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Medical Microbiology 1-15 > Lecture 15 > Flashcards

Lecture 15 Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

Define chemotherapy.

A

A treatment of diseases with chemical compounds.

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2
Q

Who coined chemotherapy and in what century? By which means did he make this discovery?

A

1900s by Paul Ehrlich. Discovered the first antibacterial chemotherapeutic agent.

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3
Q

What was Paul Ehrlich’s the agent called and what was it effective against?

A

Salvarsan 606. Treponema pallidum, the causative agent of syphilis.

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4
Q

Define what infectious diseases are.

A

Diseases caused by microbes

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5
Q

True or false. Chemotherapeutic agents are prepared synthetically in the lab.

A

True.

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6
Q

True or false. Byproducts of the metabolic activity of bacteria and fungi are known to be a antibiotic and not chemotherapy.

A

True.

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7
Q

Name the four ideal properties of an antimicrobial chemotherapeutic agent.

A

1: Must be selectively toxic
2. They must be effective against several pathogens
3. The host should not become allergic
4. The microbes should not become resistant to them.

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8
Q

Define what “selectively toxic” means.

A

They can kill or inhibit the growth of the microbe but they are not toxic to the cells of the host.

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9
Q

What are sulfonamides also considered and who discovered them and what year?

A

Also known as sulpha drugs, Gerhard Domagk in 1935.

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10
Q

How did the discovery of the sulfonamide occur?

A

In 1933, a red dye called Prontosil was reported to have cured staphylococcus and to be effective against streptococcal as well.

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11
Q

True or false. Because sulfonamides cause toxic sides effects, researchers later discovered similar compounds with less side effects.

A

True

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12
Q

Name four bullet points of the sulfonamides.

A

1: They are absorbed in the blood stream when taken orally.
2: They are excreted in the urine.
3: They damage the kidneys because they crystallize under acidic conditions.
4: Some are not absorbed by the intestines.

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13
Q

What are sulfonamides best used for in terms of treating infections?

A

Intestinal infections or as an intestinal antisepsis prior to intestinal surgery. ie. Sulfasuxidine and Sulfathalidine

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14
Q 
Here is a list of potentially susceptible bacteria:
staphylococci
streptococci
E.coli
Enterobacter aerogenes
Proteus vulgaris
Haemophilus influenza
Neisseria meningitis.
Explain why sulfonamides are not used as much as they used to.
A

Because some bacteria sulfonamide-resistant are now prevalent.

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15
Q

What are sulfonamide still used for?

A

Urinary infections

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16
Q

Sulfisoxazole is treated for cytisis
Septra for urinary tract infection
Sulfatrim for prostatitis
What are the combination of trimethoprim and sulfamethoazole for Septra and Bactrim

A

1:5 combination

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17
Q

What is the mechanism of action of the sulfonamides?

A

They inhibit the synthesis of folic acid, a vitamin required by bacteria.

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18
Q

What does the acronym PAS stand for?

A

Para-aminosalicylic acid

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19
Q

Name 3 points of PAS

A

1: It’s weakly active against Mycobacterium tuberculosis
2: It was used concurrently with the antibiotic streptomycin in the treatment of tuberculosis.
3: It reduced the cells that are resistant to M. tuberculosis.

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20
Q

What does INH

A

Isonicotinic acid hydrazide

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21
Q

True or false. The INH is very active agains M tuberculosis and has negligible effects on most other bacteria.

A

True

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22
Q

True or false. INH is currently being used with streptomycin or ethambutol to reduce the possibility that cells of M.tuberculosis, resistant to streptomycin or ethambutol, will be selected out of the population.

A

True

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23
Q

True or false. INH is use as means of precaution (prophylactically) against M. tuberculosis for up to 6 months.

A

False. Up to 12 months.

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24
Q

Name the four antibiotics that inhibit protein synthesis

A

1: Chloramphenicol
2: Tetracyclines
3: Erythromycin
4: Streptomycin

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25
Q

What actinomycete is Chloramphenicol produced by?

