Ribosomal RNA gene restriction patterns provide increased sensitivity for typing Salmonella typhi strains

Area of Science:

• Microbiology
• Epidemiology
• Molecular Biology

Background:

• Epidemiologic associations of Salmonella typhi strains traditionally rely on phage typing.
• Phage typing may have limited discriminatory power, especially when common phage types are involved.

Purpose of the Study:

• To evaluate the utility of ribosomal RNA gene restriction patterns for differentiating Salmonella typhi strains.
• To compare the discriminatory power of ribosomal RNA gene restriction patterns with phage typing.

Main Methods:

• Analysis of chromosomal DNA from Salmonella typhi strains using restriction enzymes.
• Digestion of DNA with restriction enzymes, including PstI, followed by pattern analysis.
• Comparison of ribosomal RNA gene restriction patterns with existing phage types.

Main Results:

• Ribosomal RNA gene restriction patterns successfully separated most independently isolated strains of identical phage types.
• The PstI enzyme demonstrated high sensitivity, differentiating 16 of 20 strains across 8 phage types.
• Identical ribosomal RNA gene restriction patterns were observed for some strains with different phage types, and vice versa.

Conclusions:

• Ribosomal RNA gene restriction pattern analysis is a valuable method for Salmonella typhi strain differentiation.
• This molecular technique complements traditional phage typing, improving epidemiologic investigations.
• The stability of ribosomal RNA gene restriction patterns supports its use in tracking bacterial outbreaks.