Module 5 Flashcards
(34 cards)
Koch’s postulates
- Microorganism must be found in every case to be called the Causative Agent.
- Microorganism must be grown in a pure culture
- Disease must be reproduced when pure culture is injected into healthy host
- Microorganism must be recoverable from the injected host
Transient normal flora
Bacteria different from usual flora and present for a short time
Contamination
Presence of bacteria in/on body site
Not part of normal flora
Bacteria not growing
Colonization
Contamination, but bacteria are growing
No host reaction
Infection
Bacteria growing in/on a body site
Causes host infection
Pathogenicity
Ability of a microorganism to cause disease
Virulence
Degree of pathogenicity
Pathogen
Microorganism capable of causing disease
Nonpathogen
Microorganism not capable of causing disease
Very few microorganisms can be classified this way
6 factors contributing to pathogenicity
Capsules Hyaluronidase Collagenase Hemolysins Leukocidins Kinases
Hyaluronidase
Extracellular enzyme mainly produced by GPO bacteria
Dissolves hyaluronic acid (compound in connective tissue matrix) and allows bacteria to spread
Collagenase
Breaks down collagen (in connective tissue)
Allows bacteria to spread faster in connective tissue
Hemolysins
Lyse RBCs
Decrease host’s immunity
Leukocidins
Kills phagocytic cells creating pus
Exotoxins
Mainly produced by GPO bacteria Excreted from living bacterial cells Mainly protein molecules Antigenic (causes an immune response) Have a specific site of action in the host Eg. Botox
Endotoxins
Produced by GN bacteria
Part of the cell wall (lipopolysaccharide of outer membrane)
Released when cell walls are lysed (by antibiotics)
Nonspecific sites of action in the host (whole body)
Signs of bacterial infection
Fever, lymph node swelling, inflammation, exudate, granulomatous infection, cellulitis
Purulent exudate
AKA Polymorphonuclear neutrophils (PMNs)
Many WBC, neutrophils, pus
Serous exudate
Watery fluid is few polymorphonuclear neutrophils (PMNs) and less protein
Transudate
Noncellular fluid (leakage from blood or lymph vessels)
Granulomatous infection
Granuloma formed at site of infection
Collections of macrophages
Results in increased capacity for phagocytosis and digestion
Epidemic
Many people in an area having a disease over a short period of time
Endemic
Disease constantly present in a small percentage of the population
Pandemic
Worldwide epidemic
