Interexaminer variability in common ratings in reading Streptococcus mutans dip-slides with or without a microscope

Area of Science:

• Microbiology
• Diagnostic methods

Background:

• Accurate detection of Streptococcus mutans (S. mutans) is vital for dental caries prevention.
• Dip-slide methods offer a convenient way to assess S. mutans levels.
• Observer variability can impact the reliability of dip-slide readings.

Purpose of the Study:

• To evaluate observer variability in reading S. mutans dip-slides.
• To compare the accuracy of different reader groups (bacteriologist, dentists, laymen).
• To determine the necessity of stereomicroscopic counting for practical application.

Main Methods:

• 145 S. mutans dip-slides were read by a panel including a bacteriologist, dentists, and laymen.
• Slides were classified into four categories by comparing with standard photographs.
• Stereomicroscopic counts served as the reference standard.

Main Results:

• Visual readings showed both under- and overestimation compared to microscopic counts.
• Scoring trends increased logically with higher microscopic reference scores.
• Individual agreement percentages ranged from 54% (laymen) to 79% (bacteriologist).
• Reclassifying into three categories significantly increased agreement.
• Stereomicroscope use did not significantly improve reading agreement.

Conclusions:

• Visual S. mutans dip-slide reading exhibits observer variability, influenced by reader experience.
• High agreement is achievable with experience and appropriate classification methods.
• Stereomicroscopic counting is not essential for practical S. mutans dip-slide assessment.
• Methodological understanding and experience are critical for reliable dip-slide interpretation.