Features of resistance formation of gram-negative non-fermenting bacteria to antibiotics
The problem of the antibiotic resistance development of pathogenic microorganisms to the main groups of antibacterial drugs has evolved from medical to socio-economic. There is a resistance increase of P.aeruginosa, A.baumannii belonging to the group of gram-negative non-fermenting bacteria (GNB), to antibiotics that are used in medicine. The possibility of acquiring GNB resistance to the main groups of antibacterial drugs is related to the ability of bacteria to acquire new genetic information. The production of metal-beta-lactamase by GNB become a widespread problem of resistance to beta-lactam antibiotics. Detection of resistance genes to beta-lactam antibiotics blaVIM, blaOXA 23, blaOXA 40, blaOXA 69 and blaOXA 100 was performed using real time polymerase chain reaction (PCR-RT). Sensitivity of isolated strains of microorganisms to antibiotics was investigated using the standard disco-diffusion method (DDM). Influence of meropenem on formation of microorganism resistance was investigated in vitro by method of microorganisms passage on meat-peptone broth (MPB) with increasing concentrations of antibiotics.
In the process of research, 14 clinical strains of P. aeruginosa and 30 strains of A.baumannii were isolated and identified, almost all strains of these types of bacteria, characterized by resistance to antibiotics-carbapenems and third and fourth generation of cephalosporins. At the same time, the three strain-carries of markers of beta-lactamase products exhibited resistance to carbapenems, and one of the strains (P.aeruginosa No. 68) was capable of producing MBL, according to DDM, was sensitive to carbapenems and MCC was 31.2 μg / ml for it. Among the investigated strains of A.baumannii 18 (60%) out of 30 isolated ones were potential producers of beta-lactamases, capable of inactivating carbapenem antibiotics. In this case, only 6 out of 18 strains showed resistance to carbapenems according to DDM. Sensitivity to carbapenems revealed all strains of the beta-lactamase producers OXA 69 and OXA 100 and three strains – OXA 23. In this work, modern ideas about the mechanisms of development of resistance of GNB were described, isolated from patients of medical institutions (Vinnytsa city), the most common are producers of beta-lactamase types of OXA 23, OXA 69, OXA 100 and VIM.
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