A

Streptomycines venezuelae

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26
Q

Define actinomycete

A

They are mold like bacteria

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27
Q

True or false. Chloromycetin, the brand name of Chloramphenicol, is the only antibiotic synthesized chemically rather than isolated as a product of microbial metabolism.

A

True

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28
Q

True or false. Chloramphenicol is not a bacteriostatic

A

Fale. It is.

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29
Q

What is Chloramphenicol used to treat mainly?

A

Typhoid fever, paratyphoid fever and rickettsial infections.

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30
Q

Why is Chloramphenicol not used for an extensive period of time, except for ear drops?

A

It causes bone marrow depressions that could lead up to aplastic anemia.

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31
Q

Define aplastic anemia

A

When your body does not produced new blood cells. It leaves you feeling fatigued and susceptible in catching infections.

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32
Q

Describe Chloramphenicol’s mechanism of action.

A

The inhibition of protein synthesis in the procaryotic cells.

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33
Q

True or false. Tetracyclines are a group of antibiotics with each possessing different physical and pharmacological properties.

A

True

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34
Q

From what species are the Tetracyclines deprived from?

A

The bacterial genus Streptomyces

35
Q

True or false. The tetracyclines are bacteriostatic

A

True

36
Q

What infections are Tetracyclines mainly used for?

A

Rickettsial infections, chlamydial infections, brucellosis, tularaemia and cholera.

37
Q

Define Rickettsiae

A

Intracellular parasitic bacteria similar to Gram-negative bacterial and have anthropods as vectors.

38
Q

Define Chlamydia

A

Intracellular parasitic bacteria, similar to Gram negative bacteria. They have a complex way to reproduce that differs them from Rickettsiae. They are not transmitted by arthropods.

39
Q

What type of antibiotic is Erythromycin?

A

Macrolide

40
Q

True or false. The producing bacterias for Erythromycin is Strptomyces erythreus

A

True

41
Q

True or false. The spectrum of activity is similar to that of penicillin G (Gram positive bacteria, N gonorrhoea, N meningitidis and spirochetes.

A

True

42
Q

For what disease is Erythromycin the antibiotic of choice for?

A

Legionnaires’ disease.

43
Q

True or false. Erythromycin is not a bacteriostatic.

A

False. It is.

44
Q

Define Erythromycin’s mechanism of action?

A

Inhibition of protein synthesis in procaryotes

45
Q

True or false. Streptomycin is an amino glycoside antibiotic?

A

True

46
Q

Who discovered Streptomycin?

A

A. Waksman

47
Q

What is the producing bacterium for Streptomycin?

A

Streptomyces griseus

48
Q

True or false. Streptomycin is a bacteriostatic.

A

False. It’s a bactericidal

49
Q

What disease is Streptomycin mainly used for?

A

Mycobacterium tuberculosis.

50
Q

What is the mechanism of action of Streptomycin?

A

Initiation of protein synthesis in procaryotes.

51
Q

Name other amnoglycoside antibiotics

A

Amikacin, gentamycin, kanamycin, neomycin, spectinomycin and tobramycin

52
Q

True or false. Streptomycin is an aminoglycoside. Elaborate.

A

False. It’s a amonocyclietol, however, it shares chemical, pharmacological and antimicrobial properties with amonoglycosides.

53
Q

Define a side effect of prolonges use of the amonoglycoside antibiotics.

A

Damage to the eight cranial nerve, hearing impairment and kidney damage.

54
Q

Name two antibiotics that inhibit cell wall synthesis

A

Penicillins

Cephalosporins

55
Q

What year was penicillin made available for treatment?

A

1943

56
Q

Who discovered penicillin?

A

A Fleming in 1929

57
Q

True or false. Penicillins are called beta-lactam antibiotics due to the fact that they possess a beta-lactam ring in their structure.

