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Infectious Disease > Beta Lactam Antibiotics > Flashcards

Beta Lactam Antibiotics Flashcards

1
Q

How do beta-lactam antibiotics work?

A

inhibits cell wall biosynthesis by binding to penicillin binding proteins (PBPs). bactericidal of growing bacteria.

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2
Q

How do bacteria develop resistance to beta lactams?

A

by synthesizing β-lactamase (penicillinase), an enzyme that breaks down the beta-lactam ring and inactivates the antibiotic.

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3
Q

How do we overcome beta-lactam resistance?

A

β-lactam antibiotics are often given with β-lactamase inhibitors such as clavulanic acid.

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4
Q

What are the classes of beta-lactam compounds?

A

Penicillins, Cephalosporins, Beta-Lactamase Inhibitors- combined w/ PCN’s

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5
Q

What are the classifications of penicillins?

A 
Penicillin G (IM or IV, if oral form it’s called penicillin B). Antistaphlococcal PCNs: nafcillin, dicloxacillin, Oxacillin, cloxacillin. Broad Spectrum PCNs: 2nd generation- ampicillin, amoxicillin or 3rd generation
carbenicillin, ticarcillin or 4th generation piperacillin
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6
Q

What are the penicillin combos w/beta-lactamase inhibitors?

A

amoxacillin/potassium clavulanate (Augmentin), ampicillin/sulbactam (unasyn), Ticarcillin/potassium clavulanate (Timentin), Piperacillin & tazobactam sodium (Zosyn)

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7
Q

What are some precautions of PCNs?

A

should be given on an empty stomach (one hr before eating or 2 hrs after eating), Giving PCNs with probenecid (500mg q 6 hrs) increases blood levels of all PCNs. PCNs can cause encephalopathy, somnolence, stupor, coma, seizures, diarrhea or C.diff

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8
Q

What infections are treated with Penicillin G?

A

sepsis, pneumonia, pericarditis, endocarditis, meningitis, anthrax

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9
Q

What type of organisms is Penicillin G active against?

A

Gram-positive cocci (streptococci, staphylococci), Gram-positive rods (Listeria), Gram-negative cocci (Neisseria). Most anaerobes

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10
Q

What is the usual dosage of Penicillin G?

A

1-24 million units/day divided every 4-6 hours. Erysipelas: IV: 1-2 million units every 4-6 hours x 7-10 days. Neurosyphilis: IV: 18-24 million units/day in divided doses every 4 hours for 10-14 days

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11
Q

What is the activity of antistaphylococcal PCNs (dicloxacillin, oxacilliln, nafcillin)?

A

used for infection with beta-lactamase-producing staph, also used against PCN susceptible strains strep, & pneumococci. Inactive against Enterococci & methicilliin resistant strains

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12
Q

What are the usual dosages of antistaphylococcal PCNs?

A

Dicloxacillin 125-500 mg PO q 6h. Oxacillin 250-1000mg IM/IV q4-6h. Nafcillin 0.5-2g IV q4-6h

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13
Q

What are 2nd generation (ampicillin and amoxicillin) PCNs active against?

A

most E. coli, Proteus mirabilis, Salmonella, Shigella & H. influenzae. Used to treat otitis, sinusitis, lower RTI.

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14
Q

What are the usual dosages of 2nd generation PCNs?

A

amoxicillin 250-500 mg q8hr (ampicillin q6h). Augmentin (amoxicillin + clavulanic acid) 875mg q12 h (expands coverage to gram +/- and anaerobes)

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15
Q

Why is ampicillin not recommended for mononuclesosis?

A

A high percentage of patients with infectious mononucleosis have developed rash during therapy

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16
Q

What is the activity of 3rd generation (carbenicillin and ticarcillin) PCNs?

A

strep, enteric gram-neg bacilli (E. coli, Klebsiella pneumoniae, Enterobacter cloacea, Enterobacter aerogenes and Proteus miriabilis), Pseodomonas and anaerobes.

17
Q

What is the dosage for 3rd generation (carbenicillin and ticarcillin) PCNs?

A

ticarcillin IV 3 g q4-6h, 150-200 mg/kd/d in 2-3 doses. available in combo w/ Clavulanate K+ (Temectin)

18
Q

What is the standard therapy anti-pseudomonal med in hospitals?

