plasmid profile, antibiotic resistance, and phenotypic virulent strains of s. flexneri

shigellosis is an acute gastroenteritis caused by shigella species. the purpose of this study was to determine plasmid profile, antibiotic resistance and phenotypic virulent by congo red between s. flexneri strains. the isolated bacteria were identified by standard bacterial and biochemical methods. plasmids were isolated by alkaline lysis method. antibiotic susceptibility test was performed according to”kirby-bauer” method. serological reactions were carried by slide agglutination tests with both polyclonal and monoclonal antiserum kits. virulent strains were isolated on a tsa plate contained congo red dye concentration. from 350 isolated shigella species, 142 (40.57%) were s. flexneri. eleven distinct plasmid profile patterns were identified. of s. flexneri isolates, 95% were resistant to tetracycline, 85.6% to sxt and 75.3% to ampicillin. all the isolates were sensitive to ciprofloxacin. our results showed that 39% were serotype ii. 45.56% of s. flexneri were congo red positive. antibiotic resistant determination in each case may prevent drug resistance increase. since congo red binding test is cheap and simple it can be used to determine virulence properties of s. flexneri.