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STEP1 2015 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What organisms can you treat with aminopenicillins (amoxicillin, ampicillin)

HEELPS

A 
gram positives
Also, gram negative rods including HEELPSS
h. influenzae
h. pylori
e. coli
listeria monocytogenes
proteus mirabilis
salmonella
shigella
enterococci
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2
Q

Antipseudomonal penicillins

A

ticarcillin
carbenicillin
piperacillin

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3
Q

bacterial resistance against penicillin agents

A

production of beta- lactamase (hydrolyzes the beta- lactam ring)
alteration of beta lactamase targets

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4
Q

beta- lactamase inhibitors

A

sulbactam
clavulanic acid
tazobactam

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5
Q

clinical use of dicloxacillin, nafcillin, oxacillin

A

these are penicillinase- resistant penicillins. THey have a bulky R group that blocks access of beta- lactamase to beta- lactam rings.
Used for s. aureus (but only methicillin sensitive strains)

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6
Q

side effects of penicillin

A

hypersensitivity reactions, hemolytic anemia, thrombocytopenia

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7
Q

side effects of amoxicillin and ampicilin

A

hypersensitivity, rash, pseudomembranous colitis

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8
Q

ampicillin and amoxicillin- what are they?

A

extended- spectrum penicillins. Combine with clavulanic acid to protect against destruction by beta lactamase.
Amoxicillin is PO and has greater oral bioavailability than ampicillin, which is given by IV.

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9
Q

cephalosporins

A

like penicillins in that they inhibit cell wall synthesis and are therefore bactericidal
but they are less susceptible to penicillinases and have more gram + and gram - coverage.

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10
Q

organisms not covered by cephalosporins are LAME

A

listeria
atypicals (chlamydia, mycoplasma)
MRSA
Enterococci

Exception: ceftaroline covers MRSA

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11
Q

1st generation cephalosporins

A 
cefazolin, cephalexin 
PEcK
proteus mirabilis
E. coli
Klebsiella pneumoniae

cefazolin (ancef) used prior to surgery to prevent s. aureus wound infections

cephalexin commonly used for UTI

Can be used against URIs
Prophylaxis against viridans endocarditis

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12
Q

2nd generation cephalosporins

A

cefoxitin, cefaclor, cefuroxime, cefprozil
HENS PEcK

Haemophilis influenzae
Enterobacter aerogenes
Neisseria spp (gonorrhea resistance is growing so we generally don’t use cephalosporins to treat gonorrhea)
Serratia marcescens

Proteus mirabilis
E. coli
Klebsiella pneumoniae

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13
Q

3rd generation cephalosporins

A

ceftriazone, cefotaxime, ceftazidime, cedinir

coverate of serious gram neg infections that would be resistant to other beta lactams

E. coli
Proteus mirabilis
Klebsiella
Enterobacter
Serratia
Citrobacter
Neisseria
Haemophilus influenzae

Strep pneumoniae!! still!

choice for gram negative meningitis

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14
Q

Ceftriaxone IV

A

3rd generation cephalosporin,
choice for neisseria gonorrhea, meningitis, disseminated Lyme

safety increased because it is excreted in the bile

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15
Q

3rd generation cephalosporin with pseudomonas coverage

A

Ceftazidime

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16
Q

3rd generation PO cephalosporin used for resistant otitis media

A

Cefdinir

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17
Q

Big gun 4th gen cephalosporin

A

Cefepime- 4th generation, gram negative organisms with increased activity against Pseudomonas and gram- positive organisms

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18
Q

5th generation cephalosporin that covers MRSA

A

ceftaroline
Broad gram positive and gram negative organism coverage including MRSA.
Does not cover Pseudomonas

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19
Q

Cephalosporins are LAME against

A

Listeria
Atypicals (mycoplasma, chlamydia)
MRSA (except ceftaroline)
Enteroccoci

for PNA (CAP), azythromycin can be added on for atypicals. 
Ceftriaxone and azythromycin are a common combination
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20
Q

