R factors derived from Shigella flexneri strains

Area of Science:

• Microbiology
• Bacteriology
• Genetics

Background:

• Antibiotic resistance in Shigella flexneri poses a significant public health challenge.
• Understanding the genetic basis of resistance, particularly R factors, is crucial for effective treatment strategies.

Purpose of the Study:

• To investigate the prevalence and characteristics of antibiotic resistance in Shigella flexneri strains from Hungary.
• To determine the role of R factors in mediating antibiotic resistance and their fertility inhibition properties.

Main Methods:

• Isolation and antibiotic susceptibility testing of Shigella flexneri strains from dysenteric patients.
• Detection and characterization of R factors using fertility inhibition experiments with F specific phages.
• Identification of common antibiotic resistance markers, including chloramphenicol and tetracycline.

Main Results:

• 30.8% of 2492 Shigella flexneri strains showed resistance to 1-5 antibiotics.
• R factors were responsible for resistance in 79.2% of resistant strains.
• The chloramphenicol-tetracycline resistance determinant was the most prevalent (46.4%), often associated with non-fertility inhibiting (fi-) R factors.

Conclusions:

• R factors are a major mechanism of antibiotic resistance in Shigella flexneri in Hungary.
• Non-fertility inhibiting (fi-) R factors, particularly those conferring chloramphenicol resistance, are common.
• These findings highlight the importance of monitoring R factor epidemiology in combating Shigella infections.