Rahat, A. | bioRxiv Science

bioRxiv2020

Situation of antibiotic resistance in Bangladesh and its association with resistance genes for horizontal transfer

The study investigated the spectrum of antibiotic resistance and the associated genes for aminoglycoside, macrolide and ESBL class of antibiotics using clinical isolates. A total of 430 preserved bacterial strains (Acinetobacter baumannii, n= 20; Pseudomonas aeruginosa, n= 26; Klebsiella pneumoniae, n= 42; E.coli, n= 85; Staphylococcus aureus, n= 84; Salmonella Typhi, n= 82; Enterococcus spp., n= 27; Streptococcus pneumoniae, n= 36 and CNS, n= 28) were examined. The strains were isolated from patients admitted to various tertiary hospitals of Dhaka city between 2015 and 2019 with either acute respiratory infections, wound infections, typhoid fever or diarrhea. The isolates were reconfirmed by appropriate microbiological and biochemical methods. Antimicrobial susceptibility tests were done using Kirby-Bauer disk diffusion approach. PCR amplification using resistance gene-specific primers for aminoglycoside, macrolide and ESBL class of antibiotics was done and the amplified products were confirmed by Sanger sequencing. Of the total isolates, 53% came out as MDR with 96.6% of E. coli and 90% of Staphylococcus aureus. There was a year-wise gradual increase of MDR isolates from 2015-2018 and by 2019 the increase in MDR isolates became almost 2-fold compared to 2015. Among the five ESBL genes investigated, CTXM-1 came out as the most prevalent (63%) followed by NDM-1 (22%) and E. coli isolates were the predominant reservoir of these genes. ErmB (55%) was the most frequently detected macrolide resistance gene, whereas aac(6)-Ib (35.44%) was the most prevalent aminoglycoside resistance gene and these genes were most prevalent in E. coli and P. aeruginosa isolates, respectively. CTXM-1 and ErmB (16.66%) were the most frequent partners of coexistence followed by CTXM-1 and aac(3)-II.

microbiology↗

bioRxiv2019

ChIP-seq of plasma cell-free nucleosomes identifies cell-of-origin gene expression programs

AbstractGenomic DNA is packed by histone proteins that carry a multitude of post-translational modifications that reflect cellular transcriptional state. Cell-free DNA (cfDNA) is derived from fragmented chromatin in dying cells, and as such it retains the histones markings present in the cells of origin. Here, we pioneer chromatin immunoprecipitation followed by sequencing of cell-free nucleosomes (cfChIP-seq) carrying active chromatin marks. Our results show that cfChIP-seq provides multidimensional epigenetic information that recapitulates the epigenetic and transcriptional landscape in the cells of origin. We applied cfChIP-seq to 268 samples including samples from patients with heart and liver pathologies, and 135 samples from 56 metastatic CRC patients. We show that cfChIP-seq can detect pathology-related transcriptional changes at the site of the disease, beyond the information on tissue of origin. In CRC patients we detect clinically-relevant, and patient-specific information, including transcriptionally active HER2 amplifications. cfChIP-seq provides genome-wide information and requires low sequencing depth. Altogether, we establish cell-free chromatin immunoprecipitation as an exciting modality with potential for diagnosis and interrogation of physiological and pathological processes using a simple blood test. One Sentence SummaryChIP-seq of plasma-circulating nucleosomes (cfChIP-seq) from a simple blood test provides detailed information about gene expression programs in human organs, and cancer.

molecular biology↗