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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
when is zosyn used ( tazobactam + piperacillin)
broadest antibacterial spectrum. Used to treat severe cases of nosocomial pneumonia
26
What are some mechanisms to resistance to penicillins
1. penicillin binding protein ( transpeptidase can be altered, reducing affinity for penicillin) 2. efflux pump 3.production of B-lactamase 4. when bacteria decrease porin production, decreased ability of antibiotic to reach PBP
27
what is resistant to penicillins
MRSA
28
what are some adverse effect to penicillin
hypersensitivity cdad with ampicillin neurotoxicity hepatotoicity anosmia
29
which cephalosporin have excellent CSF penetration
3,4 and 5 gen
30
what is 1st and 2nd gen cephs not active against
enterococci or P. aeruginosa
31
what are the egs of 1st gen cephs and what is it active against
cefazolin (iV), cephalexin, cefadroxil, cephradine. Mostly taken orally Very active against gram positives streptococci, staph aureus
32
example of gen 2 cephs and its usage
cefuroxime, used for e coli, klebsiella, proteus, haemophilus influenzae
33
example of gen 3 cephs and its uses
cefotaxime, ceftriaxone,ceftazidime used for p. aeruginosa, neisseria gonorrhoeae, enterobacteriaceae. Activity for s aureus, strep pneumoniae, strep pyogenes comparable to first generation agents
34
example of 4th gen ceph and their uses
cefepime . covers pseudomonas, more resistance to some B-lactamases. Comparable to 3rd gen
35
example of 5th gene, and uses
Ceftaroline.ONLY ONE TAHT COVERS MRSA. covers VRSA, strep pneumoniae, haemophilus influenzae, moraaxella catarrhalis. DOes not cover ESBL producing strains
36
Which ceph is most active against s. aureus and s. pyogenes
cefotaxime
37
how is ceph eliminated, what is the exception
renally, except ceftriaxone through hepaticd
38
what are some adverse reactions of ceph
hypersensitivity GIT, CDAD Thrombophlebitis
39
What is carbapenem first line agent
ESBL producing bacteria
40
what are the types of carbapenem
imipenem, meropenem, ertapenem
41
which is the more limited spectrum of carbapenem and why
ertapenem, lacks activity against p. aeruginosa and enterococcus
42
how is carbapenem excreted
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
what is resistant to carbapenem
MRSA
44
what are some adverse effects of carbapenem
GIT Rashes neurotoxicity at high blood concentrations cross hypersensitivity with penicillins
45
What is the example of monobactam
aztreonam
46
what is monobactam used for
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
how is azteronam administered
IV, IM, penetrates BBB in patients with inflammed meninges
48
What are the adverse effects of aztreonam
generally well tolerated, can cause occasional skin rash and transaminasemia. Little or no cross sensitivity with other penicillin
49
What does vancomycin covers
primarily acts on gram positive bacteria
50
How is vancomycin administered
orally and IV, but oral administration poor
51
what is vancomycin used to treat
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
how does vancomycin works
interferes with transglycosylation of cell wall precursor units, inhibiting bacterial cell wall synthesis
53
what are some adverse reactions of vancomycin
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
what is the pregnancy category for vancomycin
Cat C for parentral, cat B for oral
55
how can vancomycin face resistance
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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