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cell wall synthesis inhibitors Flashcards

1
Q

What is the difference between g+ and g- bacteria cell wall

A

g+ have a thick cell wall which is comprised of peptidoglycan and lipoteichoic acid, absence of outer membrane

g- have a thin cell wall, but have an outer membrane consisting of LPS

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2
Q

What are beta lactam

A

4 membered ring
can be fused to 5 membered or 6 membered ring

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3
Q

how does B lactam interfere with cell wall synthesis

A

they bind to active site of transpeptidase, which catalyses the cross linking of terminal peptide components of linear polymer chains

This weakens the cell wall structure of actively growing bacterial cells, lead to build up in intracellular osmotic pressure and lysis of bacterial cells

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4
Q

what type of natural penicillins are there

A

pen g

pen V

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5
Q

what is pen g and pen v used for

A

against B lacatamase negative strains of G+ and G-. for G+ is strep and bacillus diphtheriae. For Gi is gonococci, meningococci, treponema palladium

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6
Q

what is natural penicillins not useful for

A

-> amoebae, plasmodia, rickettsiae, fungi or virus

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7
Q

how is natural pen excreted

A

renally

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8
Q

which has better oral bioavailability, pen g or pen v, and why

A

pen V, more acid stable

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9
Q

what first line treatment is pen V used in

A

in the management of orofacial infections

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10
Q

what are examples of penicillinase resistant penicillins

A

cloxacillin, oxacillin, flucloxacillin

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11
Q

what is penicillinase resistant penicillins most potent against

A

inhibitors of most penicillinase producing staphylococci

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12
Q

what is PRP ineffective against

A

G-ve organisms. all are less effective against microorganisms susceptible to pen G

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13
Q

how is PRP excreted by

A

renal clearance

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14
Q

why is PRP resistant to b-lactamase

A

bulky side group confers protection by limiting their accessibility to the catalytic site of action

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15
Q

What are some examples of broad spectrum penicillins ( aminopenicillins)

A

amoxiciliin, ampicillin

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16
Q

what is the route of administration for aminopenicillins

A

Oral, IV, Oral for amoxicillin is better than ampicillin

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17
Q

what is aminopenicillins indicated for

A

B-lactamase negative strains of microogranisms

In UTI against ecoli
prophylaxis against infective endocarditis
detal abscesses
in URI against S. pneumoniae, H. influenzae
Ampicillin in bacterial meningitis, caused by salmonella, E.coli, neisseria meningiditis. S. pneumoniae etc

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18
Q

what does Aminopenicillins not cover

A

pseudomonas, klebsiella

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19
Q

what is an example of anti psuedomonal penicillin

A

piperacillin

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20
Q

what coverage does piperacillin have

A

greater activity against g- bacteria like pseudomonas, proteus and some species of klebsiella.

has been used against non B lactamase g+ like staphylococcus spp, s. pyogenes, enterococcus

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21
Q

how is piperacillin administered

A

IV

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22
Q

how does piperacillin cleared

A

primary renal clearance, dose adjustment required with renal dysfunction

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23
Q

how does B- lactamase inhibitors work

A

binds to b- lactamses, protecting other B lactams antibiotics from being targeted by B lacatamase

24
Q

clavulanic acid is a suicide inhibitor. Explain

A

they covalently bond to B lactamase and restructure it permanently inactivating it

25
Q

when is zosyn used ( tazobactam + piperacillin)

A

broadest antibacterial spectrum. Used to treat severe cases of nosocomial pneumonia

26
Q

What are some mechanisms to resistance to penicillins

A
  1. penicillin binding protein ( transpeptidase can be altered, reducing affinity for penicillin)
  2. efflux pump

3.production of B-lactamase

  1. when bacteria decrease porin production, decreased ability of antibiotic to reach PBP
27
Q

what is resistant to penicillins

A

MRSA

28
Q

what are some adverse effect to penicillin

A

hypersensitivity

cdad with ampicillin

neurotoxicity

hepatotoicity

anosmia

29
Q

which cephalosporin have excellent CSF penetration

A

3,4 and 5 gen

30
Q

what is 1st and 2nd gen cephs not active against

A

enterococci or P. aeruginosa

31
Q

what are the egs of 1st gen cephs and what is it active against

A

cefazolin (iV), cephalexin, cefadroxil, cephradine.

