Reductive catalytic fractionation of pine wood: elucidating and quantifying the molecular structures in the lignin oil.

In-depth structural analysis of biorefined lignin is imperative to understand its physicochemical properties, essential for its efficient valorization to renewable materials and chemicals. Up to now, research on Reductive Catalytic Fractionation (RCF) of lignocellulose biomass, an emerging biorefinery technology, has strongly focused on the formation, separation and quantitative analysis of the abundant lignin-derived phenolic monomers. However, detailed structural information on the linkages in RCF lignin oligomers, constituting up to 50 wt% of RCF lignin, and their quantification, is currently lacking. This study discloses new detailed insights into the pine wood RCF lignin oil's molecular structure through the combination of fractionation and systematic analysis, resulting in the first assignment of the major RCF-derived structural units in the 1H-13C HSQC NMR spectrum of the RCF oligomers. Specifically, ß-5 γ-OH, ß-5 ethyl, ß-1 γ-OH, ß-1 ethyl, ß-ß 2x γ-OH, ß-ß THF, and 5-5 inter-unit linkages were assigned unambiguously, resulting in the quantification of over 80% of the lignin inter-unit linkages and end-units. Detailed inspection of the native lignin inter-unit linkages and their conversion reveals the occurring hydrogenolysis chemistry and the unambiguous proof of absence of lignin fragment condensation during proper RCF processing. Overall, the study offers an advanced analytical toolbox for future RCF lignin conversion and lignin structural analysis research, and valuable insights for lignin oil valorization purposes.

Antimicrobial resistance in leprosy: results of the first prospective open survey conducted by a WHO surveillance network for the period 2009-15.

OBJECTIVES: Antimicrobial resistance (AMR) is a priority for surveillance in bacterial infections. For leprosy, AMR has not been assessed because Mycobacterium leprae does not grow in vitro. We aim to obtain AMR data using molecular detection of resistance genes and to conduct a prospective open survey of resistance to antileprosy drugs in countries where leprosy is endemic through a WHO surveillance network. METHODS: From 2009 to 2015, multi-bacillary leprosy cases at sentinel sites of 19 countries were studied for resistance to rifampicin, dapsone and ofloxacin by PCR sequencing of the drug-resistance-determining regions of the genes rpoB, folP1 and gyrA. RESULTS: Among 1932 (1143 relapse and 789 new) cases studied, 154 (8.0%) M. leprae strains were found with mutations conferring resistance showing 182 resistance traits (74 for rifampicin, 87 for dapsone and 21 for ofloxacin). Twenty cases showed rifampicin and dapsone resistance, four showed ofloxacin and dapsone resistance, but no cases were resistant to rifampicin and ofloxacin. Rifampicin resistance was observed among relapse (58/1143, 5.1%) and new (16/789, 2.0%) cases in 12 countries. India, Brazil and Colombia reported more than five rifampicin-resistant cases. CONCLUSIONS: This is the first study reporting global data on AMR in leprosy. Rifampicin resistance emerged, stressing the need for expansion of surveillance. This is also a call for vigilance on the global use of antimicrobial agents, because ofloxacin resistance probably developed in relation to the general intake of antibiotics for other infections as it is not part of the multidrug combination used to treat leprosy.

Tuberculin survey in Bangladesh, 2007-2009: prevalence of tuberculous infection and implications for TB control.

OBJECTIVES: To assess the prevalence of tuberculous infection and the annual risk of tuberculous infection (ARTI) for 2007-2009 in Bangladesh, approximately 45 years after the first tuberculin survey in 1964-1966. METHODS: A tuberculin survey was conducted along with the National Tuberculosis Disease Prevalence Survey in 2007-2009. This was a multistaged community-based, cross-sectional survey, including 17,718 children aged 5-14 years. The prevalence of tuberculous infection was estimated using the mixture method and a cut-off point of ≥ 8 mm. RESULTS: The prevalence of infection was 10.0% (interquartile range [IQR] 8.6-12.2) in children aged 5-9 years and 17.9% (IQR 15.4-20.2) in those aged 10-14 years using the mixture analysis. Prevalence was 12.4% (95% confidence interval [CI] 11.7-13.1) in children aged 5-9 years and 22.6% (95%CI 21.6-23.4) in those aged 10-14 years using a cut-off point of ≥ 8 mm. The estimated ARTI was respectively 1.5% and 1.7% in 5-9 and 10-14 year olds using the mixture method and respectively 1.9% and 2.1% using the cut-off method. CONCLUSIONS: The moderate reduction in the prevalence of infection and slow decline of the ARTI after two decades of DOTS implementation indicates considerable ongoing transmission.

Intervention to increase detection of childhood tuberculosis in Bangladesh.

BACKGROUND: Despite a well-functioning adult tuberculosis (TB) control programme, children with TB remain grossly under-detected in Bangladesh. It is conservatively estimated that annually around 21,000 children with TB go undetected, due to an almost exclusive focus on sputum smear-positive TB and the absence of training or guidelines in paediatric TB. OBJECTIVE: To double child TB detection by increasing general awareness and training of health care workers at microscopy centres supported by the Damien Foundation (DF) Bangladesh. METHODS: A cluster-randomised trial was carried out with provision of child TB guidelines, training and logistics support to staff of 18 microscopy centres, while 18 non-adjacent microscopy centres continued their usual practice and served as controls. Paediatric data on TB suspect referral and case detection were collected at baseline and during the intervention at both control and intervention sites. RESULTS: Child TB case detection increased in both intervention and control microscopy centres, but the increase was three times the baseline in the intervention centres (from 3.8% to 12%) in comparison to less than double the baseline in the control centres (from 4.3% to 7%, P = 0.001). CONCLUSION: Simple guidelines and training on child TB case detection, together with basic logistics support, can be integrated into the existing National TB Control Programme and improve service delivery to children in TB-endemic areas.

