Anti-microbial sensitivity and resistance of organisms in blood-culture samples from prolonged fever cases: evidence from a tertiary care hospital in West Bengal, India

Background: Currently there is a rise in resistance to anti-microbials which is a matter of concern in treatment of systemic infections. Blood culture is considered “gold standard” in diagnosis of suspected systemic infection. The susceptibility to antibiotics thereafter determine the future course of treatment. The current study aims to find out the sensitivity and resistance pattern of the blood culture isolates.Methods: A cross-sectional study was performed on the blood culture samples sent within 24hours of admission of the adult patients reporting fever for 7 days or more with no history of consumption of any antibiotics within last month. Total 134 blood samples were analysed. The proportion of sensitivity and resistance to anti-bacterial agents was calculated among those samples which showed growth in the culture. Background information of the patients in terms of age, sex and religion were also noted.Results: Mean age of the patients was 39.33 (±12.19) years. Overall 47.76% were female patients and remaining were male. Among the Hindu patients majority were male while among Muslims majority were female. Of the total number of blood cultures examined 46.27% showed growth of bacteria. Staphylococcus aureus was the most frequently found bacteria isolated in cultures, followed by coagulase negative Staphylococcus and Pseudomonas. Of the frequently used antibiotics, higher sensitivity was seen with vancomycin, amikacin, netilmycin, imipenem, gentamicin. High resistance was observed in use of antibiotics like cefixime, amoxicillin-clavulanic acid and azithromycin.Conclusions: High level of resistance to several commonly used advanced antibiotics warrant judicial and evidence-based use of these drugs.

On modelling the Fast Radio Burst population and event rate predictions

Assuming that Fast Radio Bursts (FRBs) are of extragalactic origin, we have developed a formalism to predict the FRB detection rate and the redshift distribution of the detected events for a telescope with given parameters. We have adopted FRB 110220, for which the emitted pulse energy is estimated to be E0 =5.4×1033 J, as the reference event. The formalism requires us to assume models for (a) pulse broadening due to scattering in the ionized intergalactic medium – we consider two different models for this, (b) the frequency spectrum of the emitted pulse – we consider a power-law model Eν ∝ν −α with −5 ≤ α ≤ 5, and (c) the comoving number density of the FRB occurrence rate n(E, wi, z) – we ignore the z dependence and assume a fixed intrinsic pulse width wi = 1ms for all the FRBs. The distribution of the emitted pulse energy E is modelled through (a) a delta function where all the FRBs have the same energy E = E0, and (b) a Schechter luminosity function where the energies have a spread around E0. The models are all normalized using the four FRBs detected by Thornton et al. Our model predictions for the Parkes telescope are all consistent with the inferred redshift distribution of the 14 FRBs detected there to date. We also find that scattering places an upper limit on the redshift of the FRBs detectable by a given telescope; for the Parkes telescope, this is z ~ 2. Considering the upcoming Ooty Wide Field Array, we predict an FRB detection rate of ~0.01 to ~103 d−1

Nanoscale On-Silico Electron Transport via Ferritins

Silicon is a solid-state semiconducting material that has long been recognized as a technologically useful one, especially in electronics industry. However, its application in the next-generation metalloprotein-based electronics approaches has been limited. In this work, the applicability of silicon as a solid support for anchoring the iron-storage protein ferritin, which has a semiconducting iron nanocore, and probing electron transport via the ferritin molecules trapped between silicon substrate and a conductive scanning probe has been investigated. Ferritin protein is an attractive bioelectronic material because its size (X-ray crystallographic diameter ∼12 nm) should allow it to fit well in the larger tunnel gaps (>5 nm), fabrication of which is relatively more established, than the smaller ones. The electron transport events occurring through the ferritin molecules that are covalently anchored onto the MPTMS-modified silicon surface could be detected at the molecular level by current-sensing atomic force spectroscopy (CSAFS). Importantly, the distinct electronic signatures of the metal types (i.e., Fe, Mn, Ni, and Au) within the ferritin nanocore could be distinguished from each other using the transport band gap analyses. The CSAFS measurements on holoferritin, apoferritin, and the metal core reconstituted ferritins reveal that some of these ferritins behave like n-type semiconductors, while the others behave as p-type semiconductors. The band gaps for the different ferritins are found to be within 0.8 to 2.6 eV, a range that is valid for the standard semiconductor technology (e.g., diodes based on p–n junction). The present work indicates effective on-silico integration of the ferritin protein, as it remains functionally viable after silicon binding and its electron transport activities can be detected. Potential use of the ferritin–silicon nanohybrids may therefore be envisaged in applications other than bioelectronics, too, as ferritin is a versatile nanocore-containing biomaterial (for storage/transport of metals and drugs) and silicon can be a versatile nanoscale solid support (for its biocompatible nature)

Structure, dissociation pathways and thermochemistry of some nitrogen-containing astrophysical molecules: a theoretical study

