antibiotics

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antibiotics
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2011-10-18 22:05:53
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antibiotics
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pharm and the nursing process ch38-40
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  1. Antibiotics- definition
    • medications used to treat bacterial infections, ideally before beginning antibiotic therapy.
    • C=culture, allow organisms to grow (24-72hrs), identify the causative organism (staph, strep, e-coli, pseudomonas).
    • S=susceptibility, what antibiotic is effective against this organism.
    • C&S culture and sensitivity
  2. Culture & Sensitivity
    • Culture-what bacteria (gram+ vs. gram-)what bacteria (stap/strep).
    • Sensitivity- what antibiotic will kill the bacteria.
    • S=sensitve
    • I=Intermediate
    • R=Resistant
    • Antimicrobial MIC- minumum inhibitory concentration. How much med it takes to kill bacteria.
    • (the lower the number the more effective the drug)
  3. Choose the best antibiotic
    • gram+ vs. gram-?
    • strength against bacteria?
    • oral vs. injectable?
    • cost factors?
  4. Actions of antibiotics
    • bactericidal- kill bacteria
    • bacteriostatic- inhibits growth of susceptible bacteria, does not killimmediately, will eventually lead to bacterial death.
  5. empiric therapy
    treatment of an infection before specific sulture information has been reported/obtained. based on most common organisms (skin-staph/strep)
  6. prophylactic therapy
    treatment with antibiotic to prevent infection (heart surgery, joint replacement, trauma)
  7. therapeutic response
    decrease in specific s/s- fever, wbc, redness, inflammation, drainage, pain
  8. subtherapeutic response
    s/s of infection, do not improve.
  9. factors which influence therapy
    superinfection, antibiotic resistance, host factors, genetic host factors (G6PD deficiency, slow acetylation), allergic reactions
  10. antibiotic classes
    sulfonamides, penicillins, cephalosporins, tetracyclines, aminoglycosides, quinolones, macrolides, others
  11. Methods of administration
    oral (tablet, capsule, syrup), injection (IM), intravenous (IVPB).
  12. four common mechanism of action
    • -interfere with cell wall synthesis
    • -interfere with protein synthesis
    • -interfere with DNA replication,
    • -interfere with metabolic reactions inside the bacterial cell.
  13. Sulfonamides
    • bacteriostatic.
    • sulfadiazine, sulfamethoxazole, sulfasoxazole.
    • MOA- prevent synthesis of folic acid required for production of purines and nucleic acid within bacterial cell. effects organsims that synthesis their own folic acid.
  14. sulfonamides- indications
    • treatment of UTIs caused by susceptible strains of: enterobacter, e-coli, klebsiella, proteus mirabilis, portues vulgaris, staphylococcus aureus.
    • also upper respitatory tract infections, pneumocystis jiroveci pneumonia (PJP).

    • Often combined with other antibiotics-
    • trimethoprim (bactrim, septra)-used to treat UTIs, PJP, otitis media.
    • erythromycin/sulfisoxazole (pediazole)- used to treat otitis media.
    • sulfisoxazole (gantrisin)- used to treat otitis media, UTIs.
  15. Sulfonamides- adverse effects
    • blood- emolytic & aplastic anemia, agranulocytosis, thrombocytopenia.
    • skin-photosensitivity, exfoliative dermatitis (rash/itching/sloughing), Stevens-Johnson syndrome, epidermal necrolysis.
  16. Penicillins
    • bactericidal, 1940s, inhibit cell wall synthesis, kill wide variety of bacteria, also called Beta- lactams-
    • penicillins, cephalosporins, carbapenems, monobactams.
  17. Penicillins MOA
    enter the bacteria via cell wall, inside the cell they bind to penicillin- binding protein. bacterial cell wall synthesis is distrupted, bacteria cells die from cell lysis. Penicillins do not kill other body cells
  18. Penicillins- indications
    • prevent and treatment of infections caused by susceptible bacteria, such as-
    • gram+ bacteria: streptococcus, enterococcus, staphylococcus. (strep throat).
  19. natural penicillins
    penicillin G, penicillin V, potasium
  20. penicillinase- resistant drugs
    • cloxacillin, dicloxacillin
    • nafcillin, oxacillin
  21. aminopenicillins
    amoxicillin, ampicillin, bacampicillin
  22. extended- spectrum penicillins
    pieracillin, ticarcillin, carbenicillin
  23. penicillin-beta-lactamase inhibitor combined drugs
    • ampicillin+sulbactum= Unasyn
    • amoxicillin+clavulanic acid= Augmentin
    • ticarcillin+clavulanic acid= Timentin
    • piperacillin+tazobactum= Zosyn
  24. PCNs adverse effects
    • allergic reactions: occur in 0.7%-4% of cases.
    • uticaria, pruritis, angioedema.
