Unit 1. Lec 8,9,10-Antimicrobials I Flashcards
What are antimicrobials (antibiotics)?
Chemicals produced by microorganisms that inhibit or kill other microorganisms (BACTERIA only)
Include natural products as well as synthetic drugs
List Determinants (4) of bacterial responses
- Synergism
- Clearance
- Age
- Pregnancy
What is the goal of antibiotics?
Selectivity Toxicity: Kill or damage a microbe w/out damage to the host
Explain the Ideal Antibotic
Will kill pathogenic microbes w/out side effects for the patient
e.g. penicillin G
How does antibiotics obtain selectivity toxicity?
- Antibiotics target cellular differences btw the host & the pathogenic microbe
- E.g., penicillin inhibits the cell wall which is not in the mammalian cells
Explain the Therapeutic ratio (index)
Selective Toxicity
- Ratio of the toxic dose to the effective dose of the drug, e.g., TI=LD50/ED50 (high LD, low ED)
- Differs for each antimicrobial agent, i.e., some more toxic than others
What are the human body natural defenses against bacteria?
- Barriers:e.g skin & mucous membranes
- Immune Responses: Antibodies, complement systems, etc
Why are antimicrobials used with the bodies natural defenses?
Human body naturally kill pathogenic microbes. However, antimicrobial are used when the natural defenses are overwhelmed or damaged
What are the two effects of microbials?
- Bactericidial
- Bacteriostatic
Define BacteriCIDAL
Kills bacteria (lysis of cell wall to cause death)
Penicillins, Aminoglycans, Cephalosporins (PACS a punch)
Define BacterioSTATIC
Inhibit bacterial cell replication
Tetracylines, Erythromycins, Chloramphenicol (TEC)
Describe the cell walls of Gram + bacteria
- Lactamase outside
- Thicker peptidoclycan wall
Describe Gram - cell wall
- Outer membrane with porin channel
- Thin peptidoglycan layer
- Lactamase inside
Describe the mechanism of cell wall cross-linking
- NAG (N-acetyl-glucosamine) uses Pyruvyl transferase + D-Ala-D-Ala to become NAM (N-Acetyl-muramic acid)
- Peptidoglycan than cross-links the NAM and NAGs to make the cell wall
What drugs should you not give d/t age and the side effects?
Neonates
- Chloramphenicol–>Gray Baby syndrome [lower dose]
- Sulfonamides–>Kernicterus or Toxic Encephalopathy [Contraindication]
Children
- Tetracycline–>Bone growth/Teeth discoloration
CHF (Congestive Heart Failure)
- Ticarcillin disodium/Clavulanate potassium–> Edema/Arrythmia
What drug do we increase to infants and young children?Why?
- Gentamicin becasue volume of distribution
- As we age, we increase lipid profile and younger pts are more aqueous
What type of drugs are Penicllins?
All β-lactams (Cell wall synthesis inhibitor)
List Pregnacy Contraindication (5)
DO NOT GIVE when pregnant
- Metronidazole (Mutagenic)
- Sulfonamides (Breast milk, Kernicterus (incr. bilirubin, displaced from albumin)
- Antifolate drugs (decr. conc. of folic acid in pregnant women-can lead to spina bifida)
- Fluoroquinolones (Afffect cartilage growth)
- Tetracyclines (Inhibit bone growth, tooth enamel dysplasia)
List Penicllin drugs
- Penicillin G
- Ampicillin
- Penicillin V
- Dicloxacillin
- Ticarcillin
- Piperacillin
- Amoxicillin
Mechanisms of Action for Penicillin
- Inhibit peptidoglycan transpeptidase (cross-linking of the glycopeptide polymers)
- Pencillin binding proteins (PBP)-lethal effects
- Trigger autolysis
PBP-requied for maintance of rod shape
Explain the Pharmocokinetics of Penicillins
- Majority undergo renal clearance
- Distribute widely throughout body spaces
- Passage into cerebrospinal, joint, & occular fluids, poor in the absense of imflammation
Side Effects of Peniciilins
- PO: gastric distress, diarrhea (NVD)
- Superinfection of GI tract: C. diff
- Penicilin Allergy
- Neurotoxixity, ie sexiures, penicillin G, inhibit GABA
