Characterization of virulent Escherichia coli strains isolated from patients with urological infection

Abstract

Objective. Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) affect 150 million people annually.Purpose: Characteristics of non-hospital strains of UPEC isolated from patients with UTI in Yaroslavl in 2016– 2017.Materials and methods. Susceptibility of UPEC strains (n = 20) to antibacterials was measured by the serial dilution method; the antibiotic resistance and virulence genes, phylogroups, O-serogroups and sequence types were identified by PCR and whole genome sequencing. The virulence of the strains was studied using the model of Galleria mellonella larvae.Results. UPEC strains were classified as resistant (n = 11) and multi-drug resistant (n = 9) pathogens. Betalactamase genes blaTEM (n = 10), blaCTX-M (n = 6), class 1 integrons (n = 8), and gene cassettes dfrA17-aadA5 (n = 2), dfrA1 (n = 1) and aacA4-cmlA1 (n = 1) were identified. UPEC-virulence genetic determinants coding adhesins fimH, papG, sfaS, focG, afa/draBC, csgA, siderophores iroN, fyuA, iutA, counteracting factors of host immunity ompT, traT, toxins hlyA, cnf1, usp, capsule transporter kpsMTII, colicin cvaC, and pathogenicity islands I536, II536, III536, IV536, IIJ96 и IICFT073 were detected. Highly virulent and slightly virulent for G. mellonella larvae UPEC strains were obtained with LD50 104–105 and 106–107 CFU, respectively. The phylogroups A, B1, B2, E and F, serogroups О2, О4, О6, O9, O11, О15, О18, О25, О75 and O89, known sequence types ST14, ST58, ST69, ST73, ST93, ST127, ST131, ST-141, ST165, ST297, ST457, ST537, ST744, ST1434 and novel ST9239 and ST10102 were revealed.Conclusions. The identified genetic diversity of non-hospital UPEC strains is consistent with the observed global trend in the spread of human pathogens, which are characterized with both high virulence and multiple drug resistance. This makes possible to assess prospectively the current epidemiological situation, give a forecast for its development in the future, as well as determine the optimal therapeutic options.