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immunology drugs > Antibacterials I > Flashcards

Antibacterials I Flashcards

1
Q

What are the examples of inhibitors of cell wall synthesis ?

A

β-lactams, cycloserine, vancomycin and bacitracin

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2
Q

What are the categories of β-lactam antibacterials?

A

Penicillins
Cephalosporins
Monobactams
Carbapenems

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3
Q

What are the two enzymatic activities of Penicillin Binding Proteins?

A

Transpeptidase: cross-links amino acid side chains
Glucosyltransferase: links subunits of glycopeptide polymer

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4
Q

What is the general structure of penicillins?

A

Penicillin nucleus
6-amino acid penicillanic acid
β-lactam nucleus

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5
Q

What is the general structure Cephalosporins?

A

Cephalosporin Nucleus
7 - amino acid cephalosporanic acid
β-lactam nucleus

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6
Q

Are β-lactams mainly bactericidal or bacteriostatic?

A

Mainly bactericidal

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7
Q

What is the mechanism of action of β-lactams?

A

Bind to specific PBP located inside bacterial cell wall

Inhibit transpeptidase

Inhibit peptidoglycan cross-link formation during cell wall synthesis

Bacterial cell wall enzymes (autolysis) cause lysis

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8
Q

What is the spectrum activity of Penicillins?

A

Gram +/-
Anaerobes

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9
Q

What is the spectrum activity of Carbapenems?

A

Broad Gram -
Anaerobes
Narrow Gram +

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10
Q

What is the spectrum of activity of Monobactams?

A

Aerobic
Gram -

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11
Q

What is the spectrum activity of Cephalosporins?

A

1st and 2nd generations: Mostly gram + and some gram -

3rd and 4th generations: Most gram -

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12
Q

What is the mechanism of bacterial resistance to penicillins and cephalosporins?

A

Inactivation of drug by β-lactamase

Altered structure of PBP

Efflux pump

Presence of permeability barrier: mainly occurs in gram - bacteria that have an outer membrane that limits penetration of hydrophilic antibiotic

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13
Q

What are β-lactamases?

A

A family of enzymes that limit the efficacy of β-lactams

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14
Q

Can the β-lactamase activity be transferred?

A

Yes, it is genetically controlled and can be transferred from one bacterium to the next (through the transfer of plasmids)

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15
Q

What are the classes of penicillins?

A

Natural Penicillin
β-lactamase resistant penicillins
Extended spectrum (β-lactamase sensitive)

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16
Q

What are the examples of natural penicillins?

A

Benzyl-penicillin & analogs

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17
Q

What are examples of extended spectrum penicillins?

A

Aminopencillins
Antipseudomonal Penicillins

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18
Q

What makes up the penicillin nucleus?

A

Thiazolidine ring and lactam ring

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19
Q

What is the chief structural requirement of the penicillin for?

A

Biological activity

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20
Q

What happens if there is metabolic transformation or chemical alteration to the penicillin nucleus?

A

Loss of all significant antibacterial activity

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21
Q

What are natural penicillins made from?

A

A fungus Penicillium Chrysogenum

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22
Q

Are natural penicillins resistant or sensitive to β-lactamases?

A

Sensitive to destruction

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23
Q

What are the pharmacokinetics of natural penicillins?

A

Penicillin G: IV or IM
Benzathine Penicillin G: IM (sustained release)!

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24
Q

What is the spectrum of activity pf natural penicillin, Penicillin G?

A

Gram +/- cocci
Gram + bacilli (non β-lactamase producing)

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25
Q

What are the examples of non-β-lactamse producing Gram + bacilli?

A

Staphylococcus
Streptococcus
Pneumococcus
Clostridium
Neisseria meningitis
Treponema

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26
Q

What is the pharmacokinetics of natural Penicillin, Penicillin V?

A

Given orally

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27
Q

What is the spectrum of activity of Penicillin V?

A

Same as Penicillin G but less potent
Used in gonorrhoea and meningococcal meningitis

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28
Q

What are examples of β-lactamasse resistant penicillins?

