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pathopharm exam 4
CHAPTER 84
Question | Answer |
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Penicillins | Active against a variety of bacteria•Direct toxicity: Low •Principal adverse effect: Allergic reaction •Structure includes a beta-lactam ring •Beta-lactam family: Includes cephalosporins, aztreonam, imipenem, meropenem, and ertapenem |
Mechanism of action | Weaken the cell wall, causing bacteria to take up excessive water and rupture •Active only against bacteria undergoing growth and division •Bactericidal |
Bacterial resistance | •Inability of penicillins to reach their target•Inactivation of penicillins by bacterial enzymes |
Mechanisms of Bacterial Resistance | Three factors •Inability of penicillins to reach their targets•Inactivation of penicillins by bacterial enzymes•Production of penicillin-binding proteins (PBPs) that have a low affinity for penicillins |
Cell Envelope | Three layers• Thin cell wall and an additional outer membrane that is difficult to penetrate |
Gram-positive cell envelope | Thin cell wall and an additional outer membrane that is difficult to penetrateGram-negative cell envelope •Only two layers •Relatively thick cell wall that is easily penetrated |
Penicillinases | Beta-lactamases Enzymes that render penicillin inactive Bacteria can produce a large variety of these enzymes specific for penicillins (and other beta-lactam antibiotics) |
Classification of Penicillins | Narrow-spectrum penicillins •Penicillinase sensitiveNarrow-spectrum penicillins •Penicillinase resistantBroad-spectrum penicillinsExtended-spectrum penicillins |
Penicillin G (Benzylpenicillin) SYPHILLIS, PHARYNGITIS(STREP) GASGANGRENE ANTHRAX FERROUS SALT | Bactericidal to numerous gram-positive and some gram-negative organismsAdverse effects •Least toxic of all antibiotics •Penicillins are the most common cause of drug allergy |
Penicillin Allergy | Development of penicillin allergy CROSS-ALLERY-SENSITIVITY Skin tests for penicillin allergy LEAST TOXIC OUT OF THEM ALL WEAR ID BRACELET |
PEN G HYERKALEMIA | MGMNT of patients w/ HX of penicillin allergy Assess for penicillin allergy in each patient who will be receiving penicillin •HX of mild reaction, consider cephalosporin •If HX of anaphylaxis, avoid administration of penicillin or cephalosporins |
Penicillin Allergy | Immediate (reaction in 2 to 30 minutes) •Accelerated (reaction in 1 to 72 hours) •Delayed (reaction takes days or weeks to develop) |
Anaphylaxis | Laryngeal edema •Bronchoconstriction•Severe hypotension IMMEDIATE HYPERSENSITIVITY RECTION MEDIATE BY IGE |
Penicillin Allergy | Treatment •Epinephrine •Respiratory support(MONITOR BREATHING,) •Prevention: Skin testing |
Drug Interactions PEN V IS MORE STABLE, MORE PO FORM | Aminoglycosides(GENTAMICIN) INACTIVATE IT Bacteriostatic antibiotics Probenecid |
Penicillinase-Resistant Penicillins NARROW-SPECTRUM-STAPH AUREUS AND EPIDERMIS RESISTANT=VANCOMYCIN | Available in the United States •Nafcillin •Oxacillin •Dicloxacillin |
Broad-Spectrum Penicillins | Broad-spectrum penicillins (aminopenicillins) •Ampicillin -EFFECT A/G GRM NEGATIVE, LIKE PEN G CAUTION W/ KIDNEY IMPAIRMENT Adverse effects •Rash•Diarrhea •Amoxicillin - IN CHILDREN-LESS DIARRHEA |
Extended-Spectrum Penicillins -Antipseudomonal penicillins USE W/AMINOGLYCOSIDE | •Piperacillin•Broad-spectrum, but penicillinase sensitive •Effective against organisms susceptible to the aminopenicillins plus Pseudomonas aeruginosa, Enterobacter species, Proteus (indole positive), Bacteroides fragilis, and many Klebsiella specieS |
Penicillin Combinations | Beta-lactamase inhibitors •Clavulanic acid, tazobactam, sulbactam Extends antimicrobial spectrum when combined with penicillinase-sensitive antibiotics•Ampicillin/sulbactam [Unasyn]•Amoxicillin/clavulanic acid [Augmentin]•Piperacillin/tazobactam [Zosyn] |
A patient with a history of a severe anaphylactic reaction to penicillin has an order to receive cephalosporin. What should the nurse do? Contact the health care provider for a different antibiotic. | A few patients with penicillin allergy (about 1%) display cross-sensitivity to cephalosporins. If at all possible, patients with penicillin allergy should not be treated with any member of the penicillin family. |
A prescriber states that a patient will need to receive penicillin intravenously. The nurse anticipates administering which drug? | D. Potassium penicillin G Procaine penicillin G AND BENZATHINE=NEVER IV PENECILLIN V=ORAL |
Which statement about allergic reactions to penicillin does the nurse identify as true? Anaphylactic reactions occur more frequently with penicillins than with any other drug | . Allergy to penicillin can decrease over time. Epinephrine is the drug of choice for anaphylaxis. Vancomycin, erythromycin, and clindamycin are effective and safe alternatives for patients with penicillin allergy. |