Evaluation of Polyhexamethylene Biguanide (PHMB) as a Disinfectant for Adenovirus

IMPORTANCE Swimming pools can be a vector for transmission of adenovirus ocular infections. Polyhexamethylene biguanide (PHMB) is a disinfectant used in swimming pools and hot tubs. OBJECTIVE To determine whether PHMB is an effective disinfectant against ocular adenovirus serotypes at a concentration used to disinfect swimming pools and hot tubs. DESIGN In vitro laboratory study. INTERVENTIONS The direct disinfecting activity of PHMB was determined in triplicate assays by incubating 9 human adenovirus types (1, 2, 3, 4, 5, 7a, 8, 19, and 37) with PHMB concentrations of 50 and 0 ppm (micrograms per milliliter) for 24 hours at room temperature to simulate swimming pool temperatures or 40oC to simulate hot tub temperatures. MAIN OUTCOME MEASURES Plaque assays were performed to determine adenovirus titers after incubation. Titers were log10 converted and mean (SD) log10 reductions relative to controls were calculated. Virucidal (>99.9%) decreases in mean adenovirus titers after PHMB treatment were determined for each adenovirus type and temperature tested. RESULTS At room temperature, 50 ppm of PHMB produced mean reductions in titers less than 1 log10 for all adenovirus types tested. At 40°C, 50 ppm of PHMB produced mean reductions in titers less than 1 log10 for 2 adenovirus types and greater than 1 but less than 3 log10 for 7 of 9 adenovirus types. CONCLUSIONS AND RELEVANCE At a concentration of 50 ppm, PHMB was not virucidal against adenovirus at temperatures consistent with swimming pools or hot tubs. Recreational water maintained and sanitized with PHMB can serve as a vector for the transmission of ocular adenovirus infections.