A

Methicillin, nafcillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin

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29
Q

Which is the prototype of β-lactamase resistant penicillins?

A

Methicillin

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30
Q

What is the spectrum of β-lactamase resistant penicillins?

A

Same as Penicillin G but less potent
Minimal activity against gram - infections

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31
Q

When are β-lactamase resistant penicillins used?

A

Mainly with β-lactamase -producing staphylococcus like MSSA

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32
Q

What are the different examples of extended spectrum penicillins?

A

Aminopenicillins
Antipsuedomnal penicillins

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33
Q

What are the examples of aminopenicillins?

A

Ampicillin and Amoxicillin

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34
Q

What is the pharmacokinetics of Ampicillin?

A

Given orally or IV

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35
Q

What is the pharmacokinetics of Amoxicillin?

A

Given orally

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36
Q

What is the pharmacokinetics of Aminopenicillins?

A

Same as Penicillin G and have improved activity against Gram -
Less potent than Penicillin G

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37
Q

What happens if you add β-lactamase inhibitor?

A

Further extends spectrum

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38
Q

What are the combinations of aminopenicillins and β-lactamase inhibitor?

A

Amoxicillin/ Clavulanate
Ampicillin/Sulbactam

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39
Q

What are the examples of antipseudomonal penicillins ?

A

Carbepenicillin
Ticarcillin
Piparacellin

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40
Q

What is the spectrum of the antipseudomonal penicillins?

A

Same as aminopenicillins plus activity against pseudomonas, proteus, and klabsiella

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41
Q

What are the generalised pharmacokinetics of Penicillins?

A

Orally or Parenterally
Widely distributed; exhibit 45 to 68% protein-binding mainly to albumin
Penetrate inflamed meninges and reach CSF
Eliminated via kidneys –> tubular secretion

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42
Q

What are the adverse effects of penicillins?

A

Hypersensitivity reactions
GI disturbances
Cross-sensitivity to other penicillins or cephalosporins

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43
Q

What are some examples of therapeutic use of Penicillins?

A

Meningitis
Listeriosis
Endocarditi
Anaerobic LRTI
URTI
Anthrax
Gonorrhoea
Syphilis

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44
Q

What are examples of the β-lactamase inhibitor?

A

Clavulanic acid
Tazobactam
Sulbactam

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45
Q

Mechanism of action of β-lactamase inhibitor?

A

Resemble β-lactams in structure,
No significant antibacterial activity
Inhibit many β-lactamases

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46
Q

What is Augmentin?

A

Combination of β-lactamase inhibitor with hydrolazable β-lactams

Amoxicillin + Clavulanic Acid

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47
Q

What do the side chain modifications of the cephem nucleus confer?

A

Improved spectrum
Pharmacokinetic advantages
Additional side-effects

48
Q

What are the similarities between penicillins and cephalosporins?

A

Similar to penicillins chemically, in MOA and toxicity

49
Q

What are the differences between Penicillins and cephalosporins?

A

Cephalosporins are more stable than penicillins to β-lactamases

Broader spectrum than penicillins

50
Q

How many generations of cephalosporins are there?

A

4 + 1 generations

51
Q

What are the examples of first generation cephalosporins?

A

Cephadroxin
Cephalexin
Cafzolin

52
Q

What are examples of the second generation cephalosporins?

A

Cefuroxime
Cefaclor
Cefprozil
Cefoxitin
Cefofetan

53
Q

What are examples of the third generation of cephalosporins?

A

Cefotaxime
Ceftriaxone
Cefdinir
Cefixime

54
Q

What are examples of the fourth generation of cephalosporins?

A

Cefepime
Cefpirome

55
Q

What are the examples of advanced generation?

A

Ceftaroline
Ceftobiprole

56
Q

What is the spectrum of activity as the generations of cephalosporins progress?

A

Gram + activity becomes less, Gram - increases

57
Q

Which cephalosporin generation covers pseudomonas?

