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pr3151 > bacteria cell wall synthesis inhibitors - beta lactams > Flashcards

bacteria cell wall synthesis inhibitors - beta lactams Flashcards

1
Q

what are the gram pos cocci

A
  1. staphylococcus (aureus, epidermis)
  2. streptococcus (pyrogenes, pneumoniae)
  3. enterococcus (faecalis, faecium)
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2
Q

what are the gram pos bacilli

A
  1. listeria monocytogenes
  2. bacillus
  3. clostridium species
  4. diphtheria
  5. actinomyces
  6. mycobacterium
  7. corynebacterium
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3
Q

what are the gram neg cocci

A
  1. neisseria gonorrhoeae/ gonoccoci
  2. neisseria meningitis/ meningococcus
  3. moraxella catarrhalis
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4
Q

what are the gram neg bacilli

A
  1. enterobacter, citrobacter, klebsiella, ecoli, salmonella, shigella, serratia
  2. pseudomonas
  3. acinetobacter
  4. h. influenzae
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5
Q

what is the process of gram staining

A

application of crystal violet -> application of iodine -> alcohol wash (decolourisation) -> application of safranin (counter stain)

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6
Q

what colour is gram neg staining

A

from colourless in alcohol wash step to pink from safranin

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7
Q

what colour is gram pos staining

A

remain purple all the way

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8
Q

what is the structure of beta lactams

A

a four membered beta lactam ring alone or fused with a five membered or six membered ring

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9
Q

what is the different names of beta lactams

A

five membered: penam (/), penem (//)
six membered: cepham (/), cephem (//)

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10
Q

what are examples of a penam

A

penicillin, sulbactam, tazobactam

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11
Q

what is an example of a cephem

A

cephalosporins

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12
Q

differentiate between penams, carbapenams, oxopenams

A

penams: S atom
carbapenams: C atom
oxopenams: O atom

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13
Q

what is the moa of a beta lactam

A

beta lactams interfere with the synthesis of bacterial cell wall peptidoglycan by binding to the active site of transpeptidase enzyme called penicillin binding protein which catalyses the crosslinking of terminal peptide components of the linear polymer chain, weakening the bacterial cell wall structure of an actively growing bacterial cell resulting in a buildup in intracellular osmotic pressure and causing lysis of the bacterial cell

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14
Q

what are examples of beta lactams

A

penicillin, cephalosporins, carbapenems, monobactam (aztreonam), vancomycin

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15
Q

what are the classes of penicillins

A

natural penicillin, penicillinase resistant penicillin, aminopenicllins, anti pseudomonal penicllins

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16
Q

what are the coverages of the different classes of penicllin

A

natural penicillin: gram pos and neg
penicillinase resistant penicillin: gram pos
aminopenicillin: gram pos and neg
anti pseudomonal penicillin: gram pos and neg

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17
Q

what are the properties of the R side chain

A

influences acid stability, PK properties, penicillinase resistance, ability to bind to PBPs

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18
Q

what is beta lactamase

A

enzyme produced by bacteria that is resistant towards beta lactams

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19
Q

what is inflammed meningitis

A

swelling of protective membrane covering brain and spinal cord

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20
Q

what are drugs are aminopenicillins

A

ampicillin, amoxicillin

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21
Q

route, indication, csf, excretion and dose adjustments, structure, others ampicillin

A

IV/PO, beta lactamase neg gram neg or gram pos, IV has adequate csf penetration and it increases in inflamed meningitis, renal clearance and excreted unchanged in urine, renal dose adjustments required, excreted by tubular secretion so use probenecid to block and prolong effect, incomplete PO absorption can cause D, additional hydrophilic group allows penetration into gram neg via porins, addition of beta lactamase inhibitor can extend spectrum of use to cover beta lactamase producing strains

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22
Q

what are the limitations of ampicillin

A

does not cover klebsiella and pseudomonas, not effective against amoebae, plasmodia, rickettsiae, fungi and virus, not for MRSA as the PBP is modified so less targetable

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23
Q

route, indication, csf, excretion and dose adjustments, structure, others amoxicillin

