Extensively Drug-Resistant Tuberculosis, Pakistan

Frequency of extensively drug-resistant tuberculosis in Pakistan increased from 1.5% in 2006 to 4.5% in 2009 (p<0.01). To understand the epidemiology, we genotyped selected strains by using spoligotyping, mycobacterial interspersed repetitive units–variable number of tandem repeats, and IS6110 restriction fragment length polymorphism analysis

Genotyping and drug resistance patterns of M. tuberculosis strains in Pakistan

<p>Abstract</p> <p>Background</p> <p>The incidence of tuberculosis in Pakistan is 181/100,000 population. However, information about transmission and geographical prevalence of <it>Mycobacterium tuberculosis </it>strains and their evolutionary genetics as well as drug resistance remains limited. Our objective was to determine the clonal composition, evolutionary genetics and drug resistance of <it>M. tuberculosis </it>isolates from different regions of the country.</p> <p>Methods</p> <p><it>M. tuberculosis </it>strains isolated (2003–2005) from specimens submitted to the laboratory through collection units nationwide were included. Drug susceptibility was performed and strains were spoligotyped.</p> <p>Results</p> <p>Of 926 <it>M. tuberculosis </it>strains studied, 721(78%) were grouped into 59 "shared types", while 205 (22%) were identified as "Orphan" spoligotypes. Amongst the predominant genotypes 61% were Central Asian strains (CAS ; including CAS1, CAS sub-families and Orphan Pak clusters), 4% East African-Indian (EAI), 3% Beijing, 2% poorly defined TB strains (T), 2% Haarlem and LAM (0.2). Also TbD1 analysis (<it>M. tuberculosis </it>specific deletion 1) confirmed that CAS1 was of "modern" origin while EAI isolates belonged to "ancestral" strain types.</p> <p>Prevalence of CAS1 clade was significantly higher in Punjab (P < 0.01, Pearsons Chi-square test) as compared with Sindh, North West Frontier Province and Balochistan provinces. Forty six percent of isolates were sensitive to five first line antibiotics tested, 45% were Rifampicin resistant, 50% isoniazid resistant. MDR was significantly associated with Beijing strains (P = 0.01, Pearsons Chi-square test) and EAI (P = 0.001, Pearsons Chi-square test), but not with CAS family.</p> <p>Conclusion</p> <p>Our results show variation of prevalent <it>M. tuberculosis </it>strain with greater association of CAS1 with the Punjab province. The fact that the prevalent CAS genotype was not associated with drug resistance is encouraging. It further suggests a more effective treatment and control programme should be successful in reducing the tuberculosis burden in Pakistan.</p

Evaluation of microscopic observation drug susceptibility assay for diagnosis of multidrug-resistant Tuberculosis in Viet Nam

