A rapid antimicrobial susceptibility test for Bacillus anthracis.

Area of Science:

• Microbiology
• Molecular Biology
• Public Health

Background:

• Effective response to Bacillus anthracis requires rapid antimicrobial susceptibility testing.
• Conventional methods take 16-20 hours, delaying treatment and prophylaxis.
• Faster testing is crucial for timely medical countermeasures.

Purpose of the Study:

• To develop a rapid antimicrobial susceptibility testing method for Bacillus anthracis.
• To reduce the time required for susceptibility testing from hours to minutes.
• To enable quicker selection and distribution of appropriate medical countermeasures.

Main Methods:

• Combined modified broth microdilution (BMD) with real-time quantitative PCR (qPCR).
• Assessed growth inhibition of B. anthracis in varying ciprofloxacin (CIP) and doxycycline (DOX) concentrations.
• Utilized fluorescence threshold cycle (C(T)) differences (DeltaC(T)) to determine susceptibility.

Main Results:

• The combined BMD-qPCR method provided results in under 6 hours.
• DeltaC(T) values effectively differentiated susceptible and non-susceptible B. anthracis strains.
• Results correlated with conventional susceptibility testing methods across diverse strains.

Conclusions:

• The rapid BMD-qPCR method offers a significant time reduction for B. anthracis susceptibility testing.
• This accelerated testing facilitates faster clinical decisions and public health interventions.
• The method is effective for diverse B. anthracis strains, supporting its use in emergencies.