Transmission Pattern of Drug-Resistant Tuberculosis and Its Implication for Tuberculosis Control in Eastern Rural China

OBJECTIVE: Transmission patterns of drug-resistant Mycobacterium tuberculosis (MTB) may be influenced by differences in socio-demographics, local tuberculosis (TB) endemicity and efficaciousness of TB control programs. This study aimed to investigate the impact of DOTS on the transmission of drug-resistant TB in eastern rural China. METHODS: We conducted a cross-sectional study of all patients diagnosed with drug-resistant TB over a one-year period in two rural Chinese counties with varying lengths of DOTS implementation. Counties included Deqing, with over 11 years' DOTS implementation and Guanyun, where DOTS was introduced 1 year prior to start of this study. We combined demographic, clinical and epidemiologic information with IS6110-based restricted fragment length polymorphism (RFLP) and Spoligotyping analysis of MTB isolates. In addition, we conducted DNA sequencing of resistance determining regions to first-line anti-tuberculosis agents. RESULTS: Of the 223 drug-resistant isolates, 73(32.7%) isolates were identified with clustered IS6110RFLP patterns. The clustering proportion among total drug-resistant TB was higher in Guanyun than Deqing (26/101.vs.47/122; p,0.04), but not significantly different among the 53 multidrug-resistant isolates (10/18.vs.24/35; p,0.35). Patients with cavitary had increased risk of clustering in both counties. In Guanyun, patients with positive smear test or previous treatment history had a higher clustering proportion. Beijing genotype and isolates resistant to isoniazid and/or rifampicin were more likely to be clustered. Of the 73 patients with clustered drug-resistant isolates, 71.2% lived in the same or neighboring villages. Epidemiological link (household and social contact) was confirmed in 12.3% of the clustered isolates. CONCLUSION: Transmission of drug-resistant TB in eastern rural China is characterized by small clusters and limited geographic spread. Our observations highlight the need for supplementing DOTS with additional strategies, including active case finding at the village level, effective treatment for patients with cavities and drug susceptibility testing for patients at increased risk for drug-resistance

In-Depth Molecular Characterization of Mycobacterium tuberculosis from New Delhi – Predominance of Drug Resistant Isolates of the ‘Modern’ (TbD1−) Type

BACKGROUND: India has the highest estimated burden of tuberculosis in the world, accounting for 21% of all tuberculosis cases world-wide. However, due to lack of systematic analysis using multiple markers the available information on the genomic diversity of Mycobacterium tuberculosis in India is limited. METHODOLOGY/PRINCIPAL FINDINGS: Thus, 65 M. tuberculosis isolates from New Delhi, India were analyzed by spoligotyping, MIRU-VNTR, large deletion PCR typing and single nucleotide polymorphism analysis (SNP). The Central Asian (CAS) 1 _DELHI sub-lineage was the most prevalent sub-lineage comprising 46.2% (n = 30) of all isolates, with shared-type (ST) 26 being the most dominant genotype comprising 24.6% (n = 16) of all isolates. Other sub-lineages observed were: East-African Indian (EAI)-5 (9.2%, n = 6), EAI6_BGD1 (6.2%, n = 4), EAI3_IND, CAS and T1 with 6.2% each (n = 4 each), Beijing (4.6%, n = 3), CAS2 (3.1%, n = 2), and X1 and X2 with 1 isolate each. Genotyping results from five isolates (7.7%) did not match any existing spoligopatterns, and one isolate, ST124, belonged to an undefined lineage. Twenty-six percent of the isolates belonged to the TbD1+ PGG1 genogroup. SNP analysis of the pncA gene revealed a CAS-lineage specific silent mutation, S65S, which was observed for all CAS-lineage isolates (except two ST26 isolates) and in 1 orphan. Mutations in the pncA gene, conferring resistance to pyrazinamide, were observed in 15.4% of all isolates. Collectively, mutations in the rpoB gene, the katG gene and in both rpoB and katG genes, conferring resistance to rifampicin and isoniazid, respectively, were more frequent in CAS1_DELHI isolates compared to non-CAS_DELHI isolates (OR: 3.1, CI95% [1.11, 8.70], P = 0.045). The increased frequency of drug-resistance could not be linked to the patients' history of previous anti-tuberculosis treatment (OR: 1.156, CI95% [0.40, 3.36], P = 0.79). Fifty-six percent of all new tuberculosis patients had mutations in either the katG gene or the rpoB gene, or in both katG and rpoB genes. CONCLUSION: CAS1_DELHI isolates circulating in New Delhi, India have a high frequency of mutations in the rpoB and katG genes. A silent mutation (S65S) in the pncA gene can be used as a putative genetic marker for CAS-lineage isolates

