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Genetic and molecular characterization of an epidemic plasmid coding for multidrug resistance in Salmonella
P L Sharma1, S Sharma, K Prakash
1National Salmonella Phage Typing Center, Lady Hardinge Medical College, New Delhi, India.
Abstract:
All 201 multidrug resistant Salmonella typhimurium strains isolated from epidemics in India contained nonconjugative (157 strains) or conjugative (44 strains) Inc F1me multiresistance plasmids. Two small R-plasmids of 7 MDa which coded for resistance to either ampicillin or streptomycin and sulfamethoxazole were also detected along with other plasmids. The small plasmids were members of group 1 and group 2 incompatibility groups. Restriction endonuclease analysis of conjugative (96 MDa) and nonconjugative (88 MDa) Inc F1me plasmids showed considerable similarity except for the presence of unique fragments among both the groups and the loss of fragments corresponding to the smaller size of the nonconjugative plasmid. A single Inc F1me plasmid appears responsible for various outbreaks of multiresistant S. typhimurium in different parts of India.
Insights
Multidrug-resistant Salmonella typhimurium strains in India carry Inc F1me plasmids, responsible for outbreaks. These plasmids confer resistance, with variations noted in conjugative and nonconjugative forms.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Multidrug resistance in Salmonella typhimurium poses a significant public health threat.
- Salmonella typhimurium outbreaks in India have been linked to antimicrobial resistance.
Purpose of the Study:
- To characterize the plasmids responsible for multidrug resistance in Salmonella typhimurium strains from Indian epidemics.
- To investigate the genetic relatedness and features of Inc F1me plasmids.
Main Methods:
- Plasmid isolation and characterization from 201 multidrug-resistant Salmonella typhimurium strains.
- Restriction endonuclease analysis of conjugative and nonconjugative Inc F1me plasmids.
- Detection of smaller R-plasmids and their incompatibility groups.
Main Results:
- All 201 strains harbored either nonconjugative (157) or conjugative (44) Inc F1me multiresistance plasmids.
- Two small R-plasmids (7 MDa) conferring resistance to ampicillin or streptomycin/sulfamethoxazole were identified.
- Restriction analysis revealed significant similarity between conjugative (96 MDa) and nonconjugative (88 MDa) Inc F1me plasmids, with distinct fragment patterns.
Conclusions:
- A single Inc F1me plasmid type is implicated in diverse outbreaks of multidrug-resistant Salmonella typhimurium across India.
- Understanding plasmid diversity and transfer mechanisms is crucial for controlling resistant bacterial infections.