Combination of urease inhibitor and antiseptic inhibits urea decomposition-induced ammonia production by Proteus mirabilis

Abstract

The decomposition of urea into ammonia by urease-producing bacterium shows an elevation in the pH level, which can lead to incontinence-associated dermatitis (IAD). This study aimed to examine the efficacy of a combination of antiseptic and urease inhibitor in inhibiting the decomposition of urea by the urease-producing bacterium Proteus mirabilis. We performed in vitro assays to compare the effects of a combination of antiseptic and urease inhibitor, antiseptic only, urease inhibitor only, and an untreated control with the effects of a urea-containing solution. Cultured P. mirabilis was mixed with urea-containing solution, followed by the addition of antiseptic and/or urease inhibitor. The main outcome used to assess the efficacy of the different treatments was ammonia concentration at 4-hours post-treatment initiation, and multiple comparison analysis was performed using Dunnett's test to compare the results between groups. Ammonia concentrations in samples treated with either antiseptic or urease inhibitor were lower than those in the untreated control, while the combination of antiseptic and urease inhibitor resulted in decreased ammonia concentrations compared with either treatment alone. Therefore, the application of both urease inhibitor and antiseptic is more effective for the inhibition of urea decomposition by urease-producing bacteria. Novel preventive strategies using these reagents may be effective for preventing IAD.

Keywords: ammonia; incontinence-associated dermatitis; microbiology; urea; urease.

FIGURE 1

Efficacy of a combination of antiseptic and urease inhibitor for the inhibition of urea decomposition into ammonia by P. mirabilis in urea‐containing solution. A, Four treatment groups with urea (BU, BU‐A, BU‐I, and BU‐AI) and one without urea (B) were prepared. B, OD values were significantly decreased in cultures BU‐A and BU‐AI compared with culture B at 4 hours post‐inoculation. C, The culture pH was significantly increased in the BU treatment compared with that of culture B at 4 hours post‐inoculation. D, The ammonia concentration was significantly increased in the BU culture compared with that of culture B at both 2 and 4 hours post‐inoculation. Cultures BU‐A, BU‐I, and BU‐AI showed significant decreases in ammonia concentration compared with the BU culture at 4 hours post‐inoculation. *P < .05 compared with culture B at the same time point; **P < .01 compared with culture B at the same time point. ^# P < .05 compared with the BU culture the same time point; ^## P < .01 compared with the BU culture at the same time point

FIGURE 2

Efficacy of various concentration of antiseptic and urease inhibitor for the inhibition of urea decomposition into ammonia by P. mirabilis in artificial urine. A, OD values at 4 hours post‐inoculation for all treatment groups were significantly decreased compared with the culture without antiseptic or urease inhibitor, with decreases in OD occurring in an antiseptic concentration‐dependent manner. B, The pH values of the different cultures varied immediately after inoculation (0 hours), with random pH changes observed at 4 hours post‐inoculation. C, The ammonia concentrations of all treatment groups were significantly decreased compared with that of the culture without antiseptic or urease inhibitor, with decreases in ammonia concentration associated with increases in the concentrations of urease inhibitor and antiseptic. *P < .05 compared with the culture containing 0 ppm urease inhibitor and 0 ppm antiseptic at the same time point; **P < .01 compared with the culture containing 0 ppm urease inhibitor and 0 ppm antiseptic at the same time point