Final answer:
A disinfectant must be capable of killing various microbes, such as vegetative cells, fungi, and viruses, and may also destroy endospores in the case of high-level germicides. Effectiveness depends on concentration, temperature, and contact time. Suitable germicides like formaldehyde and halogens are chosen based on the requirement for sterilization or disinfection.
Step-by-step explanation:
A chemical agent used to disinfect must be capable of killing a broad spectrum of microorganisms, including vegetative cells, fungi, viruses, and in some cases, endospores. High-level germicides are powerful enough to achieve sterilization, which is the complete elimination of all forms of life, including endospores, typically found in the most resistant forms of bacteria. Intermediate-level germicides are somewhat less potent, often failing to destroy all viruses and endospores. Low-level germicides, the least powerful, are restricted to killing only vegetative cells and some viruses, particularly those with an envelope, but not endospores, which are capable of surviving harsh conditions.
Factors that affect the effectiveness of a disinfectant include the concentration of the disinfectant, the temperature at which it is used, and the duration of exposure. Specific applications require careful selection of the appropriate level of disinfectant to ensure safety and efficacy. For example, alkylating agents like formaldehyde and halogens such as iodine and chlorine are commonly used in various settings for their broad-spectrum disinfecting capabilities.