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Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
CHAPTER 39
Antibiotics Part 2
2Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate 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. multi-daily dosing Peak and trough blood levels
Synergistic effects Post-antibiotic effect (PAE)
3Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Antibiotic Therapy: Toxicities
Ototoxicity Temporary or permanent hearing loss, balance problems
Nephrotoxicity Varying degrees of reduced renal function Rising serum creatinine may indicate reduced creatinine
clearance Monitor trough levels every 5 to 7 days while on
therapy or as ordered Monitor serum creatinine levels at least every 3 days
as an index of renal function
4Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Aminoglycosides
gentamicin (Garamycin) neomycin (Neo-fradin) tobramycin (Nebcin) amikacin (Amikin) kanamycin streptomycin
5Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Aminoglycosides (cont’d)
Natural and semisynthetic Produced from Streptomyces Poor oral absorption; no PO forms Very potent antibiotics with serious toxicities Bactericidal; prevent protein synthesis Kill mostly gram-negative bacteria; some
gram-positive also
6Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Aminoglycosides: Indications
Used to kill gram-negative bacteria such asPseudomonas spp., E. 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
7Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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
8Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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
9Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Aminoglycosides: Adverse Effects (cont’d)
Ototoxicity and nephrotoxicity are the most significant Headache Paresthesia Fever Superinfections
Vertigo Skin rash Dizziness
10Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Quinolones
ciprofloxacin (Cipro) norfloxacin (Noroxin) levofloxacin (Levaquin) moxifloxacin (Avelox)
11Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Quinolones (cont’d)
Also called “fluoroquinolones” Excellent oral absorption Absorption reduced by antacids Effective against gram-negative organisms
and some gram-positive organisms
12Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Quinolones: Mechanism of Action
Bactericidal Alter DNA of bacteria, causing death Do not affect human DNA
13Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Quinolones: Indications
Gram-negative bacteria such as pseudomonas
Respiratory infections Bone and joint infections GI infections Skin infections Sexually transmitted diseases Anthrax
14Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Fluoroquinolones: Adverse Effects
Body System Adverse Effects
CNS Headache, dizziness, fatigue, depression, restlessness, insomnia
GI Nausea, vomiting, diarrhea, constipation, thrush, increased liver function studies, others
Cardiac Prolonged QT interval
15Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Fluoroquinolones: Adverse Effects (cont’d)
Body System Adverse Effects
Integumentary Rash, pruritus, urticaria, flushing, photosensitivity (with lomefloxacin)
Other Fever, chills, blurred vision, tinnitus
Black box warning: increased risk of tendonitis and tendon rupture
16Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics
clindamycin (Cleocin) linezolid (Zyvox) metronidazole (Flagyl) nitrofurantoin (Macrodantin) quinupristin and Dalfopristin (Synercid) daptomycin (Cubicin) vancomycin (Vancocin) colistimethate (Coly-mycin)
17Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
clindamycin (Cleocin) Used for chronic bone infections, GU infections,
intraabdominal infections, other serious infections May cause pseudomembranous colitis
18Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
linezolid (Zyvox) New class: oxazolidinones Used to treat vancomycin-resistant Enterococcus
faecium (VREF, VRE), hospital-acquired skin and skin structure infections, including those with MRSA
May cause hypotension, serotonin syndrome if taken with SSRIs, and reactions if taken with tyramine-containing foods
19Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
metronidazole (Flagyl) Used for anaerobic organisms Intraabdominal and gynecologic infections Protozoal infections Several drug interactions
20Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
nitrofurantoin (Macrodantin) Primarily used for UTIs (E. coli, S. aureus,
Klebsiella spp., Enterobacter spp.) Use carefully if renal function is impaired Drug concentrates in the urine May cause fatal hepatotoxicity Usually well-tolerated if patient is kept well-
hydrated
21Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
quinupristin and dalfopristin (Synercid) 30:70 combination, work synergistically Used for bacteremia and infections caused by
vancomycin-resistant Enterococcus (VRE) and other complicated skin infections
May cause arthralgias, myalgias
22Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
daptomycin (Cubicin) New class: lipopeptide Used to treat complicated skin and
soft-tissue infections
23Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
vancomycin (Vancocin) Natural, bactericidal antibiotic Destroys cell wall Treatment of choice for MRSA and other
gram-positive infections Must monitor blood levels to ensure therapeutic
levels and prevent toxicity May cause ototoxicity and nephrotoxicity Should be infused over 60 minutes Rapid infusions may cause hypotension
24Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Other Antibiotics (cont’d)
vancomycin (Vancocin) (cont’d) Monitor IV site closely Red man syndrome may occur
• Flushing/itching of head, neck, face, upper trunk
• Antihistamine may be ordered to reduce these effects
Ensure adequate hydration (2 L fluids/24 hr) if not contraindicated to prevent nephrotoxicity
Monitor trough levels carefully
25Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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
26Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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 when they feel better
27Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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
28Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Nursing Implications (cont’d)
Each class of antibiotics has specific adverse effects and drug interactions that must be carefully assessed and monitored
29Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
Nursing Implications (cont’d)
Aminoglycosides Monitor peak and trough blood levels of these
drugs to prevent nephrotoxicity and ototoxicity Symptoms of ototoxicity include dizziness, tinnitus,
and hearing loss Symptoms of nephrotoxicity include urinary casts,
proteinuria, and increased BUN and serum creatinine levels
30Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
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