What killing percentage of the original inoculum defines the minimum bactericidal concentration (MBC)?

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Multiple Choice

What killing percentage of the original inoculum defines the minimum bactericidal concentration (MBC)?

Explanation:
Minimum bactericidal concentration is defined as the lowest concentration of an antimicrobial that kills 99.9% of the initial inoculum, which corresponds to a 3-log reduction in viable bacteria. This threshold is used because it reflects a substantial, durable kill rather than just inhibiting growth. To determine it, you assess killing by comparing to the starting CFU/mL and then subculture from tubes with no growth onto drug-free media; the smallest concentration that yields no growth on recovery is the MBC. Since complete elimination (100%) is rarely achievable due to resistant or dormant cells, 99.9% kill is the standard measure, making it the best choice.

Minimum bactericidal concentration is defined as the lowest concentration of an antimicrobial that kills 99.9% of the initial inoculum, which corresponds to a 3-log reduction in viable bacteria. This threshold is used because it reflects a substantial, durable kill rather than just inhibiting growth. To determine it, you assess killing by comparing to the starting CFU/mL and then subculture from tubes with no growth onto drug-free media; the smallest concentration that yields no growth on recovery is the MBC. Since complete elimination (100%) is rarely achievable due to resistant or dormant cells, 99.9% kill is the standard measure, making it the best choice.

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