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Flashcards in Intro to Antibiotics Deck (57):
1

Bactericidal

Directly kill bacteria (doesn’t require functioning immune system from the host for antibiotic to work appropriately)
Inhibitors of cell wall synthesis, cell membrane disruptors, aminoglycosides, DNA gyrase inhibitors

2

Bacteriostatic

Arrest the growth or replication of bacteria. Host immune system then eliminates the pathogens. (slow down infection, but require host immune system for it to work)
Non-aminoglycoside inhibitors of protein synthesis (i.e. macrolides), antifolate drugs

3

agents that inhibit cell wall synthesis

Penicillins
Cephalosporins
Cycloserine
Vancomycin
Bacitracin

4

Agents that act directly on the cell membrane of the microorganism affecting permeability and leading to leakage of intracellular compounds.

Detergents
Polymyxin

5

Agents that interfere with protein synthesis by Interaction with bacterial ribosomes

Chloramphenicol
Tetracyclines
Macrolides
Clindamycin
Streptogramins
Ketolides

6

The antimetabolites—blocking bacterial folic acid pathway

Trimethoprim
Sulfonamides

7

When do you use antibiotics as empirical therapy?

before you get lab results and know which specific infection you’re treating. You know there’s infection but you don’t know which bacteria you have yet.
Goal: Broad spectrum- want to cover as many bacterium as possible.

8

what are some of the reasons resistance to antibiotics occurs?

1) drug fails to reach target
2) Drug is inactivated- Beta lactam antibiotics.
3) Target is altered (change in binding site)
4) Adaptations that bypass need for binding site

9

Examples of multiple drug-resistant bacteria:

Methicillin-resistant Staphylococcus aureus (MRSA)
Mycobacteria tuberculosis

10

Beta Lactam compounds

Penicillins:
--Natural Penicillin (G and V)
--Aminopenicillins
--Penicillinase Resistanct Penicillins
--Extended Spectrum Penicillins (Anti- pseudomonal)
Cephalosporins:
--First Generation
--Second Generation
--Third Generation
--Fourth Generation
--Fifth Generation
Others:
--Carbapenems
--Monobactams
--Beta lactamase inhibitors

11

Beta-lactam antibiotics are generally...

Bactericidal- because these are destructors of the cell wall
Most active against growing organisms (if you inhibit organisms growth by adding bacteriostatic, these wont work—general rule)

12

What are the "natural penicillins?"

Penicillin G or V.
Narrow spectrum, PCN G acid labile—breaks down in acid (have to administer non-oral route), penicillinase sensitive (same as beta lactamas sensitive)
Highly active against sensitive strains of gram positive cocci (except staphylococcus)
Streptococcus, Enterococcus faecalis, Listeria monocytogenes (rod)

13

What are some anaerobes and gram negative bacteria that "natural penicillins" work against?

Anaerobes such as Bacteroides species and Fusebacterium species
Some gram negative such as E. coli, H. influenzae, N. gonorrhoeae, Treponema pallidium

14

What are some infections that natural penicillins treat?

infections of upper and lower respiratory tract, throat, skin, GU tract

15

In what cases are natural penicillins used as prophylaxis?

Prophylaxis for rheumatic fever, dental procedures for those at risk of endocarditis*** (IV drug user at huge risk), gonorrhea or syphilis exposure (so pt that has a partner that’s infected with gonorrhea or syphilis)—but don’t want to pass out penicillin to everybody…just when you have a SPECIFIC concern.

16

What are the Aminopenicillins?

Ampicillin and amoxicillin

17

What bacteria Aminopenicillins treat?

Activity of Pen G plus improved coverage of gram-negative cocci and Enterobacteriaceae
Not active against Treponema sp. or Actinomyces sp. (which we did see w/ natural penicillins)

18

What are the therapeutic uses of aminopenicillins?

URI (otitis, sinusitis), uncomplicated UTI, meningitis, salmonella infections
Depends on resistance patterns in your area
Resistance has lead to combinations with beta- lactamase inhibitors
Augmentin = amoxicillin + clavulanic acid
Ampicillin + Sulbactam (Unasyn)
Better coverage against H. influenzae and Klebsiella sp.

19

What are the Penicillinase-Resistant Penicillins?

