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Microbiology > Lecture 1 & 2 > Flashcards

Lecture 1 & 2 Flashcards

1
Q

What are the three points of the triangle of conflicts?

A
  • patient
  • microbes
  • drug
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2
Q

A disease causing microbe can most commonly be acquired by a susceptible individual from what exogenous sources?

A
  • animals
  • food/water
  • humans
  • air/soil
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3
Q

What does exogenous mean?

A

An outside source

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4
Q

Colonization is the presence of microbes on the human body and does not contribute to disease. What class of microbe predominantly colonizes in humans?

A

Bacteria

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5
Q

What are the events that occur in the establishment of infectious diseases?

A
  • encounter
  • entry
  • spread
  • multiplication
  • damage
  • outcome
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6
Q

What does each event require?

A

It requires a breach of host defenses (gate keepers)

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7
Q

If there is a breach, what happens?

A

You’ll have microbes multiplying and spreading.

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8
Q

What is the cause of typhoid fever?

A

Salmonella typhi

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9
Q

Can Salmonella typhi be life threatening?

A

Yes

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10
Q

How many cases of S. typhi occur in the US per year? In the developing world?

A

5700 cases (21.5 million in the developing world)

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11
Q

How do sick people carry S. typhi?

A

They carry the organism in blood and the intestinal tract.

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12
Q

Describe S. typhi carriers.

A

They are asymptomatic, but still carry S. typhi bacteria.

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13
Q

How does S. typhi spread?

A

Via contaminated water and sewage; and by infected persons.

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14
Q

What is the typical incubation period of S. typhi?

A

60 to 90 days

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15
Q

What symptoms occur from S. typhi?

A
  • fever
  • malaise
  • anorexia
  • abdominal pain
  • diarrhea
  • enlarged spleen
  • septicemia
  • rash (in some)
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16
Q

Describe the carrier state of S. typhi.

A

Asymptomatic excretion of S. typhi in feces for over 1 year (3% of infected)

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17
Q

Who was Typhoid Mary?

A

Mary Mallon–a cook who infected 47 people; 3 died. She was forced to live on a NY island for 28 years until she passed away.

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18
Q

What is the infection flow chart for no transmission?

A

exposure –> incubation period –> no illness/illness –> infection clears –> no transmission

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19
Q

What is the infection flow chart for asymptomatic transmission?

A

exposure –> incubation period –> no illness/illness –> colonization or carrier state develops –> asymptomatic transmission

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20
Q

What is the infection flow chart for symptomatic transmission?

A

exposure –> incubation period –> illness –> symptomatic transmission

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21
Q

What is the relationship from patient to microbes?

A

host defenses

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22
Q

What is the relationship from microbes to patient?

A

morbidity

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23
Q

What are supportive measures?

A

Treatments other than drugs

24
Q

What supportive measures can be done in the case of an S. typhi infection?

A
  • oral/IV hydration
  • anti-pyretics
  • appropriate nutrition
  • blood transfusions
25
Q

What anti-microbial therapy can be done in the case of S. typhi infection?

A

*fluroquinolones (ciprofloxacin, perfloxacin) ; more effective than ampicillin, amoxicillin, and bactrim

26
Q

What is encounter?

A

Sterile existence in the mother’s womb

27
Q

What protection is there in encounter?

A
  • placenta (fetal membrane)

* blood is sterile

28
Q

When is the first encounter with microbes at birth?

A
  • vaginal canal (during birthing)

* contact with mother/family care

29
Q

What does the mother’s circulation provide to the fetus?

A

Passive protection of immunological for 6 months. After that, humans are on their own.

30
Q

Describe an endogenous encounter.

A

Some microbes are normally found on our skin or mucous membranes (normal flora)

31
Q

Why is it good for microbes to colonize humans?

A

Some species are good and that is great. However, there are some bad microbes.

32
Q

How do you make a distinction between colonization versus infection?

A
  • no clear distinction

* pathogens vs opportunists (commensals/breaching)

33
Q

What is exogenous?

A

external factors that originate outside the organism

34
Q

What is endogenous?

A

growing or originating from within an organism

35
Q

What various ways can disease causing microbes be acquired from the environment (exogenous)?

A
  • food
  • water
  • air
  • insect bites
  • animals
  • humans
36
Q

Infection is predominantly acquired from…

A

…an infected person (symptomatic) or a carrier (asymptomatic) through inhalation or contact (ingestion or sexual).

37
Q

Are most body sites sterile?

A

Yes

38
Q

What body sites are not sterile?

A
  • digestive tract

* lower genitourinary system

39
Q

What is ingress?

A

entry to mucosa occurs from a portal of entry (mouth, nose, or genitalia)

40
Q

What is penetration?

A

microbes gain direct access to a sterile site, crossing an epithelial barrier and go into blood–an example is sharing dirty needles

41
Q

What are some examples of ingress?

A
  • respiratory or salivary spread (not readily controllable)
  • fecal-oral spread (controllable by public health measures)
  • venereal spread (genital to genital contact) – difficult to control as social factors are involved
42
Q

What are some examples of penetration?

A
  • vector (biting arthropod) – examples are malaria, sandfly fever, and typhus
  • vertebrate reservoir (dog to human or farmers with sheep) – examples are rabies and Q fever
  • vector-vertebrate reservoir (flea to mouse to human) –examples are plague and yellow fever
43
Q

Describe ingress inhalation.

A

Inhalation of infective droplets either large or small can arrive in lower reaches of the respiratory tract.

44
Q

What host defense mechanisms are there against ingress inhalation?

A
  • cough reflex

* upward sweeping action of ciliary epithelium and upward flow of mucus

45
Q

What is the chemical disinfect chamber in humans?

A

The stomach–it is host defense I–the acid in the stomach

46
Q

When microbes escape the stomach, where do they go?

A

They enter the duodenum, but in reduced numbers. This is where host defense II is–pancreatic enzymes and bile salts in the duodenum and the sweeping force of peristalsis.

47
Q

What are the different host defenses of ingress ingestion?

A 
#1--acid in the stomach
#2--pancreatic enzymes and bile salts in the duodenum and the sweeping force of peristalsis
48
Q

How can penetration happen?

A
  • Microbes pass directly through multi-layered skin epithelia (insect bites)
  • Deeper invasion into the bloodstream via organ transplants and blood transfusions.
49
Q

What happens during spread/dissemination?

A

Microbes use a variety of arsenals to penetrate into the deeper tissues (mucosa –> lymphatics –> blood stream –> end organs (liver))

50
Q

What is multiplication?

A

Microbes multiply to a large number that can overwhelm the immunological defense system. (very few microbes survive initial host barriers, chemical and immunological onslaughts to make it to this point)

51
Q

What are the two types of damage microbes can do?

A
  • direct

* in direct (inflammation)

52
Q

Describe direct damage.

A
  • caused by microbial toxins

* inflicts cell death through: direct action of toxins or programmed cell death (apoptosis)

53
Q

Describe indirect damage.

A
  • meant to control infection via a local response to cellular injury
  • serves as a mechanism initiating the elimination of microbes and of damaged tissue
54
Q

What is inflammation useful for?

A
  • wounds

* wound healing

55
Q

Describe systemic inflammation.

A

It can be life threatening.

Microbiology (10 decks)

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