Mostly taken orally

Very active against gram positives streptococci, staph aureus

32
Q

example of gen 2 cephs and its usage

A

cefuroxime,

used for e coli, klebsiella, proteus, haemophilus influenzae

33
Q

example of gen 3 cephs and its uses

A

cefotaxime, ceftriaxone,ceftazidime

used for p. aeruginosa, neisseria gonorrhoeae, enterobacteriaceae.

Activity for s aureus, strep pneumoniae, strep pyogenes comparable to first generation agents

34
Q

example of 4th gen ceph and their uses

A

cefepime . covers pseudomonas, more resistance to some B-lactamases. Comparable to 3rd gen

35
Q

example of 5th gene, and uses

A

Ceftaroline.ONLY ONE TAHT COVERS MRSA.

covers VRSA, strep pneumoniae, haemophilus influenzae, moraaxella catarrhalis. DOes not cover ESBL producing strains

36
Q

Which ceph is most active against s. aureus and s. pyogenes

A

cefotaxime

37
Q

how is ceph eliminated, what is the exception

A

renally, except ceftriaxone through hepaticd

38
Q

what are some adverse reactions of ceph

A

hypersensitivity

GIT, CDAD

Thrombophlebitis

39
Q

What is carbapenem first line agent

A

ESBL producing bacteria

40
Q

what are the types of carbapenem

A

imipenem, meropenem, ertapenem

41
Q

which is the more limited spectrum of carbapenem and why

A

ertapenem, lacks activity against p. aeruginosa and enterococcus

42
Q

how is carbapenem excreted

A

imipenem hydrolysed rapidly by DHP-1 found in brush borer of proximal renal tubules. cilastatin added to recover more of the active form

meropenem and ertapenem excreted renally. stable against hydrolysis by DHP-1

43
Q

what is resistant to carbapenem

A

MRSA

44
Q

what are some adverse effects of carbapenem

A

GIT

Rashes

neurotoxicity at high blood concentrations

cross hypersensitivity with penicillins

45
Q

What is the example of monobactam

A

aztreonam

46
Q

what is monobactam used for

A

only for gram negative bacteria, useful against many B-lactamase producing gram negative bacteria

like

enterobacteriaceae, p. aeruginosa, h. influenzae. n. gonorrhoeae

Indicated for

UTI by enterobacteriaceae

LRTI due to E. coli, Klebsiella, P. aeruginosa, Haemophilus influenzae

Septicemia and intra abdominal infections by E. coli, Klebsiella pneumoniae, enterobacter and P. aeruginosa

47
Q

how is azteronam administered

A

IV, IM, penetrates BBB in patients with inflammed meninges

48
Q

What are the adverse effects of aztreonam

A

generally well tolerated, can cause occasional skin rash and transaminasemia.

Little or no cross sensitivity with other penicillin

49
Q

What does vancomycin covers

A

primarily acts on gram positive bacteria

50
Q

How is vancomycin administered

A

orally and IV, but oral administration poor

51
Q

what is vancomycin used to treat

A

CDAD( the oral prep), or antibiotic associated pseudomembranous colitis

common indication is osteomyelitis, endocarditis

infections caused by susceptible organisms in individuals with penicillin allergy

Prophylaxis treatment where MRSAis expected

52
Q

how does vancomycin works

A

interferes with transglycosylation of cell wall precursor units, inhibiting bacterial cell wall synthesis

53
Q

what are some adverse reactions of vancomycin

A

red man syndrome
- can be prevented by prolonging duration of infusion to 1-2 hrs

thrombophlebitis with fever chills

nephrotoxicity and ototoxicity which is rare but can be increased when used with other agents that cause this as well like aminoglycoside

54
Q

what is the pregnancy category for vancomycin

A

Cat C for parentral, cat B for oral

55
Q

how can vancomycin face resistance

A
  1. emergence of s aureus that expresses reduced susceptibility to vancomycin
  2. expression of enyme that modify the cell wall precursore, substituting terminal D-alanine for D-lactate or D-serine, reducing vancomycin binding affinity

pharmaco (19 decks)

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