Salmonella serotype typhimurium phage typing. A critical evaluation

Area of Science:

• Microbiology
• Epidemiology
• Bacteriology

Background:

• Salmonella serotype typhimurium is a significant pathogen in both human and animal health.
• Phage typing has been a traditional method for differentiating Salmonella strains.
• A rise in 'nontypable' strains complicates epidemiological surveillance.

Purpose of the Study:

• To analyze the phage typing patterns of Salmonella serotype typhimurium strains over a defined period.
• To identify prevalent phage types and assess trends in typability.
• To highlight the need for alternative typing methods for nontypable strains.

Main Methods:

• Analysis of 12,930 Salmonella serotype typhimurium strains phage typed between 1985-1988.
• Evaluation of strain typability using Anderson's phage set.
• Identification of common phage patterns and their association with human and non-human origins.

Main Results:

• Over 45% of strains were nontypable by Anderson's set, with typability decreasing significantly from 1986 to 1988.
• Phage types 1, 18, and 104 were most frequent across human and non-human sources.
• Phage types 1 and 36 were prevalent in foodborne outbreaks.
• Most phage types were found in both humans and animals, with exceptions for lysotypes 198 and 95.

Conclusions:

• The increasing proportion of nontypable Salmonella serotype typhimurium strains poses a challenge for traditional phage typing.
• Alternative and advanced typing methodologies are crucial for accurate epidemiological tracking and public health surveillance.
• Understanding the distribution of phage types is essential for controlling Salmonella outbreaks.