In-silico insights of ESBL variants and tracking the probable sources of ESBL-producing Escherichia coli in a small-scale poultry farm.

Commercial broiler farms face challenges of extended spectrum beta-lactamase (ESBL)-producing Escherichia coli transmitted from both vertical and horizontal routes. Understanding the dynamics of ESBL-E. coli transmission in compromised biosecurity settings of small-scale rural poultry farms is essential. This study aimed to elucidate the probable transmission pathways of ESBL-E. coli in such settings, employing phylogenetic analysis and molecular docking simulations to explore the catalytic properties of ß-lactamase variants. Sampling was conducted on a small-scale poultry farm in West Bengal, India, collecting 120 samples at three intervals during the broiler production cycle. E. coli isolates underwent resistance testing against eight antimicrobials, with confirmation of ESBL production. Genotypic analysis of ESBL genes and sequencing were performed, alongside molecular docking analyses and phylogenetic comparisons with publicly available sequences. Among 173 E. coli isolates, varying resistance profiles were observed, with complete resistance to cefixime and high resistance to amoxicillin and tetracycline. The incidence of ESBL-E. coli fluctuated over the production cycle, with dynamic changes in the prevalence of blaCTX-M-type and blaSHV-type genes. Phylogenetic analysis indicated partial clonal relationships with human clinical strains and poultry strains from the Indian subcontinent. Molecular docking confirmed the catalytic efficiencies of these ESBL variants. The study highlights probable vertical transmission of ESBL-E. coli and emphasizes drinking water as a potential source of horizontal transmission in small-scale poultry farms. Strict biosecurity measures could prevent the spread of antimicrobial-resistant bacteria in birds and their products in a small scale poultry farm.

Docking analysis of circulating CTX-M variants in multi-drug resistant, beta-lactamase and biofilm-producing E. coli isolated from pet animals and backyard livestock.

The generation of antimicrobial-resistant bacteria largely depends on the use of antimicrobials not only in humans but also in pet animals and livestock. The present study was conducted to detect the occurrence of beta-lactamase and biofilm-producing- E.coli in healthy pet and backyard livestock. The study also intended on molecular docking experiments to confirm the nature of the catalytic mechanism in ß-lactamase enzymes, encoded by the various blaCTX-M genotypes and phylogenetic analysis to reveal clonal relationship of the animal origin E. coli isolates with human clinical strains. The rectal swabs were collected from healthy dogs (n = 254), cats (n = 108), sheep (n = 119) and goats (n = 143) in India. In total 247 (76.47%) E. coli strains were identified as ESBL producers. The possession of ESBL-producers was significantly more (p < 0.05) in pets than in the backyard livestock. Most of the strains possessed blaCTX-M-15 like clones. E. coli strains possessing blaCTX-M-15.2, blaCTX-M-157, blaCTX-M-181 and blaCTX-M-218 like clones, isolated from pets were not reported earlier. The study detected 56.65% of E. coli strains as moderate or strong biofilm producers possessing biofilm-associated genes (csgA, rcsA, rpoS, sdiA). ESBL-producing E. coli showed phenotypical resistance to tetracycline (93.1%), azithromycin (89.8%), ampicillin (84.2%), cefotaxime (80.9%), doxycycline (82.5%), co-trimoxazole (80.9%), ampicillin/cloxacillin (76.9%). The CTX-M variants obtained in this study were modelled by the SWISS-MODEL and verified. Ligand having minimum binding energy, show the highest affinity of ß-lactamases for cefotaxime and cefpodoxime. The Gibbs free energy release for all 14 different complex ranges between -6.9 (CTX-M-15.2+cefpodoxime) to -5.3 (CTX-M-218+cefpodoxime) Kcal/mol. Phylogenetic analysis of the animal origin ESBL-E. coli strains revealed a partial clonal relationship with the clinical isolates of local human patients. The present study described the significant presence of biofilm and ß-lactamase producing, multi-drug resistant E. coli in pet animals having public health importance.

Exploring broilers and native fowls of Andaman and Nicobar Islands as a source of ß-lactamase-producing Enterobacteriaceae even with limited anthropogenic activities and docking-based identification of catalytic domains in novel ß-lactamase variants.

