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Title: Prevalence and Molecular Characterization of New Delhi Metallo-B-Lactamase Producing Escherichia Coli and Evaluation of Lytic Potential of Coliphages Against NDM Postitive Strains
Authors: Sarwar, Faiza
Keywords: Biological & Medical Sciences
Issue Date: 2022
Publisher: Government College University, Faisalabad
Abstract: Escherichia coli are the main cause of morbidity and mortality worldwide. The emergence of drug resistance has been renowned in E. coli isolated from human, environmental and animal reservoirs. Although resistant E. coli strains have distinct prevalence rates for different populations and their impact on antibiotics is ubiquitous. Plasmids carrying virulence determinants may be associated with the dissemination of resistance. Moreover, extensive consumption of antibiotics in the community leads to the evolution and significant dissemination of AMR bacteria. The current study aimed to evaluate the detection and molecular characterization of NDM variants among E. coli isolated from hospitals in southern Punjab, Pakistan followed by the lytic potential of coliphages against these isolates. Overall, 215 E. coli were isolated from several clinical samples. After the identification of isolates, antimicrobial susceptibility testing was performed with the Kirby-Bauer disc diffusion technique, and the MIC was evaluated using the broth microdilution method. The existence of resistance-encoding genes ESBLs, MBLs, blaNDM, and 16S rRNA methylases were assessed by PCR. MLST was performed to assess the genomic diversity of blaNDM-producing E. coli. According to results, out of 215 E. coli, maximum isolates were recovered from urine (37.2%), followed by blood (14.8%), pus (14.4%), tracheal secretions (11.10), sputum (8.3%), wound swab (6.5%), tips (6%), fluids (1.3%) and CSF (0.4%), respectively. The isolates were highly resistant (100%) to Extended-spectrum cephalosporins (cefotaxime, ceftriaxone, cefepime, ceftazidime) and imipenem class of antibiotics. Among E. coli isolates, ESBL (77.2%) and MBL (24.1%) production were observed. Through PCR, ESBL producing genes blaCTX-M (76.7%), blaCTX-M-1 (40%) and CTXM-15 (18.75%) were evaluated. Carbapenemase encoding blaVIM (49.3%), blaNDM (42%) and blaIMP (21.4%) were detected among E. coli strains. Among NDM-producing isolates, NDM-1 was the most prevalent gene followed by blaNDM-5, blaNDM-7, and blaNDM-4. Resistant genes encoding 16S rRNA methylases armA (35.5%) and rmtB (52.2%) were also determined. MLST results revealed ST131 (37.8%) as the most prevalent sequence type. Coliphages were isolated from 40% of hospital drains. Phage titer (1.4 × 109 PFU/ml) was evaluated using an enrichment assay. The lytic activity of isolated coliphages against NDM-producing E. coli strains was checked by counting the number of plaques. The stability assay revealed maximum activity of phages at optimum temperature (370C-380C), pH (7-8), and minimum chloroform concentration. The study highlighted that the frequency of E. coli isolates producing NDM xxiv is increasing progressively in developing countries including Pakistan. The emergence of resistance should be prevented by continuous surveillance and formulation of appropriate policies to cope with drug resistance problems. However, the abundant growth of coliphages in sewage and its potential application might be a good substitute against blaNDM-producing E. coli strains.
Gov't Doc #: 27434
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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