Bactericidal Capacity

the capacity of physical, chemical, and biological factors to kill microorganisms. The term usually characterizes the capacity to destroy all microbial species, although it is more correct to use the term “microbicidal capacity” in this context. Among physical factors, thermal and radiant forms of energy have the highest bactericidal capacity. The majority of microbes are highly sensitive to shortwave—specifically ultraviolet—radiation, which is widely used to disinfect rooms (operating rooms, wards, and so on). Chemical substances able to kill bacteria are called bactericidal substances. Bactericidal capacity is also inherent in human and animal blood serums because they contain a special substance (complement) and in tears, saliva, and milk, which contain lysozyme; gastric juice, which contains hydrochloric acid; and the skin. It is not clear why the skin kills microbes. Several factors are obviously at work: drying, the acidic reaction of the horny layer, substances such as lysozyme, and the disinfecting action of high-molecular fatty acids (caprylic, lauric, and others). Plants also secrete substances—phytoncides—that kill microbes and are widely used for therapeutic purposes.