Comparison of two Salmonella enteritidis phage typing methods

Area of Science:

• Microbiology
• Epidemiology
• Bacteriology

Background:

• Phage typing is crucial for tracking Salmonella enteritidis outbreaks.
• Discrepancies in phage typing methods have led to confusion in identifying predominant phage types (PTs) globally.
• Standardization of phage typing is essential for accurate epidemiological surveillance.

Purpose of the Study:

• To compare the efficacy of two distinct phage typing methods for Salmonella enteritidis.
• To analyze the phage type distribution of Hungarian Salmonella enteritidis isolates using comparative methods.
• To address the confusion arising from different phage typing systems in international reports.

Main Methods:

• Comparative analysis of 1487 Salmonella enteritidis strains isolated in Hungary (1990-1991).
• Utilized two phage typing sets: a modified Hungarian method (László et al.) and the Colindale method (Ward et al.).
• Assessed typability rates and identified frequent phage types for each method.

Main Results:

• Both methods demonstrated high typability rates (98.0% and 98.3%).
• The Hungarian method identified 18 PTs, while the Colindale method identified 19 PTs.
• The Hungarian method resolved the predominant Colindale PT 1 into subtypes (1, 1c, 1b, 1d), offering finer discrimination. PT 18 and PT 7 correlated with Colindale PTs 26 and 21, respectively.

Conclusions:

• The modified Hungarian phage typing method offers a more detailed classification of Salmonella enteritidis strains compared to the Colindale method.
• Implementing standardized and refined phage typing protocols is vital for accurate Salmonella enteritidis surveillance and control.
• Comparative studies are necessary to reconcile discrepancies between different phage typing systems.