A

IV/PO

beta lactamase neg gram neg or gram pos

IV has adequate csf penetration and it increases in inflamed meningitis

renal clearance and excreted unchanged in urine, renal dose adjustments required, excreted by tubular secretion so use probenecid to block and prolong effect

better PO absorption than ampicillin

additional hydrophilic group allows penetration into gram neg via porins, addition of beta lactamase inhibitor can extend spectrum of use to cover beta lactamase producing strains

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24
Q

what are the limitations of ampicillin

A

does not cover klebsiella and pseudomonas, ineffective against amoebae, plasmodia, rickettsiae, fungi and virus, not for MRSA as PBP modified so less targetable

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25
Q

what are the drugs that are natural penicilin

A

penicilin G (benzylpenicilin) and penicilin V (phenoxylmethylpenicilin)

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26
Q

route, indication, csf, excretion, others for penicillin G

A

IV for PG potassium, IM for PG procaine, IM for PG benzathine

indicated for gram pos (streptococci, bacillus, diphtheria) and gram neg (meningococci, gonococci, spirochetes, beta lactamase neg strain)

aq PG has greater csf penetration than procaine and benzathine, penetration increases with inflamed meningitis

renal, excreted unchanged in urine, excreted by tubular secretion so can use probenecid to block and prolong effect

PG procaine and PG benzathine can distribute into storage tissues to be released slowly

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27
Q

limitations of penicillin G

A

not effective against amoebae, plasmodia, rickettsiae, fungi, virus

not for MRSA as PBP modified

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28
Q

benefit of natural penicillins over aminopenicillins

A

natural penicillins cover klebsiella and pseudomonas

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29
Q

route, indication, csf, excretion, others for penicillin V

A

PO

gram pos (streptococci, bacillus, diphtheria), gram neg (meningococci, gonococci, spirochetes, beta lactamase neg strain)

penetration increased with inflamed meningitis

renal, unchanged in urine, excreted by tubular secretion so can use probenecid to block and prolong effect

PO absorption better than PG because more acid stable

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30
Q

limitations of penicillin V

A

not effective against amoebae, plasmodia, rickettsiae, fungi, virus

not for MRSA as PBP modified

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31
Q

what are the drugs that are penicillinase resistant pencillin

A

cloxacillin, oxacillin, flucloxacillin

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32
Q

what are penicillinase resistant penicillin known as

A

anti staphylococcus penicillin

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33
Q

route, indication, csf, excretion, others, structure of cloxacillin

A

IV/ IM/ PO

staphylococci and other gram pos, MSSA

not therapeutic levels in csf

renal, unchanged in urine, excreted by tubular secretion so can use probenecid to block and prolong effect

best taken on empty stomach

bulky side chains allow for narrower spectrum of activity

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34
Q

limitations of cloxacillin

A

not effective against amoebae, plasmodia, rickettsiae, fungi, virus

not for MRSA as PBP modified

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35
Q

route, indication, csf, excretion, others, structure of oxacillin

A

IV/ IM/ PO

staphylococci and other gram pos, MSSA

non therapeutic levels in csf

renal, unchanged in urine, excreted by tubular secretion so can use probenecid to block and prolong effect

best taken on empty stomach

bulky side chains allow for narrow spectrum of activity

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36
Q

limitations of oxacillin

A

not effective against amoebae, plasmodia, rickettsiae, fungi, virus

not for MRSA as PBP modified

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37
Q

route, indication, csf, excretion, others, structure of flucloxacillin

A

IV/ IM/ PO

staphylococci and other gram pos, MSSA

non therapeutic levels in csf

renal, unchanged in urine, excreted by tubular secretion so can use probenecid to block and prolong effect

best absorbed on an empty stomach

bulky side groups allow for narrow spectrum of activity

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38
Q

limitations of flucloxacillin

A

does not cover amoebae, plasmodia, rickettsiae, fungi, virus

not effective for MRSA as PBP modified

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39
Q

what drugs are anti pseudomonal penicillin

A

piperacillin

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40
Q

route, indication, csf, excretion, others of piperacillin

A

IV

gram neg (pseudomonas, klebsiella, proteus, bacteremia, pneumoniae), non beta lactamase producing gram pos strains of streptococci and enterococci

fairly well in inflamed meningitis

renal, 70% unchanged in urine, excreted by tubular secretion so can use probenecid to block and prolong effect

greater activity against other penicillin for pseudomonas, klebsiella and proteus, susceptible to inactivation by bacterial beta-lactamase production

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41
Q

limitation of piperacillin

A

not effective against MRSA as PBP modified

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42
Q

what are examples of beta lactamases inhibitors

A

clavulanic acid, sulbactam, tazobactam

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43
Q

what are the combination products with penicillins and beta lactamases inhibitors

A

clavulanic acid with amoxicillin (augmentin)
sulbactam with ampicilin (unasyn)
tazobactam and piperacillin (zosyn)

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44
Q

what is the moa of beta lactamase inhibitors

A

work primarily by inactivating serine beta lactamases which are enzymes that hydrolyse and inactivate the beta lactam ring especially in gram neg bacteria, has strong affinity for beta lactamases and allows them to bind to it and inactivate or bind irreversibly to protect beta lactam abx from being targeted by beta lactamases

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45
Q

how does clavulanate interact with beta lactamase

A

it is a suicide inhibitor and acts by covalently bonding to a beta lactamase which causes permanent restructuring thus inactivating it

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46
Q

how does sulbactam interact with beta lactamases

A

sulbactam irreversibly binds to beta lactamase at or near its active site

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47
Q

how does tazobactam interact with beta lactamases

A

tazobactam irreversibly binds to beta lactamase at or near its active site

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48
Q

route, indication, csf, excretion of augmentin

A

IV, PO

beta lactamase producing gram pos (staphylococcus), gram neg (influenzae, gonoccoci, e coli)

modest penetration of clavulanate thus not recc for cns infection

renal, excreted unchanged in urine, renal dose adjustments required

49
Q

what kinds of infections would augmentin be used for

A

skin, lrti, uti

50
Q

route, indication, csf and excretion of unasyn

A

IV

beta lactamase producing strains of gram pos (staphylococci), gram neg aerobes, anaerobes

pentration of sulbactam variable, depends on presence of inflamed meningitis

renal, excreted unchanged in urine, renal dose adjustments required

51
Q

what kinds of infections would unasyn be used for

A

skin, intra abdominal, gynaecological

52
Q

route, indication, csf and excretion of zosyn

A

IV

enterobacteriaceae, bacteriodes species

modest penetration of tazobactam, discouraged for use of cns infections

tazobactam and its metabolised excreted in urine, renal dose adjustments required

53
Q

what kinds of infections would zosyn be used for

A

appendicitis, moderate to severe nosocomial pneumonia

54
Q

what are the mechanisms of resistance to penicillins

A
  1. alteration to PBP resulting in less affinity for penicillins (MRSA expresses PBP2a)
  2. production of beta lactamases by bacterial which causes hydrolysis of beta lactam ring
  3. decreased ability of reaching PBP when bacteria decreases porin production
  4. presence of efflux pumps
55
Q

what are the adverse drug reactions of penicillins

A
  1. allergy, hypersensitivity
  2. clostridiodes difficile associated diarrhoea with ampicillin, amoxicillin, augmentin
  3. neurotoxicity
  4. hepatotoxity with oxacillin, flucloxacillin
  5. anosmia
  6. seizures
56
Q

what are the chemical properties of cephalosporins

A

modifications at position 7 at beta lactam ring associated with alterations in antibacterial activity

substitution at position 3 of the dihydrothiazine ring alters metabolism and PK properties of the drugs

57
Q

what are the properties of cephalosporins

A

relatively stable in dilute acid, widely distributed, third forth fifth gen have excellent csf penetration

58
Q

what are the first gen cephalosporins

A

cefazolin, cephalexin, cefadroxil, cephradine

59
Q

what are the second gen cephalosporins

A

cefuroxime

60
Q

what are the third gen cephalosporins

A

cefotaxime, ceftriaxone, ceftazidime

61
Q

what are the forth gen cephalosporins

A

cefepime

62
Q

what are the fifth gen cephalosporins

A

ceftaroline, ceftobiprole

63
Q

how does the gram neg activity vary between the different cephalosporins

A

low activity for first gen, higher activity for second and third gen, highest activity for forth gen