Mechanism (4) of Resistance of Penicillin
HIGH yield
Same for all β-lactams
- Changes in PBP
- Tolerance: deficiency in autolytic enzymes
- Changes in the porins (Gram -)
- β-lactamase
List the therapeutic uses of Penicillin G,V
- Spectrum
- Sensitive/Resistant
- Pathogens
Penicillins
- Narrow Spectrum
- Penicillinase-sensitive
- S. pneumoniae, P. magnus, T. pallifum, S. pygones (Necrotizing fasciitis)
*Strep, Pepto, Trep, Necrotize
List the therapeutic uses of Dicloxacillin
- Spectrum
- Sensitive/Resistant
- Pathogens
Pencillins
- Narrow Spectrum
- Pencillinase-Resistant
- MSSA, MSSE, Skin/soft tissue (little infection)
MSSA: Methicillin-sensitive Staphylococcus aureus, MSSE: Methicillin-sensitive Staphylococcus epidermidis
List the therapeutic uses of Amoxicillin, Ampilcillin
- Spectrum
- Sensitive/Resistant
- Pathogens
Penicillins
- Broad Spectrum
- Pencillinase-sensitive
- H. influenzae, E. coli, L. monocytogenes, Community-acquired-ear/URTI
URTI: upper respiratory tract infections
List the therapeutic uses of Ticarcillin
- Spectrum
- Sensitive/Resistant
- Pathogens
Penicillin
- Broad Spectrum
- Pencillinase-sensitive
- P. aeruginosa,E. cloacae, S. marcenscens, G-nocosomial (hospital acquired), also amoxicillan pathogens
Pseudo aeru+ G-nocosomial (hospital acquired)
List the therapeutic uses of Piperacillin
- Spectrum
- Sensitive/Resistant
- Pathogens
Pencillin
- Extended Spectrum
- Pencillianase-sensitive
- K. pneumoniae, G-nosocomial infections, also ticarcillin pathogens
What type of drugs are Cephalosporins?
β-lactam (Cell wall synthesis inhibitor)
List Cephalosporin drugs
All begin w/ Cef- (5 gens)
- Cefazolin 1st gen
- Cefoxitin 2nd gen
- Ceftriaxone 3rd gen
- Cefepime 4th gen
- Ceftaroline 5th gen
Mechanism of Action of Cephalosporins
Same as Penicillin
- Inhibit peptidoglycan transpeptidase (cross-linking)
- Pencillin binding proteins (PBP)-lethal effects
- Trigger autolysis
DO NOT give to patients w/ history of severe penicillin reaction
Pharmacokinectics of Cephalosporins
- Renal Elimination
Ceftriaxone-Treatment of Mengitis
Side Effects of Cephalosporins
- Less immunogenic than pencillins (DO NOT give to pts w/ severe pencillin reations)
- Hypersensitivity reactions
- Local reactions, e.g. pain at intramuscular site
Mechanisms (4) of Resistance to Cephalosporins
Similar to Pencillin
- Changes in PBP
- Tolerance: Deficiency in autolytic enzymes
- Changes in the porins
- β-lactamase
List the therapeutic uses of Cefazolin, Cephalexin, 1st
- Pathogens
- Treatment
Cephalosporins
PEKS
- MSSA, P. mirabilis, E.coli, K. pneumoniae, S. pneumoniae (PEKS)
- Prevention or treatment of Staph or Steph infections
- Surgical prophylaxis
List the therapeutic uses of Cefoxitin, Cefaclor, Cefuroxime 2nd
- Pathogens
- Treatment
Cephalosporins
HEN PEKS
- H. influenzae, E. aerogenes, N. gonorrhoeae + 1st gen pathogens (P. mirabilis, E.coli, K. pneumoniae, S. pneumoniae)
- <G+ coverage, Prophylaxis during surgery
List the therapeutic uses of Ceftriaxone, Cefotaxime, Ceftazidime 3rd
- Pathogens
- Treatments
Cephalosporins HIGH yield
ACES
- A. calcoaceticus, C. diversus, E. cloacae, S. marcescens
- Serious G- infections, Meningitis
List the therapeutic uses of Cefepime 4th
- Pathogens
- Treatment
Cephalosporins
- MSSA, S. pyogenes, P. aeruginosa, C. freundii + 3rd gen pathogens (ACES-A. calcoaceticus, C. diversus, E. cloacae, S. marcescens )
- > β-lactamase resistance, Serious G-nosocomial infections
List the therapeutic uses of Ceftaroline 5th
- Pathogens
- Treatment
HIGH yield
Cephalosporins
- MRSA + 4th gen pathogens -(MSSA, S. pyogenes, C. freundii; except P. aeruginoisa)
- Acute bacterial skin+skin structures infections, community acquired pneumonia
What type of drugs are Carbapenems?
