title: [Substrate specificity of extended spectrum beta-lactamases CTX-M isolated from intensive care pacients in Faculty Hospital in Ostrava and in Regional Hospital T. Baťa in Zlín].
abstract: OBJECTIVE
  Evaluation of kinetic parameters isolated extended spectrum beta-lactamases and evaluation of their substrate specifities.
  
  
  METHODS
  Fourty strains of Escherichia coli with evidence of producing extended spectrum beta-lactamases (ESBLs) and their designated type by polymerase chain reaction and sequencing was used in the study. Strains were stored in bacteriological collection at the Department of Microbiology Teaching Hospital and Palacký University and originated from clinical specimens of ICU, Faculty Hospital Ostrava and Regional Hospital of T. Baťa patients. Strains were collected from hospitalized patients in one year (1. 1. 2009 - 31. 12. 2009). The isolated enzymes were used for spectrofotometric measurement of specific activities by hydrolysis of antibiotics. Beta-lactamases of the six selected strains were purified and used for the measurement of other kinetic parameters.
  
  
  RESULTS
  Measurement of specific activities in lysates with partially purified enzyme (beta-lactamases CTX-M-15 or CTX-M-27) showed that the best hydrolyzed antibiotic was cefazolin. Extended spectrum beta-lactamase-type CTX-M-15 had the highest affinity for cefoperazon, the highest catalytic efficiency and high hydrolytic efficiency against cefazolin. The values of kinetic parameters of purified type ESBLs CTX-M-27 was slightly different between strains and showed a high efficiency against cefoperazone and cefuroxime, high hydrolytic activity against cefazolin and strong catalytic effeciency against cefazolin and cefotaxime.
  
  
  CONCLUSIONS
  Comparison of the measured data enabled to evaluate cefazolin as the best substrate for used ESBLs. The studied enzymes showed very strong hydrolytic activity and catalytic efficiency against cefazolin.
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D004926:Escherichia coli / Q000201:enzymology*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases