BIOL125_Ch13 Notes

BIOL125_Ch13 Notes - BIOL 125 (Microbiology) Text and...

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BIOL 125 (Microbiology) Text and Lecture Notes Chapter 13: Microbe-Human Interactions 13.1. WE ARE NOT ALONE a. Contact, Colonization, Infection, Disease i. Normal (Resident) Flora – microbes that engage in mutual or commensal associations with humans. ii. Infectious Disease – an infection that causes damage or disruption to tissues and organs. 1) Disease – any deviation from health. b. Resident Flora: The Human as a Habitat i. Transients – organisms that occupy the body only for short periods of time. ii. Residents – microbes that become established more permanently. iii. Microbial Antagonism – the effects “good” microbes have on intruder microorganisms. iv. Endogenous Infections – occur when normal flora is introduced to a site that was previously sterile. v. Initial Colonization of the Newborn 1) Lecture Notes: First time a new born is exposed to a microbe is during the birthing process. a) The first bacteria colonized is lactobacilli, followed by streptococci, and staphylococci . 2) Bottle-fed infants tend to acquire a mixed population of coliforms, lactobacilli, enteric streptococci, and staphylococci. 3) Breast-fed infant intestinal flora consists primarily of Bifidobacterium species. c. Indigenous Flora of Specific Regions d. Flora of the Human Skin i. Normal flora resides only in or on the dead cell layers, and except for the follicles and glands, it does not extend into the dermis or subcutaneous levels. ii. Oily, moist skin supports more flora than dry skin. iii. Normal skin residents consist primarily of bacteria ( Staphylococcus, Corynebacteriu, and Propionibacterium ) and yeasts. e. Flora of the Gastrointestinal Tract File: 1f21eba09485f8875d1084774ce0625ae8cb1564.doc Updated 8/14/09
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Microbiology Text and Lecture Notes Chapter 13: Microbe-Human Interactions Page 2 i. Stomach acid inhibits most microbes, although lactobacilli and Helicobacter can become established. ii. Flora of the Mouth 1) Most common residents are aerobic Streptococcus species. a) S. mutans and S. sanguis form sticky dextran slime layers, which contribute to dental caries. iii. Flora of the Large Intestine 1) The intestinal environment favors strictly anaerobic bacteria. 2) Coliforms are present in smaller numbers. a) Coliforms – Gram-negative, facultatively anaerobic, and lactose-fermenting microbes. b) Skatole – chemical that gives feces its smell. f. Flora of the Respiratory Tract i. Lecture Notes: Microbial flora flourish only in the upper respiratory tract (i.e. nasal passage and pharynx). 1) Bacteria include Staphylococcus, Micrococcus, Streptococcus, and Cornebacterium. 2) Lower respiratory tract does not support resident bacteria. g. Flora of the Genitourinary Tract i. Principal residents of the urethra are nonhemolytic streptococci, staphylococci, corynebacteria, and occasionally, coliforms. ii.
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This note was uploaded on 08/12/2009 for the course BIOL 125 taught by Professor Dr.sujathapamula during the Spring '09 term at San Jacinto.

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BIOL125_Ch13 Notes - BIOL 125 (Microbiology) Text and...

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