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Microbiology > Chapter 34-35 > Flashcards

Chapter 34-35 Flashcards

(49 cards)

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1
Q

Host

A

Larger organism that supports the survival and growth of a pathogenic microorganism

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2
Q

Opportunistic pathogen

A

may be part of normal microbiota and causes disease when the host is immunocompromised

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3
Q

Pathogenicity

A

Ability of a pathogen to cause disease

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4
Q

Virulence

A

Degree of harm (pathogenicity) inflicted on its host

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5
Q

Extracellular pathogens

A

Remain in tissues and fluids but never enter host cells during disease

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6
Q

Intracellular pathogens

A

Grow and multiply within host cells

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7
Q

Incubation period

A

Time between pathogen entry and development of signs and symptoms

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8
Q

Prodromal stage

A

Mild, non-specific signs and symptoms.

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9
Q

Illness period

A

Disease is most severe and display signs and symptoms

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10
Q

Convalescence

A

Recovery stage

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11
Q

what does the host provide the pathogen?

A

protection. energy, and nutrients

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12
Q

Reservoir

A

Natural environmental location in which the pathogen normally resides

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13
Q

Vector

A

Organism that spreads disease from one host to another. Ex: mosquitoes, ticks, fleas

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14
Q

Zoonosis

A

a disease transmitted from animals to humans

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15
Q

what are the types of airborne transmission?

A

Droplets—direct transmission.
* Up to 2 mm in diameter.
* Produced when liquids are placed under force (saliva, mucus)
Droplet nuclei—indirect transmission.
* 1 to 5 μm in diameter
* May remain airborne for hours or days and travel long distances
Dust particles—indirect transmission.
* Aerosolized—smaller than 1 μm can be dispersed this way farther.
* Microorganisms adhere to dust particles.
* Can survive long periods outside host and can lead to hospital-acquired infections.

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16
Q

What are the types of contact transmission

A

Direct contact (person-to-person)
* Kissing, touching, and sexual contact
Indirect contact
* Involves an inanimate object (fomite) that transfers infectious agent between hosts.

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17
Q

what is a vehicle and what is vehicle transmission?

A

Vehicles
* Materials that indirectly transmit pathogens.
* Surgical instruments, drinking vessels, food, water, biological materials (fluids and tissues), and air

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18
Q

what is vector-borne transmissions?

A

living org. that transmits pathogens
usually arthropods (ticks, mosquitoes) or vertebrates (dogs, cats)
Pathogen benefit because extensive
reproduction and spread between hosts.
* Highly virulent and cause diseases
such as malaria

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19
Q

what is vertical transmission?

A

Occurs when the unborn child acquires a pathogen from an infected mother.
Called a “congenital” infection
Ex:
*Gonorrhea
* Syphilis
* Herpes
* German measles
* Toxoplasmosis

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20
Q

infectious dose

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A

Number of microbes required to cause disease in 50% of inoculated hosts

21
Q

what are the adherence structures?

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A
  • Pili
  • Fimbriae
  • Membrane and capsular materials.
  • Specialized adhesion molecules on microbe’s cell surface.
22
Q

Infectivity

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A

ability to create a discrete point of infection

23
Q

what is active invasiveness?

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A

spread to adjacent tissues through production of lytic substances that
alter host tissue

24
Q

what is passive invasiveness?

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A

spread to adjacent tissues and not related to the pathogen itself (skin lesions,
insect bites, wounds)

