Inappropriate Use of D-Values for Determining Biocidal Activity of Various Antimicrobials

• Published in: Journal of food science Vol. 76; no. 1; pp. M8 - M11
• Main Authors: Hines, Jesse D., McKelvey, Pamela J., Bodnaruk, Peter W.
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.01.2011; Wiley; Wiley Subscription Services, Inc
• Subjects: Algorithms; Anti-Bacterial Agents - antagonists & inhibitors; Anti-Bacterial Agents - pharmacology; antimicrobial; Biocides; Biological and medical sciences; Caprylates - antagonists & inhibitors; Caprylates - pharmacology; Chlorides - antagonists & inhibitors; Chlorides - pharmacology; Colony Count, Microbial; D-value; Disinfectants - antagonists & inhibitors; Disinfectants - pharmacology; E coli; Escherichia coli - drug effects; Estimating techniques; Food industries; Food microbiology; Food science; Foods; Fundamental and applied biological sciences. Psychology; Kinetics; Listeria monocytogenes - drug effects; Microbial Sensitivity Tests; Microbial Viability - drug effects; Osmolar Concentration; Regression analysis; Salmonella; Salmonella enterica - drug effects; Sodium Hypochlorite - antagonists & inhibitors; Sodium Hypochlorite - pharmacology; Staphylococcus aureus - drug effects; Staphylococcus infections; Statistics as Topic; Studies; Stumbo method; Thiosulfates - chemistry; Triclosan - antagonists & inhibitors; Triclosan - pharmacology; antimicrobial; Use; D-value; Method; Stumbo method; Biocide; Antimicrobial agent
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2010.01923.x

:  The objective of this study was to investigate the application of established D‐value calculations to survival curves for various bacteria using the following antimicrobials: acidified sodium chlorite, triclosan, octanoic acid, and sodium hydroxide. D‐values can be calculated in 3 ways, a linear regression, an endpoint calculation, or an average of multiple endpoint calculations. The assumption made in calculating a D‐value is that the rate of kill follows 1st‐order kinetics under specified treatment conditions. Each antimicrobial solution was challenged with approximately 108 CFU/mL of Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica subsp. enterica, and Escherichia coli independently and in triplicate. Test systems were sampled at each of the 10 time points over a period of 7 min, neutralized, pour plated then incubated at 35 °C for 48 h (AOAC official method 960.09). Survival curves using the log‐transformed data were calculated using regression analysis. Correlations coefficients for all linear regression analyses ranged between 0.291 and 0.982, with 6 of the 16 different treatment systems having an R2 value below 0.7. Methods used for calculating D‐values should lead to the same result if the survival curve in a given condition is linear. The calculated D‐values were different using endpoint analysis (Stumbo method), linear regression, and average of multiple endpoints. This study demonstrates the nonlinearity of inactivation curves of antimicrobials. D‐value estimations cannot be reliably used to illustrate biocidal activity in antimicrobial test systems.