Also called “Antistaphylococcal Penicillins”
Nafcillin, Oxacillin, Dicloxacillin
Methicillin and cloxacillin no longer available in US but left up here because represents class of drugs (MSSA specific!! in MRSA pts, none of these will work. Methicillin resstant means Nafcillin, Oxacillin and Dicloxacillin won’t work)

20

What are Penicillinase-Resistant Penicillins used to treat ?

Used in treatment of staphylococcal infections with high beta-lactamase production
Cellulitis, endocarditits
Not active against gram-negative or anaerobic organisms
Specifically treats MSSA!!

21

Antipseudomonal Penicillins

Piperacillin, ticarcillin, carbenicillin (PO)

22

Which bacteria do antipseudomonal penicillins work against?

Maintain activity of Pen G (so still have coverage of strep, enterococcus) plus greater gram negative coverage including pseudomonas
coverage against H. influenzae and Klebsiella sp.
No coverage against Treponema palladium or Actinomyces sp. (lose this coverage from penecillin G)
Gram-negative infections in combo with aminoglycosides (to target some gram – infections. Can begin therapy w/ something like this. Broad spectrum)

23

What are some things antipseudomonal penicillins treat?

Bacteremias, pneumonias, resistant UTIs, infections in burn patients

24

antipseudomonal penicillins paired with beta-lactamase inhibitors

Piperacillin + tazobactam = Zosyn
Ticarcillin + clavulanic acid = Timentin

25

What are the 3 common beta-lactamase inhibitors?

clavulanic acid, sulbactam, tazobactam:
Aminopenicillins:
Amoxiciliin + Clavulanic Acid (Augmentin)
Ampicillin + Sulbactam (Unasyn)
Antipseudomonal penicillins:
Piperacillin + Tazobactam (Zosyn)

26

Which penicillins are administered orally only?

Penicillin V, amoxicillin w/ or w/o clavulanic acid

27

Which penicillins are administered orally and IV?

Nafcillin, ampicillin

28

Which penicillins are administered IV only?

Antipseudomonal penicillins = piperacillin w/ or w/o tazobactam

29

Which penicillin is the drug of choice to treat syphillis?

Penicillin G

30

What is the main route of elimination of penicillins? What drug blocks this active secretion?

Kidney excretion is main route of elimination
Active secretion can be blocked by probenecid (stops elimination)

31

Which penicillins are eliminated via biliary excretion?

Anti-pseudomonal PCN(Piperacillin, ticarcillin, carbenicillin) and nafcillin via biliary excretion

32

Which penicillins affect warfarin metabolism?

Anti-pseudomonal PCNs (Piperacillin, ticarcillin, carbenicillin)

33

1st Generation Cephalosporins

Good aerobic gram-positive, above the diaphragm anaerobes and community-acquired gram negative organism coverage
Stable against staph produced penicillinase
IV = cefazolin (Ancef)
PO = cephalexin (Keflex)

34

What are 1st Generation Cephalosporins used to treat?

Used for septic arthritis in adults, skin infections, acute otitis media, prophylaxis for clean surgeries (cefazolin)
Gram positive infections in patients who cannot take penicillins (try to see if not allergic to this)

35

2nd Generation Cephalosporins

Two classes within second generation
1) Added gram-negative coverage (ie., Moraxella, Neisseria, Salmonella, Shigella, Haemophilus influenzae)
IV and PO = Cefuroxime (Zinacef, Ceftin)
2) Added anaerobic coverage (especially B. Fragilis)- useful for anaerobics below the diaphragm
IV = Cefotetan (Cefotan)

36

Cefuroxime

2nd generation cephalosporin. IV and PO administration. Useful for sinusitis, otitis, community acquired pneumonia

37

Cefotetan

2nd generation cephalosporin. IV administration. Useful for the treatment of abdominal and gynecologic infections

38

3rd Generation Cephalosporins

Main features are expanded gram-negative coverage and penetration of BBB
Cefpodoxime (Vantin), Cefdinir (Omnicef), Cefixime (Suprax) = oral
Cefotaxime (Claforan)
Ceftriaxone (Rocephin) = IV and IM
Long half-life allows once daily administration
Ceftazidime (Fortaz) distinguishes itself with increased anti-pseudomonal coverage

39

Ceftazidime (Fortaz)

3rd generation cephalosporin. distinguishes itself with increased anti-pseudomonal coverage

40

Drugs of first choice in the treatment of meningitis, pneumonia in children and adults, sepsis, peritonitis

3rd generation cephalosporins

41

What are 3rd generation cephalosporins used for?

