Antibacterial Agents II Flashcards
Structurally, penicillin is a __________.
beta-lactam ring
There are three stages of bacterial cell wall synthesis that can be targeted by antibiotics. What are they?
(1) synthesis of cell wall parts in the cytosol; (2) polymerization of subunits at the cell membrane; and (3) cross linking of peptidoglycans at the cell wall
What antibiotics target stage 1 of cell-wall synthesis?
Fosfomycin and cycloserine
What antibiotics target stage 2 of cell-wall synthesis?
Bacitracin and vancomycin
What antibiotics target stage 3 of cell-wall synthesis?
Penicillins and cephalosporins
Beta-lactamases are _____________.
a generic term for enzymes that degrade beta-lactam rings; they are not one specific enzyme
Methicillin resistance occurs by ___________.
alterations in penicillin-binding proteins
Penicillin is ________ at neutral pH and thus does not ___________.
ionized; enter cells or cross basement membranes well
Penicillins are __________ excreted.
renally
Piperacillin and ticarcillin are great for _________, but they must be administered __________.
killing pseudomonas and anaerobic bacteria; parenterally
Name three beta-lactamase inhibitors.
Sulbactam, tazobactam (combined with piperacilln to become Zosyn), and clavulanic acid (combined with amoxicillin to become Augmentin)
What antibiotic is used to treat non-invasive streptococci infections?
Penicillin G
What drug should be given to those with enterococci-associated bacteremia and meningitis?
Penicillin G and ampicillin
Some adverse reactions to penicillins are ___________.
diarrhea (which is common), seizures, and encephalopathy
There is __________ reactivity between penicillins and cephalosporins, so if a patient has a sensitivity reaction to penicillin, then _________.
some; do not give cephalosporins (choose something totally unrelated, like a macrolide)
List the five categories of cell-wall inhibitors.
Vancomycin, penicillin, cephalosporins, carpapenems, and monobactams
Substitution at the R group can __________ penicillins.
(1) increase stability in the GI tract; (2) decrease renal excretion; (3) minimize bacterial resistance; and (4) increase bacterial susceptibility
Penicillinase is transferred via ________.
plasmids
Beta-lactamase is a generic term for __________.
enzymes that degrade penicillins and cephalosporins
MRSA is resistant by ____________.
altering its protein target (PBP2a)
Penicillins are _________ from intramuscular sites.
rapidly absorbed (because it is a neutral environment)
Penicillins penetrate tissues ________.
poorly
What are some characteristics of penicillin G?
It is the proto-typical penicillin; former antibiotic of choice, but now limited to hospitalized patients; given parenterally; susceptible to penicillinase.
Compared to penicillin G, Penicillin V is ________.
less effective, but better absorbed orally
What are the penicillinase-resistant penicillin drugs?
Nafcillin, oxacillin, veracillin, cloxacillin, and dicloxacillin
The penicillinase-resistant drugs are ________.
generally less potent than penicillin G and narrow-spectrum
How are extended spectrum penicillins different?
They are more hydrophilic (due to an extra amino or carboxyl group) and can thus pass through porins in Gram-negative bacteria more easily.
Most penicillins only work against _________; the exceptions are ________.
Gram-positive bacteria; amoxicillin, ampicillin, ticarcillin, and piperacillin, which work on some Gram-negative rods
Amoxicillin is not _________, but can be _________.
resistant to penicillinases; administered with a beta-lactamase inhibitor (such as clavulanic acid)
The only penicillins that work against Bacteroides fragilis and Pseudomonas are __________, but they have to be administered ___________.
Ticarcillin and Piperacillin; through an IV
There are three main beta-lactamase inhibitors: __________.
clavulanic acid, sulbactam, and tazaobactam
Of Gram-positive cocci, cephalosporins do not kill ________.
enterococcus (including VRE)
Haemophilus influenzae is known to cause __________.
pneumonia, sinusitis, otitis media, and menigitis
Treat Treponema pallidum with (the spirochete that causes syphilis) with _______.
penicillin G
The only drug that kills Borrelia burgdorferi (Lyme disease) is ________.
amoxicillin
Haptens are ___________.
small molecules that attach to larger molecules to form antigens
Vancomycin is administered ________.
parenterally, except in cases of Clostridial GI infections
What organisms does vancomycin kill?
All Gram-positive cocci (except VRE) and Clostridia
What is the main concern for adverse reactions with vancomycin treatment?
Ototoxicity, nephrotoxicity, and Red Man syndrome
Daptomycin targets _______ and can be used to kill ________, but it has restricted use.
cell membranes; MRSA, VRSA, and VRE
The lipoglycopeptides are ___________; they target __________; they should only be used in ___________.
oritavancin, dalbavancin, and telavancin; they same step as vancomycin, and so kill Gram-positive bacteria; patients with allergies to other drugs or infections with resistant strains
________ is the only cephalosporin that can kill MRSA.
Cefepime
Cephalosporins have a similar range of killing as amoxicillin, but they can’t kill ________.
Enterococci
Keflex is ___________.
an orally administered, first-generation cephalosporin called cephalexin
Rocephin is __________, and it is unique for its ability to kill __________.
ceftriaxone; Neisseria gonorrhoeae
The carbapenems are bactericidal to everything except ___________.
E. faecium, VRE, Clostridia, and atypical bacteria
Monobactams only kill ___________.
Gram-negative aerobic bacteria
The best antibiotics for Gram-negative Neisseria are ____________.
3rd-generation cephalosporins (ceftriaxone and cefotaxime)
Like piperacillin and ticarcillin, second generation cephalosporins (cefaclor and cefuroxime) are active against __________.
Bacteroides fragilis
In addition to cefepime and ceftaroline, ________ all also kill MRSA.
vancomycin, clindamycin, tetracyclines, and macrolides