β-lactam (Cell wall inhibitor)
List Carbapenem drugs
End witn -nem
“I Must Eat Dinner”
- Imipenem
- Meropenem
- Ertapenem
- Doripenem
Mechanism of Action of Carbapenems
Same as Penicillin
End witn -nem
- Inhibit peptidoglycan transpeptidase (cross-linking)
- Pencillin binding proteins (PBP)-lethal effects
- Trigger autolysis
Pharmacokinetics of Carbapenems
End witn -nem
- Primarly renally cleared
Side Effects of Carbapenems
End witn -nem
- Seizures
- Hypersensitvity reactions
Mechanism of Resistance to Carbapenems
Similar to Pencillin
End witn -nem
- β-lactamase
- Changes in PBP
- Changes in porin (Gram -)
- Autolysins
List the therapeutic uses of Carbapenems
- Pathogens
End witn -nem
G-, pseudo, mono
- Most G- rods (A. calcoaceticus, C, freundii, H. influenzae, E.coli), P. auruginosa,L. monocytogenes, etc
What type of drugs are Monobactam?
β-Lactam (Cell Wall Synthesis)
Example of Monobactam drug
Aztreonam
Mechanism of Action of Azteronam
Monobactam
- Inhibit peptidoglycan transpeptidase (cross-linking of the glycopeptide polymers)
- Pencillin binding proteins (PBP)-lethal effects
- Trigger autolysis
Pharmacokinetics of Monobactam
Aztreonam
- Primarly renally cleared
Side Effects of Monobactam
Aztreonam
- GI upset
- Hypersensitivity rxns, <1% of β-lactam allergic patients, cross reactivity
Mechanism of Resistance to Monobactam
Aztreonam
Similar to penicillin
- Changes in PBP
- Tolerance: deficiency in autolytic enzymes
- Changes in the porins (Gram -)
- β-lactamase
Therapeutic use of Aztreonam
Monobactam
- GIVE IF ALLERGIC TO PENCILLIN
- Mostly G- rods
- P. aeruginosa
- Others: N. gonorrhoeae
What type of drugs are Tricyclic glycopeptide?
NOT a β-lactam (Cell Wall Synthesis Inhibitor)
List examples of Tricyclic glycopeptide drugs
Vancomyin
Mechanism of Action of Vancomyin
Tricyclic glycopeptide
- Inhibitor of peptidoglycan synthase (Attaches to NAG and NAM), Binds to D-Ala-D-Ala
- Inhibitor of pentapeptide precursor & membrane carrier
Pharmacokinetics of Vancomycin
Tricyclic glycopeptide
- Renally cleared
- Can enter CSF w/ inflamed meninges
Side of Effects of Vancomycin
Tricyclic glycopeptide
- Otoxicity: rare
- Nephrotoxicity: uncommon
- Infused related flushing: Histamine release
Mechanism of Resistance to Vancomycin
Tricyclic glycopeptide
- D-Ala-D-Ala—>D-Ala-D-Lactate (1000x less affinity)
- VRE (Vancomyin resistant enterococci)
- VISA= Vancomycin intermediate Staph. Aur. OVER produced D-Ala-D-Ala to have false binding sites
Therapeutic uses of Vancomyin
Tricyclic glycopeptide
- Primarily G+, MRSA, MRSE
- Serious multi-drug resistant infections
- Other: C. difficile (PO)
What type of drug are Cyclic Lipopeptide
Cell Wall/Membrane Synthesis Inhibitor
List examples of Cyclic lipopeptide drugs
DAP the wall=PUNCHES HOLES
Daptomycin
Mechanism of Action of Daptomycin
Cyclic lipopeptide
- Binds to cell membrane
- Forms pores–>Depolarization (⬇ K+)
- Rapid cell death (⬇DNA, RNA, Protein synthesis)
Pharmacokinetics of Daptomycin
Cyclic lipopeptide
- Renally cleared
- Pulmonary surfactant inactivates it (CANNOT use for lung infection like pneumonia)
Side Effects of Daptomycin
Cyclic lipopeptide
- Myopathy, Rhabdomyolysis
- Allergic pneumonitis, If used > 2 weeks
Mechanism of Resistance to Daptomycin
- Treatment failure→⬆MIC (Minimun inhibitorry concentration)
What is the main difference btw eukaryotic ribsomes and bacterial ribosomes?
