Every food handler or employee thereof who is engaged in handling food, except when such food is in original cans, packages or containers, shall keep his person, aprons, services, caps and other articles of clothing thoroughly clean and free from dirt and filth. Failure to observe the provisions of this section shall constitute a misdemeanor and the employer of any person violating the same shall be deemed an aider and abettor and may be prosecuted as if he were the principal offender.