1.04 - Pathogenesis of Bacterial Infections & Host Resistance to Infections

Question 1

In Acid Fast Stain, what is the color of the stain that Mycobacterium would have?

Answer 1

RED

Its background will be BLUE

Question 2

It is the the scientific study of the structure, development, function and mode of action of all microorganisms especially with regard to their significance in health and disease.

Answer 2

Microbiology

Question 3

It is a laboratory equipment that protects you from the organisms and protects the organism from the environment.

Answer 3

Biosafety Cabinet

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Question 4

➢ Used for identification of microorganisms
➢ Old method, inoculum will be loaded in the tray and after 24h incubation, read/score
basing on chart colors.

Answer 4

BBL Crystal

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Question 5

➢ Used for bacterial identification (specific) automated identification
➢ Gives a reading depending on the organism that you are looking for

Answer 5

VITEK 2

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Question 6

➢ A laboratory equipment where blood culture bottles are inserted into specific slots

Answer 6

Blood Culture Machine

**If an organism will grow, the machine will alarm.

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Question 7

Used for Mycobacterium tuberculosis culture

Answer 7

BACTEC MGIT 960

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Question 8

These are the organisms that live on another living organism (human or animal) or inanimate object without causing disease

Answer 8

Normal Microbial Flora

Question 9

TRUE or FALSE. We become colonised by bacteria from the moment we are born.

Answer 9

True

Question 10

Why are viruses and parasites not considered member of the microbial flora?

Answer 10

Because they:
➢ Are not commensals
➢ Do not aid the host

Question 11

Normal microbial flora enters the body through? (2)

Answer 11

Nasal and/or Oral

Question 12

Normal microbial flora inhabiting the skin?

Answer 12

Gram-positive organisms

staphylococci, micrococci, diptheroids

Question 13

They inhabit the gingival crevice

Answer 13

Streptococcal anaerobes

Question 14

The PHARYNX can be a
- point of entry, and
- initial colonization
for which bacteria?

Answer 14

✓ Neisseria
✓ Bordetella
✓ Corynebacterium
✓ Streptococcus spp

Question 15

What keeps the population of the organisms in the stomach low?

Answer 15

Stomach acidity or acid

Question 16

It is a potential pathogen that apparently plays a role in the formation of certain ulcer types

Answer 16

Helicobacter pylori

Question 17

True or False.

▪ Ileum is sparse in normal host.
▪ Duodenal flora contains a moderately mixed flora.

Answer 17

FALSE.

▪ Duodenal flora is sparse in normal host
▪ Ileum contains a moderately mixed flora

Question 18

Large bowel flora is dense and is composed predominantly of what?

Answer 18

anaerobes

Question 19

The anaerobes in the large bowel flora participate in which processes?

Answer 19

✓ Bile acid conversion

✓ Vitamin K and ammonia production in the large bowel

Question 20

The vaginal flora changes with the? (3)

Answer 20

✓ Age of the individual
✓ Vaginal pH
✓ Hormone levels

Question 21

Give an example of a Transient organism that frequently cause vaginitis

Answer 21

Candida spp

Question 22

Species of bacteria that exists as normal flora of females

Answer 22

Lactobacillus

Question 23

Conjunctiva harbors few or no organisms but these two (2) are among the genera most often detected. State them.

Answer 23

Haemophilus and Staphylococcus

Question 24

It is the capacity to initiate a disease or how a disease occurs

Answer 24

Pathogenesis

Question 25

State the common bacteria that may be seen in the "skin" of a healthy individual but may cause disease in an immunocompromised host

Answer 25

✓ Staphylococcus aureus ✓ Staphylococcus epidermidis ✓ Propionibacterium acnes

Question 26

Type of infection that is initiated in the hospital

Answer 26

Nosocomial Infection

Question 27

It's the ability of the organism to breach the new host’s defenses

Answer 27

Infectivity

Question 28

Denotes the capacity of a pathogen to harm the host

Answer 28

Virulence

Question 29

Transmission occurs when the agent leaves its ___(1)___ or host through a __(2)__, is conveyed by some __(3)__, and enters through an appropriate __(4)__ to infect a __(5)__. This sequence is sometimes called the Chain of Infection.

