Glycogen availability and pH variation in a medium simulating vaginal fluid influence the growth of vaginal Lactobacillus species and Gardnerella vaginalis.

BACKGROUND: Glycogen metabolism by Lactobacillus spp. that dominate the healthy vaginal microbiome contributes to a low vaginal pH (3.5-4.5). During bacterial vaginosis (BV), strict and facultative anaerobes including Gardnerella vaginalis become predominant, leading to an increase in the vaginal pH (> 4.5). BV enhances the risk of obstetrical complications, acquisition of sexually transmitted infections, and cervical cancer. Factors critical for the maintenance of the healthy vaginal microbiome or the transition to the BV microbiome are not well defined. Vaginal pH may affect glycogen metabolism by the vaginal microflora, thus influencing the shift in the vaginal microbiome. RESULTS: The medium simulating vaginal fluid (MSVF) supported growth of L. jensenii 62G, L. gasseri 63 AM, and L. crispatus JV-V01, and G. vaginalis JCP8151A at specific initial pH conditions for 30 d. L. jensenii at all three starting pH levels (pH 4.0, 4.5, and 5.0), G. vaginalis at pH 4.5 and 5.0, and L. gasseri at pH 5.0 exhibited the long-term stationary phase when grown in MSVF. L. gasseri at pH 4.5 and L. crispatus at pH 5.0 displayed an extended lag phase over 30 d suggesting inefficient glycogen metabolism. Glycogen was essential for the growth of L. jensenii, L. crispatus, and G. vaginalis; only L. gasseri was able to survive in MSVF without glycogen, and only at pH 5.0, where it used glucose. All four species were able to survive for 15 d in MSVF with half the glycogen content but only at specific starting pH levels - pH 4.5 and 5.0 for L. jensenii, L. gasseri, and G. vaginalis and pH 5.0 for L. crispatus. CONCLUSIONS: These results suggest that variations in the vaginal pH critically influence the colonization of the vaginal tract by lactobacilli and G. vaginalis JCP8151A by affecting their ability to metabolize glycogen. Further, we found that L. jensenii 62G is capable of glycogen metabolism over a broader pH range (4.0-5.0) while L. crispatus JV-V01 glycogen utilization is pH sensitive (only functional at pH 5.0). Finally, our results showed that G. vaginalis JCP8151A can colonize the vaginal tract for an extended period as long as the pH remains at 4.5 or above.

Cultural dimensions of individualism and collectivism and risk of opioid misuse: A test of Social Cognitive Theory.

BACKGROUND: Despite the critical role social and cultural contexts play in pain experience, limited theoretical and empirical attention has been devoted to the interplay between social, cognitive, cultural, and psychological factors in chronic pain management and the risk of opioid misuse. METHODS: Using structural equation modeling, the present study tested the Social Cognitive Theory (SCT) of chronic pain management and risk of opioid misuse in the context of intraindividual cultural dimensions of individualism and collectivism among 316 ethnically diverse adults with chronic pain in the United States. RESULTS: Social cognitive predictors account for a significant amount of variance in pain dysfunction and risk of opioid misuse in adults with chronic pain. Satisfaction with pain support was positively associated with both greater pain acceptance and greater pain self-efficacy. Individualism was found to be positively associated with satisfaction with pain support, pain self-efficacy, and pain acceptance but negatively associated with the risk of opioid misuse. Collectivism was positively associated with the risk of opioid misuse. CONCLUSIONS: The study findings not only empirically support using SCT for adults with chronic pain, but also provide a more thorough conceptual framework that highlights the intracultural diversity and interplay among social, cognitive, and psychological factors that affect pain experience and the risk of opioid misuse among adults with chronic pain.