Journal of Infection and Molecular Biology

Research Article
J. Inf. Mol. Biol. 3 (3): 66 - 74
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John Njeru1, 4*, Suleiman Saidi 2, Joseph Ngeranwa3, George Orinda3

1Centre for Microbiology Research, Kenya Medical Research Institute, P. O. Box 19464-000202 Nairobi, Kenya; 2Department of Medical Sciences, Technical University of Mombasa, P. O. Box 90420-80100, Mombasa, Kenya; 3Department of Biochemistry and Biotechnology, Kenyatta University P. O. Box 43844-00100, Nairobi, Kenya; 4Friedrich Loeffler Institute (FLI) – Institute for Bacterial Infections and Zoonosis, D-07743, Jena-Germany.

*Correspondence | John Njeru, Friedrich Loeffler Institute – Institute for Bacterial Infections and Zoonosis, Jena, Germany; Email:

Shigellosis caused by multidrug-resistant (MDR) Shigella strains is an important cause of morbidity and mortality in developing countries. Shigella strains usually harbour heterogeneous population of plasmids which can confer resistance to different antibiotics. A hospital based survey was conducted to determine the pattern of antimicrobial resistance and plasmid profiles in Shigella species from diarrheal patients in Kwale county. Twenty nine (8.1%) Shigella spp were obtained from 360 stool samples collected and each strain screened for antimicrobial resistance to common antimicrobial agents and presence of plasmids. High antibiotic resistance was found to Sulfamethoxazole-trimethoprim (79%), Ampicillin (75.9%) and Streptomycin (75.9%). All isolates were sensitive to ciprofloxacin, cephalosporins and Aztreonam antibiotics. Ninety seven percent of the isolates screened contained one or more plasmids ranging from 1-6. Majority were small plasmids. Species specific plasmids of 3.2kb, 9.0kb, and 3.8kb were found in Shigella flexneri, Shigella dysenteriae and Shigella sonnei respectively, while 34.5% and 79.3% MDR strains harbored large (>100kb) and middle range self-transmissible plasmids (10-100kb). In all species, no association was found between specific plasmid profile and antibiotic resistance patterns. Significant association was found between carriage of 80kb plasmid in S. dysenteriae (P<0.001), combined 48kb and 80kb plasmids in S. flexneri (P=0.002) and S. sonnei (P=0.041) and MDR phenotype. The middle range plasmids specified resistance to Sulfamethoxazole-trimethoprim, Ampicillin, Streptomycin and Tetracycline. This study reports the usefulness of plasmid profiling in detection and discrimination of Shigella strains in Kenya. The study also shows that middle range self-transferable R-plasmids are widespread among the circulating MDR Shigella strains indicating the important role of these genetic elements in the development and dissemination of multidrug resistance.

Keywords | Shigella, Antibiotic-resistance, Diarrhea, Kwale, Plasmids

Editor | Tahir Yaqub, University of Veterinary and Animal Sciences, Lahore, Pakistan.

Received | July 22, 2015; Revised | August 27, 2015; Accepted | September 09, 2015; Published | October 21, 2015

Citation | Njeru J, Saidi S, Ngeranwa J, Orinda G (2015). Plasmid profile analysis and antibiotic resistance patterns of Shigella isolates from Kwale County, Kenya. J. Inf. Mol. Biol. 3(3): 66-74.

ISSN (Online) | 2307-5465; ISSN (Print) | 2307-5716

Copyright © 2015 Njeru et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.