Antibiotic Susceptibility and Plasmid Profiles of Shigella species in Sudan

This study was carried out to determine the antibiotic susceptibility, plasmid profile and conjugative abilities of Shigella species isolated from different towns in Sudan during 2005-2007. Methods: Stool specimens were collected in Carry Blair transport medium from patients presenting with diarrhea from different sites in Sudan between the years 2005-2007. All specimens were inoculated on Mac Conkey's agar and Xylose Lysine Dioxycholate (XLD) (Mast group Ltd. Merseyside UK). Bacteria was isolated and subjected to different antibiotics to detect sensitivity and transference of resistance. Results: One hundred and fourteen Shigella isolates were included in the study. Eighty (70.1%) were Shigella flexeneri representing the dominant isolate, followed by 20 (17.5%) isolates of Shigella dysenteriae, 9 (7.9%) Shigella sonnei and 5 (4.5%) Shigella boydii. Most of the isolates showed resistance to streptomycin (70%), tetracycline (52%) and co-trimoxazole (43%). They were highly sensitive to norfloxacin (97%), nalidixic acid (95%), gentamicin (89%) and chloramphenicol (77%). Multi-drug resistance to two or more antibiotics was apparent in most of the isolates (64, 56.1%). Fifty nine of the resistant Shigella isolates were studied for their ability to transfer resistance to the donor E. coli K-12 by conjugation. Of these, six were able to transfer resistance to streptomycin, tetracycline and co-trimoxazole. Extraction of the plasmid DNA from both donors and trans-conjugants showed a single type of plasmid with a molecular weight of 4.6 Kb. Conclusion The transfer of multi-drug resistant plasmids and the emergence of antibiotic Shigella and other bacterial species should raise the awareness and the seriousness of the uncontrolled (unsupervised) use of antibiotics in the medical practice.