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BIO 246: Microbiology of Human Disease > Ch 11: Host-Microbe Interactions > Flashcards

Ch 11: Host-Microbe Interactions Flashcards

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1
Q

How are host microbes acquired?

A

during and after birth through contact with people, food and the environment

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2
Q

Which body sites are colonized mainly by bacteria?

A 
skin
upper respiratory
GI tract
external genitalia
outer urethra
vagina
external ear & eye
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3
Q

Sterile sites in the body contain no microbes in a healthy host. What are these areas?

A

internal tissues and organs

  • heart, lungs, liver, etc.
  • upper reproductive tract
  • sinuses & middle ear

fluids

  • blood
  • CSF
  • urine, saliva, semen
  • amniotic fluid
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4
Q

What are the benefits of normal flora?

A

microbial antagonism

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5
Q

What are probiotics?

A

supplements of live beneficial microbes (e.g. Lactobacillus)

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6
Q

What can normal flora deficiencies lead to?

A

antibiotic superinfections

infant botulism

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7
Q

What are the adverse effects from normal flora?

A

endogenous infections by opportunists
- staph infections (wounds, surgical sites)

- urinary tract infections (UTIs) are often caused by 
   intestinal bacteria (fecal contamination)
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8
Q

In a healthy host, normal flora bacteria are expected to be found in all the following locations EXCEPT:

A.  Oral cavity
B.  Vaginal tract
C.  Urinary bladder
D.  Skin
E.  Colon
A

C. Urinary bladder

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9
Q

“Good” bacteria, or _____ , can be ingested to boost the normal flora of GI tract.

A

probiotics

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10
Q

What are the biosafety levels?

A 
BSL-1 (non-pathogens)
 - Open bench
BSL-2 (opportunists)
 - Gloves & coats
BSL-3 (treatable true pathogens)
 - Safety cabinets & vaccinations
BSL-4 (untreatable true pathogens)
 - Isolation & decontamination
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11
Q

What factors influence infection?

A

microbial pathogenicity
- virulence factors (e.g. adhesins, toxins) promote infection

condition of host defenses
- healthy or compromised

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12
Q

What is the difference between true and opportunistic pathogens?

A

true pathogens cause infection in anyone

opportunistic pathogens cause infection in compromised hosts

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13
Q

compromised hosts are more susceptible to infection. What can compromise the host?

A 
injury or surgery
age
immune deficiencies
other disease or infections
drug therapies
pregnancy
stress
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14
Q

What does a host provide for a pathogen?

A

host provides resources for the pathogen’s reproduction and transmission

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15
Q

What must a pathogen be able to do?

A

a pathogen must be able to…

  1. access portal of entry
  2. colonization
  3. survive host defenses
  4. causing damage
  5. access portal of exit
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16
Q

What are the portals of entry a pathogen must access to get into host?

A

skin & eyes
gastrointestinal tract
respiratory tract
genitourinary tract

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17
Q

What is the infectious dose?

A

the minimum number of microbes at the portal of entry required to establish infection

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18
Q

What are adhesion factors?

A

Factors affecting pathogen colonization

bacteria

  • glycocalyx
  • fimbriae

viruses
- spikes

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19
Q

What are the features of surviving host defenses?

A

antiphagocytic factors prevent elimination by host phagocytes

leukocidin is a toxin that kills WBCs (S. aureus)

capsule prevents adherence to phagocytes (S. pneumoniae)

some bacteria can survive inside phagocytes (M. tuberculosis)

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20
Q

What are the antiphagocytic factors of S. aureus?

A

coagulase produces a protective fibrin “shield” around the bacteria

phagocytes cannot eat bacteria

staphylokinase dissolves clot and releases the bacteria after multiplication

and the process repeats…

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21
Q

How do pathogens cause damage to host?

A

Exoenzymes
Endotoxins
Exotoxins

22
Q

What are exoenzymes?

A

damage host tissues and promote invasion

  • mucinase
  • hyaluronidase
  • collagenase
23
Q

What are exotoxins?

A

proteins excreted by some G+ & G- that are toxic in small doses and specific to cell type

24
Q

What are the types of exotoxins?

A

CYTOTOXINS
cell lysis/tissue damage
invasion, nutrients, weaken host, transmission
anthrax and whooping cough

NEUROTOXINS
paralysis
weaken host
tetanus and botulism

ENTEROTOXINS
fluid secretion and peristalsis in GI tract
transmission
food poisoning

25
Q

What are endotoxins?

A

lipopolysaccharide (LPS) released from outer membrane of dead G- bacteria is toxic in large doses and produces general damaging effects

26
Q

What are the effects of endotoxins?

