Module 5: Microbial and Host Interactions Flashcards
Normal Flora
- bacteria found on skin and mucous membranes
- fairly constant composition
Transient Normal Flora
- present for short time only
- caused by antibiotics, hospitalization
Contamination
- bacteria present are not normal flora
- bacteria not growing on site
ex. fecal contamination of hands or wounds
Colonization
- bacteria present are growing at site
- no host reaction to bacteria
Infection
- bacteria growing at a body site cause an immune reaction
ex. fever, inflammation, pus
Pathogenicity
Ability of a microorganism to cause disease
Virulence
Degree of pathogenicity of a bacterium
Pathogen
Microorganisms capable of causing disease
Hyaluronidase
Extra cellular enzyme mainly produced by gram positive bacteria
Collagenase
- breaks down collagen in connective tissue
- bacteria spread faster into tissue
Hemolysins
Lyse red blood cells
Leukocidins
Kill phagocytic white blood cells causing pus or exudate
Kinases
Break down fibrin clots formed by the body to isolate infecting bacteria
Exotoxins
- mainly produced by gram positive bacteria
- specific site of action in host
- antigenic (causes an immune response)
Endotoxins
- produced by gram negative bacteria
- not antigenic
- non specific sites in host affected
- part of cell wall
Inflammation
- histamine released at site of infection
- swelling, redness, pain, heat
Serous
Watery fluid, few neutrophils
Transudate
Noncellular fluid, passive leak from blood or lymph vessels
Purulent
WBC’s or PMN’s at the infection site causes pus.
Granulomatous Infection
Granuloma at site of infection contains large macrophages
Cellulitis
Under the skin loose connective tissue, fluid spreads between layers causing swelling and redness
Epidemic
Many people in an area having a disease over a short period of time ex. Bubonic Plague
Endemic
Small percentage of population constantly has a disease
ex. Pneumonia
Pandemic
World wide epidemic ex.Spanish Flu
Epidemiology
Study of when and where diseases occur
Endogenous Infection
Infecting bacteria are from your own body
ex. UTI
Exogenous Infection
Infecting bacteria come from outside the body
ex. Strep Throat
Nosocomial
Infection acquired from the hospital environment
Carrier
Person carries potential pathogens without it causing harm
Primary
Initial infection caused by bacterium
Secondary Infection
An infection following a primary infection and usually caused by a different bacterium
Nonspecific Infection
Bacterial cause of infection is not identified
Opportunistic
Low grade pathogen causes infection in immunosuppressed or chronically ill patients
Acute Infection
Short duration but nasty
ex. salmonella (5-10 days)
Chronic Infection
Long lasting
ex. reoccurring yeast infection
Localized Infection
Restricted to a small area
ex. skin lesion
Disseminated Infection
Infection spread to many body areas
ex. bacteria in bloodstream