Drugs of first choice in the treatment of meningitis, pneumonia in children and adults, sepsis, peritonitis
Also tx of UTI, skin infections and osteomyelitis, treatment of Neisseria gonorrhea infections

42

4th Generation Cephalosporins

Cefepime (Maxipime) IM/IV
Good activity against both gram-positive and gram-negative bacteria; also anaerobic coverage
P. aeruginosa, H. influenzae, N. meningitidis, N. gonorrhoeae
Enterobacteriaceae that are resistant to other cephalosporins
Intra-abdominal infections, respiratory tract infections, skin infections

43

5th Generation Cephalosporin

Ceftobiprole medocaril
Treatment of complicated skin and skin structure infections (activity against MRSA)
Inhibits PBPs involved in cell wall synthesis
Stability against hydrolysis by many gram (+) beta-lactamases and higher affinity for various PBPs
Well tolerated: nausea and taste disturbances
IV formulation only

44

Cefepime (Maxipime) IM/IV

4th generation cephalosporin

45

Ceftobiprole medocaril

5th generation cephalosporin

46

Carbapenems

Resistant to many beta-lactamases, most broad spectrum of beta-lactam class of antibiotics (gram (+) and gram (-) coverage
Ertapenem (Ivanz) and Imipenem-cilastin (Primaxin)
Coverage includes resistant gram (-) bacilli (P. aeruginosa), gram (+) bacteria (MRSA; Enterococcus) and anaerobes (Bacteroides)

47

Ertapenem (Ivanz) and Imipenem-cilastin (Primaxin)

Carbapenems

48

Meropenem (Merrem)

Carbapenem. Unique because Greater activity against gram-negative.
Treats Intra-abdominal infections and Meningitis >3 months of age

49

Monobactams

Aztreonam (Azactam) is the only monobactam available in the US.
Spectrum of activity is purely gram-negative rods
Inhibits mucopeptide synthesis in cell wall by binding to PBP
Resistant to most beta-lactamases
No cross reactivity with PCN or cephalosporin allergic patients

50

Aztreonam (Azactam)

Monobactam

51

What are monoboactams used to treat?

Indicated for treatment of variety of gram - infections: pneumonia, soft-tissue infections, UTI (e. coli), intra-abdominal and pelvic infections (pseudomonas)

52

Cycloserine

Cell wall inhibitor. MOA: competitively inhibits 2 enzymes in the synthesis of peptidoglycan. This inhibition ultimately disrupts assembly of the cell wall.
Indications: Restricted for use as a secondary anti-tubercular drug.

53

ADRs of Cycloserine

very toxic
CNS toxicity-reversible w/pyridoxine
Renal impairment will accelerate toxicity
Highly susceptible to resistance

54

Vancomycin

Acts on a different binding site than beta-lactams but has same effect on cell wall synthesis
Bactericidal

Active against gram positive organisms only
Including beta-lactamase producing varieties
Reserved for
Patients allergic to β-lactams suffering from serious gram positive infections
Infections resulting from methicillin resistant S. aureus (MRSA).

55

What is vancomycin used for?

Used in antibiotic associated enterocolitis (superinfection). Not absorbed well from GI when administered orally. The causative organism is clostridium difficle (C. Diff—a gram positive organism). Most of the normal flora is gram negative in the GI.
Main indication for parenteral vancomycin is for methicillin resistant Staph Aureus or Staph Epi
Includes endocarditis, sepsis, osteomyelitis, wound infections
Also for penicillin resistant pneumococcus
pneumonia

56

Bacitracin MOA

Polypeptide compound
Interferes w/recycling steps of the phospholipid carrier of peptidoglycan synthesis
Not a very specific target (a membrane lipid)

57

Bacitracin: clinical use

Very nephrotoxic, so limited to topical use
Most gram (+) cocci and bacilli are sensitive
Often combined with neomycin or polymyxin or both (Missouri irrigation solution)