Objectives: The present study was conducted to detect the occurrence of ß-lactamase and biofilm-producing Escherichia coli, Salmonella, and Klebsiella in broilers and native fowl reared in the Andaman and Nicobar Islands, India. The study also included molecular docking experiments to confirm the nature of the catalytic domains found in the ß-lactamase variants obtained and to reveal the clonal relationship of the isolates with human clinical strains from the database. Materials and methods: A total of 199 cloacal swabs were collected from five poultry breeds/varieties (broiler, Vanraja, Desi, Nicobari, and layer) in three districts of the Andaman and Nicobar Islands. E. coli, Salmonella enterica, and Klebsiella pneumoniae were isolated by standard techniques and confirmed by PCR. Phenotypical ß-lactamase producers were identified by a double-disc test. The genes (bla CTX, bla SHV, bla TEM , and bla AmpC) were screened, and selected sequences of ß-lactamase variants were submitted to DDBJ. Homology modeling, model validation, and active site identification of different ß-lactamase variants were done by the SWISS-MODEL. Molecular docking was performed to identify the catalytic domains of the ß-lactamase variants. The selected ß-lactamase sequences were compared with the Indian ESBL sequences from human clinical strains in NCBI-GenBank. Results: In total, 425 Enterobacteriaceae strains were isolated from the collected samples. Klebsiella pneumoniae (42.58%) was found to be the most prevalent, followed by Salmonella enterica (30.82%) and E. coli (26.58%). The phenotypical antibiogram of all 425 isolates showed the highest resistance against oxytetracycline (61-76%) and the lowest against gentamicin (15-20%). Phenotypical production of ß-lactamase enzymes was observed in 141 (33.38%) isolates. The isolation rate of ß-lactamase producing E. coli, Salmonella enterica, and Klebsiella pneumoniae was significantly higher (p < 0.05) in the birds reared in the South Andaman district (25.6, 17.5, and 18.7%, respectively) than in Nicobar (11.5, 7.6, 7.1%, respectively). Genotyping of the ß-lactamase-producing isolates revealed the maximum possession of bla TEM, followed by bla SHV and bla CTX - M. The nucleotide sequences were found to be similar with bla CTX - M-15, bla SHV - 11, bla SHV - 27, bla SHV - 228, bla TEM - 1, and bla AmpC in BLAST search. Distribution of studied biofilm-associated genes in Enterobacteriaceae strains from different varieties of the birds revealed that the layer birds had the maximum possession, followed by Vanraja, Desi, broilers, and Nicobari fowls. The phylogenetic analysis of selected sequences revealed a partial clonal relationship with human clinical strains of the Indian subcontinent. Molecular docking depicted the Gibbs free energy release for 10 different macromolecules (proteins) and ligand (antibiotic) complexes, ranging from -8.1 (SHV-27 + cefotaxime) to -7 (TEM-1 + cefotaxime) kcal/mol. Conclusion and relevance: The study revealed ß-lactamase variants circulating in the fowl population of the Andaman and Nicobar Islands (India), even in remote places with low anthropogenic activity. Most of the strains possessed bla TEM - 1, followed by bla CTX - M-15. Possession of bla SHV - 11, bla SHV - 27, and bla SHV - 228 in poultry Enterobacteriaceae strains was not reported earlier from any part of the world. The phylogenetic analysis revealed a partial clonal relationship of ß-lactamase sequences with the human clinical strains isolated from the Indian subcontinent.

Experimental Determination of η/s for Finite Nuclear Matter.

We present, for the first time, simultaneous determination of shear viscosity (η) and entropy density (s) and thus, η/s for equilibrated nuclear systems from A∼30 to A∼208 at different temperatures. At finite temperature, η is estimated by utilizing the γ decay of the isovector giant dipole resonance populated via fusion evaporation reaction, while s is evaluated from the nuclear level density parameter (a) and nuclear temperature (T), determined precisely by the simultaneous measurements of the evaporated neutron energy spectra and the compound nuclear angular momenta. The transport parameter η and the thermodynamic parameter s both increase with temperature, resulting in a mild decrease of η/s with temperature. The extracted η/s is also found to be independent of the neutron-proton asymmetry at a given temperature. Interestingly, the measured η/s values are comparable to that of the high-temperature quark-gluon plasma, pointing towards the fact that strong fluidity may be the universal feature of the strong interaction of many-body quantum systems.

Empirical formula for the prediction of off axis ratios and isodose curves for a treatment planning system.

A mathematical model has been developed for prediction of off axis ratio (OAR), using Wood - Saxon term used to represent nuclear potential. This method has been satisfactorily applied for predicting OAR in case of (60)Co γ-rays and high energy X-rays. Investigations are considered upto a depth of 25 cm in the case of 4MV LINAC for which measurements were carried out in our laboratory using indigenously developed Radiation Field Analyzer. For (60)Co γ-rays as well as 6 and 18MV LINAC beams we could get off-axis profiles only upto 20 cm. The shift δ between measured and predicted OAR is within ±2 mm except for 20 cm depth near the falling edge of the penumbra, where it is 2.80 mm. Software has been developed in Visual Basic 6 on Windows platform to plot Isodose curves, which is based on the mathematical modeling of OAR and central axis percentage depth dose.