A

4th generation

58
Q

Which cephalosporin generation covers MRSA?

A

5th generation

59
Q

What is the spectrum of generation 1 cephalosporins?

A

Really good against Gram +, moderate activity against Gram -

Does not penetrate CSF

60
Q

What are some Gram - bacteria that are covered by first generation cephalosporins?

A

E.coli,
Proteus Mirabilis
K. pneumonia

61
Q

Clinical use of first generation cephalosporins?

A

Skin and soft tissue infections, serious infections due to MSSA
Perioperative surgical prophylaxis

62
Q

What is the spectrum of activity for 2nd generation cephalosporins?

A

Slightly less active against gram +, better activity against Gram -

Do not penetrate CSF

63
Q

What are the Gram - bacteria targeted by 2nd generation cephalospsorin?

A

Hemophilus
E. coli
Enterobacter
Klabsiella
Neisseria

64
Q

Clinical use of 2nd generation cephalosporins?

A

Perioperative surgical prophylaxis
Management of URTI, urinary tract, bone & soft tissue infections

65
Q

What is the spectrum of third generation cephalosporins?

A

Less potent against gram + and better activity against gram -

66
Q

What are some gram - bacteria that are targeted with 3rd generation cephalosporins?

A

Pseudomonas aeruginosa
Enteribacter
Salmonella

67
Q

What are the pharmacokinetics of 3rd generation cephalosporins?

A

Most penetrate CSF

68
Q

Clinical use of 3rd generation cephalosporins?

A

Serious hospital-acquired gram - infection, LRTI, UTI, meningitis, Lyme disease

69
Q

What are some Gram - organisms that are targeted by 4th generation cephalosporins?

A

Pseudomonas aeruginosa
Enteribacter
S. aerus
S. pneumoniae
Hemophilus
Neisseria

70
Q

What are the pharmacokinetics of 4th generation cephalosporins?

A

Excellent penetration into CSF

71
Q

What are the PK of 4th generation cephalosporins?

A

Stable to hydrolysis by many β-lactamases

72
Q

What is the spectrum of advanced generation cephalosporins?

A

Broad gram +
Strong activity against gram -

73
Q

What are the bacteria targeted by advanced generation cephalosporins?

A

Excellent activity against MRSA,
MSSA,
H. Influenza,
Proteus,
E. coli
Klabsiella
Serratia

74
Q

What are clinical uses of advanced generation of cephalosporins?

A

Treatment of complicated skin and skin structure infections and CAP

75
Q

What are the adverse effects of Cephalosporins?

A

GI disturbances
Hypersensitivity reactions
Nephrotoxicity
Intolerance to alcohol
Bleeding disorders

76
Q

Which kind of cephalosporin is not nephrotoxic?

A

Cefotaxime

77
Q

What are the two kinds of β-lactams that are resistant to β - lactamases?

A

Monobactams
Carbapenems

78
Q

What is an example of monobactams?

A

Aztreonam

79
Q

What are monbactams?

A

Synthetic
Bacteriocidal

80
Q

Which group confers the activity of aztreonam?

A

SUlfonic acid

81
Q

What are examples of carbapenems?

A

Imipenem
Doripenem
Ertapenem
Meropenem

82
Q

Spectrum of activity of carbapenems?

A

Broadest spectrum of activity

83
Q

Antibacterial spectrum of aztreonam?

A

Different to the other β-lactams
Spectrum limited to gram (-) aerobic bacteria
No gram + or anaerobic activity

84
Q

Which drug group does the spectrum of monobactams resemble?

A

Aminoglycosides

85
Q

Which bacteria are targeted by monobactams?

A

Enterobacteriaceae and P. aeruginosa

86
Q

What would monobactams be used as an alternative of and why?

A

As an alternative to aminoglycosides because they have similar spectrum but monobactams are less nephrotoxic

87
Q

Clinical use of monobactams?

A

Skin and soft tissue infections
UTI
RTI
Intra-abdominal infections
Postoperative infections
Gynecologic infections

88
Q

Are monobactams indicated for meningitis?