64
Q

how does the resistance to beta lactamases vary between different cephalosporins

A

low for first gen, moderate for second gen, high for third and forth gen

65
Q

how does the csf distribution vary between different cephalosporins

A

poor for first and second, good for third and forth

66
Q

what is LAME

A

listeria monocytogenes, atypicals (mycoplasma, chlamydia, legionella), MRSA, enterococus

67
Q

route, indication, excretion of cefazolin and what is it a good alternative for

A

IV, IM, eyedrops

gram pos (streptococci, staphylococci)

renal

good alternative for if allergic to anti-staph penicillin

68
Q

what are the limitations of cefazolin

A

does not cover gram pos (enterococci), gram neg (pseudomonas)

lack activity against LAME

69
Q

route, indication, excretion of cephalexin

A

PO

gram pos (streptococci, staphylococci)

renal

70
Q

what is the limitation of cephalexin

A

does not cover gram pos (enterococci) and gram neg (pseudomonas)

lack activity against LAME

71
Q

route, indication, excretion of cefuroxime

A

PO

gram neg (e coli, klebsiella, proteus, influenzae), CAP

renal

72
Q

what is the limitation of cefuroxime

A

does not cover gram pos (enterococci) and gram neg (pseudomonas)

lack activity against LAME

73
Q

route, indication, csf, excretion of cefotaxime

A

IV, IM

gram neg (enterobacteriaceae, pseudomonas, gonococci), gram pos (strep, staph)

good cns penetration

renal

74
Q

benefit of cefotaxime

A

good resistance against beta lactamases and good coverage of gram neg

75
Q

limitations of cefotaxime

A

lack activity against LAME

76
Q

route, indication, csf, excretion of cetriaxone

A

IV, IM

gram neg (enterobacterieae, pseudomonas, gonococci) and gram pos (staph, strep)

good cns penetration

hepatic

77
Q

benefits of ceftriaxone

A

good resistance against beta lactamases, good coverage of gram neg

78
Q

limitations of ceftriaxone

A

lack activity against LAME

79
Q

route, indication, csf, excretion of ceftazidime

A

IV, IM

gram neg (enterobacterieae, pseudomonas, gonococci) and gram pos (staph, strep)

good cns penetration

renal

80
Q

limitations of ceftazidime

A

lack activity against LAME

81
Q

route, indication, csf, excretion of cefepime

A

IV, IM

gram neg (enterobacterieae, pseudomonas, gonococci) and gram pos (staph, strep)

good cns penetration

renal

82
Q

benefit of cefepime

A

more resistant to beta lactamases

83
Q

limitations of cefepime

A

lack activity against LAME

84
Q

route, indication, csf, excretion of ceftaroline

A

IV

gram pos (MRSA, VRSA, strep) and gram neg (influenzae, morazella catarrhalis)

good cns penetration

renal

85
Q

route, indication, csf, excretion of ceftobiprole

A

IV

gram pos (MRSA) and gram neg (ecoli, klebsiella, pseudomonas, enterobacter)

good cns penetration

renal

86
Q

what are the adverse drug reactions to cephalosporins

A
  1. hypersensitivity
  2. GI disturbances (D for PO, CDAD)
  3. thrombophlebitis
87
Q

how to minimise risk for thrombophlebitis

A

give slowly and in diluted form and rotate infusion sites

88
Q

what is the chemical structure of carbapenems

A

fused beta lactam ring with a five membered ring

89
Q

what properties does carbapenems have

A

poor oral absorption and five membered ring gives protection against most beta lactamases

90
Q

what type of bacteria does resistance to carbapenems occur

A

gram neg (klebsiella, pseudomonas, acinetobacter)

91
Q

what is the indication for carbapenems

A

ESBL, gram neg and anaerobic

92
Q

what are the drugs that are carbapenems

A

imipenem (with cilastatin), meropenem, ertapenem

93
Q

route, indication, excretion of imipenem

A

IV

gram pos (strep, entero excl faecium, staph) and gram neg (pseudomonas) and anaerobes

renal, hydrolysed rapidly by dehydropeptidase 1 (DHP1), metabolite can be nephrotoxic so renal adjustments needed

