Developing customized stepwise MIRU-VNTR typing for tuberculosis surveillance in Georgia

Area of Science:

• Microbiology
• Epidemiology
• Genetics

Background:

• Mycobacterial Interspersed Repetitive Units-Variable Tandem Repeats (MIRU-VNTR) typing is crucial for tuberculosis (TB) molecular epidemiology.
• Existing genotyping tools for Mycobacterium tuberculosis (Mtb) can be costly and labor-intensive in certain regions.

Purpose of the Study:

• To develop and validate a customized, stepwise MIRU-VNTR typing method for Mtb in Georgia.
• To reduce the cost and processing time of TB molecular typing.

Main Methods:

• A Georgia-specific set of 10 high-discriminatory MIRU-VNTR loci was selected based on Hunter-Gaston Discriminatory Index (HGDI).
• A stepwise approach was applied, using additional loci groups hierarchically for further typing.
• The customized method's efficiency was compared to the standard 24-loci panel using TB cases from Georgia's penitentiary system.

Main Results:

• The customized 10-loci typing initially identified 35.7% clustered cases among 102 Mtb isolates.
• Further hierarchical typing reduced the clustering proportion to 19.5%.
• The stepwise MIRU-VNTR approach achieved a 42.6% reduction in both processing time and costs.

Conclusions:

• The customized stepwise MIRU-VNTR typing is a cost-effective and time-saving alternative for Mtb molecular epidemiology in Georgia.
• This optimized genotyping strategy can be adapted for similar epidemiological studies in other settings.