Characteristics of antibiotic sensitivity of museum strains of Escherichia coli isolated in 1946-1959 yy.

Abstract

In the middle of ХХ century, since the moment of the widespread introduction of penicillin into the medical practice, the doctors used to hope that the era of infectious diseases is over. But in two years after the mass application of the agent it has become clear that certain microorganisms can form resistance to antibiotics. For the successful fight against antibiotic resistance in microorganisms it is necessart to understand the conditions of its development. Therefore, the studies of antibiotic resistance in microorganisms isolated before the era of widespread use if antibiotics in clinical practice are relevant to modern practice.The aim of the study was to analyze the antibiotic sensitivity in museum strains of E. Coli isolated in the 1946-1959 yy. Materials and methods. The objects of the study were 20 strains of E. coli, obtained from the Museum of Microorganisms of the SE «ІMI NAMS». The determination of the sensitivity of microbial cultures to antibiotics was carried out with the help of disc diffusion method with the use of standard commercial disks, with the help of serial dilutions in agar and broth with the use of Muller-Hinton medium. The sensitivity of E. coli to the following groups of antibiotics was studied: penicillins, cephalosporines of I-IV generations, fluoroquinolones, aminoglycosides, tetracyclines, chloramphenicol and co-trimoxazole. The preparation of microorganisms’ suspensions with the determined concentration of microbial cells was carried out based in the McFarland scale with the use of electronic device Densi-La-Meter (PLIVA-Lachema Diagnostika, Czech Republic). Statistical evaluation of the obtained data was carried out with the help of computer programs Microsoft Excel 2007, STATISTICA 6.0. Results and discussion.4 (20,0±5,2) % of the strains resistant to ampicillin were found, one of which was also resistant to the inhibitor-protected agent – ampicillin sulbactam. All strains were found to be sensitive to carboxypenicillins (carbenicillin, tikarcillin) and to ureidopenicillins (piperacilin). During the evaluation of efficacy of cefalosporins to the studied E. coli strains it was established that (25,0±6,0) % of the strains were not sensitive to cefazolin (І generation), (20,0±5,2) % were not sensitive to cefuroxime (ІІ generation), and (5,0±2,8) % of the strains of the analyzed group were not sensitive to ceftazidime (ІІІ generation), while no resistance was found to cefepime (ІV generation). Among the analyzed strains (10,0±3,9) % were found to be resistant to chloramphenicol and tetracyclin. Among the analyzed group of E. coli strains none were resistant to aminoglycoside antibiotics, as well as to fluoroquinolones and co-trimoxazole. Conclusion. Among the museum cultures of E. coli isolated in 1946-1959 yy., strains non-sensitive to ampicilline, ampicilline-sulbactam, cephalosporines of I, II, III generations, tetracycline and chloramphenicol were found. Perspectives of further studies. Antibiotic resistant museum strains of E. coli, isolated in 1946-1959 yy. will be used in our further studies in order to elucidate the mechanisms of antibiotic resistance development in bacteria.