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Background and Aim: In recent years, the production of extended-spectrum beta-lactamases (ESBLs) among clinical isolates of bacteria in particular E.coli has been on the rise. Production of beta-Lactamase in E.coli has caused many problems in the treatment of the patients. The CTX-M-2 gene is one of the several factors producing resistance due to ESBL. The aim of this study was to evaluate the antimicrobial susceptibility to beta-lactam antibiotics and investigation of the CTX-M-2 gene level in E. coli isolated from urine samples.

Material and Methods: In this study, 260 UTI samples were collected from medical centers in Sanandaj and 100 E.coli isolates were collected and confirmed by biochemical tests. Then susceptibility test to 11 selected antibiotics were performed by disk diffusion method and the ESBLs producing strains were identified by the combined disk method. Using PCR method, ESBLs positive strains were examined for the presence of CTX-M-2 gene.

Results: The results of the phenotype tests showed that out of 100 E.coli strains, 27 (27%) were ESBLs producing. Also, PCR showed that among these 27 strains, 2 (7.4%) strains contained CTX-M-2 gene.

Conclusion: Considering the high rate of resistance to the third generation cephalosporins, careful antibiogram tests is an inevitable necessity before prescribing antibiotics for the treatment of infections caused by ESBLs producing organisms.

Keywords: E.coli, ESBLs, CTX-M-2.

 

Received: Aug 16, 2015      Accepted: Nov 8, 2015

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Background and Aim:  Enterohemorrhagic Escherichia coli (EHEC) cause a wide spectrum of infections, such as diarrhea, hemorrhagic colitis and hemolytic–uremic syndrome. Considering the risks associated with antibiotic therapy against EHEC infection, vaccines can be a promising method for prevention of infections. Recombinant chimeric proteins containing multiple immunogens could induce immunity against bacterial infections. The aim of this study was to evaluate immunogenecity of trivalent chimeric antigen EspA -Stx2b -Intimin against E.coli O157 H7 infection.
Material and Methods: In this descriptive-laboratory study,recombinant chimeric protein was expressed in E.coli BL21 DE3 by use of IPTG. The protein expression was evaluated by SDS-PAGE and western blotting analysis. The recombinant protein was purified using Ni–NTA affinity chromatography. The immunization was conducted in mice with purified protein and antibody titers were determined by ELISA. Following immunization, mice were infected with E.coli O157:H7 and evaluated for bacterial shedding and mortality. Using SPSS software, statistical analysis was performed by Duncan's test and T-test.
Results: The protein was expressed in E.coli BL21 (DE3) and SDS-PAGE analysis showed expression of recombinant protein with molecular weight of 63kD. Western blot analysis confirmed presence of chimeric protein. ELISA results showed that immunogenic properties of chimeric protein induced humoral response to EspA, intimin and Stx2b. Bacterial shedding in immunized mice decreased to 10² cfu/ml and mortality rate was reduced to 60%.
Conclusion: The results showed that the chimeric protein induced humoral response and protected the mice against E.coli O157:H7.
Keywords: Enterohemorrhagic Escherichia coli; Intimin; Shiga toxin; E.coli secreted protein A, Chimeric protein, Immunogenicity.
 
Received: Sep 5, 2017     Accepted: Oct 10, 2017