Salmonella typhi R-plasmids in Hungary

Area of Science:

• Microbiology
• Bacteriology
• Genetics

Background:

• Salmonella typhi is a significant human pathogen responsible for typhoid fever.
• Antibiotic resistance in bacteria poses a growing global health threat.
• R-plasmids are known to confer antibiotic resistance and can be transferred between bacterial species.

Purpose of the Study:

• To investigate the antibiotic sensitivity of Salmonella typhi strains isolated in Hungary.
• To identify the genetic basis of antibiotic resistance in these strains.
• To characterize the R-plasmids responsible for resistance and their properties.

Main Methods:

• Testing antibiotic sensitivity of 4095 Salmonella typhi strains.
• Isolation and characterization of R-plasmids from resistant strains.
• Phage typing to assess the impact of R-plasmids on bacterial characteristics.
• Determining the incompatibility groups of the identified R-plasmids.

Main Results:

• Twelve strains from one patient and seven from chronic carriers exhibited antibiotic resistance due to R-plasmids.
• One S. typhi strain with two R-plasmids showed a phage type change attributed to one plasmid.
• A similar R-plasmid was found in an Escherichia coli strain from a carrier.
• Four R-plasmids restricted E. coli and Shigella flexneri phages; one restricted S. typhi phages.
• R-plasmids belonged to incompatibility groups I1, I2, W, and H.

Conclusions:

• R-plasmids are a significant factor in antibiotic resistance of Salmonella typhi in Hungary.
• The presence of R-plasmids can alter bacterial phage types, complicating epidemiological tracking.
• R-plasmid transfer between different bacterial species, like S. typhi and E. coli, is possible.
• Characterization of R-plasmids provides insights into their spread and mechanisms of resistance.