAB from right axillary lymphnode.
The resistance patterns of 13 MDR-TB strains were as follows: 9 were resistant to all the 5 first line drugs, 2 strains were resistant to HR and one each was resistant to SHRZ and SHRE (table 3).
Only 4 of the 13 MDR-TB patients turned up for follow up at the end of 6 months. Three patients were able to give sputum for mycobacteriological investigation and both smear and BACTEC culture for the isolation of M. tuberculosis were negative in the sputum collected from the rest 3 patients. For the other patient, FNAB was collected from the right axillary lymphnode during the first visit and the swelling had completely reduced on treatment and the patient was doing well.
The emergence of drug resistant TB, and particularly MDR-TB, has become a significant public health problem in a number of countries and an obstacle to effective TB control. Drug resistance surveillance conducted in Gujarat and Maharashtra indicated multi drug resistance levels of <3% among new TB cases and 14-17% among previously treated TB patients . But a study from Mumbai had showed arelatively high prevalence of MDR-TB of 24% and 41% among new and treated cases respectively .
In the present study, MDR-TB among new cases was 4.03%, which is slightly higher than reported by RNTCP 2010 report and a recent study by Sharma et al . The main drawback of the present study is follow up of the MDR-TB patients was possible only for four (22.2%) patients out of the 13 patients. Among the monoresistant M. tuberculosis isolates, least percentage of resistance was detected in Ethambutol (0.35%) and highest percentage in pyrazinamide (2.7%). In the 62 polyresistant strains, 37 (4.6%) were found to be resistant to both streptomycin and pyrazinamide. Thus the present study shows that prevalence of MDR-TB is increased among new cases in Chennai.
The laboratory capacity needs to be urgently strengthened in India as 20% of the world’s MDR-TB burden is reported to be from India . This is a pilot study conducted by a non-governmental organization with the support of a private funding agency interested in Public health. This type of study is useful to generate reliable data on the current status of prevalence of tuberculosis.
The authors gratefully acknowledge the financial support by Chennai Willingdon Corporate Foundation (Chennai, India) for funding the research project and the infrastructure facility provided by Vision Research Foundation.