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Microbiology and Parasitology > Module 09: Inhibiting the Growth of Pathogens in Vivo Using Antimicrobial Agents > Flashcards

Module 09: Inhibiting the Growth of Pathogens in Vivo Using Antimicrobial Agents Flashcards

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Biology 101 flashcards
1
Q

This refers to the use of any chemical or drug to treat any disease or condition.

A

Chemotherapy

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2
Q

The chemicals (or drugs) used to treat diseases are referred to as ____________. By definition, this is any drug used to treat any condition or disease.

A

Chemotherapeutic Agents

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3
Q

This aided in the treatment of dysentery.

A

Ipecac

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4
Q

This was discovered to be effective in treating malaria.

A

Quinine extract of cinchona bark

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5
Q

The chemotherapeutic agents used to treat infectious diseases are collectively referred to as ____________. Thus, this is any chemical (or drug) used to treat an infectious disease, either by inhibiting or by killing pathogens in vivo.

A

Microbial Agents

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6
Q

Drugs used to treat bacterial diseases are called ______________.

A

Antibacterial agents

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7
Q

Drugs used to treat fungal diseases are called ___________.

A

Antifungal agents

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8
Q

Drugs used to treat protozoal diseases are called _____________.

A

Antiprotozoal agents

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9
Q

Drugs used to treat viral diseases are called ______________.

A

Antiviral agents

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10
Q

This is a substance produced by a microorganism that kills or inhibits the growth of other microorganisms.

A

Antibiotics (All antibiotics are antimicrobial agents but not all are antibiotics)

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11
Q

The chemotherapeutic agents used to treat infectious diseases are collectively referred to as ___________________.

A

Antimicrobial agents.

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12
Q

Antibiotics are produced by what?

A

Certain moulds and bacteria that live in soil which gives them a selective advantage for the available nutrients.

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13
Q

What are some examples of antibiotics formed from molds?

A

(1) Penicillin
(2) Cephalosporins

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14
Q

What are some examples of microorganisms formed from bacteria?

A

(1) Bacitracin
(2) Erythromycin
(3) Chloramphenicol

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15
Q

Antibiotics that have been chemically modified to kill a wider variety of pathogens or reduce side effects are called ________________.

A

Semisynthetic antibiotics (eg ampicillin, amoxicillin and nafcillin)

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16
Q

He is a Scottish bacteriologist, accidentally discovered the first antibiotic when he noticed that the growth of contaminant Penicillium notatum mould colonies on his culture plates was inhibiting the growth of Staphylococcus bacteria

A

Alexander Fleming

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17
Q

The discovery of penicillin by Alexander Fleming where manifested by?

A

(A) Colonies of Staphylococcus aureus are growing well in this area of the plate.
(B) Colonies are poorly developed in this area of the plate because of an antibiotic (penicillin) being produced by a colony of Penicillium notatum (a mould), shown at
C

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18
Q

An ideal antimicrobial agent should:

A

(1) Kill or inhibit the growth of pathogens
(2) Cause no damage to the host
(3) Cause no allergic reaction in the host
(4) Be stable when stored in solid or liquid form
(5) Remain in specific tissues in the body long enough to be effective
(6) Kill the pathogens before they mutate and become resistant to it

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19
Q

They purified penicillin and demonstrated its effectiveness in the treatment of various bacterial infections

A

Sir Howard Walter Florey and Ernst
Boris Chain,

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20
Q

This was discovered by Gerhard Domagk which as effective against streptococcal infections in mice.

A

Protonsil

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21
Q

Him and his colleagues isolated streptomycin (the first antituberculosis drug) and subsequently discovered antibiotics such as chloramphenicol, tetracycline, and erythromycin in soil samples.

A

Selman Waksman

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22
Q

This inhibits growth of bacteria, whereas bactericidal drugs kill bacteria.

A

Bacteriostatic drugs

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22
Q

The five most common mechanisms of action of antimicrobial agents are as follows:

A

(1) Inhibition of cell wall synthesis
(2) Damage to cell membranes
(3) Inhibition of nucleic acid synthesis (either DNA or RNA synthesis)
(4) Inhibition of protein synthesis
(5) Inhibition of enzyme activity

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23
Q

These drugs inhibit production of folic acid (a vitamin) in those bacteria that require p-aminobenzoic acid (PABA) to synthesize folic acid.

A

Sulfonamide drugs

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24
Q

Why are sulfa drugs considered as competitive inhibitors?

A

They inhibit growth of microorganisms by competing with an enzyme required to produce an essential metabolite.

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25
Q

Sulfa drugs are characterized to be what?

A

Bacteriostatic because they prevent growth

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26
Q

In most Gram-positive bacteria, how does penicillin interfere?

A

synthesis and cross-linking of peptidoglycan, a component of cell walls. By inhibiting cell wall synthesis, penicillin destroys the bacteria

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27
Q

This destroys gram positive bacteria.

