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Plasmid-mediated drug resistance of shigellae in Kuwait
Abstract:
Of 153 clinical isolates of shigellae examined, 64.7% belonged to Shigella flexneri, 18.9% to Sh. sonnei, 11.8% to Sh. boydii and 4.6% to Sh. dysenteriae. Part of these isolates were resistant to sulfamethoxazole and streptomycin (88.2% each), ampicillin (66.7%), tetracycline (63.4%) and co-trimoxazole (43.1%), with levels of resistance (MIC50 and MIC90) being invariably high. Resistance to three or more drugs (multidrug resistance) was seen in 77.8% of the isolates. All the 25 strains examined for transfer of resistance contained R-plasmids, both autotransferable and non-autotransferable (mobilized by transfer factor X). The frequency of transfer of different r-determinants varied from 2.7 X 10(-8) to 1.4 X 10(-3).
Insights
Most Shigella isolates are resistant to common antibiotics, with high rates of multidrug resistance. Resistance often spreads via R-plasmids, highlighting a significant public health concern for Shigella infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Shigellosis remains a significant global health problem, primarily caused by Shigella species.
- Antimicrobial resistance in bacterial pathogens is a growing concern, complicating treatment strategies.
Purpose of the Study:
- To characterize the antimicrobial resistance patterns of clinical Shigella isolates.
- To investigate the prevalence and transferability of resistance genes in Shigella.
Main Methods:
- Antimicrobial susceptibility testing was performed on 153 clinical Shigella isolates.
- Disk diffusion and agar dilution methods were used to determine minimum inhibitory concentrations (MICs).
- Plasmid analysis and conjugation experiments were conducted to assess R-plasmid presence and transfer.
Main Results:
- Shigella flexneri was the predominant species (64.7%), followed by Sh. sonnei (18.9%).
- High resistance rates were observed for sulfamethoxazole and streptomycin (88.2% each), ampicillin (66.7%), and tetracycline (63.4%).
- Multidrug resistance (resistance to ≥3 drugs) was prevalent in 77.8% of isolates, and R-plasmids were detected in all tested strains.
Conclusions:
- Clinical Shigella isolates exhibit extensive multidrug resistance, posing a therapeutic challenge.
- The presence and transferability of R-plasmids contribute to the dissemination of antimicrobial resistance among Shigella species.
- Effective infection control and surveillance strategies are crucial to mitigate the spread of resistant Shigella strains.