Comparative Analysis of Potential Determinants of Resistance to Aminoglycosides in <i>Burkholderia pseudomallei</i> Strains with Different Level of Sensitivity to Gentamicin

The aim of the study was to identify and compare potential determinants of aminoglycoside resistance in gentamicin susceptible Burkholderia pseudomallei strains.Materials and methods. A bioinformatics analysis of whole genome shotgun sequences of three B. pseudomallei strains having different levels of sensitivity to gentamicin was carried out.Results and discussion. B. pseudomallei is intrinsically resistant to aminoglycosides. Such strains, as a rule, are not taken into account in the classical scheme of isolation and identification. At the same time, there were no significant differences in the clinical manifestations of melioidosis during infection with gentamicin-resistant and sensitive strains. In B. pseudomallei strains of different sequence types (ST70, ST948, and ST1566), point missense mutations were found in the genes of three efflux pumps of the RND family: AmrAB-OprA, BpeAB-OprB, BpeEF-OprC, and one with unknown functions, as well as in the gene aminoglycoside-6’-N-acetyltransferase AAC(6’)-III. All three strains had amino acid substitutions in the AmrA periplasmic linker: ARG160SER, Arg116Gln and Gly237Arg, Thr317Lys, respectively. In moderately sensitive strains (ST948 and ST1566), an identical Val222Met substitution was found in the repressor of the AmrAB-OprA operon, AmrR. It is likely that the intermediate level of sensitivity to gentamicin in the studied strains is mediated by the constitutive expression of the AmrAB-OprA operon, which partially compensates for the structural defects. It is also possible that a dinucleotide deletion in the AAC (6’)-III aminoglycoside-6’-N-acetyltransferase gene, as well as detected mutations in the homologues of the periplasmic linker (BPSL2234) of an uncharacterized efflux operon of the RND family, are involved in the loss of resistance to gentamicin

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: A systematic analysis for the Global Burden of Disease Study 2015

Background: The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods: We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings: Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation: Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding: Bill & Melinda Gates Foundation

Development of a Latex Agglutination Test for Detecting Pathogenic Burkholderia and its Approbation in the Endemic Regions of Vietnam

The aim of the work was development of a monoclonal antibody-based latex agglutination test to identify the causative agent of melioidosis, and the approbation of a freeze-dried experimental preparation for screening of environmental bacterial isolates in Vietnam.Materials and methods. The carriers of specific antibodies were polyacrolein latex particles with active aldehyde groups on the surface. Typical strains of the causative agents of melioidosis and glanders with a full-fledged antigenic structure, as well as the strains Burkholderia thailandensis, Burkholderia cepacia, Pseudomonas aeruginosa, and Pseudomonas putida were used to control the test specificity. The latex agglutination reaction was carried out on plastic Petri dishes with daily bacterial cultures, from which suspensions were prepared at a concentration of 1–2·109 m.c./ml. The results of the reaction were registered visually for 5–8 min using a 4-cross system against a dark background under lighting. The reaction to 3–4 crosses was recorded as positive. Colonies suspected of belonging to pathogenic Burkholderia from primary inoculations were transferred to L-agar with polymyxin B and grown for 36 hours at (37±1) °C. The species of the selected suspicious colonies was determined by multiplex PCR.Results and discussion. With collection strains, latex test demonstrated high sensitivity agglutinating 97.7 % of B. pseudomallei and all B. mallei strains. At the same time, it was negative with B. thailandensis, B. cepacia, P. aeruginos and P. putida. In microbiological screening of bacterial cultures isolated from environmental objects, the latex test had a diagnostic sensitivity of 89.4 %. Using the latex test at the stage of primary screening, it is possible to significantly reduce the time when processing a lot of samples received for analysis, as well as to reduce the consumption of reagents used at the subsequent stages of identification