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chp 39 study guide: antibiotics affecting the bacterial cell wall
Terms in this set (48)
drugs that affect the bacterial cell wall penetrate the cell wall and bind to molecular targets on the cytoplasmic membrane in the cell. they then disrupt the strength of the cell wall. this permits the high oncotic pressure inside the cell to
draw fluid into the cell. fluid is drawn in until the cell bursts. the patient's immune system cleans up the debris and fights any remaining infection
beta-lactam antibiotics are so called because their chemical structure contains a beta-lactam ring, which is required for
antibacterial action. penicillins, cephalosporins, monobactams, carbapenems, and beta-lactamase inhibitors are all considered beta-lactam antibiotics
penicillins were the first antibiotics used clinically. they are classified as narrow spectrum, broad spectrum, or extended spectrum; they may also be penicillinase resistant. penicillin G aqueous, the prototype penicillin, is a narrow-spectrum, bactericidal drug that is effect against mostly
gram-positive organisms. it is most commonly given IN. the most serious adverse effect is allergic reactions. most common adverse effects are GI. for optimum effectiveness, administer .doses around the clock. assess patients carefully, especially during the first dose, for allergic reactions.
patients allergic to one penicillin should be considered allergic to all penicillins. carbapenems also have a beta-lactam ring structure and may create a
cross-sensitivity in patients allergic to a penicillin. monobactam antibiotics have a significantly different chemical structure from other beta-lactams and are safe to give to penicillin-allergic patients
resistance to beta-lactams may occur because of the bacteria's ability to produce beta-lactamase. clavulanic acid, tazobactam, and sulbactam are beta-lactamase inhibitors that
are combined with penicillins to eradicate the microbe despite its ability to produce beta-lactamse
Imipenem, meropenem, ertapenem, and doripenem are the carbapenems approved for use in the United States. They are very broad- spectrum antibiotics with activity against
gram-positive cocci, gram-negative cocci, and bacilli, and they are the most effective beta-lactam antibiotics for use against anaerobes
Cephalosporins are similar to penicillins
in structure and activity. Penicillin-allergic patients have an increased risk of being allergic to cephalosporins. Four genera- tions of cephalosporins have been intro- duced, each with a different
spectrum of activity. Cephalosporins are the most com- monly prescribed antibiotics; this is lead- ing to cephalosporin-resistant bacteria. Cephalosporins all have generic names that begin with "ceph" or "cef".
Cefazolin, the prototype cephalosporin, is a first generation drug. Most frequent adverse effects are hypersensitivity and GI; nephro- toxicity is possible and is more likely if the patient is also receiving
aminoglycoside anti- biotics. Acute alcohol intolerance, disulfiram- like reaction may occur as an interaction of cefazolin and alcohol.
Vancomycin, a tricyclic glycopeptide antibi- otic, is the only drug in its class. In addition to altering the bacterial cell wall, it inhibits the synthesis of RNA. Because of serious toxicity, vancomycin is used only in
erious infections when other antibiotics have failed. Vancomycin-resistant enterococci (VRE) is becoming a common problem.
Vancomycin has adverse effects of neph- rotoxicity, ototoxicity, and significant his- tamine release (resulting in anaphylactoid reactions and "red man" or "red neck" syndrome). Administer drug slowly IV (at least over 60 minutes), and avoid
extravasa- tion. Monitor the peak or trough levels and hepatic and renal function. Assess for change in balance and hearing loss.
bacterial cell envelope
composed of a thick cell wall and cytoplasmic membrane
active chemical structure of many antibiotics
enzymes that disrupt the beta-lactam ring
enzymes that inactive cephalosporins
enzymes that inactivate penicillin
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