94
Q

what is the role of cilastatin added to imipenem

A

cilastatin is a DHP1 inhibitor and can recover more of active imipenem

95
Q

what can imipenem treat

A

moderate to severe nosocomial infections, intra abdominal, skin, septicaemia

95
Q

what can imipenem treat

A

moderate to severe nosocomial infections, intra abdominal, skin, septicaemia

96
Q

limitation of imipenem

A

MRSA is resistant

97
Q

route, indication, csf, excretion of meropenem

A

IV

gram pos (strep, entero excl faecium, staph), gram neg (pseudomonas) and anaerobes and some imipenem resistant pseudomonas

good csf penetration in inflamed meningitis

renal, unchanged in urine as stable against hydrolysis by DHP1

98
Q

which special population can meropenem be used in

A

in children <3m with meningitis

99
Q

limitations of meropenem

A

MRSA is resistant

100
Q

is imipenem or meropenem more active against gram pos cocci

A

imipenem

101
Q

what can meropenem treat

A

moderate to severe nosocomial infections, skin, intra abdominal, septicaemia

102
Q

what is the additional limitation of ertapenem

A

lack activity against pseudomonas and enterococci

103
Q

what are the adverse effects of carbapenems

A
  1. GI disturbances (N, V, D for tienam)
  2. neurotoxicity
  3. rashes
  4. cross hypersensitivity with penicillin (avoid with reported penicillin allergy)
104
Q

what is an example of a monobactam

A

aztreonam

105
Q

route, indication, csf, elimination of aztreonam

A

IV, IM

gram neg and beta lactamase producing gram neg (enterobacteriae, pseudomonas, influenzae, gonococci)

penetrate BBB in inflamed meningitis

renal, excreted unchanged in urine, renal dose adjustments required

106
Q

what can aztreonam treat and what bacteria spp is in each of these diseases

A
  1. uti (enterobacter)
  2. lrti (influenzae, e coli, klebsiella, pseudomonas)
  3. septicemia (e coli, klebsiella, pseudomonas, enterobacter)
  4. intra absominal (e coli, klebsiella, pseudomonas, enterobacter)
107
Q

what are the adverse effects of aztreonam

A
  1. occasional skin rash and transaminaesemia
  2. little or no cross reactivity with other penicillin
107
Q

what are the adverse effects of aztreonam

A
  1. occasional skin rash and transaminaesemia
  2. little or no cross reactivity with other penicillin
108
Q

what is the moa of vancomycin

A

binds with high affinity to the D-Ala-D-Ala terminus of pentapeptide of the NAM component of peptidoglycan and interferes with the transglycosylation of the cell wall precursor units hence inhibiting bacterial cell wall synthesis

109
Q

what is the coverage of vancomycin and why

A

gram pos coverage as vancomycin is large in size thus unable to penetrate outer membrane of gram neg

110
Q

route, indication, excretion of vancomycin

A

IV, PO

gram pos (staph incl MRSA, MSSA, enterococci, strep, bacillus, clostridium)

renal, excreted unchanged in urine, renal dose adjustments required

111
Q

what can vancomycin treat

A

osteomyelitis, endocarditis, CDAD, abx assoc pseudo membrane colitis (AAPMC), penicillin allergy, prophylaxis for MRSA, meningitis

112
Q

how is PO absorption for vancomycin and which disease do we use PO

A

poor absorption, use for CDAD and AAPMC

113
Q

is vancomycin safe in pregnancy and lactation

A

IV category C, PO category B

114
Q

what are the adverse effects of vancomycin

A
  1. thrombophlebitis
  2. redman syndrome
  3. nephrotoxicity and ototoxicity
115
Q

what are the mechanisms of resistance to vancomycin

A
  1. enterococcal resistance due to expression of enzymes that modify cell wall precursor by substituting D-Ala for D-lactate or D-serine which reduces binding affinity of vancomycin by up to 1000x
  2. emergence of VRSA
116
Q

what is red man syndrome

A

rash above nipple line involving neck, face, upper torso and is accompanied by hypotension

117
Q

why does redman syndrome occur and how to prevent

A

due to histamine release when vancomycin infused too quickly,. infuse for 1-2h

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