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Chapter 39 Antibiotics Part 2 Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Antibiotic Therapy: Concepts Multidrug resistance Therapeutic drug monitoring Minimum inhibitory concentration (MIC) Time-dependent killing Concentration-dependent killing Once-daily dosing vs. multidaily dosing Peak and trough blood levels Synergistic effects Postantibiotic effect (PAE) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2 Multidrug-Resistant Organisms Organisms that are resistant to one or more classes of antimicrobial drugs Methicillin-resistant Staphylococcus aureus (MRSA) Vancomycin-resistant Enterococcus (VRE) Organisms producing extended-spectrum betalactamases (ESBLs) Organisms producing Klebsiella pneumoniae carbapenemase (KPC) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 3 Aminoglycosides Natural and semisynthetic Produced from Streptomyces Poor oral absorption; no PO forms (exception neomycin) Very potent antibiotics with serious toxicities Bactericidal; prevent protein synthesis Kill mostly gram-negative bacteria; some gram-positive Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 4 Aminoglycosides (cont’d) gentamicin neomycin (Neo-fradin) tobramycin (TOBI) amikacin Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 5 Aminoglycosides: Indications Used to kill gram-negative bacteria, such as Pseudomonas spp., Escherichia coli, Proteus spp., Klebsiella spp., Serratia spp. Often used in combination with other antibiotics for synergistic effects Used for certain gram-positive infections that are resistant to other antibiotics Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 6 Aminoglycosides: Indications (cont’d) Aminoglycosides are poorly absorbed through the GI tract, and given parenterally Exception: neomycin Given orally to decontaminate the GI tract before surgical procedures Also used as an enema for this purpose Used to treat hepatic encephalopathy Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 7 Aminoglycosides: Adverse Effects Cause serious toxicities Nephrotoxicity (renal damage) Ototoxicity (auditory impairment and vestibular impairment [eighth cranial nerve]) Must monitor drug levels to prevent toxicities Minimum inhibitory concentration (MIC) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 8 Aminoglycosides: Adverse Effects (cont’d) Ototoxicity and nephrotoxicity are the most significant Headache Paresthesia Fever Superinfections Vertigo Skin rash Dizziness Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 9 Quinolones Also called fluoroquinolones Excellent oral absorption Absorption reduced by antacids Effective against gram-negative organisms and some gram-positive organisms Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 10 Quinolones (cont’d) ciprofloxacin (Cipro) norfloxacin (Noroxin) levofloxacin (Levaquin) moxifloxacin (Avelox) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 11 Quinolones: Mechanism of Action Bactericidal Alter DNA of bacteria, causing death Do not affect human DNA Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 12 Quinolones: Indications Gram-negative bacteria such as Pseudomonas Complicated urinary tract, respiratory, bone and joint, GI, skin, and sexually transmitted infections Anthrax (ciproflaxin) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 13 Classroom Response Question During intravenous quinolone therapy in an 88year-old patient, which potential problem is of most concern when assessing for adverse effects? A. Hepatotoxicity B. Rhabdomyolysis C. Tendon rupture D. Nephrotoxicity Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 14 Quinolones: Adverse Effects Body System CNS GI Cardiac Adverse Effects Headache, dizziness, insomnia, depression, restlessness, convulsions Nausea, vomiting, diarrhea, constipation, thrush, increased liver function studies, others Prolonged QT interval Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 15 Quinolones: Adverse Effects (cont’d) Body System Integumentary Other Adverse Effects Rash, pruritus, urticaria, flushing Ruptured tendons,* tendonitis,* fever, chills, blurred vision, tinnitus *Black box warning: Increased risk of tendonitis and tendon rupture Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 16 Miscellaneous Antibiotics clindamycin (Cleocin) linezolid (Zyvox) metronidazole (Flagyl) nitrofurantoin (Macrodantin) quinupristin/dalfopristin (Synercid) daptomycin (Cubicin) vancomycin (Vancocin) colistimethate (Coly-Mycin) telavancin (Vibativ) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 17 Miscellaneous Antibiotics (cont’d) clindamycin (Cleocin) Used for chronic bone infections, GU infections, intraabdominal infections, other serious infections May cause pseudomembranous colitis (also known as antibiotic-associated colitis, Clostridium difficile diarrhea, or C. difficile infection) Potential interaction with vecuronium Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 18 Miscellaneous Antibiotics (cont’d) linezolid (Zyvox) New class: oxazolidinones Used to treat vancomycin-resistant Enterococcus faecium (VREF, VRE), hospital-acquired, and skin structure infections, including those with MRSA May cause hypotension, serotonin syndrome if taken with SSRIs, and reactions if taken with tyraminecontaining foods Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 19 Classroom Response Question A patient is prescribed linezolid (Zyvox) to treat hospital-acquired pneumonia. It is most important for the nurse to determine if the patient is also taking which medication? A. A diuretic B. A selective serotonin reuptake inhibitor C. A cardiac glycoside D. A thyroid replacement