Transfer of drug resistance factor in Shigella sonnei isolated in Iran

Area of Science:

• Microbiology
• Infectious Diseases
• Genetics

Background:

• Shigella sonnei is a significant cause of bacterial dysentery worldwide.
• Understanding drug resistance patterns is crucial for effective treatment and control of Shigella infections.
• The prevalence and mechanisms of antimicrobial resistance in Iranian Shigella sonnei strains require investigation.

Purpose of the Study:

• To investigate the drug resistance patterns and R-factor incidence in Shigella sonnei strains from Iran.
• To determine the rate of R-factor transfer from resistant Shigella sonnei to sensitive E. coli.
• To assess the association between colicinogenic properties and drug resistance in these strains.

Main Methods:

• Isolation and antimicrobial susceptibility testing of Shigella sonnei strains.
• Mixed cultivation experiments to assess R-factor transfer to E. coli K12 F- (gamma).
• Colicin production assays on resistant and sensitive strains.

Main Results:

• 51.7% of 172 Shigella sonnei strains exhibited resistance to one or more drugs.
• Multiple drug resistance was more prevalent than single drug resistance, with Tc, Cm, Sm, Su being the predominant pattern.
• R-factor transfer was observed in 85.7% of strains from the Central Plateau and 100% from the Caspian littoral.
• Colicinogenic properties were found in 67.1% of resistant strains and 17% of sensitive strains.

Conclusions:

• Shigella sonnei strains in Iran demonstrate significant antimicrobial resistance, with a high potential for R-factor dissemination.
• The transfer of resistance determinants highlights the risk of spreading multidrug resistance.
• Colicin production may be linked to drug resistance in certain Shigella sonnei populations.