    • those allergic to pcns have 4-6xs increased risk of allergy to other beta-lactam antibiotics.
    • cross-reactivity w/PCNs-cephalosporins is 1%-18%.

    • Adverse effects: N&V&D, abd pain.
    • Interactions- NSAIDs, oral contraceptives, warfarin.
  25. Beta-lactamases
    • some bacteria produce enzymes capable of destroying PCNs, as a result, the med is not effective. Chemicals have been developed to inhibit these enzymes (bind with beta-lactamase- prevent breakdown PCN)
    • clavulanic acid, sulbactam, tazobactam
  26. cephalosporins
    • bactericidal
    • › Semisynthetic derivatives from a fungus
    • › Structurally/pharmacologically re: to PCNs
    • › Possible Cross Sensitivity
    • › First generation – Gram +, poor Gram -
    • › Second generation – Gram +, better Gram -
    • › Third generation – Good Gram -, poor Gram+
    • › Fourth generation – newest on the market
  27. cephalosporins first generation
  28. Ø cefadroxil cefazolin
    • cephradine Ancef/Kefzol IM/IV
    • cephradine Keflex PO
    • › Coverage- Good gram +, poor gram -
    • › Surgical prophylaxis, URIs, otitis media
  29. Cephalosporins: Second Generation
  30. ˜ Good gram-positive coverage
    • ˜ Better gram-negative coverage than first generation
    • Ø cefprozil (Cefzil) po
    • Ø cefuroxeme (Ceftin) po
    • Ø cefuroxime (Zinacef) po
    • Serious respiratory, urinary, skin, bone, joint infections
  31. Cephalosporins: Second Generation
    ceftriaxone (Rocephin) IVPB
  32. › › Once-a-day dosing … long half-life,
    • › Elimination is primarily hepatic
    • › Easily passes meninges and diffused into CSF to treat CNS infections
    • › Used prophylactically for abdominal /colorectal surgeriesAlso kills anaerobes
  33. Cephalosporins: Third Generation (cont’d) › ceftazidime (Fortaz, Tazidime)
  34. › IV and IM forms
    • › Excellent gram-negative coverage
    • › Used for difficult-to-treat organisms such as Pseudomonas spp.
    • › Eliminated renally instead of biliary route
    • › Excellent spectrum of coverage
  35. Cephalosporins: Fourth Generation
  36. › Newest cephalosporin drugs
    • › Broader spectrum of antibacterial activity than third generation, especially against gram-positive bacteria
    • › cefepime (Maxipime)
    • › cefdinir
    • › cefditoren pivoxil
  37. Cephalosporins: Adverse Effects
  38. › Similar to penicillins
    • › Mild diarrhea, abdominal cramps, rash, pruritis, redness, edema
    • › Potential cross-sensitivity with penicillins …. if allergies exist
  39. Carbapenems
  40. › imipenem-cilastatin (Primaxin)
    • › Very broad-spectrum antibacterial action
    • › Reserved for complicated body cavity, bone, skin and connective tissue infections
    • › May cause drug-induced seizure activity
    • › All given parenterally - IVPB
  41. Monobactams Bactericidalaztreonam (Azactam)
  42. › Synthetic β-lactam antibiotic
    • › Primarily active against aerobic gram-negative bacteria (E. coli, Klebsiella spp., Pseudomonas spp.)
    • › Used for moderately severe systemic infections and UTIs
  43. Macrolides (bacteriostatic/bacteriocidal)
  44. › erythromycin (E-mycin, E.E.S, others)
    • › azithromycin (Zithromax)
    • › clarithromycin (Biaxin)
  45. Macrolides: Mechanism of Action
  46. › Prevent protein synthesis within bacterial cells, bacteria will eventually die
    In high enough concentrations, may be bactericidal
  47. Macrolides: Indications
  48. › Strep infections
    • › Streptococcus pyogenes (group A β-hemolytic streptococci)
    • › Mild to moderate URI and LRI
    • › Haemophilus influenzae
    • › Spirochetal infections
    • › Syphilis and Lyme disease Gonorrhea, Chlamydia, Mycoplasma
  49. Macrolides: Adverse Effects
    • GI effects, primarily with erythromycin
    • › Nausea, vomiting, diarrhea, hepatotoxicity, flatulence, jaundice, anorexia
    • › Newer drugs, azithromycin and clarithromycin: fewer GI adverse effects, longer duration of action, better efficacy, better tissue penetration
  50. Ketolide - telithromycin (Ketek)
  51. › Only drug in this class
    • › Better antibacterial than macrolides
    • › Active against gram +/- bacteria,
    • (including multi-drug resistant strains of S. pneumoniae)
    • community acquired pneumonia, sinusitis)
    • › Adverse reactions:
    • › Headache, dizziness, GI discomfort, altered potassium levels w/ prolonged QT intervals
    • › Caution in cardiac disease -bradycardia
  52. Tetracyclines
  53. , bacteriostatic
    • › Tetracycline
    • › demeclocycline (Declomycin)
