113lecture2006

113lecture2006 - BIOLOGY 113 - MICROBIOLOGY Lecture 20:...

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BIOLOGY 113 - MICROBIOLOGY Lecture 20: Epidemiology - Normal flora, Koch's postulates, classifying infections Pathology is the medical discipline dealing with development of disease - Pathology addresses issues of disease etiology and pathogenesis = The etiology of a disease is the mechanism through which it occurs · In this course, we are naturally concerned with diseases that exhibit an infectious etiology · The etiology of a disease may also be congenital, nutritional, etc. · Some of the diseases receiving the greatest attention - cancers, heart disease - exhibit an etiology that is mixed or to some degree unknown = Pathogenesis refers to the the manner in which a disease develops, especially the structural and functional changes that occur in tissues - Infection is the invasion or colonization of the body by pathogenic (disease-causing) microorganisms = "Infection" implies that the organism is present in tissues where it does normally occur = Infection may exist in the absence of detectable disease All animals, including humans, serve as hosts to a normal microbiota, or "normal flora" (Tortora et al., Figures 14.1, 14.2) - These are microorganisms that colonize certain tissues and establish more or less permanent residence (Tortora et al., Table 14.1) - Abundant normal microbiota organisms are found in the nasopharyngeal and oropharyngeal regions of the upper respiratory tract, the digestive tract (especially the large intestine), the vagina, the distal end of the urethra, and the skin (Tortora et al., Figure 14.2) - The ecological relationship between the normal flora organisms and their host is generally a commensal one in which the microorganisms obtain nutrients from the animal without causing either harm or benefit = One "benefit" of the normal flora is the phenomenon of microbial antagonism: By their presence, normal flora organisms prevent colonization by pathogens = The imporgance of microbial antagonism can be seen in increased susceptibility for some infections following antibiotic treatment · Vaginitis due to Candida albicans may follow a drop in the bacterial flora of the vagina, which normally maintains a low pH that inhibits growth of
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This note was uploaded on 11/24/2011 for the course BIO 113 taught by Professor Staff during the Fall '09 term at Rutgers.

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113lecture2006 - BIOLOGY 113 - MICROBIOLOGY Lecture 20:...

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