Caphalosporin hypersensitivity reaction

A

5-10% cross- reactivity with PCNs

nephrotoxicity risk if used with aminoglycosides

example- gentamycin

disulfiram- like reaction seen with alcohol when combined with some cephalosporins

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21
Q

broad spectrum coverage for appendicitis

A

imipenem/cilastatin or meropenem

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22
Q

cell wall inhibitors effective against pseudomonas

A

cefepime
axtreonam
carbapenems
carboxypenicillins (eg ticarcillin)

23
Q

resistance to vancomycin

A

D-ala D-ala is converted to

D-ala D-lac

24
Q

Aztreonam

A

monocyclic beta lactam resistant to penicillinases, inhibits cell wall synthesis, binds to penicillin binding protein 3.

gram negative rods ONLY

for PCN- allergic patients and those with renal insufficiency

"aminoglycoside pretender"
covers gram negative
E. Coli
Klebsiella
Pseudomonas
Serratia

Usually nontoxic (few side effects), no cross- sensitivity to PCNs

25
Q

Vancomycin

A

inhibits cell wall formation by binding D-ala D-ala cell wall precursor.
Not susceptible to beta- lactamases

use for gram positive bugs, including MRSA

S. epidermidis, enterococcus, clostridium difficile (PO for pseudomembranous colitis, but use metronodozile instead possible)

Side effects: Nephtoxocity, Ototoxicity, Thrombophlebitis
Red man is diffuse flushing. When this happens, treat with antihistamines and a slower infusion rate

Reisistance via D-ala D-lac

26
Q

Carbapenems

A

imipenem (broad spectrum, must be used with cilastin)
meropenem
ertapenem
doripenem

Gram positive cocci, gram negative rods, wide spectrum but significant side effects limit use to life- threatening infections (empiric threatment)
Won’t cover MRSA.

Meropenem has decreased risk of seizures

Toxicity- GI distress, skin rash, CNS toxicity (seizures) at high plasma levels

Imipenem is more neurotoxic than meropenem which has a decreased risk of seizures,
won’t be inactivated in the renal tubules

27
Q

but AT 30, CCEL at 50

A

protein synthesis inhibitors
30S inhibitors
Aminoglycosides (bactericidal)
Tetracyclines (bacteriostatic)

50S inhibitors
Chloramphenical, Clindamycin (bacteriostatic)
Erythromycin (macrolides, bacteriostatic)
Linezolid (variable)

28
Q

Tetracyclines- how do they work and what do they cover?

  • tetracycline
  • doxycycline
  • minocycline
A

Bacteriostatic, binds 30S and prevents tRNA interaction. limited CNS penetration.
Fecally eliminated, which makes amenable to patients who have renal failure. Divalent cations block absorption ion the gut; not to be combined with milk or iron.

Side effects: GI distress (don’t use antacids- then the antibiotic won’t be absorbed at all!), discolored teeth, inhibited bone growth in children, photosensitivity, contraindicated in pregnancy
Minocycline can give blue discoloration after prolonged use

VACCUUM THe BedRoom
Vibrio cholerae
Acne
Chlamydia
Ureaplasma urealyticum
Mycoplasma pneumoniae
Tularemia
Helicobacter pylori
Borrelia burgdorferi
Rickettsia

resistance via decreased uptake or increased efflux out of bacterial cells by plasmid- encoded transport pumps

29
Q

Oxazoladinone- Linezolid

A

binds 23S RNA component of 50S large ribosomal subunit, interacts with and inhibits formation of bacterial initiation complex

used against MRSA, VRE, and is used orally against MRSA! Outpatient MRSA therapy is possible with linezolid if well controlled

Toxicity- bone marrow suppression, thrombocytopenia, peripheral neuropathy, serotonin syndrome for pts who are on SSRIs

resistance via point mutation on RNA

30
Q

AminO2glycosides

  • gentamycin
  • neomycin
  • amikacin
  • tobramycin
  • streptomycin
A

binds 30S ribosome
bactericidal
IRREVERSIBLY inhibits formation of initiation complex, causes mRNA misreading, ineffective against anaerobes (requires oxygen)

