Effect of mouth moisturizers on the antibacterial efficacy of Peridex™ Oral Rinse

Background: Ventilator-associated pneumonia (VAP) is a serious healthcare-associated infection, which leads to high mortality and high costs of treatment.  Chlorhexidine gluconate 0.12% (CHG) based oral rinses have been associated with the prevention of VAP.  These oral rinses are often used in conjunction with mouth moisturizers; however, the effect of moisturizers on the antiseptic activity of CHG oral rinses has not been established.

Objective: To determine if mouth moisturizers, used in conjunction with Peridex™ (CHG 0.12%) Oral Rinse, interfere with its antiseptic activity; and to investigate the compatibility of a new 3M moisturizer formulation with Peridex Oral Rinse. Two commercially available mouth moisturizers (Products 1 and 2) were chosen for comparative purposes.

Methods: Ex-vivo porcine mucosal tissue was treated with Peridex Oral Rinse (10μl, 0.12% CHG) for 4h at 37^oC. Then one of 3 moisturizers was applied: 3M™ Mouth Moisturizer gel, Product 1 and Product 2.  Tissue was further incubated at 37^oC for 1h.  Each tissue section was then infected with S. aureus (methicillin sensitive, MSSA), 1 x 10⁶ CFU/tissue, and incubated overnight for 18h.  Tissue sections were transferred to a neutralizing solution and vortex mixed for 2 min.  Supernatant was then plated onto blood agar using a spiral dilutor, for enumeration of bacteria.  (All experiments were performed in triplicate.)

Results: MSSA bacterial densities after 18h incubation were ~1 x 10⁸ CFU/tissue (media controls). Moisturizers alone had no intrinsic antibacterial activity. Peridex Oral Rinse significantly reduced the amount of MSSA recovered (log reduction = 4.33±0.25, p<0.05).  Product 1 completely abrogated this effect, log reduction = -1.28±0.15.  Product 2 had an intermediate effect on bacterial burden, log reduction = 2.02±0.10, which was significantly different from Peridex (p<0.05).  3M moisturizer had no effect on the antibacterial activity of Peridex, with a significant decrease in MSSA from growth controls (log reduction = 4.24±0.20, p<0.05).

Conclusions: Mouth moisturizers can reduce the overall efficacy of CHG based oral rinse (Peridex brand) for microbial kill when applied sequentially; however, the 3M moisturizer was most compatible with Peridex Oral Rinse. The reduced microbial kill appears to be due to the formation of CHG salts with specific anionic excipients listed in each of the products.