[Antimicrobial susceptibility and molecular mechanisms of resistance to beta-lactams of gram-negative microorganisms--causative agents of nosocomial infections].

Profiles and mechanisms of resistance to beta-lactam antibiotics of isolates of Gram-negative microorganisms, which are causative agents of infections in Intensive Care Unit of hospital surgery department, were studied. Two hundred and ten clinical isolates were studied: Pseudomonas aeruginosa--86 strains (40.9%), Acinetobacter baummanii--45 strains (21.4%), Klebsiella pneumoniae--52 strains (24.8%), Escherichia coli--23 strains (11%), Enterobacter spp.--4 strains (1.9%). Profiles of antibiotic resistance were studied by the method of serial microdilutions; detection of most widespread and clinically significant genes of beta-lactamases of Gram-negative bacteria was performed by polymerase chain reaction. Carbapenems and cefoperazone/sulbactam were the most active antibiotics. Local features of distribution of beta-lactamase coding genes (TEM, SHV, CTX) in K. pneumoniae and E. coli isolates were revealed. Eleven strains of P. aeruginosa resistant to carbapenems and possessing genetic determinants of VIM-group, which codes metallo-beta-lactamases, were isolated. Obtained data allows to assess the parameters of resistance to beta-lactam antibiotics and to reveal the main mechanisms of such resistance in etiologic agents of nosocomial infections, that, in its turn, allows to choose preparations for etiotropic therapy.