The structure, relative energies, dissociation pathways and thermochemistry of acetonitrile (CH3CN or methyl cyanide), acrylonitrile (CH2CHCN or vinyl cyanide), propionitrile (CH3CH2CN or ethyl cyanide) and their stable isomers have been studied in detail using density functional B3LYP, B3PW91 and ab initio MP2, QCISD and CCSD(T) methods. Several space missions have already confirmed the abundance of these molecules in different interstellar mediums (ISMs). The existence of related radicals, atoms and molecules are also confirmed using various IR-spectrometric techniques and that may be evolved in solar irradiation in the cold dark core TMC-1 or massive star-forming regions such as Sagittarius B2 or Oion-KL. Possible ways of fragmentation of ground state CH3NC, CH2CHNC and CH3CH2NC through different dissociation channels and their link to other isomers have been considered to justify the presence of such observed radicals in the interstellar cloud. Cyanide(-C≡N), iso-cyanide (-N = C) and imine (-C = N-H) isomeric forms have been considered here and out of these, cyanide isomers are more stable species compared to its iso-nitrile and imine form. Favourable product molecules, such as CH2 radical, C2H2, C2H4 and HCN/HNC, are considered in the dissociation channels.</p

Characterization of enhanced antibacterial effects of novel silver nanoparticles

In the present study, we report the preparation of silver nanoparticles in the range of 10–15 nm with increased stability and enhanced anti-bacterial potency. The morphology of the nanoparticles was characterized by transmission electron microscopy. The antibacterial effect of silver nanoparticles used in this study was found to be far more potent than that described in the earlier reports. This effect was dose dependent and was more pronounced against gram-negative bacteria than gram-positive organisms. Although bacterial cell lysis could be one of the reasons for the observed antibacterial property, nanoparticles also modulated the phosphotyrosine profile of putative bacterial peptides, which could thus affect bacterial signal transduction and inhibit the growth of the organisms

Hydrogen Bonding Inside Anionic Polymeric Brush Layer: Machine Learning-Driven Exploration of the Relative Roles of the Polymer Steric Effect, Charging, and Type of Screening Counterions

This paper employs a combination of all-atom molecular dynamics (MD) simulations and unsupervised machine learning (ML) for studying the water–water hydrogen bonds (HBs) inside the anionic poly acrylic acid (PAA) brushes modeled using all-atom MD simulations. PAA brush layer with different charge fraction (f), namely, f = 0, 0.25, and 1, is considered. Water–water interactions, both inside and outside the brush layer, are represented through distinct clusters of tupules of variables representing distances associated with the interacting water molecules. While clusters representing the HBs are present for water inside and outside the brushes, several clusters representing the long-range water–water interactions are missing for the water molecules inside the highly charged (f = 1) PAA brushes. More importantly, inside highly charged brushes, the edge of the clusters representing the water–water HBs is progressively shortened as compared to that in the bulk. Both of these results stem from the presence of the PAA brushes imparting the steric effect and the charge effect, or the effect associated with enhanced interactions of water molecules with PE charges and counterions, thereby disrupting the water connectivity. This water-charged-species interaction also increases the water–water HB angle, i.e., makes the water–water HBs less stable inside the highly charged PAA brush layer. The narrowing of the clusters representing the HBs and the alteration of the angle characterizing the HBs confirm that the conditions defining the water–water HBs change inside the PAA brush layer as a function of the charges on the PAA brush layer. Furthermore, we show that the use of the generic definition of HBs, as compared to using our simulation-motivated modified definition of water–water HBs, overpredicts the number of water–water HBs inside the PAA brush layer. Finally, we employ this all-atom-MD-ML framework to quantify the effect of other types of screening counterions (Li+, Ca2+, and Y3+ ions) in determining the water–water interactions and water–water HB properties inside the PAA brush layer. The findings of the present study, confirming the weakening of water–water HBs inside the PAA brush layer, point to the possibility that the water molecules will be more available for hydrating the brush layer and counterions, thereby leading to a more pronounced wetting of the PAA brush layer

Enhanced basepair dynamics pre-disposes protein-assisted flips of key bases in DNA strand separation during transcription initiation

Localized separation of strands of duplex DNA is a necessary step in many DNA-dependent processes, including transcription and replication. Little is known about how these strand separations occur. The strand-separated E.coli RNA polymerase–promoter open-complex structure showed four bases of the non-template strand, the master base �11A, �7, �6 and +2, in a flipped state and inserted into protein pockets. To explore whether any property of these bases in the duplex state pre-disposes them to flipping, NMR studies were performed on a wild-type promoter in the duplex state. Measurement of relaxation times indicates that a limited number of base pairs, including the flipped ones, have faster opening rates than the rest. Molecular dynamics studies also show an inherently high dynamic character of the �11A:T base pair in the wild-type strand-paired state. In order to explore the role of the RNA polymerase in the flipping process, we have used 2-aminopurine as a fluorescent probe. Slower kinetics of the increase of 2-aminopurine fluorescence was observed with RNA polymerases containing several mutant s70s. This may be interpreted as the protein playing an important role in enhancing the flipping rate. These results suggest that flipping of �11A, and perhaps other flipped bases observed in the opencomplex, is facilitated by its inherent proclivity to open-up with further assistance from the protein, thus leading to a strand-open state. Other DNA-based processes that require strand-separation may use similar pathways for strand separation. We conclude that not only basepair stability, but also dynamics may play an important role in the strand-separation