Answer 29

1. reservoir 2. portal of exit 3. mode of transmission 4. portal of entry 5. susceptible host

Question 30

These are pathogens that are capable of establishing infection and causing disease in previously healthy individuals with intact immunological defenses

Answer 30

Primary pathogens

Question 31

They are pathogens that infect when defenses are impaired/compromised

Answer 31

Opportunistic pathogens

Question 32

State the two species that part of the normal human flora (skin/mucosal surface) where they cause no harm and may actually have beneficial effects

Answer 32

1. Coagulase negative staphylococci 2. E. coli They prevent colonization by other potential pathogens

Question 33

Factors that can cause the disease. (2)

Answer 33

1. Number of the pathogen’s presence - normal flora depletion --> pathogens adhere to cells 2. Reduced peristalsis (in the intestine) - normal flora is not adherent to the mucosal surfaces --> the pathogenic bacteria would adhere to the surfaces

Question 34

Koch Postulates. Which is wrong? a. The suspected pathogen must be present in all cases of the disease and in healthy animals. b. The suspected pathogen must be grown in pure culture. c. Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal. d. The suspected pathogen must be re-isolated and shown to be the same as the original. e. Everything is wrong f. Everything is correct.

Answer 34

Letter A is wrong. The suspected pathogen must be present in all cases of the disease and ABSENT from healthy animals. If you got that wrong, read the Koch Postulates again. Ò.Ó

Question 35

State the steps involved in the Pathogenesis of bacteria. (TCAIST)

Answer 35

``` Transmission Colonization Adhesion Invasion Survival in the host Tissue Injury ```

Question 36

It is the establishment of a stable population of the bacteria on the host’s skin or mucous membranes.

Answer 36

Colonization

Question 37

It is where the bacteria REMAINS ADHERENT at the site of colonization in order to proliferate

Answer 37

Adhesion

Question 38

True or False. Adhesion comes prior to invasion

Answer 38

False. Adhesion comes prior to colonization

Question 39

Adhesion involves surface interactions between __(1)__ on the mammalian cell membrane and __(2)__ on the bacterial surface

Answer 39

1. Receptors (on the mammalian cell) | 2. Ligands (on the bacterial surface)

Question 40

It is the penetration of the organism to the host cells and tissues

Answer 40

Invasion

Question 41

Invasion is mediated by a complex array of molecules, described as?

Answer 41

Invasins

Question 42

Also known as aggressins, and facilitate pathogenesis

Answer 42

Virulence determinants

Question 43

Physical defense, such as intact skin, is what kind of defense?

Answer 43

First line of defense (Physical Barriers) This includes: - Skin - Mucous membranes - Chemicals

Question 44

Neutrophils and lymphocytes are what kind of defense?

Answer 44

2nd line of defense: Which also includes: - Phagocytosis - Complement interferon - Inflammation - Fever

Question 45

Examples of so genetic vehicles from which virulence genes can move from one bacteria to another. (3)

Answer 45

Plasmids Bacteriophage Transposons

Question 46

Antibody and complement alone is considered as what type of pathway?

Answer 46

Classical pathway

Question 47

Complement alone is what type of pathway?

Answer 47

Alternate pathway **compared to "Antibody and complement alone" which is the "classical pathway"

Question 48

It is a secretion of Staphylococcus aureus which prevents phagocytosis

Answer 48

Protein A secretion

Question 49

Protein M secretion is an anti-phagocytic component of fimbriae of?

Answer 49

Streptococcus pyogenes

Question 50

A type of immunization where antibodies are directly injected or small dose of antigen is injected into the body in order for us to react and form antibodies

Answer 50

Passive Immunization

Question 51

A type of immunization where we had the disease and we have memory B cell forming antibodies against it

Answer 51

Acquired Immunization

Question 52

In acquired immunization, this will be activated and it would be able to recognize that antigen and fight the disease

Answer 52

Memory B cell

Question 53

They are usually secreted by gram positive bacteria and are sufficiently POTENT that serious effects often result.

Answer 53

Exotoxins

Question 54

Give examples of exotoxins. (4)

Answer 54

botulism anthrax cholera diphtheria

Question 55

Are toxic components of the bacterial cell envelope

Answer 55

Endotoxins

Question 56

What is the most potent endotoxic?

Answer 56

Lipopolysaccharide

Question 57

What happens when endotoxins incite the Kupffer cells?

Answer 57

increase interleukin 1 and Tumor Necrotic Factor --> which cause FEVER

Question 58

What causes vasodilation of the vessels?

Answer 58

Endotoxins incite the NEUTROPHILS, which increases the production of kinins --> this causes dilatations of the vessels

Question 59

What is activated if the endotoxins are secreted in small amounts?

Answer 59

Memory B-cells or B lymphocytes

Question 60

What happens when endotoxins are secreted in large amounts?

Answer 60

bigger increase in interleukin-1 & Tumor Necrosis Factor --> body would go into shock or intravascular coagulation