- Eukaryotic=80S
- Bacterial=70S
What subunits and what sites on the bacterial ribosomes do the antimicrobals bind to?
- 30S (Tetracyclines, Glycylcyclines, Aminoglycosides)
- 50S (Macrolides, Chloramphenical, Lincosamides, Streptogramins, Oxazolides)
- P Site: Majority bind
- A Site: Tetracyclines & Aminoglycoside
What type of drugs are Tetracylcines
- Protein Synthesis Inhibitors
- 30S, A site
List examples of Tetracyclines drugs
- Tetracycline
- Doxycycline
- Minocycline
- Demeclocycline
Mechanism of Action of Tetracyclines
- Inhibit protei synthesis
- Bind to bacterail 30S ribosomal subunit, A site
- Prevent attachement of aminoacyl-tRNA
- Bacteriostatic
Pharmacokinectics of Tetracylclines
- Doxycyline 1° Fecally elimated–>OK w/ renal failure
Side Effects of Tetracyclines
- Contraindicated during pregnancy
- N/V
- Discoloration of teeth & inhibit bone growth in children
- Photosensitivity
- Superinfection–>C. difficle, C.albicans (causes not tx)
Mechanism of Resistance to Tetracyclines
- Plasmid-determined resistance: ↓ influx & ↑efflux
- Ribosomal change
Therapeutic uses of Tetracyclines
- M. pneumoniae
- Cutibacterium acnes
What type of drugs are Glycylcyclines
- Protein synthesis inhibitor
- 30S
- Bacteriostatic
List Glycylcylines drug examples
- Tigecycline (Reserved for: Difficult to treat infection)
Mechanism of Action of Glycylclines
Tigecycline
- Bind to bacterial 30S ribosomal subunit
- Bacteriostatic
Side Effects of Glycylcyclines
Tigecycline
- ↑ Mortality risk (0.6%), limit use for multi-resistance
- Contraindicated in pregnancy, Superinfection
Therapeutic use of Glycylcylines
Tigecyclines
- Broad spectrum, Many G+ and G- anaerobes
- MRSA, VRE, PRSP
- Complicated skin, skin structure, intra-abdominal infections
What type of drugs are Macrolides?
- Protein synthesis inhibitor
List example Macrolide drugs
- Erythromycin
- Azithromycin
- Clarithromycin
Mechanism of Action of Macrolides
Erythromycin, Azithromycin
- Inhibit protein synthesis
- Binds to the peptidyl-tRNA binding region (P site) on the 50S ribosome subunit
- Bacteriostatic
Side of Effects of Macrolides
Erythromycin, Azithromycin
- Prolong the QTc interval
- N/V/D Rash
- Cholestatic hepatitis
Mechamism of Resistance to Macrolides
Erythromycin, Azithromycin
- Methylation of the 23 rRNA-binding site, Prevents binding
Drug Interaction of Macrolides
Erythromycin, Azithromycin
- Erythromycin»clarithromycin, Inhibit CYP3A4
Therapeutic use of Macrolides
Erythromycin, Azithromycin
- C. pneumoniae, H. influenza, M. catarrhalis, Chlamydia
- Community accquired: UTRI, Pneumonia, Otitis media
What type of drug is Chloramphenicol? Mechanism of Action?
