Efficacy of liquid soap and alcohol-based hand sanitisers in eradicating viable conidia of the mushroom pathogen lecanicillium fungicola on contaminated hands

Abstract

Lecanicillium fungicola causes dry bubble disease of the white button mushroom and produces masses of sticky conidia. Humans are an important vector in the spread of this disease in mushroom farms. Three hand cleaning treatments (tap water, liquid soap and alcohol-based hand sanitisers (ABHSs)) were evaluated for their effectiveness at eliminating conidia of L. fungicola from a contaminated index finger. The hand sanitisers were highly efficacious in reducing the number of viable L. fungicola conidia on contaminated fingertips, although some variability was encountered. The tap water and liquid soap treatments had little effect. An in vitro test confirmed that the log10 reduction in viable conidia after 1 min exposure to the different treatments was <0.15 for tap water and soap and >4.5 for the ABHSs, which is similar to what is achieved in the medical care field for many bacteria and viruses. Thus, regular use of ABHSs by staff on mushroom farms may help to reduce the incidence of dry bubble disease. Their use could also be beneficial in other areas of intensive horticulture or agriculture where human hands are known to transmit plant pathogens to uninfected plants.