A

No

89
Q

What is another reason for the use of monobactams for patients that cannot take penicillin?

A

They do not tend to have a reaction to monobactams even if they are allergic to both penicillins and cephalosporins

90
Q

Spectrum of activity of carbapenems?

A

Active against a wide range of gram + and gram - organisms

Highly active against Enterobactericeae

91
Q

What are the traits that carbapenems have that make them effective antibiotics?

A

Efficient penetration through bacterial cell wall
Exceptional stability against β-lactamases
Affinity for all PBP (widest spectrum)

92
Q

What is Imipenem rapidly metabolised by?

A

Dehydropeptidase 1

93
Q

Where is dehydropeptidase 1 found?

A

Renal tubular border

94
Q

What do the imipenem metabolites cause?

A

Nephrotoxicity (toxicity to proximal tubule)

95
Q

What is cilastatin?

A

Reversible, competitive inhibitor of DHP 1 enzyme –> no imipenem metabolites –> no nephrotoxicity

96
Q

Does cilastatin have any antibacterial activity?

A

No

97
Q

What are the therapeutic uses of Imipenem - Cilastatin combination?

A

UTI
Nosocomial
LRTI
Intra-abdominal and gynaecological infections
Skin, soft tissues, bone and joint infections
Meningitis
Peritonitis

98
Q

Which drug exactly would be used for the treatment of meningitis?

A

Meropenem

99
Q

What are the PK of the imipenem-cilastatin combination?

A

IV
When given with cilastatin, about 70% of imipenem can be excreted unchanged in the urine

100
Q

What are the adverse effects of Imipenem - Cilastatin combination?

A

GI disturbances
Seizures (rarely)
Hypersensitivity reaction if allergic to other β-lactams

101
Q

Why does meropenem not require co-administration with cilastatin?

A

It is not sensitive to renal dehydropeptidase 1 like imipenem is

102
Q

What is the spectrum of activity of Meropenem?

A

Similar to imipenem, but also targets some imipenem-resistant bacteria

Less activity against gram + cocci

103
Q

What is an imipenem-resistant bacteria that is targeted by meropenem?

A

Pseudomonas aeruginosa

104
Q

Compared to imipenem is meropenem nephrotoxic?

A

No, not sensitive to DHP 1

105
Q

Compared to imipenem is meropenem more or less likely to cause seizures?

A

Less likely

106
Q

What is Vancomycin?

A

A glycopeptide

107
Q

Is Vancomycin bactericidal or bacteriostatic?

A

Bacteriocidal

108
Q

What is the mechanism of action of Vancomycin?

A

High affinity binding to d-alanyl-d-alanine (terminus of peptidoglycan precursors)

Prevents transpeptidase action on NAM & NAG

Disrupt polymerization and cross-linking

109
Q

What is another function of Vancomycin?

A

Inhibits transglycosylase

110
Q

What is the spectrum of Vancomycin?

A

Mainly against Gram + bacteria
NOT effect against most gram - bacteria

111
Q

What are some bacteria that are targeted by Vancomycin?

A

Strep
Staph (MRSA)
Enterococcus
Pneumococcus
Listeria
Corynebacteriu
Bacilus
Clostridium Difficile

112
Q

What are the PK of Vancomycin?

A

Poorly absorbed after oral
Given IV
30% of Vancomycin is plasma bound, appears in body fluids
Renal excretion
Slow CSF penetration

113
Q

What are the adverse effects of Vancomycin?

A

Nephrotoxicity
Ototoxicity
Rapid IV transfusion = erythematous reaction –> Red man syndrome
Hypersensitive reactions

114
Q

What are the therapeutic uses of Vancomycin?

A

Skin and soft tissue, bone and joint infections
RTI
CNS infections (Community and hospital-acquired meningitis)
Endocarditis
Vascular Catheter Infections
Psudomembranous Colitis

115
Q

When can Vancomycin be given orally?

A

If it is for C. difficile

immunology drugs (7 decks)

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