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PCM Exam 1 > Antibacterials 2 > Flashcards

Antibacterials 2 Flashcards

1
Q

What are some disadvantages to combination therapy

A

Can select for multiple drug resistant bacteria

Agents that act only on multiplying bacteria should not be given with bacteriostatic drugs

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2
Q

Mechanisms of synergism in combination therapy

A
  • sequential blockage: trimethoprim + sulfamethoxazole in which two steps in the same pathway are blocked
  • blockade of drug inactivating enzymes: clavulanic acid + amoxicillin; one drug that inhibits the β lactamase
  • enhanced drug uptake
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3
Q

3 mechanisms by with bacteria have antibiotic resistance

A
  • altered uptake of antibiotic; ↓ in permeability and/or uptake mechanism; ↑ in multi drug resistance pumps
  • altered target; altered receptor affinity
  • drug inactivation; bacteria produce enzymes to inactivate the drug
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4
Q

Primary resistance is _______

A

Innate

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5
Q

Transfer of genetic information for acquisition of resistance genes in bacteria can occur via: (4)

A

Conjugation
Transposons
Transduction
Transformation

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6
Q

Competent bacteria have the ability to _______

A

Uptake DNA from the environment (this process is called transformation)

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7
Q

The process of transformation is facilitated by __________ and requires ______

A

Bacterial DNA binding proteins; Calcium

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8
Q

Conjugation involves the transfer of information using _______

A

Plasmids which are circular DNA material that have restiance genes

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9
Q

_______ is the donor and ______ is the recipient in conjugation and is only found in gram ___________ bacteria

A

F+; F-; negative

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10
Q

What is the mechanism of transduction

A

Bacteriophage injects DNA into the host bacterial cell
- lytic phage infects bacterium in which ther is bacterial DNA cleavage and parts of the bacterial DNA gets packaged in the phage and are used to infect new bacterium

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11
Q

Transposons are _______

A

Mobile genetic elements that can be trasnferred through plasmids

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12
Q

Complications of antibiotic therapy

A
  • hypersensitivity
  • direct toxicity: ex. Amniglycosides causing ototoxicity
  • superinfection: a new or secondary infection that occurs during antimicrobial therapy of a primary infection
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13
Q

Drugs that are cell wall synthesis inhibitors

A 
β lactam antibiotics: penicillins, cephalosporins, carbapenems, monobactams 
Vancomycin
Daptomycin
Bacitracin
Fosfomycin
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14
Q

What organisms are cell wall synthesis inhibitors ineffective against due to primary resistance?

A

Mycoplasma, Protozoa, fungi, viruses

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15
Q

Use of cell wall synthesis inhibitor antibiotics requires ________

A

Actively proliferating bacterial because cell wall synthesis must be actively occurring

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16
Q

What drugs are β lactamase inhibitors and what is their use

A

Clavulanic Acid, sulbactam, Tazobactam

They bind and inactive most β lactamases

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17
Q

What is the target site of β lactam antibiotics?

A

Penicillin binding proteins specially transpeptidase which is a bacterial enzyme involved in the last step of cell wall synthesis

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18
Q

Are beta lactams bactericidal or bacteristatic? Why?

A

Bactericidal; inhibits last step of peptidoglycan synthesis and this will activate auto lytic enzymes which initiate cell death

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19
Q

Pencillin’s abilyt to reach the penicillin binding protein is determined by:

A

Size
Charge
Hydrophobicity

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20
Q

Pencillins can easily cross the cells all of gram _________ organisms

A

Positive

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21
Q

What synergistic combination of antibiotics is used for empirical treatment of infective endocarditis? Explain

A

Penicillin + aminoglycoside

Penicillin facilitates movement of aminoglycosides through the cell wall

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22
Q

4 mechanisms of penicillin resistance

A
  • inactivation by β lactamases
  • modification of targe PBP (penicillin binding protein)
  • impaired penetration of drug to target PBP
  • increased efflux
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23
Q

Example of altered target PBP

A

MRSA; low affinity for β lactam antibiotics

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24
Q

What is penicillin G most commonly used for?