These are for severe gram neg rod infections, and work synergistically with beta lactam antibiotics (eg am+gent)
neomycin for bowel surger

Toxicity: NNOT
nephrotoxicity (especially when used with cephalosporins)
neuromuscular blockade
ototoxicity (especially if combined with loop diuretics)
Teratogen

resistance comes with bacterial transferase enzymes capable of acetylating, phosphorylating, or adenylating the aminoglycoside

31
Q

Macrolides. macroslides

  • erythromycin
  • azithromycin
  • clarithromycin
A

inhibit protein synthesis by blocking translocation (macroslides) at the 23rRNA of the large 50S ribosomal subunit.
Bacteriostatic

used for PUS
PNA (atypical especially- mycoplasma, chlamydophila, legionella) b. pertussis

URI (strep pneumoniae, strep pyogenes)

STD (chlamydia, gonorrhea)

Toxicity:
MACRO: GI motility issues, Arrythmia due to prolonged QT, acute Cholestatic hepatitis (with erythromycin estolate), Rash, rare cases of eOsinophilia

increases serum concentration of theophyllines and oral anticoagulants (warfarin)

mostly safe in pregnancy
-azythromycin

Resistance via methylation of 23S rRNA binding site (prevents drug from binding)

32
Q

chloramphenicol

A

inhibits 50S subunit of ribosomal RNA, thereby inhibiting peptidyltransferase activity. Bacteriostatic

treats
meningitis:
haemophilus influenzae
neisseria meningitidis, streptococcus pneumoniae

RMSF

unpopular due to toxicity:
dose- dependent anemia
grey baby syndrome (babies need UDPGT to metabolize chloramphenicol, and they experience a buildup of toxic metabolites)
symptoms include vomiting, ashen gray skin tone, poor muscle tone, cyanosis, CV collapse

stop the chloramphenicol and do an exchange transfusion to treat this

try phenobarbitol to induce UDPGT

resistance: plasmid- encoded acetyltransferase can inactivate the drug

33
Q

Clindamycin

A

Clindamycin blocks peptide bond formation with the 50S ribosomal subunit. It is bacteriostatic.

Use: ANAEROBES (bacteriodes, clostridium perfringens) in aspiration PNA, lung abscesses, oral infections, invasive GAS
- above the diaphragm (versus metronidazole which is used below the diaphragm)

Can also be used against MRSA skin abscesses (oral clindamycin is a nice outpatient option), protozoal infections
topical use for acne treatment

Toxicity:pseudomembranous colitis (C. Diff), fever, diarrhea

34
Q

Streptogramins

-Quinupristin/Dalfopristin (Synercid)

A

mechanism: binds to the 23S portion of the 50S ribosome
(synthesized by the bacteria streptomyces virginiae)

Use: MRSA, VRE,
Staphylococcus and streptococcus skin infections that are very serious- this drug has a lot of side effects

Side effects: hepatotoxicity
pseudomembranous colitis, arthralgia, myalgia

inhibits CYP450

35
Q

Sulfonamides

  • sulfamethoxazole (SMX)
  • sulfdiazone
A

bacteria need to absorb folic acid- they can’t make their own

Sulfonamides inhibit folate synthesis
Para-aminobenzoic acid (PABA) antimetabolites inhibit dihydropteroate synthase

Bacteriostatic (bactericidal when combined with trimethoprim)= TMP SMX

Dapsone, used to treat lepromatous leprosy is a closely related drug that also inhibits folate synthesis

Covers gram positives AND negatives
Nocardia
Chlamydia
UTIs like E Coli

Skin infections

Toxicity-
hypersensitivity reactions
hemolysis if G6PD deficient
nephrotoxicity (tubulointerstial nephritis)
photosensitivity
kernicterus in infants- do not give to pregnant females who are about to deliver
SJS
displace other drugs from albumin (warfarin)

Resistance to the drug
altered bacterial dihydropteroate synthesis
decreased uptake
increased PABA synthesis (if this were the case you could give a bigger dose?)

