antimicrobial drugs

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Microbiology
Chapter 10
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1

1.What are the criteria for ideal antibiotics?

Selective toxicity
soluble in body fluid in (blood brain barrier)
Resists excretion (stays in the body long enough)
Shelf life
Doesn't lead to resistance
Cost not excessive
Hypoallergenic (natural or synthetic)

2

2.What is the danger of broad spectrum antibiotics?

Normal microbial flora will also be destroyed and can lead to a superinfection (when a surviving organism overgrows like fungus)

3

3.What are the actions of antimicrobial drugs?

Inhibition of cell wall synthesis (penicillins)
Inhibition of protein synthesis (erythromycin, tetracycline)
Inhibition of synthesis of essential metabolites *this makes an antimicrobial a "magic bullet" since bacteria has folic acid and we (humans) do not
Inhibition of nucleic acid replication and transcription (quinolones)

4

3.If an antimicrobial drug inhibits organelles that are 70s why is it not a "magic bullet" or in other words, why is it not an effective antimicrobial drug for humans?

In order for a drug to be a "magic bullet" it has to kill the pathogen but not hurt the host. Drugs that target organelles with 70s cannot be a magic bullet because mitochondria are also 70s and would be impacted by the drug.

5

4.What breaks the b-lactam ring?

Penicillinase

6

6.Where is all antibiotic resistance?

In the plasmid

7

7.Synergism

Occurs when the effect of two drugs together is greater than the effect of either alone. When combination of drugs provides the same effect at a fraction of the concentration of either alone

8

8.Antagonism

Occurs when the effect of two drugs together is less than the effect of either alone.

9

9.List ways in which antibiotics are misused

Using outdated, weakened antibiotics
Using antibiotics for the common cold and other inappropriate conditions
Use of antibiotics in animal feed
Failure to complete the prescribed regimen
Using someone else's leftover prescription

10

10.Nucleosides analogs

synthetic nucleosides which interfere with DNA and RNA synthesis

11

11.What is it called when a drug that kills harmful microbes without damaging the host?

selective toxicity

12

12.What is the use of drugs to treat a disease?

Chemotherapy

13

13.What interferes with the growth of microbes within a host?

antimicrobial drugs

14

14.What is a substance produced by a microbe that, in small amounts, inhibits another microbe?

antibiotic

15

15.Which spectrum have the least side effects?

Narrow spectrum - it only impacts certain types of pathogens (penicillin affects primarily Gram positive)

16

16.Antibiotics only work to destroy...

bacteria

17

17.Which spectrum antibiotics have a small range of pathogens they are effective against?

Narrow

18

18.Which spectrum antibiotics have a broad range of pathogens they are effective against?

Broad (effect Gram negative or Gram positive)

19

What are the types of symbiosis?

Mutualism, commensalism, and Parasitism

20

20.What is Mutualism?
both members benefit from their interaction; bacteria in the colon

both members benefit from their interaction; bacteria in the colon

21

21.What is commensalism?

one member of the relationship benefits without significantly affecting the other; microbiota on the skin

22

22.What is parasitism?

a parasite gets benefit while harming the host; fleas and mosquitos

23

23.What are the different types of microbiota?

Resident and transient

24

24.What are resident microbiota?

microbes that colonize the skin and mucous membranes of the body that are a part of a persons body for life.

25

25.What are transient microbiota?

microbes the remain in the body for a short time

26

26.What is axenic?

without normal microbiota such as the mother's womb

27

27.How are normal microbiota acquired?

through contact with mother and medical personel during and after birth

28

28.Describe three conditions that create opportunities for normal microbiota to cause disease.

1. Immune suppression 2. Changes in the normal microbiota 3. Introduction of a member of the normal microbiota into an unusual site in the body (translocation)

29

29.What can cause immunosuppresion?

disease, malnutrition, emotional or physical stress, age, use of radiation or chemotherapy, immunosuppressive drugs, alcohol, and recreational drugs

30

30.What are the three types of reservoirs of infection in humans?

Animal Reservoirs, Human carriers, and Nonliving Reservoirs

31

31.What is another name for an animal reservoir?

zoonoses

32

32.What are some routes for Zoonoses?

direct contact with animals and their waste, by eating animals, or bloodsucking arthropods

33

33.What is asymptomatic?

without symptoms

34

34.What is another name for non living reservoirs?

Fomites

35

35.Name some fomites

soil, water, food

36

36.What is the relationship between contamination and infection?

Contamination is the presence of microbes in or on the body; and infection is a successful invasion of microbes

37

37.Name the portals of entry

1. Skin 2. Mucous Membranes 3. Placenta 4. Parenteral Route

38

38.What are the types of adhesion factors?

adhesion disks, hooks, ligands (bind to complementary receptors on host cells)

39

39.What is disease?

