3/24/99

Microbiology II

 

Non specific defenses

·        Chapter 17

·        Immunity (defenses)—exemption from sickness due to microbes

·        Equipped w/different mechanisms to ward off or prevent the microbes from causing disease

·        Alcohol, smoking, lack of rest, stress all affect natural defenses

·        All mechanisms that our body possesses that does not recognize the invader specifically and w/o producing any specific component against the invader

·        Intact skin is the largest organ of the body and is able to prevent the penetration of many microbes; has chemicals that prevent the survival of microbes

·        Physical barrier—skin

·        Chemicals—

·        Cellular defenses—macrophages

·        Fever—defense mechanism that can damage the invading microorganism

·        Ex:  Treponema Fever Therapy

·        Inflammation

·        Species Resistance—Homo Sapiens—biochemical characteristics that are unique, we are different from other animals in many ways, including susceptibility to microorganisms

·        Racial resistance—certain races are not as prone to certain diseases  ex:  TB Native Americans are far more susceptible than Caucasians

·        Specific—antibodies specific to the organism

 

Endogenous flora—presence of many microbes in various body parts

·        Sterile—free of microbes ex:  brain

·        Blood supposed to be sterile, is known to be harboring microbes

·        Stomach is very harsh; under normal situations will not allow microbes to stay

·        Skin is loaded w/microbes like Staph epidermiditis, Cornybacterium acnes, Pityrosporum ovale (scalp)

·        Conjunctiva—corynebacterium species, Haemphilus species

·        Nose—Staph epidermidis, Corynebacterium, Haemophilus, Strep mitis, Strep salivarius, Moraxella lacunate

·        Mouth

·        Pharynx

·        Lower Intestines—coliforms

·        Vagina

·        Valuable in some respects and harmful in other respects

·        Creates an ecological niche (Amphibiontic site) do not allow pathogens to settle

·        Close antigenic similarity to pathogens—facilitates specific immunity

·        Production of vitamins and growth factors

·        In immunocompromised individuals the same organisms can become deadly ex:  Clostridium difficile causing endocarditis and pneumonia

·        Moved from one organ to another where they are not normally found