Prevalence of smear-positive tuberculosis in persons aged ≥ 15 years in Bangladesh: results from a national survey, 2007-2009.

The aim of this study was to determine the nationwide prevalence of smear-positive tuberculosis (TB) in Bangladesh. A multi-stage cluster survey of a random sample of persons aged ≥ 15 years was included in 40 clusters (20 urban, 20 rural). Two sputum samples were collected from study participants and tested initially by fluorescence microscopy and confirmed by the Ziehl-Neelsen method. The crude and adjusted prevalence rates and 95% confidence intervals (CIs) were calculated using standard methods. A total of 33 new smear-positive TB cases were detected among 52 098 individuals who participated in the study. The average participation rate was over 80%. The overall crude prevalence of new smear-positive TB in persons aged ≥ 15 years was estimated as 63.3/100 000 (95% CI 43.6-88.9) and the adjusted prevalence was 79.4/100 000 (95% CI 47.1-133.8). TB prevalence was higher in males (n = 24) and in rural areas (n = 20). The prevalence was highest in the 55-64 years age group (201/100 000) and lowest in 15-24 years age group (43.0/100 000). The prevalence was higher in persons with no education (138.6/100 000, 95% CI 78.4-245.0). The overall prevalence of smear-positive TB was significantly lower than the prevalence estimate of the previous nationwide survey in Bangladesh in 1987-1988 (870/100 000).

Scanty AFB smears: what's in a name?

SETTING: A tuberculosis control project in Bangladesh. OBJECTIVE: To document the frequency and diagnostic value of smears with scanty acid-fast bacilli (AFB) (IUATLD/WHO scale, < 10/100 high power fields), and to assess the appropriateness of the current positivity threshold. DESIGN: Analysis of databases of laboratory registers, patient records and the diagnostic yield of sputum collection strategies. RESULTS: Scanty smears constituted about 10% of suspect and almost 50% of follow-up smears. In suspect series, 10% of scanty 1-9/100 were not confirmed by another positive or scanty AFB sputum, compared to 7.5% of results at the current cut-off value of 10/100. Considering such results as positive by adopting a lower cut-off as low as the 1/100 used in the ATS scale added 1.5% false positives at the most. In return, the gain in confirmed positive cases was up to 10%, and that in positive results exceeded the incremental yield of the third diagnostic sputum. Significance of scanty follow-up smears at the end of the intensive phase was suggested by their association with treatment failure and unfavourable outcome overall. CONCLUSIONS: Scanty results (IUATLD/WHO scale) are not rare and should not be ignored. Adoption of a considerably lower positivity threshold would be appropriate in control programmes where basic conditions for reliable AFB microscopy, including regular quality assessment, are present.

Optimal tuberculosis case detection by direct sputum smear microscopy: how much better is more?

SETTING: A tuberculosis control project in Bangladesh. OBJECTIVE: To define the efficiency of numbers of microscopic fields screened and the sputum collection scheme used for diagnostic smear examination. DESIGN: Quality controllers noted cumulative numbers of acid-fast bacilli per 100 fields screened. The incremental diagnostic yield of different sputum sampling strategies was determined. Doubtful series were re-checked and/or further samples examined. RESULTS: Acid-fast bacilli were found in 99.6% of 1412 positive and in 79.3% of 576 scanty slides in the first 100 fields. Examination of a third specimen yielded a maximum of 2.7% positives incrementally. The most efficient strategy, using three morning specimens, yielded 94.2% positives on the first and 1.0% on the third sputum; although 10% of suspects did not return, only 1.5% of the positives were among them and more cases were confirmed and treated. The positive predictive value of a single positive or scanty smear was very high (99.2%). CONCLUSIONS: Reading more than 100 fields per smear or examining a third sputum has insufficient marginal returns to justify the workload. Examining morning samples only is more efficient, and their collection does not necessarily inconvenience patients. Treatment can be started on the basis of one positive smear. Provided that a well functioning system of smear-microscopy quality control is in place, we propose a strategy based on examination of two morning sputum samples for negative suspects, with the diagnosis based on a single positive result.

Bleach sedimentation method for increased sensitivity of sputum smear microscopy: does it work?

SETTING: A non-governmental organisation (NGO) supported tuberculosis control programme in Bangladesh with good smear microscopy. OBJECTIVE: To verify whether bleach sedimentation method increases the sensitivity of sputum smear microscopy for acid-fast bacilli (AFB), and if so, how. DESIGN: Duplicate smears from successive routine specimens, peripheral centres examining direct smears, and blind examination of bleach sediment smears at central laboratories. RESULTS: When all 3,287 sputum samples were examined in duplicate and the International Union Against Tuberculosis and Lung Disease cut-off for positivity was applied, more positives were not found by bleach sedimentation. Using the much lower American Thoracic Society (ATS) threshold, the percentage positives rose slightly from 15.5% for direct smear to 16.6% after bleach. The gain was more evident when suspect examinations only were taken into consideration, as bleach missed many positives identified by direct follow-up smear. When patients rather than individual smears were counted, more suspects were detected by bleach (10% gain on average), but with considerable variation between the centres (range 6-16%). To arrive at this gain, the ATS cut-off was used, with corrections for false results. Under routine conditions, however, this threshold is too low in view of possible transfer of AFB. CONCLUSIONS: Bleach sedimentation can increase the diagnostic yield, but only to a minor extent if all other factors have been optimised already; it is not a panacea. Precautions against false negatives as well as false positives should be taken, and the additional workload is not negligible.