- Protein Synthesis inhibitor
- Binds to the 50S subunit
- Bacteriostatic-inhibits peptide bond formation
- Bactericidal for Meningitis tx
Side Effects of Chloramphenicol
- Amenia (dose-related)
- Aplatic anemia (dose-independent)
- Gray baby syndrome (premature infants, ↓ UGT)
Therapeutic uses of Chloramphenicol
- H. influenzae, N. meningitidis, S. pneumoniae, R. rickettsii
What type of drug are Lincosamides
Protein synthesis Inhibitors
List example Lincosamides drugs
“CCC”
- Clindamycin
- Camrsa
- CDAD
Mechanism of Action of Lincosamides
Clindamycin
- Binds to 50S ribosome subunit
- Bacteriostatic
Side Effects of Lincosamides
Clindamycin
- CDAD
- Rash
- Diarrhea
- Fever
- Neutropenia (rare)
Mechanism of Resistance to Lincosamides
Clindamycin
- Methylation of the 23 rRNA binding site, prevents binding
Therapeutic uses of Lincosamides
- CA-MRSA, S. pneumoniae
- Lung abscess
- BLA ( β-lactam allergy)
What type of drug are Streptogramins
Protein synthesis inhibitor
List example drugs of Streptogramins
- Quinopristin+Dalfopristin (In the same dose)
Synergy
Mechanism of Action of Streptogramins
Quinopristin+Dalfopristin
- Binds to 50S ribosome subunit
- Bactericidal
Side Effects of Streptogramins
Quinopristin+Dalfopristin
- Pain, phlebitis at infusion site
- Arthralgias
- Myalgias
Mechanism of Resistance to Streptogramins
Quinopristin+Dalfopristin
- Ribosomal methylase (Q)
- Acetyltransferase (D)
Therapeutic uses of Lincosamides
Quinopristin+Dalfopristin
- 1° G+
- E. faecium (VRE), MRSA, S. pyogenes, PRSP, Osteomyelitis, Endocarditis
What type of drug are Oxazolidinones
Protein synthesis Inhibitor
List drug examples of Oxazolidinones
end w/ -zolid
- Linezolid
- Tedizolid
Mechanism of Action of Oxazolidinones
Linezolid, Tedizolid
- Bind to 50S ribosome subunit
- Bacterostatic
Side Effects of Oxazolidinones
Linezolid, Tedizolid
- Myelosupression
- MAOI: Monoamine oxidase inhibitor
- Rash
- Perpiheral neuropathy
Mechanism of Resistance of Oxazalidinones
Linezolid, Tedizolid
- Ribosomal binding site mutation
Therapeutic uses of Oxazolidinones
Linezolid, Tedizolid
- E. faecium (L) & E. faecalis (VRE), MRSA, MRSE (L), PRSP (L), Skin infections, Pneumonia (L), Bacteremia (L)
What type of drug are Aminoglycosides
Protein synthesis inhibitors
List example drugs of Aminoglycosides
- Gentamicin
- Tobramycin
- Amikacin
- Streptomycin
- Paromomycin
- Neomycin
Mechanism of Action of Aminoglycosides
Gentamicin, Tobramycin
- Inhibit protein synthesis
- Bind to the 30s ribosomal subunit
- Bactericidal
- Concentration-dependent killing, Post-antibiotic effect
- Synergistic with β-lactams
Pharmacokinetics of Aminoglycosides
Gentamacin, Tobramycin
- 1° renally cleared
- Polar → ↓ distribution (CNS, lungs)
Side Effects of Aminoglycosides
Gentamicin, Tobramycin
- Nephrotoxicity
- Ototoxicity
- Neuromuscular blockade
- Teratogen (8th CN)
- Myelosuppression (rare)
Mechanism of Resistance to Aminoglycosides
Gentamicin, Tobramycin
- ↓ porin permeation
- ↓ ribosomal binding
- Enzymatic inactivation: acetyltransferase, phosphotransferase
Therapeutic uses of Aminoglycosides
Gentamicins, Tobramycins
- 1° for aerobic G-, (G,T,A)
- P. aeruginosa (T > G), E. cloacae, S. marcescens (G > T), P. vulgaris, K. pneumoniae, E. faecalis (S), L. monocytogenes (S)
- Serious G- nosocomial infections,
What type of drug are Macrocylic antibiotic
Protein synthesis Inhibitor
List example drugs of Macrocyclic antibiotic
Fidaxomicin