A
  • Syphilis
  • strep infections
  • susceptible pneumococci

Penicillin G is susceptible to β lactamases

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25
Q

Applications of penicillin G Benzathine and how is it administered

A

Syphilis
Rheumatic fever prophylaxis

Given via IM (regular penicillin G is given via IV)

This form of penicillin has a longer half life

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26
Q

Route of administration of penicillin V

A

Orally because it is more acid stable

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27
Q

What is penicillin V used to treat?

A

Pharyngitis, tonsillitis, and skin infections

Mostly mild-moderate infections

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28
Q

What are the antistaphylooccal penicillins? (4) and are they β lactamase resistant?

A
  • methicillin
  • nafcillin
  • oxacillin
  • dicloxacillin

They are β lactamase resistant and inactive against MRSA

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29
Q

Extended spectrum pencillins: (2) and they are usually given with _____

A

Ampicillin, amoxicillin

Β lactamase inhibitors

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30
Q

Amoxicillin is typically given with _______ and is the preferred prophylactics treatment for _________

A

Clavulanic acid; treatment for dog, cat and human bites

Also given for: acute otitis media, strep pharyngitis, pneumonia, skin infections and upper respiratory infections, and UTI’s

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31
Q

Ampicillin is typically given with __________

A

Sulbactam

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32
Q

Antipseudomonal pencillins: (3) and when are they given

A

Carbenicillin, ticarcillin, piperacillin

Often combined with β lactamase inhibitors

Given to treat moderate to severe infections such as: uncomplicated and complicated skin, gynecological and intra-abdominal infections and febrile neutropenia

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33
Q

Penicillins achieve therapeutic levels in _____________ but not in __________

A

Pleural, pericardial, peritoneal, synovial fluids, and urine;

Not in prostate and eye (cant be used to treat prostatits and uveitis)

34
Q

Which antibiotic would you give a patient who has renal failure?

A

Nafcillin because that is the only one that is excreted in the bile

The others are primarily excreted via the kidney so a patient with renal failure would not be able to excrete them

35
Q

Adverse effects of pencillins

A

GI disturbances (diarrhea)

36
Q

Adverse effect of ampicillin

A

Pseudomembranous colitis

37
Q

Macuopapular rash is an adverse effect seen in ________ and ______

A

Ampicillin; amoxicillin

38
Q

_______________ is an adverse effect in taking methicillin

A

Interstitial nephritis

39
Q

An adverse effect of nafcillin is _______

A

Neutropenia

40
Q

Cephalosporins are less/more susceptible to β lactamases than pencillins

A

Less

41
Q

As you go from first to later generation cephalosporins, gram __________ activity diminishes while gram ___________ activity increases

A

Positive; Negative

Positive ↓ Negative ↑

42
Q

________ generation of cephalosporin can be used to treat MRSA

A

5th

43
Q

_________ generation of cephalosporins is broad spectrum

A

4th

44
Q

What organism are all cephalosporins inactive against?

A

LAME

Listeria
Atypical: Legionella, chlamydia, acinetobacter
Mycoplasma
Enterococcus

45
Q

1st generation cephalosporin drugs and main use

A

Cefazolin
Cephalexin

Resistant to staphylococcal penicillinase

Mainly used as a substitute for penicillin G

46
Q

____________ (drugs) are used as a substitute for penicillin G

A

Cefazolin and cephalexin

47
Q

__________ is the drug of choice for surgical prophylaxis (hint: cephalosporin)

A

Cefazolin (1st gen)

48
Q

2nd generation cephalosporin drugs:

What organisms do they have good activity against

A

Cefaclor, cefoxitin, cefotetan, cefamandole

H influenza, enterobacter aerogenes and some neisseria

49
Q

2nd generation cephalosporins are primary used to treat ________, _______, and __________.

________ and ________ are second generation cephalosporins that can be used for prophylaxis and therapy of abdominal and pelvic cavity infections

A

Sinusitis; otitis; lower respiratory tract infections

Cefotetan and cefoxitin

50
Q

Cefotetan and cefoxitin are ________ generation cephalosporins are used for _______

A

2nd;
Prophylaxis and therapy of abdominal and pelvic cavity infections because there is ↑ risk of gram negative bacteria being present there

51
Q

What is the drug of choice for meningitis

A

Ceftriaxone (3rd generation cephalosporin)