25
what is invasion?
Once under mucous membrane, a pathogen can penetrate deeper tissues
26
Bacteremia invasion
presence of viable bacteria in the blood
27
Septicemia invasion
bacterial or fungal toxins in the blood
28
what does the formation of an actin tail by intracellular bacterial pathogens do?
Actin tail propels bacteria to the host’s cell surface where it forms a protrusion. * Protrusion is engulfed by adjacent cell. * Evades immune response
29
what do microbes do to overcome host defenses?
* Produce Type VI secretion system (direct contact to deliver harmful molecule). * Find shelter to avoid recognition by defense cells. * Survive and replicate inside host cells. * Squeeze between host cells. * Make capsules to avoid phagocytosis. * Burrow under mucus. * Secrete exopolysaccharides to form communal shelters within biofilms. * Produce enzymes that inactivate innate (physical, chemical barriers) resistance mechanisms. * Excrete specialized proteins to selectively kill host cells.
30
Phage variation
switch among different genes that encode similar proteins
31
how do microbes evade and suppress the host's immune response? (5 ways)
- Production of decoy proteins to bind antimicrobial proteins. - Mutate cell surface proteins. - Reduce the number of cell surface proteins - infect cells of the immune system and diminish their function -Bacteria such as Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae produce a slippery mucoid capsule that prevents phagocytosis by host immune cells. - Eliminate O-antigen on lipopolysaccharide to diminish immune recognition and clearance
32
intoxications
diseases that result from entry of a specific preformed toxin into host. * Do not require the presence of the actively growing pathogen, just the toxin
33
exotoxins
-Often travel from the site of infection to other body tissues or target cells, where they exert their effects. - Encoded by genes on plasmids or prophages within bacteria. - Among the most lethal substances known
34
AB toxin
type of exotoxin A subunit catalyze reaction that cause toxicity B subunit binds to host-cell receptor
35
Superantigens
type of exotoxin Stimulate about 30% of host T cells of the immune system. - Causes the T cells to overexpress genes that encode cytokines and release pro-inflammatory molecules. - Results in failure of multiple host organs allowing time for the microbe to disseminate
36
Lipopolysaccharide (LPS)
type of ENDOTOXIN In Gram-negative cell wall is toxic to mammals. it is bound to the bacterium and released when the microorganism lyses Toxic component is the lipid portion, lipid A
37
what is an endotoxin?
-heat stable - most are similar in structure - cause shock, fever, diarrhea, etc.
38
Healthcare-acquired infections (HAI)
-5 to 10% of all hospital patients acquire a HAI. -Often caused by noninvasive bacteria from normal microbiota. -Many hospital strains are antibiotic-resistant
39
what are the endogenic sources of HAIs?
Endogenous sources * Catheter-associated UTI * Surgical site infections * Central line-associated bloodstream infections * Ventilator-associated pneumonias
40
Vaccine
Preparation of one or more microbial antigen that induce protective immunity
41
what are the types of whole-pathogen vaccines
Inactivated vaccines (killed) * Effective, but less immunogenic. * Often require boosters. Attenuated vaccines (live but avirulent) * Effective at stimulating both humoral and cell-mediated immunity. * Single dose Whole pathogen usually bad for immunocompromised people
42
acellular/subunit vaccines
Use of purified macromolecules derived from pathogenic microorganisms Forms of subunit vaccines: * Capsular polysaccharides. * Recombinant surface antigens. * Inactivated exotoxins (toxoids)
42
DNA Vaccines
DNA fragments introduced into host cell. DNA taken into nucleus and pathogen’s DNA fragment is expressed. * Host immune system responds to foreign proteins produced.
42
Recombinant-Vector Vaccines
Pathogen genes that encode major antigens inserted into nonvirulent viruses or bacteria which serve as vectors and express the gene product.
43
RNA Vaccines
Hurdles overcome in mRNA research: * Minimized RNA degradation. * Limited innate immunogenicity. * Designed a delivery system that would facilitate entry into the cell. COVID-19 vaccine
44
What kind of transmission is droplets?
Airborne direct come from coughing and sneezing
45
what type of transmission is droplet nuclei?
Airborne indirect small droplets can travel longer distances
46
what type of trasmission are dust particles?
indirect transmission comes from aerosolized droplets can survive for kong periods of time bc microbes attatch to dust and can cause Hospital Acquired Infections
47
what are the exogenic sources if HAIs?
Exogenous sources * Animate sources—hospital staff, patients, and visitors. * Inanimate sources—flowers, food, and computers.

Microbiology (12 decks)

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