EVOTECH® endoscope cleaner and reprocessor (ECR) simulated-use and clinical-use evaluation of cleaning efficacy

<p>Abstract</p> <p>Background</p> <p>The objective of this study was to perform simulated-use testing as well as a clinical study to assess the efficacy of the EVOTECH^®Endoscope Cleaner and Reprocessor (ECR) cleaning for flexible colonoscopes, duodenoscopes, gastroscopes and bronchoscopes. The main aim was to determine if the cleaning achieved using the ECR was at least equivalent to that achieved using optimal manual cleaning.</p> <p>Methods</p> <p>Simulated-use testing consisted of inoculating all scope channels and two surface sites with Artificial Test Soil (ATS) containing 10⁸cfu/mL of <it>Enterococcus faecalis, Pseudomonas aeruginosa </it>and <it>Candida albicans</it>. Duodenoscopes, colonoscopes, and bronchoscopes (all Olympus endoscopes) were included in the simulated use testing. Each endoscope type was tested in triplicate and all channels and two surface sites were sampled for each scope. The clinical study evaluated patient-used duodenoscopes, bronchoscopes, colonoscopes, and gastroscopes (scopes used for emergency procedures were excluded) that had only a bedside flush prior to being processed in the ECR (i.e. no manual cleaning). There were 10 to 15 endoscopes evaluated post-cleaning and to ensure the entire ECR cycle was effective, 5 endoscopes were evaluated post-cleaning and post-high level disinfection. All channels and two external surface locations were sampled to evaluate the residual organic and microbial load. Effective cleaning of endoscope surfaces and channels was deemed to have been achieved if there was < 6.4 μg/cm²of residual protein, < 1.8 μg/cm²of residual hemoglobin and < 4 Log₁₀viable bacteria/cm². Published data indicate that routine manual cleaning can achieve these endpoints so the ECR cleaning efficacy must meet or exceed these to establish that the ECR cleaning cycle could replace manual cleaning</p> <p>Results</p> <p>In the clinical study 75 patient-used scopes were evaluated post cleaning and 98.8% of surfaces and 99.7% of lumens met or surpassed the cleaning endpoints set for protein, hemoglobin and bioburden residuals. In the simulated-use study 100% of the Olympus colonoscopes, duodenoscopes and bronchoscopes evaluated met or surpassed the cleaning endpoints set for protein, and bioburden residuals (hemoglobin was not evaluated).</p> <p>Conclusions</p> <p>The ECR cleaning cycle provides an effective automated approach that ensures surfaces and channels of flexible endoscopes are adequately cleaned after having only a bedside flush but no manual cleaning. It is crucial to note that endoscopes used for emergency procedures or where reprocessing is delayed for more than one hour MUST still be manually cleaned prior to placing them in the ECR.</p

Identification of a Contaminating Mycobacterium tuberculosis Strain with a Transposition of an IS6110 Insertion Element Resulting in an Altered Spoligotype

Molecular fingerprinting with the IS6110 insertion sequence is useful for tracking transmission of Mycobacterium tuberculosis within a population or confirming specimen contamination in the laboratory or through instrumentation. Secondary typing with other molecular methods yields additional information as to the relatedness of strains with similar IS6110 fingerprints. Isolated, relatively rare, random events within the M. tuberculosis genome alter molecular fingerprinting patterns with any of the methods; therefore, strains which are different by two or more typing methods are usually not considered to be closely related. In this report, we describe two strains of M. tuberculosis, obtained from the same bronchoscope 2 days apart, that demonstrated unique molecular fingerprinting patterns by two different typing methods. They were closely linked through the bronchoscope by a traditional epidemiologic investigation. Genetic analysis of the two strains revealed that a single event, the transposition of an IS6110 insertion sequence in one of the strains, accounted for both the differences in the IS6110 pattern and the apparent deletion of a spacer in the spoligotype. This finding shows that a single event can change the molecular fingerprint of a strain in two different molecular typing systems, and thus, molecular typing cannot be the only means used to track transmission of this organism through a population. Traditional epidemiologic techniques are a necessary complement to molecular fingerprinting so that radical changes within the fingerprint pattern can be identified