Diversity of Salmonella isolates using serotyping and multilocus sequence typing.

Area of Science:

• Microbiology
• Food Safety
• Genetics

Background:

• Salmonella contamination in food, feed, and live chickens poses a significant public health risk.
• Global surveillance of Salmonella subtypes is crucial for effective control strategies.

Purpose of the Study:

• To characterize Salmonella subtypes from diverse sources across 13 countries.
• To compare the discriminatory power of serotyping and multilocus sequence typing (MLST).
• To identify novel Salmonella serotypes and sequence types (STs).

Main Methods:

• Serotyping of 121 Salmonella isolates.
• Multilocus Sequence Typing (MLST) for genetic profiling.
• Analysis of nucleotide diversity and discriminatory power using Simpson's index.

Main Results:

• 36 Salmonella serovars were identified, including three novel serotypes (S. Babelsberg, S. Fresno, S. II) in mainland China.
• Serotyping achieved a discriminatory power of 0.943.
• MLST identified 42 unique STs with a discriminatory power of 0.947, closely matching serotyping.
• The hisD gene exhibited the highest nucleotide diversity within MLST.
• ST-92 and ST-367 were the most prevalent STs.
• Seven new alleles led to the identification of nine new STs.

Conclusions:

• MLST and serotyping are comparable methods for Salmonella subtyping.
• MLST generally correlates with serotype but not with epidemiological source or antimicrobial resistance patterns.
• The study identified novel Salmonella serotypes and STs, contributing to global Salmonella surveillance data.