52
Q

What are the 3rd generation cephalosporin drugs

A
  • ceftriaxione
  • cefoperazone
  • cefotaxime
  • ceftazidime
  • cefixime
53
Q

What is the drug of choice for gonorrhea

A

Ceftriaxone

54
Q

What are the clinical uses for ceftriaxone

A
  • empirical treatment and prophylaxis of meningitis
  • gonorrhea
  • treatment of disseminated Lyme disease (CNS or joint infection)
55
Q

Anti pseudomonas cephalosporins:

A

Cefaperazone and ceftazidime

56
Q

What is a 4th generation cephalosporin drug and what is its route of administration

A

Cefipime; given IM

4th generation cephalosporin is a broad spectrum

57
Q

5th generation cephalosporin and main use

A

Ceftaroline

Given to treat MRSA

58
Q

What makes treating MRSA with ceftaroline special?

A

Ceftataroline has a similar spectrum to 3rd generation cephalosporins so it has activity against more gram NEGATIVE pathogens too → can be used to treat skin and soft tissue infection in MRSA that are co-infected by gram negative pathogens unlike other anti-MRSA drugs like vancomycin

59
Q

Most of the cephalosporins are given parententerally except ______, _______, and _______ which are given orally

A

Cephalexin, cefaclor, cefixime

60
Q

________ and ________ cephalosporin drugs are excreted in the bile

A

Ceftriaxone; cefoperazone

61
Q

What are some adverse effects of cephalosporins

A

Superinfections via C. Difficult

Kernicterus in pregnant women due to ceftriaxone

62
Q

________, __________ and _______ are cephalosporins that contain methyl-thiotetrazole group and this can cause 2 specific adverse reactions:

A

Cefamandole, cefoperazone, cefotetan

  • hypoprothombinemia (give vitamin K1 to treat)
  • disulfiram like reactions (avoid alcohol)
63
Q

What are the carbapenem drugs and what makes them special and method of administration

A
  • Doripenem
  • Ertapenem
  • Imipenem
  • meropenem

Resists hydrolysis by most β lactamases

IV

64
Q

Carapenems a very broad spectrum of activity and can be used to treat infections by P. Aeruginosa but __________ is one that cannot be used to treat Pseudomonas aeruginosa

A

Ertapenem

65
Q

Can carbapenems be used to treat MRSA?

A

NO

66
Q

risks associated with carbapenem drug metabolism

A

Imipenem is metabolized by a special anezyme and forms a potentially toxic metabolite

Doripenem, Ertapenem and meropenem are not metabolized by the same drug

67
Q

What drug is given with imipenem and why?

A

Cilastatin, a dehydrodpeptidase I inhibitor to prevent nephron toxicity and ↑ availability

68
Q

Cilastatin inhibits ___________

A

Dehydropeptidase I

69
Q

High levels of Imipenem can cause __________

A

CNS toxicity e.g. seizures

70
Q

What drug is a monobactam and what makes monobactams special?

A

Aztreonam

  • they have the least least cross - allergenicity with pencillin
71
Q

Monobactams are effective against __________

A

ONLY aerobic gram NEGATIVE rods (including pseudomonas)

72
Q

Are monobactams resistant to β lactams?

A

Yes

73
Q

Main clinical application for monobactams

A

Used to treat gram negative infections in patients that are allergic to penicillin

74
Q

Vancomycin is active against _______

A

Gram positive ONLY but specially effective against multi drug resistant organisms

can not pass through cell wall of gram negative

75
Q

Mechanism of action of vancomycin

A

Binds to D-Ala-D-Ala terminus of the peptidioglycan → inhibits the cell wall synthesis and peptidoglycan formation

76
Q

Is vancomycin susceptible to β lactamase

A

NO

77
Q

Cause of resistance to vancomycin is _______

A

Modification of D-Ala-D-Ala binding site to D- Lactate

Plasmid mediated changes in drug permeability

78
Q

Vancomycin is given with an aminoglycoside for empiric treatment of ____________

A

Infective endocarditis

79
Q

Vancomycin is used to treat _____________

A

MRSA and beta lactam resistant gram POSITIVE organisms

80
Q

Vancomycin is given orally for the treatment of _________ or antibiotic associated __________

A

Staphylococcal enterocolitis; pseudomembranous colitis (C. Difficile)

PCM Exam 1 (22 decks)

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