medical microbiology. 一 concept of microoranism : 二 type of microorganism: 1 non-cell type 2...
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Medical Microbiology
一 concept of microoranism : 二 type of microorganism: 1 non-cell type 2 prokaryotes 3 eukaryotes 三 general properties of M: 1 tiny in size 2 simple in structure 3 active in metabolism 4 fast rate in multiplication 5 easy in variation 6 widely distributed
四 relationship to human ( 一 ) C .N circulation in nature
( 二 ) in industry 、 agricuture 、 medicine ( 三 ) make up of normal flora of human being 1 anti-pathogen 2 provide nutrition ( 四 ) some M are pathogens 1 pathogens 2 opportunistic pathogens
五 history : leeuwenhoek . 1676 .microscopy (>200 times )
Pasteur (1822-1895 ) :
1 yeast cells cause wines sour 2 pebrine caused by protozoan 3 spontaneous generation controversy
4 chickens: 42 , do not acquire anthrax℃ 37 ,do ℃5 vaccine for rabies
koch : (1843—1910)
1 cultivation techniques 2 staining 3 isolated TB 4 Koch’s postulates :
①microbes are observed in tissue specimens from dead animals ; ②isolated and grown in pure culture ; ③inoculated to a health animal ; ④the disease is produced in the animal ; ⑤then 1 ⑥then 2
六 object of medical microbiology pathogens 七 why we study medical microbiology 八 how to study ---:
Chapter 1 . Bacterial
Morphology and Structure
§1 . size and shape of bacteria
size :tiny um (1um=1/1000 mm) shape : coccus : diplo~ , strepto~ tetrad ,sarcina , staphylo ~ bacillus : spiral bacterium :vibrio spirillum
§2 . structure of bacterium Structure of Bacteria: Essential structure: cell wall cell membrane cytoplasm nuclear material (nucloid) Special Structure capsule flagella pilus spore
一 Essential structure of bacteria ( 一 ) cell wall : 1 peptidoglycan : (1) a backbone (2) tetrapeptide side chains (3) cross bridges
2 teichoic acid (G+) (1) membrane ~ (LTA) (2) wall ~
functions : a. major surface Ag of G+ b. Regulating passage of ions into and out of G+ c. binding B onto host cell surface 3 G- (1) outer membrane . (2) LPS a. lipid A b. core polysaccharide c. O-specific polysaccharide
表 1 - 1 革兰阳性菌与阴性菌细胞壁结构比较
强度 较坚韧 较疏松
厚度 20 ~ 80nm 10 ~ 15nm
肽聚糖层数 可多达 50 层 1 ~ 2 层
肽聚糖含量 占细胞壁干重 50% ~ 80% 占细胞壁干重 5% ~20%
糖类含量 约 45% 15% ~ 20%
脂类含量 1% ~ 4% 11% ~ 22%
磷壁酸 + -
外膜 - +
细胞壁 革兰阳性菌 革兰阴性菌
4 Functions of CW . (1) to form the external shape of B . (2) to protect B from bursting due to high osmolarity :G- 5~6 G+ 20~25 (3) A barrier to certain substances into and out of B . (4) Take part in B multiplication . (5) Associated with B antigenicity .
5 B with deficiency in CW (L Forms ) : Bacterium L-forms : (B with deficiency in CW ):
1 pleomorphic 2 grow in 5% NaCl , 12-15% sucrose . 3 grow slowly ( 2-7d ) 4 antibiotics resistant cells . 5 “fried egg” colony PC , 6 G+ , G- ----------- L – form lysozyme G+ protoplast G- spheroplast 7 Clinic significant
( 二 ) cell membrane . Functions (1) Transportation (2) Respiration (3) Biosynthesis (4) Secretion Mesosome : (1) Respiration (chondroid) (2) Take part in dividing of B
( 三 ) cytoplasm 1 Ribosome : 50S + 30S = 70S | | Erythromycin streptomycin 2 plasmid 3 cytoplasmic granules ( 四 ) Nuclear material (nucleoid )
二 special structure of Bacteria ( 一 )Capsule :
1 chemical component : polysaccharide polypeptide 2 Functions of capsule : (1)against phagocytosis (2)adhesion (3)protect B from damage. (against dry) Glycocalyx
(二) Flagellum :
1 structure 2 chemical composition : pro 3 Function : (1) Motility (2) Antigenicity (H – Ag) (3) Associated with pathogenicity (4) Differentiation for B
(三) Pilus :
1 common pilus : pathogenicity 2 sexpilus :conjugation F+ →F-
(四) spore :
1 Formation and Germination 2 Functions of spore high resistance to kill spore : 121.3 , 15-20min℃ 1.05kg / cm2
To kill spore is an important index of
autoclaving .
§3 Methods for Identification and Detection of B 一 microscope magnification 1 light microscope 2 electron microscope 二 staining : (一) Gram stain Step1 step2 step3 1min 1min Crystal ------ Iodine ----- 95% Alcohol Violet wash 30Sec step4 30Sec -------- Safranin -------- microscope . (二) Acid – fast stain .
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