Rationale: The stability of Lactobacillus rhamnosus GG capsules (Culturelle™) at temperatures higher than room temperature is uncertain. However, L. rhamnosus GG capsules may be exposed to higher temperatures during product storage or shipment. Ensuring stability is necessary for evaluating the effect of this probiotic on infectious outcomes in a randomized trial in critically ill patients.
Objectives: This study will determine the impact of high temperatures over time on L. rhamnosus GG viability in preparation for a trial testing L. rhamnosus GG versus placebo in mechanically ventilated patients in the intensive care unit (ICU) (PROSPECT, clinicaltrials.gov #NCT01782755).
Methods: We evaluated the stability for shipping and storage purposes of a random sample of L. rhamnosus GG capsules (Culturelle™) at 3 temperatures (room temperature [~ 23°C], 30°C and 37°C) for up to 14 days. These probiotic capsules were selected from 2 different lots (Lot 16 and 17). Capsule CFUs were determined on days 0, 7, 10, and 14. CFUs assessments at each time point for each of 2 lots tested were performed in 3 randomly selected capsules from different cards. Bacterial density was evaluated by enumerating the content of the probiotic capsule by serial dilution. Subsequently, the number of CFUs were counted to determine the total number of viable bacteria in each of the capsules tested and a two-sided t-test was performed to compare CFUs between results at room temperature and at 37°C. Furthermore, we conducted a one-sided t-test with a mu0 of 1010 at days 7, 10, and 14 to ensure that the capsule counts remained above the 1010 CFUs/capsule threshold.
Results: In total, 3 capsules for both lots were tested at baseline and 3 capsules for each of the 3 temperatures were tested at day 7, 10 and 14 for each lot (n=60). Of the 60 capsules tested, 4 (6.7%) were excluded from the analysis due to contamination of the culture medium. Following the 14 days, all of the remaining 56 capsules tested recovered more than the critical threshold of 1010 CFU/capsule of L. rhamnosus GG. Differences between the room temperature controls and 30°C CFUs were not statistically significant over the duration of the experiment. A modest decrease in CFUs between the room temperature controls and 37°C was observed at day 10 and 14 for both lots (lot 16 day 10 p = 0.006, day 14 p = 0.0003; lot 17 day 10 p = 0.027, day 14 p = 0.0009). Both lots were significantly above the 1010 threshold at ~23°C and 30°C on all 3 days. Lot 16 was not significantly above the threshold at 37°C on day 14, and lot 17 did not have sufficient data at 37°C on day 14 to conduct a test.
Conclusions: At room temperature and 30°C, all capsules tested for both lots remained significantly above the critical threshold of 1010 CFUs/capsule of L. rhamnosus GG after the 2 week study period. At 37°C, analysis was only possible for Lot 16 for which absolute counts remained non-significantly above the 1010 CFUs/capsule at 2 weeks.
Rationale: The stability of Lactobacillus rhamnosus GG capsules (Culturelle™) at temperatures higher than room temperature is uncertain. However, L. rhamnosus GG capsules may be exposed to higher temperatures during product storage or shipment. Ensuring stability is necessary for evaluating the effect of this probiotic on infectious outcomes in a randomized trial in critically ill patients.
Objectives: This study will determine the impact of high temperatures over time on L. rhamnosus GG viability in preparation for a trial testing L. rhamnosus GG versus placebo in mechanically ventilated patients in the intensive care unit (ICU) (PROSPECT, clinicaltrials.gov #NCT01782755).
Methods: We evaluated the stability for shipping and storage purposes of a random sample of L. rhamnosus GG capsules (Culturelle™) at 3 temperatures (room temperature [~ 23°C], 30°C and 37°C) for up to 14 days. These probiotic capsules were selected from 2 different lots (Lot 16 and 17). Capsule CFUs were determined on days 0, 7, 10, and 14. CFUs assessments at each time point for each of 2 lots tested were performed in 3 randomly selected capsules from different cards. Bacterial density was evaluated by enumerating the content of the probiotic capsule by serial dilution. Subsequently, the number of CFUs were counted to determine the total number of viable bacteria in each of the capsules tested and a two-sided t-test was performed to compare CFUs between results at room temperature and at 37°C. Furthermore, we conducted a one-sided t-test with a mu0 of 1010 at days 7, 10, and 14 to ensure that the capsule counts remained above the 1010 CFUs/capsule threshold.
Results: In total, 3 capsules for both lots were tested at baseline and 3 capsules for each of the 3 temperatures were tested at day 7, 10 and 14 for each lot (n=60). Of the 60 capsules tested, 4 (6.7%) were excluded from the analysis due to contamination of the culture medium. Following the 14 days, all of the remaining 56 capsules tested recovered more than the critical threshold of 1010 CFU/capsule of L. rhamnosus GG. Differences between the room temperature controls and 30°C CFUs were not statistically significant over the duration of the experiment. A modest decrease in CFUs between the room temperature controls and 37°C was observed at day 10 and 14 for both lots (lot 16 day 10 p = 0.006, day 14 p = 0.0003; lot 17 day 10 p = 0.027, day 14 p = 0.0009). Both lots were significantly above the 1010 threshold at ~23°C and 30°C on all 3 days. Lot 16 was not significantly above the threshold at 37°C on day 14, and lot 17 did not have sufficient data at 37°C on day 14 to conduct a test.
Conclusions: At room temperature and 30°C, all capsules tested for both lots remained significantly above the critical threshold of 1010 CFUs/capsule of L. rhamnosus GG after the 2 week study period. At 37°C, analysis was only possible for Lot 16 for which absolute counts remained non-significantly above the 1010 CFUs/capsule at 2 weeks.