Molecular diagnosis and anti-microbial resistance patterns among Shigella spp. isolated from patients with diarrhea

Aim: This study aims to determine the serogroup distribution and molecular diagnosis, as well as antimicrobial resistance profiles among Shigella spp. isolated from patients with diarrhea in Kerman, southeast of Iran

Background: Shigella species are frequent cause of bacterial dysentery worldwide. Previous studies have been reported that S. sonnei and S. flexneri are the most prevalent serogroups in various parts of Iran

Patients and Methods: A total of 624 stool samples were randomly collected from patients with diarrhea from June 2013 to August 2014. Biochemical and serological characterizations were performed for identifying Shigella spp. In addition, the multiplex PCR assay was carried out for the detection and differentiation of three pathogenic Shigella spp. Antibiotic susceptibility testing was performed according to the Clinical Laboratory Standards Institute [CLSI] guidelines

Results: Fifty six [9%] Shigella strains were isolated from stool samples. The most common species were S. flexneri 31[55.4%], followed by S. sonnei 18[32.1%] and S. boydii 7[12.5%]. S. dysentery was not detected in the present study. All the isolates that identified by serological test as Shigella spp. were confirmed by the multiplex PCR method. The highest rate of resistance was observed for ampicillin and trimethoprim-sulphamethoxazole antibiotics with 52[92.9%] resistant, followed by tetracycline 44[78.6%] and cefotaxime 33[58.9%]. All Shigella isolates were susceptible to ciprofloxacin. A significant relationship was found between the Shigella species and cefotaxime resistance [p<0.05]

Conclusion: S. flexneri was found as the most prevalent serogroup causing shigellosis. The high rate of resistance to third-generation cephalosporins limits the treatment options available for the management of shigellosis in Kerman, Iran

role of different supplements in expression level of monoclonal antibody against human CD20

Recombinant monoclonal antibodies have been marketed in last three decades as the major therapeutic proteins against different cancers. However choosing a proper medium and supplements to reach the high expression is a challenging step. Despite of commercial serum free and chemically defined media, there are still numerous researches seeking the optimum media to gain higher expression titer. Selecting the best basal media followed by proper supplementation to increase the cell density and expression titer needs proper and accurate investigation. In this study, we have determined the expression titer of monoclonal antibody against human CD20 using soy extract, Essential Amino Acid, Non-Essential Amino Acid, Panexin NTS, Peptone, Yeast extract, Insulin-transferrin selenite, Human Serum Albumin, Bovine Serum Albumin, Lipid, and two commercially available supplements, Power and Xtreme feed. In each experiment, the expression level was compared with a well defined media, ProCHO5, RPMI 1640 and DMEM-F12. It has been shown that supplementing the ProCHO5 basal medium with 10% power feed or combination of 5% PanexinNTS,1.5 g/L yeast and 1.5g/L peptone results in the best production levels with 450 and 425 mg/L of anti CD20 mAb expression level, respectively. Panexin NTS, yeast and peptone cane be proper supplement for fed-batch cell culture instead of commercial Power feed supplement which is a cost effective way to increase expression level. And thereby ProCHO5 may be replaced with common media such as RPMI 1640 and DMEM-F12