Non-b lactam wall inhibitors Flashcards
What are the three classes of non-b-lactam cell wall inhibitors?
Glycopeptides
Fosfomycin
Bacitracins
Vancomycin is a
Glycopeptide
Oral formulation of vancomycin is used exclusively for
C. difficile colitis
ADME Vancomycin
IV
PO ***
IV vancomycin is used for
Systemic infections
With inflammation, vancomycin can get into
Bone and CSF
Vancomycin MOA
Inhibits cell wall synthesis by binding to D-Ala-D-Ala terminal of peptidoglycan precursors
Vancomycin is bactericidal for most gram —- bacteria
Positive
Vancomycin therapeutic uses PEMOC
Pneumonia MRSA
Endocarditis MRSA
Meningitis (in combo)
Osteomyelitis MRSA
C. difficile colitis
Nephrotoxicity, ototoxicity, red man syndrome are adverse effects of
Vancomycin
Vancomycin contraindications
Hypersensitivity
Severe renal impairment
Concurrent nephrotoxic drugs
Vancomycin shouldn’t be combined with
Aminoglycosides
NSAIDs (AINES)
The use of contrast agents can be dangerous when taking —–
Vancomycin
DRESS syndrome occurs with the use of
Vancomycin
All species of gram negative bacteria and mycobacteria are resistant to ——–
Vancomycin
Vancomycin-Resistant enterococci
VRE
E. faecium
E. faecalis
VanA gene is the most important Vancomycin resistance mechanism because it…
Alters D-Ala-D-Ala to D-Ala-D-Lac, reducing binding
Other resistance mechanisms of vancomycin
Thickened cell walls
Vancomycin-resistant Enterococcus (major clinical concern)
Fosfomycin ADME
Oral (PO) and IV
Fosfomycin is excreted unchanged in urine, which means it can…
Achieve high urinary concentrations
Fosfomycin MOA
Inhibits bacterial cell wall synthesis at an early stage
Blocks MurA enzyme, preventing peptidoglycan precursor formation
Fosfomycin is ——– against susceptible organisms
Bactericidal
Fosfomycin therapeutic uses
Uncomplicated UTIs
Complicated UTIs
Fosfomycin is active against
ESBL-producing and carbapenem-resistant Enterobacterales
For complicated UTIs, fosfomycin is given in
IV formulation
Fosfomycin adverse effects
Gastrointestinal upset (nausea, diarrhea)
Headache
Rare hypersensitivity reactions
Possible hepatotoxicity (elevated liver enzymes in some cases)
Fosfomycin contraindications
Severe renal impairment (CrCL <10 ml/min)
Hypersensitivity to fosfomycin
Not recommended for systemic infections
Fosfomycin resistance mechanisms
Alterations in MurA enzyme, reducing fosfomycin binding
Efflux pumps, lowering intracellular drug concentration
Enzymatic inactivation (fosA, fosB genes in resistant Gram-negative bacteria)
Fosfomycin gram positive spectrum
S. aureus
MRSA
Enterococcus faecalis
VRE
Strepto (limited)
Fosfomycin gram-negative spectrum
E. coli
K. pneumoniae
Proteus
Enterobacter
Serratia
Pseudomonas aeruginosa
Bacitracin ADME
Topical and ophtalmic use
Poor oral absorption
Bacitracin MOA
Inhibits bacterial cell wall synthesis by interfering with bactoprenol, a carrier molecule necessary for peptidoglycan assembly
Bacitracin is —— against susceptible organisms
Bactericidal
Topical treatment of skin infections (wounds, cuts, burns) is treated with
Bacitracin
Ophtalmic infections like bacterial conjunctivitis is treated with
Bacitracin
——– is part of triple antibiotic ointments along with NEOMYCIN and POLYMIXIN B
Bacitracin
Bacitracin adverse effects
Nephrotoxicity (if used systemically)
Hypersensitivity
Superinfection with prolonged use
Bacitracin contraindications
Systemic use is avoided due to high nephrotoxicity
Deep wounds or large burns (increased risk of toxicity)
Bacitracin resistance mechanisms
- Alterations in cell wall precursors, preventing bacitracin binding
- Efflux pumps in some Gram-negative bacteria
- Intrinsic resistance in most Gram-negative bacteria
Bacitracin gram positive spectrum
S. aureus
S. pyogenes
Clostridium
Bacitracin is ineffective against:
Most Gram-negative bacteria, including Pseudomonas and Enterobacterales