A

True.

58
Q

The penicillin produced in cultures of Penicillium notatum and Penicillium chrysogenum is actually a mixture of ___ penicillins.

A

Five.

59
Q

Name the five natural penicillins

A

X,G,F, dihydro F and K

60
Q

Name the most frequently prescribed natural penicillin

A

Benzyl penicillin (Penicillin G).

61
Q

True or false. Penicillins inhibit a terminal step in peptidoglycan biosynthesis and are bactericidal.

A

True

62
Q

Name the four potentially susceptible bacteria that penicillin treats

A

1: Gram-positive bacteria
2: Neisseria gonorrhoeae
3: Neisseria meningitidis
4. Spirochaetes

63
Q

Name three limitation of a natural penicillin

A
  1. Easily destroyed by acids- not effective when taken orally.
  2. They are destroyed by the enzyme penicillinase (beta lactase). Staph, gonorrhoea is therefore resistant to penicillin.
  3. They are considered narrow spectrum antibiotic considering that they are only effective against Gram-positive bacteria.
64
Q

Give an example of a penicillin that is more resistant to acid.

A

Phenoxymethyl penicillin (penicillin V). This happens when phenooxyacetic acid is added to penicillin.

65
Q

Name two ways in which to create semisynthetic penicillins

A
  1. Chemically removing a side chain and adding a new one.

2. interrupting the synthesis of penicillin at 6 amino penicillanic acids and then chemically adding one.

66
Q

Name four semisynthetic penicillins

A

Methicillin and Oxacillin ( resistant to penicillinase)

Ampicillin and Amoxicillin (broader spectrum of activity and they are effective against certain Gram negative bacteria.

67
Q

Which species is the Cephalosporins produced by?

A

Cephalosporium species.

68
Q

True or false. Cephalosporin is a mild genus.

A

True

69
Q

True or false. Cephalosporins are beta-lactam making them different than penicillins

A

False. This is a common trait that penicillins and Cephalosporins have

70
Q

When was the first generation Cephalosporins discovered?

A

In 1960

71
Q

True or false. The Cephalosporins have a similar spectra to Gram-positive cocci (except enterococci), E.coli, Klebsiella, Proteus mirabilis and H influenza.

A

True

72
Q

When was the second generation of Cephalosporins discovered?

A

1970

73
Q

True or false, the second generations of cephalosporins are semisynthetic as they have an altered side chain.

A

True

74
Q

When was the third generation of Cephalosporins discovered?

A

1980

75
Q

Why are the third generation of the Cephalosporins considered semisynthetic? What alteration do they have to their chain.

A

They possess a O atom rather than a S atoms in the ring.

76
Q

Define a drug resistant or drug fast when speaking of drugs used in chemotherapy.

A

A drug fast or drug resistant is a microbe that becomes resistant to a chemotherapeutic agent.

77
Q

True or false. The drug causes the microbe to because resistant?

A

False.

78
Q

How does the drug become resistant?

A

Because of mutation or genetic recombination

79
Q

True of false. The strain of Shigella dysenteria that are resistant to sulfomanides, troptomycin, chloramphenicol and tetracyclines.

A

True

80
Q

True or false. When speaking of chemotherapeutic agents, a resistant cell can be transferred to a sensitive cell. Which occurs by transformation, transduction and conjugation.

A

True

81
Q

In prescription of antibiotic, indiscriminate use must be avoided. Why is that?

A

Because antibiotics act as selective agents for resistant microbes.

82
Q

Where is the resistant factor located on the cell?

A

Located on the plasmid, a small piece of DNA located on the cytoplasm.

83
Q

Name a few points of complications of chemotherapy

A
  1. Patient can develop an allergy
  2. Chemotherapy agent can cause side effects
  3. The normal flora can be altered- making the body more susceptible to infectious diseases.

Medical Microbiology 1-15 (15 decks)

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