    • › doxycycline (Doryx, Vibramycin)
    • › Minocycline
  54. › Natural and semisynthetic
    • › Obtained from cultures of Streptomyces
    • › Inhibit protein synthesis
  55. Tetracyclines:
    • › Indications - Wide spectrum
    • › Gram-negative and gram-positive organisms, protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme disease, acne, others
    • Adverse Effects Alteration in intestinal flora:
    • › Superinfection (overgrowth of organisms)
    • › Vaginal candidiasis, gastric upset, Enterocolitis
    • › Diarrhea, pseudomembranous colitis
  56. Tetracyclines (cont’d)
    • › Bind (chelate) to Ca2+ and Mg2+ and Al3+ ions to form insoluble complexes
    • Thus, dairy products, antacids, iron salts ↓ oral absorption
    • › Should not be used in children under age 8 or in pregnant/lactating women
    • » retards fetal skeletal development
    • » tooth discoloration occurs
    • as the drug binds to the calcium
  57. Tetracyclines: Adverse Effects (cont'd)
    • May also cause:
    • › Gastric upset
    • › Maculopapular rash
    • › Other effects
  58. Aminoglycosides
  59. › gentamicin (Garamycin)
    • › streptomycin
    • › tobramycin (Nebcin)
    • › Natural & semisynthetic (from Streptomyces)
    • › Poor oral absorption; no PO forms
    • › Potent antibiotics with serious toxicities
    • › Bactericidal; prevents protein synthesis
    • › Gram – some Gram+
    • › Pseudomonas spp., E. coli, Proteus spp., Klebsiella spp., Serratia spp
  60. Aminoglycosides: Indications
    • › Aminoglycosides are poorly absorbed through the GI tract – give IVPB
    • › Exception: neomycin
    • › Given orally to decontaminate the GI tract before surgical procedures
    • › Also used as an enema for this purpose
  61. Aminoglycosides (cont’d)
    • › Cause serious toxicities
    • › Nephrotoxicity (renal damage)\
    • › Ototoxicity (auditory impairment and vestibular [eighth cranial nerve])
    • › Must monitor drug blood levels to prevent toxicities –
    • Check therapeuric levels
  62. Aminoglycosides:
    • › Adverse Effects
    • › Ototoxicity and nephrotoxicity are the most significant
    • › Headache
    • › Paresthesia
    • › Fever
    • › Superinfections
    • › Vertigo
    • › Skin rash
    • › Dizziness
  63. Fluoroquinolones
  64. – bacteriocidal
    • › ciprofloxacin (Cipro)
    • › levofloxacin (Levaquin)
    • › norfloxacin (Noroxin)
    • › gatifloxacin (Tequin)
    • › moxifloxacin (Avelox)
    • › gemifloxacin (Factive)
  65. Fluoroquinolones (cont’d)
    • › Also called “quinolones”
    • › Excellent oral absorption
    • › Absorption reduced by antacids
    • › Mechanism of action
    • › Alter DNA of bacteria, causing death
    • › Does not affect human DNA
    • › Effective against gram-negative organisms and some gram-positive organisms
  66. Fluoroquinolones: (con’t)
    • › Indications
    • › Lower respiratory tract infections
    • › Bone and joint infections
    • › Infectious diarrhea
    • › Urinary tract infections
    • › Skin infections
    • › Sexually transmitted diseases
    • › Anthrax
  67. Fluoroquinolones:
    • Adverse Effects
    • Body System Adverse Effects
  68. CNS Headache, dizziness, fatigue, depression, restlessness, insomnia
    GI Nausea, vomiting, diarrhea, constipation, thrush, increased liver function studies, others
  69. Fluoroquinolones:
    Adverse Effects (cont'd)
  70. Body System Adverse Effects
    • Integumentary Rash, pruritus, urticaria, flushing, photosensitivity
    • Other Fever, chills, blurred vision, tinnitus
  71. others
  72. Miscellaneous Antibiotics
    • › clindamycin (Cleocin)
    • › metronidazole (Flagyl)
    • › nitrofurantoin (Macrodantin)
    • › dapsone
    • › linezolid (Zyvox)
    • › Quinupristin, dalfopristin (Synercid)
    • › daptomycin (Cubicin)
  73. Other Antibiotics
    • › clindamycin (Cleocin)
    • › Used for chronic bone infections, GU infections, intraabdominal infections, other serious infections
    • › May cause pseudomembranous colitis
    • › metronidazole (Flagyl)
    • › Used for anaerobic organisms
    • › Intraabdominal and gynecologic infections
    • › Protozoal infections
    • › Several drug interactions
  74. 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
    • › Usually well-tolerated if patient is kept well-hydrated
  75. Other Antibiotics (cont’d)
    • › quinupristin and dalfopristin (Synercid)
    • › 30:70 combination, work synergistically
    • › Used for bacteremia and VRE & other complicated skin infections
    • › May cause arthralgias, myalgias
    • › dapsone