<p>Abstract</p> <p>Background</p> <p>Early diagnosis of tuberculosis (TB) and multidrug resistant tuberculosis (MDR TB) is important for the elimination of TB. We evaluated the microscopic observation drug susceptibility (MODS) assay as a direct rapid drug susceptibility testing (DST) method for MDR-TB screening in sputum samples</p> <p>Methods</p> <p>All adult TB suspects, who were newly presenting to Pham Ngoc Thach Hospital from August to November 2008 were enrolled into the study. Processed sputum samples were used for DST by MODS (DST-MODS) (Rifampicin (RIF) 1 μg/ml and Isoniazid (INH) 0.4 μg/ml), MGIT culture (Mycobacterial Growth Indicator Tube) and Lowenstein Jensen (LJ) culture. Cultures positive by either MGIT or LJ were used for proportional DST (DST-LJ) (RIF 40 μg/ml and INH 0.2 μg/ml). DST profiles on MODS and LJ were compared. Discrepant results were resolved by multiplex allele specific PCR (MAS-PCR).</p> <p>Results</p> <p>Seven hundred and nine TB suspects/samples were enrolled into the study, of which 300 samples with DST profiles available from both MODS and DST-LJ were analyzed. Cording in MODS was unable to correctly identify 3 Mycobacteria Other Than Tuberculosis (MOTT) isolates, resulting in 3 false positive TB diagnoses. None of these isolates were identified as MDR-TB by MODS. The sensitivity and specificity of MODS were 72.6% (95%CI: 59.8, 83.1) and 97.9% (95%CI: 95.2, 99.3), respectively for detection of INH resistant isolates, 72.7% (95%CI: 30.9, 93.7) and 99.7% (95%CI: 98.1, 99.9), respectively for detecting RIF resistant isolates and 77.8% (95%CI: 39.9, 97.1) and 99.7% (95%CI: 98.1, 99.9), respectively for detecting MDR isolates. The positive and negative predictive values (PPV and NPV) of DST-MODS were 87.5% (95%CI: 47.3, 99.6) and 99.3% (95%CI: 97.5, 99.9) for detection of MDR isolates; and the agreement between MODS and DST-LJ was 99.0% (kappa: 0.8, <it>P </it>< 0.001) for MDR diagnosis. The low sensitivity of MODS for drug resistance detection was probably due to low bacterial load samples and the high INH concentration (0.4 μg/ml). The low PPV of DST-MODS may be due to the low MDR-TB rate in the study population (3.8%). The turnaround time of DST-MODS was 9 days and 53 days for DST-LJ.</p> <p>Conclusion</p> <p>The DST-MODS technique is rapid with low contamination rates. However, the sensitivity of DST-MODS for detection of INH and RIF resistance in this study was lower than reported from other settings.</p

Comparason Of Extraction Methods For Pcr Detection Of Burkholderia Cepacia Complex (Bcc) From Cystic Fibrosis Patients

Direct detection of Burkholderia cepacia complex (BCC) and its genomovars from sputum by molecular tests emerges as a method for rapid identification. In this study, four DNA extraction methods were evaluated forth e identification for BCC from sputum of CF patients. Sputa from 28 CF patients were aliquoted and spiked with BCC reference strain. Boiling, phenol-chloroform, CTAB methods and a commercial spin column kit was used for DNA extraction. Total DNA yields were determined by spectrophotometry and single-round recA PCR was used for detection of BCC. No significant difference was observed in DNA yields from different extraction methods. Lower limit of detection for recA PCR was determined as 10(6) cfu/ml. Amplification was observed in 7/16 (43.7%) of sputa for boiling, 8/16 (50%) of sputa for GTAB and 13/16 (81.2%) of sputa for phenol-chloroform method and spin column kit in the assay sensitivity range determined in the study. Phenol-chloroform and commercial spin column kit were found to be better suited for DNA purification from sputum of CF patients for BCC identification. Diagnostic impact of single-round recA PCR directly from sputum was limited to chronically-infected patients.WoSScopu

Predictive factors for treatment failure in patients with presumed ocular tuberculosis in an area of low endemic prevalence

AIM: To assess the impact of antitubercular therapy (ATT), oral steroids and steroid sparing immunosuppressive treatment on treatment success in cases with presumed ocular tuberculosis in an area of low endemic prevalence. METHODS: A retrospective cross-sectional study was performed for 213 patients with presumed ocular tuberculosis from a database from a tertiary referral eye hospital in the UK. A logistic regression model was constructed incorporating demographics, baseline characteristics and different cut-offs of QuantiFERON-TB Gold In-Tube test (QFT-G) to identify significant factors accounting for the variability of the response variable ('failure') across the whole group. Treatment failure was defined as the recurrence of inflammation or inability to taper steroids within 6 months of completion of ATT or after at least 6 months of treatment in the non-ATT group. RESULTS: There were 126 patients who had at least 6 months of ATT. Patients with QFT-G values >1.50 (OR=0.20, 95% CI 0.09 to 0.48, p1.5) are more likely to have treatment success with ATT. In our model, steroid sparing immunosuppressive agents reduced the chances of success in both ATT and non-ATT-treated patients. It is unclear whether this effect reflects the intrinsic underlying severity of disease (ie, study bias), or whether steroid sparing immunosuppressive agents mitigate against successful ATT.RD&E staff can access the full-text of this article by clicking on the 'Additional Link' above and logging in with NHS OpenAthens if prompted