Genetic markers in s. Paratyphi c reveal primary adaptation to pigs

Salmonella enterica with the identical antigenic formula 6,7:c:1,5 can be differentiated biochemically and by disease syndrome. One grouping, Salmonella Paratyphi C, is currently considered a typhoidal serovar, responsible for enteric fever in humans. The human-restricted typhoidal serovars (S. Typhi and Paratyphi A, B and C) typically display high levels of genome degradation and are cited as an example of convergent evolution for host adaptation in humans. However, S. Paratyphi C presents a different clinical picture to S. Typhi/Paratyphi A, in a patient group with predisposition, raising the possibility that its natural history is different, and that infection is invasive salmonellosis rather than enteric fever. Using whole genome sequencing and metabolic pathway analysis, we compared the genomes of 17 S. Paratyphi C strains to other members of the 6,7:c:1,5 group and to two typhoidal serovars: S. Typhi and Paratyphi A. The genome degradation observed in S. Paratyphi C was much lower than S. Typhi/Paratyphi A, but similar to the other 6,7:c:1,5 strains. Genomic and metabolic comparisons revealed little to no overlap between S. Paratyphi C and the other typhoidal serovars, arguing against convergent evolution and instead providing evidence of a primary adaptation to pigs in accordance with the 6,7:c:1.5 strains

Vertical distribution of aerosols over the east coast of India inferred from airborne LIDAR measurements

The information on altitude distribution of aerosols in the atmosphere is essential in assessing the impact of aerosol warming on thermal structure and stability of the atmosphere. In addition, aerosol altitude distribution is needed to address complex problems such as the radiative interaction of aerosols in the presence of clouds. With this objective, an extensive, multi-institutional and multi-platform field experiment (ICARB-Integrated Campaign for Aerosols, gases and Radiation Budget) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP) over continental India and adjoining oceans during March to May 2006. Here, we present airborne LIDAR measurements carried out over the east Coast of the India during the ICARB field campaign. An increase in aerosol extinction (scattering + absorption) was observed from the surface upwards with a maximum around 2 to 4 km. Aerosol extinction at higher atmospheric layers (>2 km) was two to three times larger compared to that of the surface. A large fraction (75-85%) of aerosol column optical depth was contributed by aerosols located above 1 km. The aerosol layer heights (defined in this paper as the height at which the gradient in extinction coefficient changes sign) showed a gradual decrease with an increase in the offshore distance. A large fraction (60-75%) of aerosol was found located above clouds indicating enhanced aerosol absorption above clouds. Our study implies that a detailed statistical evaluation of the temporal frequency and spatial extent of elevated aerosol layers is necessary to assess their significance to the climate. This is feasible using data from space-borne lidars such as CALIPSO, which fly in formation with other satellites like MODIS AQUA and MISR, as part of the A-Train constellation

Use of Nanopore Sequencing to Characterise the Genomic Architecture of Mobile Genetic Elements Encoding bla CTX-M-15 in Escherichia coli Causing Travellers' Diarrhoea

Increasing levels of antimicrobial resistance (AMR) have been documented in Escherichia coli causing travellers’ diarrhoea, particularly to the third-generation cephalosporins. Diarrhoeagenic E. coli (DEC) can act as a reservoir for the exchange of AMR genes between bacteria residing in the human gut, enabling them to survive and flourish through the selective pressures of antibiotic treatments. Using Oxford Nanopore Technology (ONT), we sequenced eight isolates of DEC from four patients’ specimens who had all recently returned to the United Kingdome from Pakistan. Sequencing yielded two DEC harbouring bla(CTX-M-15) per patient, all with different sequence types (ST) and belonging to five different pathotypes. The study aimed to determine whether bla(CTX-M-15) was located on the chromosome or plasmid and to characterise the drug-resistant regions to better understand the mechanisms of onward transmission of AMR determinants. Patients A and C both had one isolate where bla(CTX-M-15) was located on the plasmid (899037 & 623213, respectively) and one chromosomally encoded (899091 & 623214, respectively). In patient B, bla(CTX-M-15) was plasmid-encoded in both DEC isolates (786605 & 7883090), whereas in patient D, bla(CTX-M-15) was located on the chromosome in both DEC isolates (542093 & 542099). The two bla(CTX-M-15)-encoding plasmids associated with patient B were different although the bla(CTX-M-15)-encoding plasmid isolated from 788309 (IncFIB) exhibited high nucleotide similarity to the bla(CTX-M-15)-encoding plasmid isolated from 899037 (patient A). In the four isolates where bla(CTX-M-15) was chromosomally encoded, two isolates (899091 & 542099) shared the same insertion site. The bla(CTX-M-15) insertion site in isolate 623214 was described previously, whereas that of isolate 542093 was unique to this study. Analysis of Nanopore sequencing data enables us to characterise the genomic architecture of mobile genetic elements encoding AMR determinants. These data may contribute to a better understanding of persistence and onward transmission of AMR determinants in multidrug-resistant (MDR) E. coli causing gastrointestinal and extra-intestinal infections

WGS for surveillance of antimicrobial resistance:A pilot study to detect the prevalence and mechanism of resistance to azithromycin in a UK population of non-typhoidal Salmonella

Objectives: WGS and phenotypic methods were used to determine the prevalence of azithromycin resistance in Salmonella enterica isolates from the UK and to identify the underlying mechanisms of resistance.  Methods: WGS by Illumina HiSeq was carried out on 683 Salmonella spp. isolates. Known genes associated with azithromycin resistance were detected by WGS using a mapping-based approach. Macrolide resistance determinants were identified and the genomic context of these elements was assessed by various bioinformatics tools. Susceptibility testing was in accordance with EUCAST methodology (MIC ≤16 mg/L).  Results: Fifteen isolates of non-typhoidal Salmonella enterica belonging to serovars Salmonella Blockley, Salmonella Typhimurium, Salmonella Thompson, Salmonella Ridge and Salmonella Kentucky showed resistance or decreased susceptibility to azithromycin (from 6 to >16 mg/L) due to the presence of macrolide resistance genes mphA, mphB or mefB. These genes were either plasmid or chromosomally mediated. Azithromycin-resistant Salmonella Blockley isolates harboured a macrolide inactivation gene cluster, mphA-mrx-mphr(A), within a novel Salmonella azithromycin resistance genomic island (SARGI) determined by MinION sequencing. This is the first known chromosomally mediated mphA gene cluster described in salmonellae. Phylogenetic analysis and epidemiological information showed that mphA Salmonella Blockley isolates were not derived from a single epidemiologically related event. The azithromycin MICs of the 15 Salmonella spp. isolates showed that the presence of the mphA gene was associated with MIC ≥16 mg/L, while the presence of mefB or mphB was not.  Conclusions: Azithromycin resistance due to acquisition of known macrolide resistance genes was seen in four different Salmonella serovars and can be either plasmid-encoded or chromosomally encoded

BANDGAP ANALYSIS OF NANO CRYSTALLINE L0.1ZY0.9BCCO CERAMICS

Crystalline Ceramic Lanthanum Zirconium Yttrium barium Calcium Copper oxide(L0.1ZY0.9BCCO)  was prepared by a high-energy ball milling process through mechanically assisted synthesis at a high temperature to acquire the desired homogeneity and phase formation. Inorder to study the optical properties like reflectivity, absorptivity, refractive index, the UV-VIS analysis of the above nonstochiometric sample was carried out. The dispersion of refractive index was analyzed by the Wemple-DiDomenico single-oscillator model.The band gap energy of the sample was elucidated from the Tauc plot. The refractive index n was calculated and  the results obtained are plotted  with the wavelength.Â