Nester's microbiology Chapter 5 with complete solutions

bacterial endospores most resistant, only extreme heat or chemical treatment destroys them Protozoan cysts and oocysts resistant to disinfectants; excreted in feces; causes diarrheal disease if ingested 00:24 01:40 Mycobacterium tuberculosis and leprosy Psuedomonas can form biofilms in the lower respiratory tract leading to a chronic pneumoina in CF patients that is very difficult to eliminate. naked viruses lack lipid envelope; more resistant to disinfectants Sterilization methods dry heat, moist heat, radiation, incineration Moist Heat Sterilization Moist heat denatures proteins Boiling dry heat sterilization Kills by oxidation Flaming Incineration Hot-air sterilization Irradiation Ionizing radiation applied to food to kill microorganisms and other pests. Ionizing radiation disrupts the internal molecular workings of cells, killing them. ionizing radiation enough energy to dislodge electrons from atoms, forming ions; capable of causing cancer (gamma, X-rays, UV) ultraviolet radiation destroys microbes directly; harmful to skin and eyes high pressure denatures proteins 00:00 01:40 sterilants Can destroy all microorganisms, including endospores and viruses. High level disinfectant Hospital disinfectant with tuberculocidal activity Intermediate level disinfectant destroys m. tuberculosis, viruses, fungi, and vegetative bacteria and is used for disinfecting semi-critical instruments