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Abstract Background and Objective: One of the main causes of increased mortality in cancer patients is bacteremia. On the other hand, antibiotic resistance is the major cause of treatment failure in malignant diseases especially in hematological malignancies. The aim of this study was to diagnose the bacterial strains isolated from blood specimens of cancer patients and to determine their antibiotic susceptibility. Material and Methods: In this cross-sectional study, 0.5 ml of venous blood was taken from 613 cancer patients especially leukemia, and blood cultures and antibiotic susceptibility tests were performed using standard methods. Using disc diffusion method, antibiotic susceptibility was performed with a wide range of antibiotics. Results: Out of 613 cultured specimens, 153 (25%) were found to be positive including 76.47% of gram negative and 23.53% of gram positive bacteria. The most common isolated bacteria were E. coli, coagulase-negative Staphylococci, Klebsiella, Staphylococcus aureus and Pseudomonas aeroginosa, respectively. Conclusion: It seems that Ceftriaxone is the best choice for the treatment of gram negative caused bacteremia and Gentamicin for bacteremia caused by gram positive agents. Given the high level of resistance to the commonly used antibiotics, it seems reasonable to avoid of early and inappropriate use of antibiotics to prevent the development of drug resistant bacteria. Keywords: Cancer, Blood Cultures, Bacteremia, Antibiotic Resistance

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ABSTRACT 
Background and objectives: Lactic acid bacteria (LAB) are potential candidates for the mucosal vaccine. Staphylococcal enterotoxin B (SEB), as a potent superantigen exotoxin is associated with widespread dietary poisoning and induction of toxic shock syndrome. Also, cholera toxin is the most important virulence factor in Vibrio cholera pathogenicity. CTB, a well-known immune adjuvant, enhances immunity and is mainly used to produce recombinant vaccines as antigen immunization enhancers. This study aimed to produce recombinant Lactobacillus Plantarum as a candidate vaccine against Vibrio cholera producing Cholera toxin and Staphylococcus aureus producing enterotoxin SEB. Methods:  A gene sequence encoding  SEB, devoid of superantigenic activity, and CTB were successfully designed, synthesized, cloned, and then expressed in a secreted form in the Lactobacillus Plantarum. The recombinant protein containing His-Tag was purified by Ni-NTA Agarose ion-exchange chromatography column.  The purified protein was confirmed by Western blotting. Results: The result of this study demonstrated the expression of this recombinant protein in the Lactobacillus Plantarum system by pnz7021 expression vector. The protein electrophoresis showed that the molecular weight of recombinant fusion protein was 52 kDa. Western blot analysis also confirmed the production of recombinant protein. The use of recombinant vaccines has received a great deal of attention today. LP-pnz7021–SP-rseb-ctxB can be used as a suitable candidate in recombinant vaccines against Vibrio cholera producing Cholera toxin and Staphylococcus aureus producing enterotoxin SEB.