Aim:

The members of Enterobactericeae family are always accepted as pathogenic when they are isolated from blood cultures. The carbapenems are preferred for the treatment of serious infections caused by ESBL producing multidrugresistant Enterobactericeae isolates. Carbapenems are used extensively for treatment of serious infections caused by ESBL producing bacteria, this situation leads to emerging of carbapenemase producing strains. The main purposes of this study were to investigate ESBL positivity and the presence of carbapenemase by phenotypic method and molecular method from Enterobactericeae (E.coli and K.pneumoniae) strains isolated from blood cultures.

Material and Method:

56 E. coli and 11 K.pneumoniae isolates isolated from the blood samples sent to the Namık Kemal University Health Practice and Research Center Microbiology Laboratory between 01.01.2013 and 30.04.2016 were taken to the study. ESBL positivity were determined by Kirby-Bauer disc diffusion method based on suggestion of Clinical and Laboratory Standards (CLSI). The zone diameter of carbapenem; measured as <28 mm diameter of isolates then, carbapenem activity was determined by using of MASTDISCSID Carbapenemase Detection Set and temocillin disc as phenotypic methods and by using of PCR as the molecular method and the results of these methods were compared.

Results:

In this study, ESBL positivity for 30 of 56 E.coli and 6 of 11 K.pneumoniae isolates were detected. Metallo-beta-lactamase (MBL) was detected in three E. coli isolates with the MASTDISCS ID and the temocillin disc, and the presence of OXA-48 in the fourth. PCR did not detect MBL positivity but OXA gene was detected in four isolates and OXA type of two isolates could not be determined.

Conclusion:

As a result of this study, it was seen that the rate ESBL positivity were high for E.coli and K.pneumoniae isolates from the blood culture samples in our hospital (54%) during three years. The presence of carbapenemase were detected by PCR in three out of five ESBL positive isolates. In addition, if OXA-48 type is common as carbapenemase in your country, it is necessary to use a temocillin disc beside MAST DISCS ID.

Keywords: Blood culture, ESBL, carbapenemase, E. coli, K. pneumonia