The study of sub-MIC ciprofloxacin effects on Shigella dysenteriae

Shigella dysenteriae causes one of the most acute kinds of diarrhea which could be established as chronic infection with alternative periods of recurrence. Administration of normal doses of antibiotics will suppress microbial infections however it is possible to control these infections by consumption of sub-MIC doses of certain antibiotics. In this basic study, a strain of Shigella dysenteriae (PTCC:1188) was used. After determination of MIC by microdilution method in Muller-Hinton Broth and MBC in Muller-Hinton Agar, the different dilutions (½,¼,⅛) of MIC were prepared in order to study the sub-MIC effects of ciprofloxacin on some traits of Shigella dysenteriae. The results showed that different sub-MIC dilutions of ciprofloxacin could cause morphological changes in Shigella. The Shigella cells became filamentous in ½ MIC whereas this configuration was weaker in ¼ MIC and ⅛ MIC. Meanwhile, the appearance of colonies was changed significantly due to the higher concentrations of sub-MIC. Some of the biochemical traits were affected by sub-inhibitory concentrations of ciprofloxacin. Ciprofloxacin is a drug of choice for shigellosis. According to the results of this study, treatment of Shigella infections would be possible by lower doses of ciprofloxacin.