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Microbiology and Microorganisms: Definitions and Interactions, Quizzes of Microbiology

Definitions and explanations for various terms related to microbiology, including the normal microbiota, symbiosis, mutualism, commensalism, parasitism, and disease. It also discusses the benefits of mutualism to the host, the concept of a niche, and the criteria for microbial pathogenicity.

Typology: Quizzes

2012/2013

Uploaded on 07/18/2013

cantwell77515
cantwell77515 🇺🇸

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TERM 1
The normal microbiota or microflora
DEFINITION 1
An ever-present dynamic population of microorganismsthat
inhabits most of our epithelial/mucosal surfaces
TERM 2
Symbiosis
DEFINITION 2
living together or close association of two dissimilar
organisms
TERM 3
Mutualism
DEFINITION 3
beneficial to both (microbe & host)
TERM 4
Commensalism
DEFINITION 4
beneficial to one (microbe) , neither harmful or beneficial to
other (host
TERM 5
Parasitism
DEFINITION 5
beneficial to one (microbe), harmful to the other (host) =
pathogenic
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The normal microbiota or microflora

An ever-present dynamic population of microorganismsthat inhabits most of our epithelial/mucosal surfaces TERM 2

Symbiosis

DEFINITION 2 living together or close association of two dissimilar organisms TERM 3

Mutualism

DEFINITION 3 beneficial to both (microbe & host) TERM 4

Commensalism

DEFINITION 4 beneficial to one (microbe) , neither harmful or beneficial to other (host TERM 5

Parasitism

DEFINITION 5 beneficial to one (microbe), harmful to the other (host) = pathogenic

Mutualism Benefits to the Host

synthesize and excrete vitaminsenteric bacteria secrete Vitamin K and Vitamin B12 / germ-free animals Vit K deficient lactic acid bacteria produce certain B-vitaminsprevent colonization by pathogenspossibly most important beneficial aspectcompete for attachment sites &/or for essential nutrientsgerm-free animals infected by 10 Salmonella; ID for normal animals is ~ 106 TERM 7

Mutualism Benefits to the Host -Continued

DEFINITION 7 antagonize/ control other normal flora & pathogenic bacteriaproduction of substances which inhibit or kill other indigenous bacteriarelatively nonspecific fatty acids and peroxides to highly specific bacteriocins stimulate the production of cross- reactive antibodiesantigenic primingbehave as antigens & induce an immunological responsecross react with certain related pathogens"natural" antibodies - lacking in germ-free animals TERM 8

What % of the cells you carry around

everyday are you & what % are microbes?

DEFINITION 8 ~91% microbes, ~9% humanmore bacterial cells (~10^14) associated with your body than there are human ones (~10^13) TERM 9

ECOLOGY

DEFINITION 9 relationship between living organisms & their environment TERM 10

Physical (Host) Factors

DEFINITION 10 nature of host tissue surfaceoxygen availability pHtemperatureavailable nutrients

some microorganisms exclusively associated

with disease

Vibrio choleraeYersinia pestis TERM 17

some microorganisms very rarely cause

disease (NON-PATHOGENS

DEFINITION 17 Micrococcus speciesLactobacillus species TERM 18

many microorganisms between these two

extremes

DEFINITION 18 Escherichia coliStaphylococcus aureusStreptococcus pneumoniaPseudomonas aeruginosa TERM 19

How do exogenous pathogens get to

you?

DEFINITION 19 pass from one person to another TERM 20

Modes of Transmission

DEFINITION 20 congenitaldirect contactaerosol/respiratoryingestiontraumaIV transfusion / percutaneoussexual

Portals of Entry -for exogenous

pathogens

skin Staphylococcus aureus respiratory tract Mycobacterium tuberculosisgastrointestinal tract Salmonella typhigenitourinary tract Treponema pallidum TERM 22

OPPORTUNISTIC PATHOGENS

DEFINITION 22 microorganisms that are capable of producing disease given the opportunitymany opportunistic pathogens are members of the normal microbiota TERM 23

OPPORTUNITIES FOR OPPORTUNISTIC

PATHOGENS

DEFINITION 23 impaired host defense immunocompromised / chemotherapy / antibiotic treatmentaccidental access to blood or tissues TERM 24

Antibiotic-induced opportunistic infection -

Pseudomembranous colitis

DEFINITION 24

  • diarrhea, yellowish-white plaques on colonic mucosa, may be life threatening - caused by treatment with clindamycin & other broad spectrum antibiotics - frequently used to treat B. fragilis infections
  • other normal colonic bacteria are also sensitive to clindamycinClostridium difficle - normal microbiota in ~ 3% of population - naturally resistant to clindamycin - overgrowth of C. difficle causes pseudomembraneous colitis TERM 25

Accidental access of normal microbiota to

blood or tissues of host

DEFINITION 25 Streptococcus sanguinis Gram-positive facultative coccus - normal inhabitant of dental plaque - entry into bloodstream & colonize heart valves - most common cause of bacterial endocarditis