A

Vasomycin

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28
Q

These only Gram-negative bacteria; they are referred to as narrow-spectrum antibiotics.

A

Colistin and Nalidixic acid

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29
Q

Antibiotics that are destructive to both Gram-positive and Gram-negative bacteria are called _____________.

A

Broad Spectrum Antibiotics (Ciproflaxin, Ceftriaxone, Tetracycline)

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30
Q

These agents agents should be used only in patients whose host defense mechanisms (see Chapters 15 and 16) are functioning properly (i.e., only in patients whose bodies are capable of killing the pathogen once its multiplication is stopped).

A

Bacteriostatic agents should be used in immunosuppressed patient and leukopenic patients

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31
Q

In this, sometimes one drug is not sufficient; two or more drugs may be used simultaneously, as in the treatment of tuberculosis

A

Multidrug therapy

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32
Q

This is when two antimicrobial agents are used together to produce a degree of pathogen killing that is greater than that achieved by either drug alone.

A

synergism

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33
Q

This is when two drugs actually work against each other. The extent of pathogen killing is less than that achieved by either drug alone.

A

Antagonism

34
Q

These are referred to as ß-lactam drugs because their molecular structure includes a four-sided ring structure known as a ß-lactam ring

A

Penicillin

35
Q

What does penicillin inhibit?

A

Synthesis of cell wall (have maximum effect on those that are dividing)

36
Q

These are referred to as natural penicillin.

A

Penicillin G and penicillin V (have good effect on gram positive bacteria namely Streptococcus, anaerobic bacteria, spirochetes.

37
Q

These are also β-lactam antibiotics and, like penicillin, are produced by molds. Also, like penicillin’s,
these interfere with cell wall synthesis and are bactericidal.

A

Cephalosporins

38
Q

These cephalosporins are primarily against are active primarily against Gram-positive bacteria

A

First generation

39
Q

These cephalosporins have increased activity against Gram-negative bacteria

A

Second generation

40
Q

These cephalosporins have even greater activity against Gram negatives (including Pseudomonas aeruginosa)

A

Third generation

41
Q

This is an example of a fourth-generation cephalosporin with activity against both Gram positives and Gram negatives, including P. aeruginosa.

A

Cefepime

42
Q

This is a fifth-generation cephalosporin that has expanded activity against aerobic Gram positive cocci, including methicillin resistant Staphylococcus aureus (MRSA) and methicillin resistant
Staphylococcus epidermidis (MRSE).

A

Ceftaroline

43
Q

These are among the most powerful antibacterial agents in use today. They also include a β-lactam ring (Fig. 9-4).

A

Carbapenems

44
Q

What do carbapenems inhibit?

A

Cell wall synthesis and is effect among aerobic Gram positive, aerobic Gram negative, and anaerobes.

45
Q

These are considered the “antibiotics of last resort” because of their activity against Gram negative bacteria that have developed resistance to many different antimicrobial agents.

A

Carbapenems (imipenem and meropenem)

46
Q

If Klebsiella or Enterobacter spp. become resistant to the carbapenems, they are referred to as ______________

A

carbapenem-resistant
Enterobacteriaceae (CRE).

47
Q

They also target the bacterial cell wall. They have excellent activity against most aerobic and anaerobic Gram-positive bacteria, but have no activity against most Gram-negative bacteria.

A

Glycopeptides (vancomycin)

48
Q

Bacteria, especially enterococci, are becoming resistant to these drugs, and they have a number of toxic side effects. When enterococci become resistant to vancomycin, they are referred to as ____________________.

A

vancomycin-resistant enterococci (VRE).

49
Q

These are broad-spectrum drugs that exert their effect by targeting bacterial ribosomes and thereby halting protein synthesis.

A

Tetracyclines

50
Q

Tetracyclines are characterized as what?

A

Bacteriostatic

51
Q

These are effective against a wide variety of bacteria, including chlamydia’s, mycoplasmas, rickettsia’s, Vibrio cholerae, and spirochetes, such as Borrelia spp. and Treponema pallidum.

A

Tetracyclines

52
Q

These are bactericidal broad-spectrum drugs that also inhibit bacterial protein synthesis. The major factor that limits their use is their toxicity.

A

Aminoglycosides

53
Q

These are effective against a wide variety of aerobic Gram-negative bacteria, but are ineffective against anaerobes. They are used to treat infections with members of the family Enterobacteriaceae

A

Aminoglycosides

54
Q

These inhibit protein synthesis. These include erythromycin, clarithromycin, and azithromycin. They are effective against chlamydia’s, mycoplasmas, T. pallidum, H. influenzae, and Legionella spp.

A

Macrolides

55
Q

Macrolides are?

A

(bacteriostatic at lower doses; bactericidal at higher doses

56
Q

These are bactericidal drugs that inhibit DNA synthesis. The most commonly used against members of the family Enterobacteriaceae and P. aeruginosa.