Mechanism of Action of Fidaxomicin
Macrocylic antibiotic
- Binds to the sigma unit of RNA polymerase
- Inhibits protein synthesis
Pharmcokinectics of Fidaxomicin
Macrocylic antibiotic
PO: very little systemic absorption, High fecal concentration
Side Effects of Fidaxomicin
Macrocylic antibiotic
- N/V
- Abdominal pain
- GI hemorrhage
- BMS (2%)
Therapeutic use of Fidaxomicin
Macrocylic antibiotic
- C. difficile
- CDAD
Only Fidaxomicin & Vancomycin tx C. diffcile
What type of drug are Sulfomamides
Folic Acid Inhibitors
List example drugs of Sulfonamides
- Sulfamethoxazole
- Sulfisoxazole
- Sulfadiazine
- Mafenide
- Sulfacetamide
Mechanism of Action of Sulfonamides
Sulfamethoxazole
- Inhibition of dihydropteroate synthase which inhibits the biosynthesis of folic acid
- PABA antagonists, Therefore, ↓ biosynthesis of DNA, RNA, AA,
- Bacteriostatic
Pharmacokinetics of Sulfonamides
Sulfamethoxazole
- Renally cleared
- NAT (1°) & UGT substrate, Metabolites less active
- Inhibit CYP2C9 → ↑ Warfarin AUC
Mechanism of Resistance to Sulfonamides
Sulfamethoxazole
- Do not biosynthesize folic acid
- ↑ PABA production
- Dihydropteroate synthase, Low affinity for Sulfa
- ↓ Sulfa permeability
Side Effects of Sulfonamides
Sulfamethoxazole
- Rash: Sulfa allergy, SJS, TEN
- Ppt in the kidneys: crystalluria, hematuria, obstruction
- Aplastic anemia, Hemolytic anemia (↓G6PD)
- Kernicterus: Newborn Encephalopathy, Bilirubin deposits in brain, Sulfa displacement on albumin
Therapeutic Use of Sulfonomides
Sulfamethoxazole
- Ophthalmic, Sulfacetamide, Tx of conjunctivitis, trachoma
- Burns, Ag Sulfadiazine (Top, Synergistic), Mafenide
What is the mechanism of action for Trimethoprim+Sulfamethoxazole
- Folic Acid Inhibitor
- DHFRI- dihydropteroate reductase inhibitor (Trimethoprim)
- DHPSI- dihydropteroate synthase inhibitor (Sulfamethoxazole)
- Synergism
- Bacteriostatic
- Can be Bactericidal in blood, urine
Mechanism of Resistance to Trimethoprim
- ↓ DHFR affinity
- ↓ cell permeation
- DHFR overproduction
Side Effects of Trimethoprim+Sulfamethoxazole
- BMS
- Rash
- Hemolytic anemia (↓G6PD)
Therapeutic uses of Trimethoprim+Sulfamethoxazole
- MRSA, S. pneumoniae, H. influenzae, M.catarrhalis, K. pneumoniae, E coli, S. dysenteriae, S. typhi
- UTI
- Prostatitis
What type of drug are Quinolones
DNA Replication Inhibitor
List example drugs of Quinolones
- Ciprofloxacin
- Levofloxacin
- Moxifloxacin
- Ofloxacin
- Gemfloxacin
- Enoxacin
Mechanism of Quinolones
Ciprofloxacin, Levofloxacin
- Inhibit Topoismerase II (bacterial DNA gyrase, DNA supercoil),
- Inhibit DNA replication
- Topisomerase IV (DNA relax)
- Bactericidal
Side Effects of Quinolones
Ciprofloxacin, Levofloxacin
- Tendonitis, Tendon rupture (↑ risk > 60 y/o, Glucocorticoids, & Kidney, Heart, Lung transplant, Contraindicated, Pregnancy, Nursing, Children < 18 y/o, Except for life-threatening infections)
- Myasthenia gravis (May exacerbate muscle weakness)
- GI (N/V/D)
- Neurotoxicity (Seizures, Hallucinations, Depression, Peripheral neuropathy)
- Skin reactions (Hypersensitivity reactions (rashes), phototoxicity (sunburn))
Drug Interactions of Quinolones
Ciprofloxacin, Levofloxacin
- Chelation, Al, Mg, Fe, Ca , ↓ PO absorption, 4-6 hours
- Inhibit CYP1A2, ↑ caffeine, theophylline AUC, Enoxacin > Ciprofloxacin» others
Mechanisms of Resistance of Quinolones
Ciprofloxacin, Levofloxacin
- Mutations in Topoismerase II or IV, ↓ Binding
- ↑ Efflux
- ↓ Influx