2. Materials and methods

At the first stage, bacterial tests of urine samples (n = 6438) isolated from patients in cases of UTI at the multispecialty regional children's hospital from 2008 to 2016 were analyzed. Patients were aged from 3 days to 17 years.

At the second stage, biological properties and genetic variability of enterococci were studied. E. faecalis (n = 71) were isolated from urine of children with urinary tract infections and age from 3 days to 17 years in the diagnostic titer from 104 CFU/ml and higher during from 2013 to 2016. E. faecalis NCTC 12697 was used as the typical culture. All strains of uropathogenic


Table 1. Oligonucleotide primers used in the study.

1. Introduction

Urinary tract infection (UTI) is a topical problem of the contemporary pediatrics, pediatric nephrology, and urology, which takes the second or third place in the structure of children's morbidity [1, 6, 9, 12]. Risk factors of UTI in children include neonatal period, in particular premature birth, family medical history, abnormalities of urinary tract development, disruptions of urodynamics, including vesicoureteric reflux, obstructive uropathy, neurogenic bladder malfunction, urolithiasis, constipation, fecal and perianal colonization, immunocompromising conditions, including AIDS, immunosuppression therapy, frequent bladder catheterization, diabetes, sexual activity in teenagers [1, 14, 15, 18]. Newborns and infants are under high risk of UTI development, among other factors, since their immune system is not yet sufficiently developed [7]. Among the many factors, which affect development and forecast of UTI, biological properties of microorganisms, which inhabit kidney tissue, are of no small importance [10, 22, 35, 43].

86 Microbiology of Urinary Tract Infections - Microbial Agents and Predisposing Factors

Etiological structure of UTI in children has changed recently. Many studies show the growing etiological significance of Enterococcus faecalis [1, 6, 8, 20, 37]. Clinical significance of enterococci, which were earlier considered in different saprophytes, is being reassessed currently [4, 10].

Increase in etiological significance of enterococci is caused by many reasons, including development of antibiotic resistance, in particular, resistance to cephalosporin, widely used for treating UTIs in children [8]. Enterococci can initiate the infectious process due to their genes coding many pathogenicity factors involved in adhesion and invasion processes, development of biofilms, and hystodamaging effect (Esp, Asa1, EfaA, CylA, CylM, GelE, FsrB, etc.) [6, 13, 16, 30, 35, 42]. It is known that virulence of microorganisms depends upon the quantity of these genes [17]. Scientists from Europe, England, America, India, and Japan are doing research in this area [21, 33, 38, 39, 41]. No research related to characteristics of intraspecific genetic variability, including pathogenicity factors, in uropathogenic E. faecalis isolates from children having UTI, has been done in Russia until now. All the above has been determined in

The aim of this research was to identify genetic variability and phenotypic features of biologic properties in uropathogenic E. faecalis isolates from children having urinary tract infections to

At the first stage, bacterial tests of urine samples (n = 6438) isolated from patients in cases of UTI at the multispecialty regional children's hospital from 2008 to 2016 were analyzed. Patients

At the second stage, biological properties and genetic variability of enterococci were studied. E. faecalis (n = 71) were isolated from urine of children with urinary tract infections and age from 3 days to 17 years in the diagnostic titer from 104 CFU/ml and higher during from 2013 to 2016. E. faecalis NCTC 12697 was used as the typical culture. All strains of uropathogenic

the topic of the research, which was undertaken in the present paper.

assess its virulent potential and clinical significance.

2. Materials and methods

were aged from 3 days to 17 years.

E. faecalis were previously investigated using classical microbiological methods [22, 43]. Antimicrobial susceptibility was performed using disk diffusion method on the Muller-Hinton agar according to EUCAST.

Bacterial DNA of E. faecalis was isolated using DNA-express kit (Lytech, Russia). The testing of enterococci (n = 31) pathogenicity genes was made by polymerase chain reaction (PCR), using previously developed primer sets (Table 1) [5, 11, 32, 34], synthesized by Eurogen (Russia), on TProfessional 96 (Biometra, Germany). The amplification products were analyzed in a 1% agarose gel containing 1 μg/ml ethidium bromide in ultraviolet light using BioDocAnalyze (Biometra, Germany).

The obtained data were processed using the parametric analysis method. From the indicators of descriptive statistics, the relative values (P, %), their errors (mp, %) were calculated. To evaluate the degree of interrelation, the Pearson correlation analysis (R) was performed with calculation of correlation coefficient (r) and reliability of correlation (p). At statistical processing of the received materials, the software package Statistica 10.0 is used in the operating environment Windows 2010.

The research was approved by Interdisciplinary Committee for Ethics of the Federal State Budgetary Educational Institution of Higher Education "Pacific State Medical University" of the Ministry of Healthcare of the Russian Federation (protocol no. 4, 26.12.2016).
