Comparative analysis of the antibiotic sensitivity level of Escherichia coli strains of different isolation periods

Introduction. The problem of the spreading of the microorganisms resistance to antimicrobial drugs is so acute nowadays, that the XXI century can rightly be called the "era of antibiotic resistance". In our opinion, to study the mechanisms of antibiotic resistance in the population of microorganisms, it is important to analyze the antibiotic sensitivity of microorganisms isolated during different periods of antibiotics use in clinical practice. The aim of the study was to compare antibiotic sensitivity profiles of E. coli strains isolated in the preantibiotic, metaantibiotic and modern periods. Material & methods. Objects of the study: 41 E. coli museum strains from the collection of the Museum of microorganisms stored in a lyophilized state for 44-73 years, and 55 circulating E. coli strains. Determination of the sensitivity of microbial cultures to antibiotics was performed using disco-diffusion method, serial broth dilution method and serial agar dilution method. Statistical data processing was performed using computer programs Microsoft Excel 2007, STATISTICA 6.0. Results & discussion. A comparative analysis of the results of the study of antibiotic sensitivity of E. coli of different isolation periods demonstrated significant decrease in activity of the antibiotics of aminopenicillin group (ampicillin, ampicillin-sulbactam), generation I-III cephalosporins, tetracycline, chloramphenicol against modern clinical E. coli strains. In contrast to the museum strains, the circulating population of E. coli showed resistance to carboxy- and ureidopenicillins, generation IV cephalosporins, carbapenems, aminoglycosides, doxycycline, fluoroquinolones, and cotrimoxazole. The vast majority (70,0%) of the antibiotic-resistant museum strains showed resistance to 1–3 antibiotics groups, while 52,2% of the modern strains showed resistance to antibiotics of the 4–7 chemical groups. Conclusion. Comparative analysis of the antibiotic sensitivity profiles of E. coli isolated during different historical periods showed an increase in the proportion of resistant strains among circulating E. coli and an expansion of the range of antibiotics groups for which resistance was identified.