Antibiotics Part 1 Flashcards
What is the drug of choice for strep pharyngitis?
Penicillin V
What is the drug of choice for syphilis?
Penicillin V
What is the drug of choice for acute otitis media?
Amoxicillin
What is the drug of choice for meningitis?
Ceftriaxone + Vancomycin
What is the drug of choice for N. gonorrhea?
IM Ceftriaxone
What is the drug of choice for HCA-MRSA?
Vancomycin
Mechanism of Action for Vancomycin
Inhibits bacterial cell wall synthesis at earlier step than Beta lactams
Spectrum of Activity for Vancomycin
G+ : very active against; Staph, MRSA (HCA) and MRSE- DOC for both Strep (including all strep pneumoniae) Enterococcus
G-: No coverage
Vancomycin Resistant Strains
Vancomycin Resistant S. aureus
Vancomycin Resistant Enterococcus
Common uses of Vancomycin
Serious infections caused my HCA-MRSA (DOC), MRSE, and Enterococci (good option if penicillin allergic)
Serious infections caused by S. aureus, Enterococcus, or Strep in pts tolerant of Beta lactams
Clostridium dificile colitis (po) because Vanco will stay in the GI tract
Endocarditis prophylaxis
Adverse effects of Vancomycin
Nephrotoxicity
Ototoxicity
Red neck/man syndrome
Vancomycin Monitoring
Obtain peak/trough levels around 4th dose
Recommended trough levels: 10-15 micrograms/ml
Mechanism of Action for Carbapenems
Binds to PBPs and interferes with cell wall synthesis
Spectrum of Activity for Carbapenems
G +: Staph and Strep
G -: Good activity including Pseudomonas
Anaerobes: Good activity except C. diff
Mechanism of Bacterial Resistance fro Carbapenems (Imipenem specifically)
Generally stable in the prescence of most types of Beta lactamases
Pseudomonas has shown altered permeability to imipenem
Antagonism has been seen when Imipenem is used with other Beta lactams d/t increased Beta lactamase production
Common Uses of Carbapenems
Serious nosocomial infections Serious polymicrobial infections Nosocomial intra-abdominal infections Pseudomonas infection Febrile neutropenia
Adverse Effects of Carbapenems
Allergy: rash, anaphylaxis (cross sensitivity with Beta lactam anaphylaxis
Seizures: (Imipenem primarily) Generally occurs in pts predisposed to seizures; DO NOT use in meningitis
GI problems
Common uses of Ertapenem…the other Carbapenem
Intra-abdominal infections
Skin and skin structure infections
UTI, pylonephritis
Spectrum of Activity for Ertapenem
Similar to Imipenem BUT no pseudomonas, MRSA, or Enterococcus coverage
Mechanism of Action for Monobactams
Binds to PBPs and therefore inhibits cell wall formation
Spectrum of Activity for Monobactams
Considered a G - specialist; good against G- anaerobes including Pseudomonas
Common Uses for Monobactams
G- sepsis UTI G- osteomyelitis G- pneumonia Intra-abdominal infections CF (inhaled)
Adverse Effects of Monobactams
Rash, N/V/D, rare cross sensitivity to PCNs and cephalosporins reported
Mechanism of action for Penicillins
inhibit bacterial cell wall synthesis by inhibiting the transpeptidase rxn that cross links the peptidoglycan component of the cell wall
Penicillin classification
Beta-lactam abx
Mechanism of bacterial resistance to penicillins:
B-lactamase enzymes, reduced affinity of PBP for the abx, and decreased entry of the drugs into bacteria through outer membrane porins – in some bacteria it is a combination of these effects.
Describe the host factors that should be considered when selecting antibiotic therapy.
- drug allergies (not all allergies are the same; if patient is allergic to one drug in a class, then he/she is allergic to all the rest in the class)
- age (tetracycline is not be used for children less than 8 YOA)
- pregnancy
- renal and hepatic function (reduced function implies the need to reduce dosage to avoid toxicity)
- site of infection (a higher dose may be needed for the blood brain barrier or male prostate)
- concomitant drug therapy
- underlying disease states
Describe the drug factors that should be considered when selecting antibiotic therapy.
- antimicrobial activity (bactericidal, bacteriostatic) -antimicrobial spectrum of activity (narrow, extended, broad, MIC, microbial sensitivity, antibiotic resistance [decreased permeability, drug efflux, drug inactivation, altered target])
- pharmacokinetics & pharmacodynamics (MIC, CDKR, PAE]
- tissue penetration (need adequate antibiotic concentration as site of infection)
- adverse effects
- cost
- convenience
