354 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 7O 6O rr •3 50 o z 4o • 2o 10 984 M P 984 ß tip TE8T SYSTEM Figure 2. Comparison of D-values for P. aeruginosa 9027, P. cepacia 13945, P. fluorescens 13525, and P. puti&• 12633, determined by preservative efficacy testing of the nonionic lotion containing 0.2% MP, 0.2% 934, or both 0.2% MP and 0.2% 934. be much more resistant to the preservative system of the lotion containing 0.2% MP q- 0.2% 1342. Even though the ?. stutzeri inoculum contained 1.7 x 107/ml, this or- ganism was not recovered from the initial sampling in the MP q- Na2EDTA solution. Similarly, ?. stutzeri was inactivated more rapidly than all other test organisms in the lotion containing MP q- 1342 (Table II). Hardness analyses of tap water, tap water containing 0.01% Na2EDTA, and deionized water gave mean hardness values of 137 (s = 5.0), 109 (s = 1.4), and 20 (s = 14) ppm CaCO 3, respectively. These means were significantly different (p 0.05). The STs obtained in Table V were used to calculate survivor curve slopes and D-values and to demonstrate synergy for all Pseudomonas test organisms in 0.1% MP q- 0.01% Na2EDTA solutions, except for ?. cepacia 13945 (Table VI). It was possible to calculate a slope and D-value where STs were known, as in the case for ?. cepacia 13945 in 0.2% Table IV Effect of 0.1% CaC12 on Preservative Efficacy Test Results of Nonionic Lotion Containing 0.2% MP and 0.2% 1342 Challenged With P. aeruginosa 9027, P. cepacia 13945, P. fluorescens 13525, and P. putid• 12633 Test organism Lotion Lotion with CaCl2 P. aeruginosa 1.8 (0.8) 10' (0) P. cepacia 90* (16) 13' (0.7) P. fluorescens 2.0 (0.07) 8.5 (0.4) P. puti&• 2.2 (0.28) 11' (1.0) Table values are mean D-values from duplicate experiments, with standard deviations in parentheses. * D-values over 10 hr were rounded to the nearest whole number.
SYNERGY OF PRESERVATIVES 3 5 5 Table V Determination of Sterilization Times of Several Pseudomonas Species in MP, Na2EDTA, and MP + Na2EDTA Solutions 0.2% MP solutions: Test organism 0 hr 2 hr 4 hr 24 hr 48 hr ST MPST P, aeruginosa 9027 + + + + + P. aeruginosa 27853 + + + + + P, aeruginosa 9721 + + + + + P. aeruginosa 10145 + + + + + P. cepacia 13945 + + + + - P. cepacia 25416 + + + + + P. fluorescens 13525 + + + + + [2] P. putid• 12633 + + + + - P. stutzeri 17588 + + + + + Pseudomonas sp. 9230 + + + + + S. aureus 6538 + + + + + E. coli 8739 + + + + + 48 48 48 48 48 48 -- 48 48 __ 48 48 48 48 0.01% Na2EDTA solutions: Test organism 0 hr 2 hr 4 hr 24 hr 48 hr ST MPST P. aeruginosa 9027 + + + + + -- 48 P. aeruginosa 27853 + + + + + -- 48 P. aeruginosa 9721 + + + + + -- 48 P. aeruginosa 10145 + + + + + -- 48 P. cepacia 13945 + + + + + -- 48 P. cepacia 25416 + + + + + -- 48 P. fluorescens 13525 + + + [s] + + -- 48 P. putid• 12633 + + +[s] +[2] - 48 -- P. stutzeri 17588 + - +[1] - - 24 -- Pseudomonas sp. 9230 + + + + + -- 48 S. aureus 6538 + + + + + -- 48 E. coli 8739 + + + + + -- 48 0.2% MP + 0.01% Na2EDTA solution: Test organism 0 hr 2 hr 4 hr 24 hr 48 hr ST MPST P. aeruginosa 9027 + + [s] - - - 4 -- P. aeruginosa 27853 + +[s] +[2] - - 24 -- P. aeruginosa 9721 + + [s] - - - 4 -- P. aeruginosa 10145 + +[1] - - - 4 -- P. cepacia 13945 + + + + - 48 -- P. cepacia 25416 + .... 2 -- P. fluorescens 13525 + .... 2 -- P. putid• 12633 + .... 2 -- P. stutzeri 17588 ..... 0.1' -- Pseudomonas sp. 9230 + + + [ 1] - - 24 -- S. aureus 6538 + + + + + -- 48 E. coli 8739 + + + + + -- 48 Deionized water (control): Test organism 0 hr 2 hr 4 hr 24 hr 48 hr ST MPST P. aeruginosa 9027 + + + + + P. aeruginosa 27853 + + + + + P. aeruginosa 9721 + + + + + P. aeruginosa 10145 + + + + + 48 48 48 48 (continued)
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