drug Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 20 Miscellaneous Antibiotics (cont’d) metronidazole (Flagyl) Used for anaerobic organisms Intraabdominal and gynecologic infections Protozoal infections Several drug interactions Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 21 Miscellaneous Antibiotics (cont’d) nitrofurantoin (Macrodantin) Primarily used for urinary tract infections (UTIs) (E. coli, Staphylococcus aureus, Klebsiella spp., Enterobacter spp.) Use carefully if renal function is impaired Drug concentrates in the urine May cause fatal hepatotoxicity Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 22 Miscellaneous Antibiotics (cont’d) quinupristin/dalfopristin (Synercid) 30:70 combination, work synergistically Used for bacteremia and infections caused by vancomycin-resistant Enterococcus (VRE) and for treatment of complicated skin and skin structure infections caused by S. pyogenes and S. aureus, including MRSA May cause arthralgias, myalgias Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 23 Miscellaneous Antibiotics (cont’d) vancomycin (Vancocin) Treatment of choice for MRSA and other grampositive infections Oral vancomycin is indicated for the treatment of antibiotic-induced colitis (C. difficile) and for the treatment of staphylococcal enterocolitis Must monitor blood levels to ensure therapeutic levels and prevent toxicity May cause ototoxicity and nephrotoxicity Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 24 Classroom Response Question A 58-year-old man is receiving vancomycin as part of the treatment for a severe bone infection. After the infusion, he begins to experience some itching and flushing of the neck, face, and upper body. He reports no chills or difficulty breathing. The nurse should suspect: A. an allergic reaction has occurred. B. an anaphylactic reaction is about to occur. C. the medication will not be effective for the bone infection. D. the IV dose may have infused too quickly. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 25 Miscellaneous Antibiotics (cont’d) vancomycin (Vancocin) (cont’d) Red man syndrome may occur • Flushing/itching of head, neck, face, upper trunk • Antihistamine may be ordered to reduce these effects Additive neuromuscular blocking effects in patients receiving neuromuscular blockers Should be infused over 60 minutes Rapid infusions may cause hypotension Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 26 Miscellaneous Antibiotics (cont’d) daptomycin (Cubicin) Only drug of the new class known as lipopeptides Mechanism of action is not completely known Binds to gram-positive cells in a calcium-dependent process and disrupts the cell membrane potential Used to treat complicated skin and soft-tissue infections caused by susceptible gram-positive bacteria, including MRSA and VRE Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 27 Miscellaneous Antibiotics (cont’d) colistimethate (Coly-Mycin) Polypeptide antibiotic that penetrates and disrupts the bacterial membrane of susceptible strains of gramnegative bacterial Commonly referred to as colistin Serious adverse effects Can cause acute respiratory failure when administered by inhalation Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 28 Miscellaneous Antibiotics (cont’d) telavancin (Vibativ) Lipoglycopeptide Indicated for the treatment of skin and skin structure infections caused by susceptible gram-positive organisms Effective against MRSA and VRE Most common adverse effects include renal toxicity, infusion-related reactions, and QT prolongation Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 29 Nursing Implications Before beginning therapy, assess drug allergies; hepatic, renal, and cardiac function; and other lab studies Be sure to obtain thorough patient health history, including immune status Assess for conditions that may be contraindications to antibiotic use or that may indicate cautious use Assess for potential drug interactions Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 30 Nursing Implications (cont’d) It is ESSENTIAL to obtain cultures from appropriate sites BEFORE beginning antibiotic therapy Instruct patients to take antibiotics exactly as prescribed and for the length of time prescribed; they should not stop taking the medication early even if they feel better Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 31 Nursing Implications (cont’d) Assess for signs and symptoms of superinfection: fever, perineal itching, cough, lethargy, or any unusual discharge For safety reasons, check the name of the medication carefully because there are many drugs that sound alike or have similar spellings Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 32 Nursing Implications (cont’d) Each class of antibiotics has specific adverse effects and drug interactions that must be carefully assessed and monitored Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 33 Classroom Response Question A group of office workers is concerned because a package was opened that contained a white powder substance. There is a concern that the white powder is anthrax. Which drug does the nurse anticipate being prescribed for the office workers? A. daptomycin (Cubicin) B. colistimethate (Coly-Mycin) C. ciprofloxacin (Cipro) D. quinupristin/dalfopristin (Synercid) Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 34 Nursing Implications (cont’d) Monitor for therapeutic effects Improvement of signs and symptoms of infection Return to normal vital signs Negative culture and sensitivity tests Disappearance of fever, lethargy, drainage, and redness Monitor for adverse reactions Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 35