Biological and molecular characterization of fEg-Eco19, a lytic bacteriophage active against an antibiotic-resistant clinical Escherichia coli isolate

Abstract

Characterization of bacteriophages facilitates better understanding of their biology, host specificity, genomic diversity, and adaptation to their bacterial hosts. This, in turn, is important for the exploitation of phages for therapeutic purposes, as the use of uncharacterized phages may lead to treatment failure. The present study describes the isolation and characterization of a bacteriophage effective against the important clinical pathogen Escherichia coli, which shows increasing accumulation of antibiotic resistance. Phage fEg-Eco19, which is specific for a clinical E. coli strain, was isolated from an Egyptian sewage sample. Phage fEg-Eco19 formed clear, sharp-edged, round plaques. Electron microscopy showed that the isolated phage is tailed and therefore belongs to the order Caudovirales, and morphologically, it resembles siphoviruses. The diameter of the icosahedral head of fEg-Eco19 is 68 ± 2 nm, and the non-contractile tail length and diameter are 118 ± 0.2 and 13 ± 0.6 nm, respectively. The host range of the phage was found to be narrow, as it infected only two out of 137 clinical E. coli strains tested. The phage genome is 45,805 bp in length with a GC content of 50.3% and contains 76 predicted genes. Comparison of predicted and experimental restriction digestion patterns allowed rough mapping of the physical ends of the phage genome, which was confirmed using the PhageTerm tool. Annotation of the predicted genes revealed gene products belonging to several functional groups, including regulatory proteins, DNA packaging and phage structural proteins, host lysis proteins, and proteins involved in DNA/RNA metabolism and replication.

Virus Dynamics and Decay in Evaporating Human Saliva Droplets on Fomites

“…Lysozyme morphology was identified according to the method of Sett et al SEM is a surface imaging method and, as such, enables characterization of the relative spatial distribution between virus and lysozyme particles. The virions aggregate or cluster, as in the SEM observation of bacteriophage. , At low humidity (RH 20%), the lysozyme and virus particles were distinctly observed, with modest overlap (Figure A). At higher humidity, the distributions of virus and lysozyme particles were broader, and the overlap region was wider (Figure A).…”

“…The virions aggregate or cluster, as in the SEM observation of bacteriophage. 60,61 At low humidity (RH 20%), the lysozyme and virus particles were distinctly observed, with modest overlap (Figure 8A). At higher humidity, the distributions of virus and lysozyme particles were broader, and the overlap region was wider (Figure 8A).…”

Isolation and characterization of bacteriophages from wastewater as potential biocontrol agents for Escherichia coli.

“…• Phage isolation is fast, simple, and cost-effective. Phages are present in soil, water, ocean, plants, sewage, and this makes their isolation easy, fast, and cheap (Badawy et al, 2022).…”

“…• Compared to antibiotics, the development of bacterial resistance to phages is much slower, and phages are effective even against MDR bacteria (Badawy et al, 2022).…”

“…Additionally, bacteriophages are now regarded as safe, efficacious, and innovative alternatives to the use of antibiotic therapy (Loc-Carrilo and Abedon, 2011;Endersen and Coffey, 2020). Studies have revealed that phages are more prevalent in sewage than in other environmental sources (Matilla et al, 2015;Kiljunen et al, 2018;Topka et al, 2019;Badawy et al, 2022). Therefore, the presence of lytic phages that are infecting E. coli ATCC 25922 in wastewater samples from the Darvill wastewater treatment plant (WWTP) is not surprising.…”