A

3rd generation PCNs (carbenicillin and ticarcillin)

19
Q

What is Zosyn?

A

4th generation PCN piperacillin + tazobactam. broad spectrum; used for cellulitis, postpartem endometritis, peritonitis, pneumonia.

20
Q

What are some complications of PCN therapy?

A

can cause bleeding problems, interstitial nephritis, neurological complications and seizures, or secondary infections such as vaginal candidiasis

21
Q

What are the beta-lactamase inhibitors?

A

clavulanic acid, sulbactam, tazobactam

22
Q

Describe the use of beta-lactamase inhibitors

A

only in combination with a PCN. they inactivate aminoglycosides. By themselves don’t have antimicrobial activity.

23
Q

What is the dosing of Augmentin (amoxacillin-clavulanic acid?

A

adult: 500-875mg q 12h
ped: 20-40 mg/kg/d q8-12h

24
Q

What is the dosing of Zosyn (piperacillin-tazobactam)?

A

adult: 4.5g IV q6-8h
ped: 240 mg/kg/d q8h IV

25
Q

Describe cephalosporins

A

as they progress from 1st-4th generation there’s an increase in gram (-) coverage and loss in gram (+). They’re well absorbed from GI tract w/food. 3-10% allergic cross-reactivity w/PCNs.

26
Q

What is the standard med for a pregnant women w/an UTI?

A

Keflex (cephalexin)

27
Q

What are the 1st generation cephalosporins and their activity?

A

cefadroxil, cephalexin (Keflex), and cefazolin (Ancef). gram positive streptococcus and staphylococcus, good against anaerobic cocci (eg, peptococcus, peptostreptococcus)

28
Q

What are the usual dosages of 1st gen cephalosporins?

A

cephalexin (Keflex) 250-500 mg qid used for cellulitis, cefazolin (Ancef) used for surgical prophylaxis 1-2 gm IV

29
Q

What are the 2nd generation cephalosporins and their activity?

A

cefuroxime (po 250-500mg bid: IV 1-1.5g q8h), cefoxitin(IV 1-2g q6-8h), cefotetan(IV 1-2g q12h)‏. active against gram-pos cocci, some gram negative coverage Klebsiellae, H. influenzae

30
Q

What is cefuroxime used to treat?

A

sinusitis, otitis, RTI, CAP

31
Q

What is cefoxitin used to treat?

A

peritonitis & diverticulitis because active against gram-neg rods & Bacteroides

32
Q

What are the 3rd generation cephalosporins and their activity?

A

cefotaxime (IV 1-2g q6-12h), ceftazidime (IV 1-2g q8-12h), ceftriaxone (1-4g q24h)‏. gram-neg meningicoccus, citrobacter, beta-lactamase strains of haemophilus and neisseria,

33
Q

What are 3rd generation cephalosporins used to treat?

A

ceftriaxone & cefotaxime treat meningitis,
empirical therapy serious infections because effective against PCN-resistant strains pnemonococci, & sepsis. ceftriaxone used to treat gonorhea/Lyme disease

34
Q

What is the 4th generation cephalosporin and its activity?

A

cefepime (IV 0.5-2g q12h, peds 75-120mg/kg/d divided 2-3 doses). Gram positive and negative, including pseudomonas, S aureus, S pneumoniae, haemophilus and Neisseria

35
Q

What is cefepime used to treat?

A

meningitis, serious infections and sepsis. sometimes use with an aminoglycoside when treating pseudomonas

36
Q

What is effective therapy for pseudomonas meningitis?

A

ceftazidime (3rd gen cephalosporin)

37
Q

What are carbapenems and their activity?

A

Imipenem/cilastatin (IV 250-500mg q6-8h), meropenem (IV 1-2g q8h)‏. resistant to cleavage (beta-lactamase); gram-pos(including Enterococcus faecallis & listeria), gram-neg (H influenzae, N gonorrhoeae, Enterobacter & Pseudomonus), Anerobes (including Bacteroides)‏

38
Q

What are carbapenems used to treat?

A

meropenem for meningitis, intraabdominal infections, pseudomonus and with or without an aminoglycoside for neutropenic patient

Infectious Disease (17 decks)

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