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Relationship between multiple drug-resistance & enterotoxin production by Shigella species
Abstract:
Culture filtrates prepared with strains of Shigella dysenteriae 1 and those of Sh. flexneri and Sh. sonnei, collected from different geographical locations in India caused accumulation of fluid in rabbit gut loops, indicating their capability to produce Shiga and Shiga-like toxins respectively. Sh. boydii strains were noted for the first time to produce Shiga-like toxins. The failure of production of fluid accumulation in rabbit gut by Shigella strains that lacked the R-markers of the antibiotics tested and the gradual enhancement in the secretory response by strains containing R-markers in the increasing order indicate a possible correlation between acquisition of higher number of R-markers and enterotoxic activity. The non-transferable and non-curable nature of most of the drug resistance markers, coupled with the failure of the two transconjugants to elicit a secretory response and the capacity of the single cured variant to retain this property suggest the involvement of certain chromosomal locii in mediating drug resistance and enterotoxicity in Shigella.
Insights
Shigella bacteria produce toxins that cause fluid accumulation in the gut. Drug resistance markers in Shigella strains correlate with increased enterotoxic activity, suggesting a link to chromosomal genes.
Area of Science:
- Microbiology
- Bacteriology
- Molecular Biology
Background:
- Shigella species are significant enteric pathogens.
- Enterotoxigenicity is a key virulence factor in Shigella infections.
- Antibiotic resistance is a growing concern in bacterial pathogens.
Purpose of the Study:
- To investigate the enterotoxic potential of Shigella strains from India.
- To explore the correlation between antibiotic resistance markers and enterotoxicity.
- To elucidate the genetic basis of drug resistance and enterotoxicity in Shigella.
Main Methods:
- Preparation of culture filtrates from Shigella strains.
- In vivo fluid accumulation assay in rabbit gut loops.
- Assessment of antibiotic resistance markers (R-markers) and their transferability.
Main Results:
- Shigella dysenteriae 1, Sh. flexneri, and Sh. sonnei strains produced Shiga and Shiga-like toxins.
- Sh. boydii strains were identified as producers of Shiga-like toxins for the first time.
- A positive correlation was observed between the number of R-markers and enterotoxic activity.
- Non-transferable and non-curable R-markers were common, and chromosomal genes likely mediate both drug resistance and enterotoxicity.
Conclusions:
- Shigella strains from India possess significant enterotoxic potential.
- Acquisition of R-markers is linked to enhanced enterotoxicity in Shigella.
- Chromosomal loci play a crucial role in mediating both drug resistance and enterotoxicity in Shigella.