Cell Wall Synthesis Inhibitors Flashcards
Cell wall synthesis inhibitors
Beta-lactam Antibiotics - Penicillin’s, Cephalosporins
Vancomycin
Stage 1 of cell wall synthesis, assembly of cell way subunits in the cytosol, is inhibited by ________ and __________
fosfomycin, cycloserine
Stage 2 of cell wall synthesis, polymerization of subunits at cell membrane, is inhibited by __________
vancomycin
The target of vancomycin is _______
transglycosylase (Stage 2)
Stage 3 of cell wall synthesis, cross-linking of peptidoglycan polymers occurring in the cell wall, is inhibited by _________ and ___________
Penicillins and cephalosporins
Penicillins and Cephalosporins target __________ and _____________
penicillin binding proteins (PBPs) - transpeptidase and carboxypeptidase
Antibiotics that inhibit cell wall synthesis are cidal or static?
cidal
The mechanism of action for penicillins is what?
inhibition of reactions involving transpeptidation
What is the resistance mechanism to Beta-lactams?
- beta-lactamase/inactivation
- Target modification of PBPs
- Decreased permeability (porins)
2 types of B lactamase to know:
Narrow spectrum beta-lactamases (penicillinases)
Extended spectrum beta-lactamases (ESBLs)
Which bacteria make penicillinases? (narrow spectrum beta-lactamases)
- 99% of S. aureus
- 100% of klebsiella
- 20-30% of E. coli
Which bacteria are known to make cephalosporinases? (Extended spectrum beta-lactamases)
GNRs - E. coli, K. pneumoniae
Penicillinases (NSBL) and cephalosporinases (ESBL) can both be inhibited by ____________
beta-lactamase inhibitors
Two inhibitors of NSBL and ESBL
Clavulanic acid & Tazobactam
(Augmentin & Zosyn)
What degrades penicillins and cephalosporins and is not inhibited by beta-lactamase inhibitors?
AmpC
KPC-NDM-1 is found mainly in _______ and _______ (what bacteria)
E. Coli and Klebsiella spp
KPC-NDM-1 is inhibited by _______ which is found in ________
avibactam, ceftazidine
Two types of altered PBPs that cause beta-lactam resistance are :
- New PBP - MRSA (mecA)
- Alter existing PBP - strep. pneumo, N. gonorrhea
The _______ gene in _____ alters the number of porin channels decreasing antibiotic susceptibility for hydrophilic antibiotics that need to enter the cell
OprD, Pseudomonas
The most common mechanism of resistance to methicillin or dicloxacillin by S. aureus is what?
Acquisition of the novel protein PBP2a
MSSA are resistant to all penicillin’s (except dicloxacillin) due to production of ________.
penicillinase (NSBL), dicloxacillin
MRSA is resistant to antibiotics that target stage ____ due to PBP2a (new target), but sensitive to drugs like vancomycin that target stage ___
3, 2
4 infections caused by Streptococci:
Antibiotics?
- pharyngitis
- pneumonia
- sinusitis
- otitis media
(URIs)
Pen V, Amoxicillin +/- clavulanate
Staph aureus: type of infection? Antibiotics?
- Localized cutaneous infections
- MSSA = Dicloxacillin (penicillinase-resistant penicillins)
-MRSA = no penicillins/beta lactams, vanco, cyclines, clindamycin
M. Catarrhalis: type of infection?
otitis media, CAP
Bacteria Pen G is used for:
Enterococci, neisseria meningititis, bacillus anthracis (anthrax), cornyebacterium diptheria
What penicillin is used to treat pseudomonas?
Pip-Tazo
Amoxicillin Clavulanate is used to treat what?
M. catarrhalis, streptococci
what type of bacteria are E. coli and pseudomonas?
gram negative rods
What type of bacteria is neisseria?
gram negative cocci
Infections caused by E. coli:
UTIs, diarrhea, hemorrhagic colitis
Infections caused by Psuedomonas:
opportunistic infections in any organ or tissue
_______ _______ is an anerobic bacteria that causes intraabdominal and brain abcess and is treated with __________
Bacteroides fragilis, Piptazo
_______ is an anerobic bacteria that causes gas gangrene, and food poisoning and is treated with _____
Clostridium perfringens, Pen G
What is used to treat syphillis? (treponema pallidum)
Pen G
What is used to treat lyme disease? (borrelia burgdorferi)
amoxicillin
Which penicillins have good oral absorption?
Pen V and amoxicillin
Which penicillin is IV only?
Piperacillin, Pen G
T/F penicillins are excreted via the kidney and should be renally dosed?
T
Pen G or V is more powerful and is used for serious infections?
Pen G, IV only
A penicillinase resistant penicillin is ______
dicloxacillin – treats MSSA
______ and _______ are extended spectrum penicillins that are given with beta lactam inhibitors and have increased penetration through porins of gram-negative bacteria
Amoxicillin and ampicillins
Piperacillin must be given via what route?
parenterally - any route except oral
Piperacillin is useful in infections caused by what 3 organisms?
B. fragilis (anerobe)
Pseudomonas
Enterococci
