Development and validation of a core-genome multilocus sequence typing scheme for Legionella longbeachae

Area of Science:

• Microbiology and Infectious Diseases
• Genomic Epidemiology
• Public Health Surveillance

Background:

• Legionella longbeachae is a significant cause of Legionnaires' disease (LD), particularly in regions like Australia and New Zealand.
• Genomic surveillance tools for L. longbeachae lag behind those available for L. pneumophila, hindering outbreak investigations.
• Accurate tracking of L. longbeachae is crucial for understanding its global health impact and controlling disease transmission.

Purpose of the Study:

• To develop and validate a core-genome multilocus sequence typing (cgMLST) scheme for Legionella longbeachae.
• To enhance genomic surveillance capabilities for L. longbeachae outbreaks and source identification.
• To provide a robust tool for public health laboratories investigating L. longbeachae infections.

Main Methods:

• Development of a cgMLST schema using 7 complete and 89 draft L. longbeachae genomes.
• Schema design based on 2,608 loci at a 95% presence threshold.
• Validation of the cgMLST scheme with 192 diverse L. longbeachae isolates.

Main Results:

• A well-defined cgMLST schema for L. longbeachae was established, with isolates showing >=98% gene target presence.
• cgMLST demonstrated high concordance with core-genome SNP typing but offered higher resolution.
• The scheme effectively captured the diversity of sequenced L. longbeachae isolates.

Conclusions:

• The developed cgMLST scheme provides a powerful tool for whole genome sequencing-based surveillance of L. longbeachae.
• This advancement will improve the ability to track outbreaks and understand the global epidemiology of L. longbeachae.
• Enhanced genomic surveillance will contribute to better control strategies for Legionnaires' disease caused by L. longbeachae.