Interferes with normal functioning of the body

40

40.How does biofilm facilitate contamination and infection?

The bacteria work together to form a sticky web that adheres to a surface within a host, this blocks the bodies defenses.

41

41.What is morbidity?

any change from a state of health

42

42.What is infection?

invasion of a pathogen

43

43.What is a sign?

signs are objective, they are observed or measured -->high heart rate, trembling

44

44.What is a symptom?

symptoms are subjective, they are felt --> anxiety, nausea

45

45.What is a syndrome?

a group of symptoms and sings that collectively characterizes a particular disease or abnormal condition

46

46.Define Etiology

the study of the cause of a disease

47

47.What are some limitations to Koch's postulates?

some pathogens cannot be cultured in the lab, some disease are caused by a combination of pathogens, ethical considerations

48

48.What is virulence?

the degree of pathogenicity

49

49.How do extracellular enzymes contribute to virulence?

enable pathogensto dissolve structural chemicals in the body to maintain an infection

50

50.How do toxins contribute to virulence?

either harm tissue or trigger host immune responses to cause damage

51

51.What are the two types of toxins?

Endotoxin and Exotoxin

52

52.What are exotoxins?

Exotoxins are secreted from the cell t0 destroy host cells or to interfere with metabolism

53

53.What are endotoxins?

Released fron bacteria when they divide, die naturally, or are digested

54

54.List the five stages of infectious disease

1. Incubation 2. Prodromal Period 3. Illness 4. Decline 5. Convalescence

55

55.List the modes of transmission

1. Contact 2. Vehicle 3. Vector

56

56.What are contact transmissions?

direct contact, indirect contact, droplet

57

57.What are vehicle transmissions?

Airborne, waterborne, fecal-oral, foodborne, and bodily fluid

58

58.What are vector transmissions?

biological vectors--> mosquitos
mechanical vectors -->houseflies' legs

59

59.Describe incidence

the number of new cases of a disease in a given area

60

60.Describe prevalence

TOTAL NUMBER of cases, both old and new in a given area during a given period of time

61

61.Describe endemic

a disease that normally occurs CONTINUALLY

62

62.describe sporadic

when only a few scattered cases occur within an area or population

63

63.describe epidemic

occurs at a greater frequency than is usual for an area or population

64

64describe pandemic

an epidemic occurs simulateously on more than one continent

65

65.Differentiate between contamination and infection.

contamination - mere presence of microbes in or on the body
infection - occurs when pathogens overcome the body's external defenses

66

66. pathogenicity

ability of a microorganism to cause disease

67

67- virulence

degree of pathogenicity

68

68.Generally speaking, what is a virulence factor?

variety of traits that enable pathogens to cause disease

69

69. contamination

mere presence of microbes in or on the body

70

70. infection

occurs when pathogens overcome the body's external defenses.

71

71.The portal of entry .

refers to the body site through which a microbe enters the tissues of the body.

72

72.The most common portals of entry are:

The skin, gastrointestinal tract, urogenital
tract, and respiratory tract.

73

73.Explain the role of adhesion

The process by which microorganisms attach themselves to a host

74

74. Adhesion factors

are specialized structures or proteins to help adhere. Most bacteria and viruses have glycoproteins/proteins (ligands) that help adhere to sites on a cell.

75

75.-Airborne:
-smaller droplets via aerosol.
-Waterborne:
-pathogen contaminated water.
-fecal oral.
-(giardia: common infection from drinking untreated water.)
-Foodborne:
-Pathogen in/on food.
Soil:
-Microbes resistant to drying.
-Bodily fluid transmission:
-BLood, urine, saliva, ejaculatory fluid.

types of vehicle transmission

76

76-adhesion disks --> protozoa
-suckers and hooks --> helminths
-ligands (adhesins and attachment proteins) --> bacteria and viruses

types of adhesion factors and the roles they play in infection

77

77.-Transmits pathogen
-Not required hosts
-Only moving from a to b
-No development of pathogen or organism

Mechanical vectors

78

78.-Transmits pathogen
-Serves as a host for pathogen
-EX: ticsk serve as biological vector of heartworm, developement of pathogen in the tick as the intermediate host.(IH)
-If a particular biological vector were to go extinct, so would the pathogen

Biological vectors

79

79.-Minimum number of microbes necessary to cause infection.
-Because infection must occur despite immune system response, an infection usually has potential to lead to disease.

infectious dose and assess its role in establishing an infection and disease.

80

80.What is an infectious dose(ID) ?

minimum number of microbes, size of the inoculum that is required for an infection to proceed.

81

81. Infectious doses are determined experimentally for many microbes;What role do infectious doses play in infection?

microbes with a smaller infectious dose have greater virulence.