36
Q

Sulfa Pills Frequently Cause Terrible Acute Symptoms

drugs that cause sulfa allergy

A

Sulfa Pills Frequently Cause Terrible Acute Symptoms

Sulfasalazine
Probenecid
Furosemide
Celecoxib
Thiazides/TMP-SMX
Acetazolamide
Sulfonylureas
37
Q

Drugs that cause SJS

A 
Penicillin drugs
Sulfa drugs
Seizure drugs
-ethosuximide
-lamotrigine
-carbamazepine
-phenobarbital
-phenytoin
Allopurinol
38
Q

Trimethoprim

A

Dihydrofolate reductase inhibitor

bacteriostatic

combine with sulfonamaides to cause sequential block of folate synthesis. 
TMP-SMX can be used for 
UTIs
shigella
salmonella
pneumocystis jirovecii
pneumonia treatment and ppx when CD4
39
Q

Drugs that inhibit dihydrofolate reductase

A

methotrexate
trimpethoprim
pyrimethamine

40
Q

nitrofurantoin

A

bacteriocidal
reduced by bacterial proteins to a reactive intermediate that inactivates bacterial ribosomes

It has be reduced in the presence of bacteria to be effective- only effective in the URINE

useful only for mild UTI (so, not pyelonephritis)
-e.coli
staphylococcus

side effects: rarely nausea, HA, diarrhea

safe in pregnancy

41
Q

Fluoroquinolones

  • levofloxacin
  • ciproflozacin
  • norfloxacin
  • levofloxacin
  • ofloxacin
  • moxifloxacin
  • gemifloxacin
  • enoxacin
  • gatifloxacin
  • nalidixic acid
A

inhibits DNA gyrase (aka topoisomerase I)

absorption inhibited if taken with antacids

used for gram negative infections, UTIs, GI tract
infections, pseudomonas

varying amounts of gram + coverage

ok for CF children if they are getting a lot of lung infections

toxicity:
GI upset
cartilage damage in children
tendinitis and tendon rupture
QT interval prolongation

Resistance: chromosome-encoded DNA gyrase mutation

42
Q

Metronidazole

A

absorbed by micro-organisms, forms toxic ROS that damage DNA

use for GET GAP on the Metro
Giardia lamblia
Entamoeba histolytica
Trichomonas
Gardnerella vaginalis
Anaerobic bacteria (c. diff, perfringens, tetani, bacteriodes  species)
Pylori (helicobacter pylori)

Can cause a disulfiram-like reaction with alcohol (sweating, nausea, hypotension)

43
Q

Polymyxins

Polymyxin E, polymyxin B

A

Cationic detergents that attack and disrupt cell membranes and also inactivate endotoxin

Use for last resort therapy against gram- negative infections (give by IV)

toxicity: neurotoxicity, nephrotoxicity (ATN)

almost always used topically

44
Q

ppx meningococcal meningitis

A

ciprofloxacin, rifampin, ceftriaxone

45
Q

ppx h. influenzae meningitis

A

rifampin

46
Q

Gonorrea

A

ceftriaxone, especially after sexual assault

47
Q

syphilis

A

benzathine penicillin G

48
Q

recurrent UTI

A

TMP-SMX, nitrofurantoin, amoxicillin, cephalexin

49
Q

prevent pneumocystis jirovecii

A

TMP-SMX, when CD4

50
Q

endocarditis from dental procedure

A

penicillin, amoxicillin, cephalexin, azythromycin

Target= viridans strep

51
Q

GBS

A

ampicilin during labor

52
Q

gonocccal/ chlamydial conjunctivitis

A

erythromycin ointment

53
Q

SAFe Children Take Really Good Care

A 
Sulfonamides-kernicterus
Aminoglycosides-ototoxicity
Fluoroquinolones- cartilage damage
Clarythromycin- embryotoxic
Tetracyclines- discolored teeth, inhibition of bone growth
Ribavirin (antiviral)- teratogenic
Griseofulvan (antifungal)- teratogenic
Chloramphenicol- gray baby syndrome

STEP1 2015 (30 decks)

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