A

inflammation
fever
coagulation

27
Q

What are the portals of exit for a pathogen?

A

Used to transmit to other hosts

Feces
Urine
Open lesions
Coughing/Sneezing
Insect Bites
28
Q

Which enzyme is produced by Staphylococcus aureus that hides the bacteria from host phagocyte?

A

coagulase

29
Q

When lipopolysaccharide is released from dead gram-negative bacteria, it is called ______ because it causes inflammation and fever.

A

endotoxin

30
Q

What is a disease reservoir?

A

can be living or nonliving
where the pathogen survives and multiplies
allows transmission to host

31
Q

What are the characteristics of a human disease reservoir (carrier)?

A 
asymptomatic
incubating
convalescent
chronic
passive
32
Q

What are the characteristics of a animal disease reservoir (carrier)?

A

zoonotic infections

  • Rabies from animal bite
  • Salmonellosis from eating contaminated poultry
  • Lyme disease from deer/mice via ticks
33
Q

What are some examples of non-living disease reservoirs?

A

soil
- tetanus

water
- cryptosporidiosis

34
Q

What are the types of transmission?

A

communicable or noncommunicable
- contagious

direct or indirect
- vehicle

horizontal or vertical
- placental or perinatal

35
Q

What are examples of direct transmission?

A

A to B

contact
- touching, kissing, biting, sex

droplet

  • sneeze, cough
  • <1 m distance between reservoir and host
36
Q

What are biological vectors?

A

Method of direct transmission

  • blood-feeding arthropods
  • ticks, mosquitoes, fleas, etc.
37
Q

What are examples of indirect transmission?

A

A to B to C using vehicles

fomites
blood, serum, &amp; tissues
soil &amp; water
food
fecal-oral transmission
38
Q

What is a nosocomial infection?

A

healthcare-acquired (HA)

39
Q

How do nonsocomial infections occur?

A

compromised hosts
pathogens
chain of transmission

40
Q

How do we prevent nosocomial infections?

A 
WASH HANDS!
universal precautions
PPE
microbial control
isolation
monitor for outbreaks
41
Q

An inert object or surface, like a doorknob or money, that serves indirectly transmit infection is called a:

A

fomite

42
Q

Rabies is a ______ infection because it is acquired from an animal reservoir.

A

zoonotic

43
Q

What are koch’s postulates?

A

systematic method used to establish the etiologic agent of disease

  1. Find evidence of a particular microbe in every case of a disease.
  2. Isolate that microbe from an infected subject and cultivate it in pure culture in the laboratory (b); perform full microscopic and biological characterization (a).
  3. Inoculate a susceptible healthy subject with the laboratory isolate (c) and observe the same resultant disease (d).
  4. Reisolate (f) the same agent (e) from this.
44
Q

Why did Warren & Marshall win the 2005 Nobel Prize in Physiology or Medicine?

A

showed that gastric ulcers were caused by a bacterium called H. pylori

45
Q

What is epidemiology?

A

the study of disease in populations

frequency & distribution data

46
Q

What is the difference between incidence and prevalence?

A

incidence
- new cases in time period (per 100,000)

prevalence
- total existing cases (% of population)

47
Q

What was recommended once it was learned that the pertussis vaccine only protected for 10 years?

A

Booster shot

48
Q

What was recommended once it was learned that mosquito-borne WNV was spreading westward?

A

Eliminate standing water
Spray for mosquitoes
Monitor birds for WNV
Warn public

49
Q

What terms can be used to describe the incidence of disease?

A

endemic - only among specific group of people
sporadic - occasional
epidemic - widespread in community
pandemic - worldwide

50
Q

What are the types of epidemics?

A

point-source epidemic: e.g., contaminated food at party

common-source epidemic: e.g., contaminated town water supply

propagated epidemic: eg. TB is spread person-to-person

51
Q

Warren and Marshall discovered the link between H. pylori and gastric ulcers. What observation did NOT follow Koch’s postulates?

A. H. pylori was isolated from the stomachs of patients with ulcers

B. When Marshall drank a H. pylori culture he developed ulcers

C. When H. pylori was eliminated with antibiotics, the ulcers went away

D. Some people who did not have ulcers had H. pylori in their stomachs

A

D. Some people who did not have ulcers had H. pylori in their stomachs

52
Q

When John Snow discovered a sewage-contaminated well was the source of a cholera outbreak, he asked city officials to remove the Broad Street water pump handle. This epidemic can be described by all the following EXCEPT:

A.  Common-source epidemic
B  Fecal-oral transmission
C.  Vehicle transmission
D.  Indirect transmisison
E.  Nosocomial infection
A

E. Nosocomial infection

BIO 246: Microbiology of Human Disease (22 decks)

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