    • › Used for leprosy (Hansen’s disease), PJP pneumonia associated with HIV/AIDS, other uses
  76. Other Antibiotics (cont’d)
    • › daptomycin (Cubicin)
    • › New class: lipopeptide
    • › Used to treat complicated skin, soft-tissue infections
    • › linezolid (Zyvox)
    • › New class: oxazolidinones
    • › Used to treat (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
  77. Other Antibiotics (cont’d)
    • › Vancomycin IVPB -60 min
    • › Natural, bactericidal - destroys cell wall
    • › Treatment of choice for MRSA, and other gram-positive infections
    • › May cause ototoxicity , nephrotoxicity – prevent with adequate hydration
    • › Red man syndrome may occur
    • › Flushing/itching of head, neck, face, upper trunk
    • › Antihistamine may be ordered to reduce these effects
    • › Must monitor blood levels to ensure therapeutic levels and prevent toxicity
  78. Antiviral medications
  79. › Virus – enter through human cell wall, uses the DNA/RNA within that cell to replicate
    • › Viral illnesses
    • › Colds, flu – influenza, small pox, warts
    • › Chicken pox, cold sores, genital herpes, shingles (herpes virus)
    • › HIV/AIDs, Hepatitis (retroviruses)
    • › Mechanism of action of ANTI VIRAL drugs–
    • › Prevent entry to cell
    • › Inhibit ability to replicate
  80. Avtiviral meds
    • Drug Treat
    • › Oseltamvir phosphjate (Tamiflu) Flu
    • Amantidine Influenza Ribavirin (Virazole) RSV, Hepatitis C
  81. › Acyclovir (Zovirax) Herpes, CMV retinitis in AIDs/HIV
    • › ValcyclovirHCl (Valtrex) Herpes, CMV retinitis in AIDs/HIV
    • › Foscarnet Na (Foscavir) CMV retinitis in AIDs/HIV
    • › Side effects/Caution – Lilly p. 628, table 40-2 & 3
  82. interventions
  83. Nursing Implications
    • › Before beginning therapy, assess:
    • › allergies; renal, liver, cardiac function
    • › Obtain thorough patient health history, including immune status
    • › Contraindications to antibiotic use or that may indicate cautious use
    • › Potential drug interactions
    • › Obtain cultures from appropriate sites BEFORE beginning antibiotic therapy
  84. Nursing Implications (cont’d)
    • › Patients should be instructed to take antibiotics exactly as prescribed and for the length of time prescribed
    • › DO NOT stop taking the medication if they feel better
    • › Assess for signs and symptoms of superinfection: fever, perineal itching, cough, lethargy, or any unusual discharge
  85. Nursing Implications (cont’d)
    • › Each class of antibiotics has specific adverse effects and drug interactions that must be carefully assessed and monitored
    • › The most common adverse effects of antibiotics are nausea, vomiting, and diarrhea
    • › All oral antibiotics are absorbed better if taken with at least 6 to 8 ounces of water
  86. Nursing Implications (cont’d)
    • Penicillins
    • › Monitored for an allergic reaction for at least 30 minutes after administration
    • › The effectiveness of oral penicillins is decreased when taken with caffeine, citrus fruit, cola beverages, fruit juices, or tomato juice
    • › Administer with at least 6 ounces of water
  87. Nursing Implications (cont’d)
    • Cephalosporins
    • › Orally administered forms should be given with food to decrease GI upset, even though this will delay absorption
    • › Some of these drugs may cause an Antabuse-like reaction when taken with alcohol
  88. Nursing Implications (cont’d)
    • Macrolides
    • › These drugs are highly protein-bound and will cause severe interactions with other protein-bound drugs
    • › The absorption of oral erythromycin is enhanced when taken on an empty stomach, but because of the high incidence of GI upset, many drugs are taken after a meal or snack
  89. Nursing Implications (cont’d)
    • Tetracyclines
    • › Avoid milk products, iron preparations, antacids, other dairy products (because of the chelation and drug-binding that occurs)
    • › All medications should be taken with 6 to 8 ounces of fluid, preferably water
    • › Due to photosensitivity, avoid sunlight and tanning beds
    • › DONOT give to pregnant/ lactating women
  90. 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
  91. Nursing Implications (cont’d)
    • Monitor for therapeutic effects
    • › Decrease signs/symptoms of infection
    • › Return to normal vital signs
    • › Negative culture and sensitivity tests
    • › Disappearance of fever, lethargy, drainage, and redness
    • Monitor for adverse reactions

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