Dreus A, Ainietdinova H, Burlaka V, Sklyar T, Kurahina N.

Oles Honchar Dnipro National University


Escherichia coli, a predominant species among the facultative anaerobic bacteria in the gastrointestinal tract, is also a major food-borne pathogen and one of the main causes of hospital-acquired infections. Thus, the search for new treatments against infections caused by E. coli is extremely relevant due to antibiotic resistance spread. A possible solution to this problem can be seen in bacteriocins or phages isolated from closely related strains by lysogenic induction.

The aim of the research was the induction of E. coli clinical strain prophages with subsequent identification of the obtained lysates.

Materials and methods. In our work we used standard virological and microbiological methods. Clinical strains of E. coli ST2, ST3, ST4, ST5, ST6 (grown on LB medium and M9+glucose medium) were chosen for obtaining lysates; control bacterial culture E. coli С600; indicator cultures Erwinia dissolvens, E. coli С600, E. coli J53, E. coli K12 (grown on LB medium). For phage induction a nalidixic acid (in 1, 2.5 and 20 mg/mL concentration) was used.

Results and discussion. As a result of prophage induction with nalidixic acid (NAL) in three different concentrations after incubation at 37 °C (E. dissolvens at 28°C), depending on the concentration of NAL, lysis spots have been detected, which indicates successful induction. Thus, lysis spots were obtained on E. coli K12 with NAL concentrations of 1, 2.5 and 20 mg/mL on sectors of the studied clinical strain E. coli ST4. Lysis spots were also found on E. coli J53 when NAL was used in a concentration of 1 mg/mL on the sector of the studied clinical strain E. coli ST4 , and when NAL was used in concentrations of 2.5 mg/mL and 20 mg/mL on the sectors of the studied clinical strains E. coli ST2, ST4, ST5, ST6. With NAL concentration of 20 mg/mL, lysis spots were found on E. dissolvens on all sectors of the studied clinical bacterial strains. The nature of the killer factors was determined by differentiation: testing lysate for ability to reproduce. Differentiation was carried out by transferring lysate from the lysis stain to the lawn of a sensitive culture, as a result of which no plaques were identified, which indicates that bacteriocins of a phage nature have been obtained.

Conclusions. Due to the positive results of the experiment further use of induced phages and bacteriocins as antibacterial agents is possible. It may contribute to better understanding of phage-host interplay in terms of clinical infections.