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Influence of technical factor variations during inoculum preparation on the agar dilution plate-count method for
Abstract:
The possible introduction of error into Staphylococcus aureus oxacillin intrinsic persister measurements by the agar dilution plate-count method resulting from technical factor variations associated with inoculum preparation was investigated. pH stability and exponential growth were shown to be present at the time of inoculum standardization. The use of glass or plastic tubes and the contamination of tube walls during inoculum broth culture produced no differences in test results. For S. aureus and oxacillin, the agar dilution plate-count method is a new and reliable approach to the quantitative study of bacterial inhibition and killing.
Insights
The agar dilution plate-count method reliably measures Staphylococcus aureus oxacillin persister cells. Technical variations in inoculum preparation do not introduce significant errors, ensuring accurate bacterial inhibition and killing studies.
Area of Science:
- Microbiology
- Bacterial Physiology
- Antimicrobial Resistance
Background:
- Persister cells are a subpopulation of bacteria that survive antibiotic treatment.
- Oxacillin is a key antibiotic used against Staphylococcus aureus infections.
- Accurate measurement of persister cells is crucial for understanding treatment failure.
Purpose of the Study:
- To investigate potential errors in measuring Staphylococcus aureus oxacillin persister cells using the agar dilution plate-count method.
- To assess the impact of technical variations in inoculum preparation on measurement accuracy.
Main Methods:
- Standardization of inoculum preparation for Staphylococcus aureus.
- Evaluation of pH stability and exponential growth phase during standardization.
- Comparison of results using glass versus plastic tubes.
- Assessment of contamination effects on tube walls during broth culture.
Main Results:
- pH stability and exponential growth confirmed at inoculum standardization.
- No significant differences in test results were observed based on tube material (glass vs. plastic).
- Tube wall contamination did not impact the accuracy of persister cell measurements.
Conclusions:
- The agar dilution plate-count method is a reliable technique for quantifying Staphylococcus aureus oxacillin persister cells.
- Technical factors in inoculum preparation, such as tube type and minor contamination, do not introduce significant errors.
- This method offers a new and dependable approach for studying bacterial inhibition and killing by oxacillin.