Pharm Anti-infective agents

Question 1

Classifications of bacteria

Answer 1

1. spheres/cocci
2. rods/bacilli
3. spirals

Question 2

Gram + or - staining process

Answer 2

1. Fixation
2. Crystal Violet
3. Iodine Treatment
4. Decolorisation
5. Counter stain with Safranin

Question 3

Gram + structure

Answer 3

Gram +:
* Cell wall thick multilayered Peptidoglycan outside of cytoplasmic mem

Gram -:
* single layered Peptidoglycan within periplasmic space
* Outer membrane= Lipopolysaccharide which prevents penetration of Gram stain

Penicillin binding proteins: found in both and strengthen peptidoglycan
Beta lactamases: chew up penicillins and cephalosporins

Question 4

Gram + overview of bacteria

Answer 4

Question 5

Gram - overview of bacteria

Answer 5

Question 6

Misc bacterial inf

Answer 6

intracellular bacteria
* chlamydia
* rickettsia
* borellia

Poorly staining
* mycoplasma
* legionella
* helicobacter

Acid fast stain
* mycobacteria
* nocardia
* tuberculosis

Question 7

Bacterial Growth stages

Answer 7

1. Lag phase- adapt to environ, synthesis
2. Log phase- doubling per unit time MOST SUSCEPT TO AB bc so fast
3. Stationary phase- nutrient depletion, accumulation of byproducts
4. Death phase- starvation

Question 8

Chemotherapy

Answer 8

anticancer tx antibiotics= chemotherapy

BOTH TARGET RAPIDLY DIVIDING CELLS

Question 9

Antibiotics come from?

Answer 9

• derived from natural biologic products ie environ competing organisms-> fungi
• daily= organisms exposed to these agents in small amounts
• we give significant doses and have consequences= resistance

Question 10

Ampicillin does work on me?

Answer 10

Agents are specific to microbes not people
* idiosyncratic pharmacokinetics and enzyme induction does differ
* mostly= its bc agents are prescribed indiscriminantely

Question 11

Choosing a drug

Answer 11

1. Host Factors- liver/kid fxn, allergies, age, prego, exposures
2. Drug factors- pharmacodynamics, kinetics, tissue penetration, toxicities
3. Bug factors- possible resistance patterns, duration of disease, likelihood of multiple organisms

Question 12

Sensitivity testing

Answer 12

1. Zone of inhibition on overnight culture-> Kirby-Bauer Method
   Tells you which AB bug will be sens to
   GET CULTURES B4 DRUG THERAPY

Question 13

Susceptibility and Resistance

Answer 13

1. Minimum Inhibitory Concentration (MIC)= lowest conc of the AB results in inhibition of visible growth
2. Minimum bactericidal conc (MBC)= lowest conc of AB that kills 99.% of original

Question 14

Pharmacokinetics

Answer 14

• Route: oral preferred but IV/IM for very sick, meningitis, endocarditis, N/V
• Decreased/Increased dosage requirements: Hepatic/Renal, burns, CF, trauma, age, Prego
• Penetration: CSF inflammation
• Monitoring: Peak and trough levels= Ththerapeutic index, substantial interpatient variability

Question 15

Tissue Specificity- Penetration

Answer 15

1. Gut infections= best tx by Oral med- cant be absorbed into body
2. CNS infections: some dont penetrate BBB
3. Bone: dependent on molecular size, protein binding, fat solubility
4. Soft tissues (cellulitis)
5. Abscesses: no blood flow= poor penetration (must be drained)

Question 16

Antimicrobial agents: MOA

Answer 16

• target bacterial cell envelope-> cell wall synthesis and cytoplasmic membrane structure= MC MECHANISM
• Block production of new proteins= bacterial ribosome
• target DNA or DNA replication= antimetabolite activity

Question 17

Basic mechanisms of resistance

Answer 17

1. Drug inactivation or modification-enzymatic deactivation of Penicillin through production of beta lactamases
2. Alteration of target site- alt Penicillin binding protein-> binding target site of penicillin MRSA
3. Alteration of metabolic pathway-sulfonamide-para aminobenzoic acid = folate precursor
4. Reduced drug accumulation- decreasing drug permeability or increasing active efflux of the drugs across the cell surface

Question 17

Basic mechanisms of resistance

Answer 17

1. Drug inactivation or modification-enzymatic deactivation of Penicillin through production of beta lactamases
2. Alteration of target site- alt Penicillin binding protein-> binding target site of penicillin MRSA
3. Alteration of metabolic pathway-sulfonamide-para aminobenzoic acid = folate precursor
4. Reduced drug accumulation- decreasing drug permeability or increasing active efflux of the drugs across the cell surface

Question 18

MRSA

Methicillin resistant Staph aureus

Answer 18

Mech: mutation by penicillin binding protein PBP
now isolates resistant vancomycin, linezolid

Question 19

Alternate Classification of Resistance

Answer 19

1. Natural or intrinsic resistance
   * inaccessibility of the target- lps in gram neg
   * multidrug efflux sys- pumping out multiple drugs
   * drug inactivation= beta lactamase
2. Acquired resistance= disseminated by plasmids or transposons
   * drug modification
   * drug inactivation- beta lactamase
   * drug efflux

Question 20

When cause is known?

Answer 20

interpretation of Culture and Sens-> Monitoring response-> Clinical failures

Question 21

Classifications of Antibiotics

Answer 21

Mode of action:
* bacteriostatic
* bactericidal

Spectrum of action
* broad
* narrow

Question 22

Antibacterial agents

Answer 22

Bactericidal: active in killing
Bacteriostatic: limit bacterial growth
Organisms can lose susceptibility to certain drugs= direct result of AB overuse

Question 23

Clinical use of AB

Answer 23

1. Initial concerns: clinical findings, clinical specimens, likely organisms, prevention of secondary cases
2. Next level: spectrum based on culture results, combination therapy, dose, route, duration, clinical response

Question 24

Use of drug combinations

Answer 24

1. Increase spectrum, polymicrobial infections, decrease development of resistance 2. Synergism: blockade of sequential metabolic steps, enzyme inhibition, enhancement of uptake 3. Antagonism: statics inhibit cidals, induction of microbial enzyme pathways

Question 25

Prophylaxis

Answer 25

Surgery, dentistry rheumatic fever HIV Malaria secondary contacts pneumococcus for HbSS or splenectomy UTIs/OM Neonates- group B strep

Question 26

Main side effects with Most antibiotics

Answer 26

1. GI side effects-> diarrhea 2. Type 1 hypersensitivity