In-vitro Resistance Development by Ciprofloxacin and Azithromycin in Shigella dysenteriae

Introduction: Drug resistance is a growing public health issue among the health care professionals. Due to improper use many bacterial species including the Shigella dysenteriae become resistant to the standard therapy.

Objectives: In the present study, we have shown the bacterial resistance development in the Shigella dysenteriae species against Ciprofloxacin and Azithromycin and therefore decrease in their antibiotic susceptibility together with DNA and morphological alteration by the presence of sub inhibitory concentration of antibiotics.

Methods: Disc diffusion method was applied to examine resistance of Shigella dysenteriae against ciprofloxacin and azithromycin and genomic anomalies were observed in ciprofloxacin resistant and sensitive strains by agarose gel electrophoresis.

Results: Sub culturing in the ciprofloxacin reduced the ZOI from 22 to 15 mm at their MIC on 13th passages but still the sensitivity was preserved in azithromycin (20 µg/dics) ZOI of 21 mm. In case of Azithromycin, zone reduced from 24 to 18 mm at their MIC after 13 subcultures, but it raised high to 25 mm for both ciprofloxacin (20 µg/dics). As documented of genomic changes in ciprofloxacin resistant strain (Azithromycin not included) by agarose gel electrophoresis, six different DNA bands found whereas one DNA band found in ciprofloxacin sensitive strain.

Conclusion: So it is clear that the misuse of existing antimicrobials may enable the microorganism to develop their less susceptible strain, by changing the restriction fragment length point which was appeared in the agarose gel, to that antimicrobial agent.