A novel technique for detecting antibiotic-resistant typhoid from rapid diagnostic tests

Area of Science:

• Microbiology
• Infectious Diseases
• Molecular Diagnostics

Background:

• Increasing prevalence of fluoroquinolone-resistant typhoid fever globally.
• Limitations of traditional typhoid diagnostics in low-resource settings.
• Need for rapid and accurate methods to detect antimicrobial resistance.

Purpose of the Study:

• To evaluate an antigen-detecting rapid diagnostic test (RDT) for typhoid diagnosis.
• To assess a molecular technique for identifying fluoroquinolone resistance mutations from RDT-positive samples.
• To determine the feasibility of field diagnosis combined with molecular resistance testing.

Main Methods:

• Utilized an antigen-detecting rapid diagnostic test (RDT) for initial typhoid diagnosis from blood cultures.
• Applied a simple, inexpensive molecular method to extract DNA from positive RDTs.
• Sequenced the gyrA gene to identify mutations associated with fluoroquinolone resistance.
• Correlated molecular findings with phenotypic susceptibility testing results.

Main Results:

• The RDT rapidly diagnosed typhoid from blood cultures.
• The molecular technique accurately identified gyrA mutations.
• Molecular resistance detection results were consistent with phenotypic susceptibility testing.
• The combined approach demonstrated potential for field application.

Conclusions:

• Antigen-detecting RDTs offer rapid typhoid diagnosis.
• Molecular testing on RDT samples provides accurate resistance data.
• Field diagnosis coupled with centralized molecular testing can enhance typhoid management and surveillance in resource-limited settings.