A

Fluoroquinolone

57
Q

These are broad-spectrum agents with activity against both Gram-positive and Gram-negative bacteria.

A

Levofloxacin and moxifloxacin

58
Q

Antifungal agents work by:

A

(1) Binding in cell membrane sterols
(2) By interfering with sterol synthesis
(3) By blocking mitosis or nucleic synthesis

59
Q

These antifungal agents have a mechanism of binding in cell membrane sterols

A

Nystatin and amphotericin B

60
Q

These antifungal agents have a mechanism of interfering with sterole synthesis.

A

Fluconazole and miconazole; echinocandins)

61
Q

These antifungal agents have a mechanism of blocking mitosis and nucleic acid synthesis.

A

Griseofulvin and 5-flucytosine

62
Q

These are usually toxic to the host.

A

Antiprotozoal agents

63
Q

Antiprotozoal agents work by:

A

(1) Interfering with DNA and RNA synthesis (chloroquine, pentamidine, and quinacrine)
(2) Interfering with protozoal metabolism

64
Q

These antiprotozoal agents have the mechanism of interfering with protozoal metabolism

A

Metronidazole

65
Q

These are the newest weapons in antimicrobial methodology. Difficult to develop these agents because viruses are produced within host cells.

A

Antiviral agents

66
Q

Some drugs have been developed that are effective in certain viral infections, but not others; they work by inhibiting _____________within cells.

A

Viral Replication

67
Q

These are (several antiviral drugs that are administered simultaneously) are being used to treat HIV infection.

A

Cocktails

68
Q

These are microbes (mainly bacteria) that have become resistant to one or more antimicrobial agents. Infections caused by superbugs are difficult to treat!

A

Superbugs

69
Q

If bacteria that were once susceptible to a particular drug
become resistant, this is called _____________.

A

Acquired resistance

69
Q

Bacterial superbugs include?

A

(1) Methicillin-resistant Staphylococcus aureus (MRSA)
(2) Vancomycin-resistant Enterococcus spp. (VRE)
(3) Multidrug-resistant Mycobacterium tuberculosis
(MDRTB)
(5) Multidrug-resistant strains of Acinetobacter,
Burkholderia, Pseudomonas
(6) Neisseria gonorrhoeae
(7) Carbapenemase-producing Klebsiella pneumoniae (KPC

69
Q

Some bacteria are naturally resistant because they lack the specific target site for the drug or the drug is unable to cross the organism’s cell wall or cell membrane and, thus, cannot reach its site of action. Resistance of this type is known as

A

Intrinsic resistance

69
Q

Before a drug enters a bacterial cell, it must first bind to proteins on the surface of the cell; these proteins are called _______________.

A

Drug-binding sites

70
Q

A chromosomal mutation that
affects the structure of a drug-binding site can prevent the drug from binding, resulting in _____________.

A

Drug resistance

71
Q

Many bacteria have become resistant to penicillin because they have acquired the gene for ______________.

A

Penicillinase production during conjugation.

72
Q

A plasmid that contains multiple genes for drug resistance is known as a ___________.

A

Resistance factor (R-factor).

73
Q

Bacteria can also become resistant to drugs by developing the ability to produce _________________. An MDR pump enables the cell to pump drugs out before they can damage or kill the cell

A

Multidrug-resistance (MDR) pumps (also known as MDR transporters or efflux pumps).
–

74
Q

Every penicillin, cephalosporin, and carbapenem molecule contains a double-ringed structure (referred to as a “house and garage”). The “garage” is known as the ____________.

A

β-lactam ring.

75
Q

Some bacteria produce enzymes, ____________, that destroy this ring; when the β-lactam ring is destroyed, the drug no longer works

A

β-lactamases

76
Q

Types of β-lactamases:

A

Penicillinases
Cephalosporinases
Carbapenemases

77
Q

Drug companies have developed special drugs that combine a

A

β-lactam antibiotic with a β-lactamase inhibitor (e.g. piperacillin/tazobactam)

78
Q

This is when drug therapy is initiated before laboratory results are available (i.e., before the pathogen is identified and/or before susceptibility test results are available).

A

Empiric Therapy

79
Q

Reasons why antimicrobial agents should not be used indiscriminately:

A

(1) Organisms susceptible to the agent will die, but resistant ones will survive; this is known as selecting for resistant organisms.
(2) The patient may become allergic to the agent.
(3) Many agents are toxic to humans and some are very toxic.
(4) With prolonged use, a broad-spectrum antibiotic may destroy the normal flora, resulting in an overgrowth of bacteria known as a superinfection, such as Clostridium difficile-associated diarrhea.

80
Q

Selecting for Drug-Resistant Organisms

A

A/ Indigenous microbiota of a patient before antibiotic therapy (S, susceptible; R, resistant).
B. After antibiotic therapy has been initiated.
C. Resistant organisms multiply and become the predominant organisms.

Microbiology and Parasitology (9 decks)

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