Screening for penicillin tolerance in viridans streptococci by a simple disk method

Area of Science:

• Microbiology
• Bacteriology
• Antimicrobial Susceptibility Testing

Background:

• Viridans streptococci are common oral bacteria.
• Penicillin tolerance in bacteria can lead to treatment challenges.
• Accurate detection of penicillin tolerance is crucial for effective therapy.

Purpose of the Study:

• To develop a rapid and reliable method for detecting penicillin tolerance in viridans streptococci.
• To provide a screening test that differentiates tolerant strains from susceptible ones.

Main Methods:

• A modified disk diffusion method was employed.
• Standard penicillin susceptibility disks were replaced with disks containing penicillinase.
• Plates were reincubated to observe bacterial regrowth.

Main Results:

• Penicillin-tolerant viridans streptococci strains showed regrowth in the zone adjacent to the penicillinase disk.
• This regrowth pattern served as a clear indicator of tolerance.
• The method proved to be a rapid screening test for penicillin tolerance.

Conclusions:

• The developed disk method effectively demonstrates penicillin tolerance in viridans streptococci.
• This technique offers a practical approach for identifying tolerant strains in clinical settings.
• The method facilitates faster screening compared to traditional approaches.