BIOL125_Ch17 Notes

BIOL125_Ch17 Notes - BIOL 125(Microbiology Text and Lecture Notes Chapter 17 Diagnosing Infections 17.1 PREPARATION FOR THE SURVEY OF MICROBIAL

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BIOL 125 (Microbiology) Text and Lecture Notes Chapter 17: Diagnosing Infections 17.1. PREPARATION FOR THE SURVEY OF MICROBIAL DISEASES a. Lecture Notes. i. Three categories of identification tests: 1) Phenotypic – morphology, biochemistry, and physiology exhibited by the microbe. 2) Genotypic – genetic make up of the microbe. 3) Immunological – serology analysis of blood using antibody-antigen reactions. ii. Important consideration when diagnosing an infectious agent: 1) Whether the microbe is actually causing the disease or normal flora. 2) Similarity between normal flora bacteria and the disease-causing pathogen. 3) Whether it can be grown in the lab. b. Phenotypic Methods i. Microscopic Morphology ii. Macroscopic Morphology iii. Physiological/Biochemical Characteristics iv. Chemical Analysis c. Genotypic Methods d. Immunologic Methods 17.2. ON THE TRACK OF THE INFECTIOUS AGENT: SPECIMEN COLLECTION a. Overview of Laboratory Techniques 17.3. PHENOTYPIC METHODS a. Immediate Direction Examination of Specimen i. Lecture Notes. 1) Direct examination of the specimen. a) Physical appearance. b) Staining: Gram and acid fast. File: 7dcbba1f17644702053f3d2efcdb32ee65acf8d8.doc Updated 8/14/09
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Microbiology Text and Lecture Notes Chapter 17: Diagnosing Infections Page 2 c) If culturing is a problem, direct fluorescence antibody test is used. i) Pathogen is exposed with fluorescence labeled antibody, using pathogen specific antigen. d) Cultivation with differential media. i) Mannitol Salt Media – S. aureus metabolizes mannitol and changes the medium color to yellow; S. epidermis metabolizes mannitol, but does not change the color to yellow. ii) MacConkey Agar – allows lactose fermentation of enteric bacteria (ex. E. coli form pink colonies). iii) Enterotube – used to identify enterobacteria (ex. E. coli, Enterobacter, Shigella, Salmonella ). b. Cultivation of Specimen i. Isolation Media ii. Biochemical Testing 1) Prominent biochemical tests include: carbohydrate fermentation (acid and/or gas); hydrolysis of gelatin, starch, and other polymers; enzyme actions such as catalase, oxidase, and coagulase; and various by- products of metabolism. iii. Miscellaneous Tests 1) Phage typing is chiefly used for tracing strains of bacteria in epidemics. a) Lecture Notes. i) Phage typing uses the property of viruses to infect specific strains of bacteria. 1
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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_Ch17 Notes - BIOL 125(Microbiology Text and Lecture Notes Chapter 17 Diagnosing Infections 17.1 PREPARATION FOR THE SURVEY OF MICROBIAL

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