Two Newly Isolated Enterobacter-Specific Bacteriophages: Biological Properties and Stability Studies

Abstract

In an era of antibiotic therapy crisis caused by spreading antimicrobial resistance, and when recurrent urinary tract infections constitute a serious social and medical problem, the isolation and complex characterization of phages with a potential therapeutic application represents a promising solution. It is an inevitable, and even a necessary direction in the development of current phage research. In this paper, we present two newly isolated myoviruses that show lytic activity against multidrug-resistant clinical isolates of Enterobacter spp. (E. cloacae, E. hormaechei, and E. kobei), the genomes of which belong to a poorly represented phage group. Both phages were classified as part of the Tevenvirinae subfamily (Entb_43 was recognized as Karamvirus and Entb_45 as Kanagawavirus). Phage lytic spectra ranging from 40 to 60% were obtained. The most effective phage-to-bacteria ratios (MOI = 0.01 and MOI = 0.001) for both the phage amplification and their lytic activity against planktonic bacteria were also estimated. Complete adsorption to host cells were obtained after about 20 min for Entb_43 and 10 min for Entb_45. The phage lysates retained their initial titers even during six months of storage at both −70 °C and 4 °C, whereas storage at 37 °C caused a complete loss in their activity. We showed that phages retained their activity after incubation with solutions of silver and copper nanoparticles, which may indicate possible synergistic antibacterial activity. Moreover, a significant reduction in phage titers was observed after incubation with a disinfectant containing octenidinum dihydrochloridum and phenoxyethanol, as well as with 70% ethanol. The observed maintenance of phage activity during incubation in a urine sample, along with other described properties, may suggest a therapeutic potential of phages at the infection site after intravesical administration.

Biological Properties of 12 Newly Isolated Acinetobacter baumannii-Specific Bacteriophages

“…For five phages, the optimal MOI was 1 (Aclw_9, Acba_13, Acba_14, Acba_16, and Acba_18), and for one phage the MOI was 10 (Acba_15). For some phages, lower values of MOI (MOI = 0.1) are more effective [ 60 , 62 ], which is also the case for phages against other species, as described for Enterobacter -specific bacteriophages [ 34 ]. For other phages, the highest phage titer values will be obtained with a higher MOI, for example, an MOI of 20 [ 8 ].…”

“…The search for bacteriophages was carried out in accordance with the procedure proposed by Ślopek et al (1984) [ 33 ] and is described by Cieślik et al (2022) [ 34 ]. Single colonies of the appropriate bacterial strain were suspended in sugar broth (per 1000 mL of water: meat extract 0.40 g, yeast hydrolysate 1.70 g, NaCl 3.50 g, Bacto Peptone 4.00 g, enzymatic hydrolysate of casein 5.40 g, glucose 10.00 g) and then incubated at 37 °C for 2 h until the optical density at a wavelength of 600 nm (OD 600 ) gained in the range of 0.4–0.6 measured spectrophotometrically (BioSpectrometer basic, Eppendorf, Hamburg, Germany).…”

“…In order to determine phage adsorption constant and assess the phage adsorption kinetics to bacterial cells, the previously described procedures were used with some modifications [ 34 , 37 ]. In brief, the same volumes of phage lysate and 2-h bacterial suspension (10 mL of each) were mixed at MOI = 0.1 (10 6 PFU/mL and 10 7 CFU/mL, respectively).…”

Multifunctional nanoreactors with nutrient consumption and ROS generation capabilities for antibacterial and skin repair

“…The excellent antibacterial and skin repair properties, as well as the good biosafety make GOx@Cu-ZIF-8 an innovative biomaterial for antibacterial and tissue regeneration. In order to further exploit the advantages of the nanoreactor and promote its therapeutic effect, we plan to use the nanoreactor to deliver bacteriophage, a promising antibacterial and tissueregenerating agent, [35][36][37][38] in future studies.…”

Effectiveness of a Phage Cocktail as a Potential Biocontrol Agent against Saprophytic Bacteria in Ready-To-Eat Plant-Based Food

“…Bacteriophages are highly specific bacterial viruses and usually can infect only one species or strain of bacteria and, unlike antibiotics, do not destroy the natural commensal microbiota of the human digestive tract [ 21 , 29 ]. Research shows that phages are insensitive to many stress conditions during food processing (stability over a wide range of temperatures and pH) [ 20 , 21 , 29 , 32 ]. Their pH stability increases at lower temperatures [ 22 ].…”