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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
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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)
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Choose the best antibiotic
- gram+ vs. gram-?
- strength against bacteria?
- oral vs. injectable?
- cost factors?
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Actions of antibiotics
- bactericidal- kill bacteria
- bacteriostatic- inhibits growth of susceptible bacteria, does not killimmediately, will eventually lead to bacterial death.
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empiric therapy
treatment of an infection before specific sulture information has been reported/obtained. based on most common organisms (skin-staph/strep)
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prophylactic therapy
treatment with antibiotic to prevent infection (heart surgery, joint replacement, trauma)
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therapeutic response
decrease in specific s/s- fever, wbc, redness, inflammation, drainage, pain
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subtherapeutic response
s/s of infection, do not improve.
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factors which influence therapy
superinfection, antibiotic resistance, host factors, genetic host factors (G6PD deficiency, slow acetylation), allergic reactions
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antibiotic classes
sulfonamides, penicillins, cephalosporins, tetracyclines, aminoglycosides, quinolones, macrolides, others
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Methods of administration
oral (tablet, capsule, syrup), injection (IM), intravenous (IVPB).
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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.
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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.
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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.
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Sulfonamides- adverse effects
- blood- emolytic & aplastic anemia, agranulocytosis, thrombocytopenia.
- skin-photosensitivity, exfoliative dermatitis (rash/itching/sloughing), Stevens-Johnson syndrome, epidermal necrolysis.
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Penicillins
- bactericidal, 1940s, inhibit cell wall synthesis, kill wide variety of bacteria, also called Beta- lactams-
- penicillins, cephalosporins, carbapenems, monobactams.
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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
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Penicillins- indications
- prevent and treatment of infections caused by susceptible bacteria, such as-
- gram+ bacteria: streptococcus, enterococcus, staphylococcus. (strep throat).
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natural penicillins
penicillin G, penicillin V, potasium
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penicillinase- resistant drugs
- cloxacillin, dicloxacillin
- nafcillin, oxacillin
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aminopenicillins
amoxicillin, ampicillin, bacampicillin
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extended- spectrum penicillins
pieracillin, ticarcillin, carbenicillin
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penicillin-beta-lactamase inhibitor combined drugs
- ampicillin+sulbactum= Unasyn
- amoxicillin+clavulanic acid= Augmentin
- ticarcillin+clavulanic acid= Timentin
- piperacillin+tazobactum= Zosyn
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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.
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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
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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
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cephalosporins first generation
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Ø cefadroxil cefazolin
- cephradine Ancef/Kefzol IM/IV
- cephradine Keflex PO
- Coverage- Good gram +, poor gram -
- Surgical prophylaxis, URIs, otitis media
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Cephalosporins: Second Generation
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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
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Cephalosporins: Second Generation
ceftriaxone (Rocephin) IVPB
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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
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Cephalosporins: Third Generation (cont’d) ceftazidime (Fortaz, Tazidime)
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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
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Cephalosporins: Fourth Generation
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Newest cephalosporin drugs
- Broader spectrum of antibacterial activity than third generation, especially against gram-positive bacteria
- cefepime (Maxipime)
- cefdinir
- cefditoren pivoxil
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Cephalosporins: Adverse Effects
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Similar to penicillins
- Mild diarrhea, abdominal cramps, rash, pruritis, redness, edema
- Potential cross-sensitivity with penicillins …. if allergies exist
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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
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Monobactams Bactericidalaztreonam (Azactam)
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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
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Macrolides (bacteriostatic/bacteriocidal)
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erythromycin (E-mycin, E.E.S, others)
- azithromycin (Zithromax)
- clarithromycin (Biaxin)
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Macrolides: Mechanism of Action
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Prevent protein synthesis within bacterial cells, bacteria will eventually die
In high enough concentrations, may be bactericidal
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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
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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
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Ketolide - telithromycin (Ketek)
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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
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, bacteriostatic
- Tetracycline
- demeclocycline (Declomycin)
- doxycycline (Doryx, Vibramycin)
- Minocycline
- Natural and semisynthetic
- Obtained from cultures of Streptomyces
- Inhibit protein synthesis
- 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
- 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
- Tetracyclines: Adverse Effects (cont'd)
- May also cause:
- Gastric upset
- Maculopapular rash
- Other effects
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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
- 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
- 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
- Aminoglycosides:
- Adverse Effects
- Ototoxicity and nephrotoxicity are the most significant
- Headache
- Paresthesia
- Fever
- Superinfections
- Vertigo
- Skin rash
- Dizziness
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– bacteriocidal
- ciprofloxacin (Cipro)
- levofloxacin (Levaquin)
- norfloxacin (Noroxin)
- gatifloxacin (Tequin)
- moxifloxacin (Avelox)
- gemifloxacin (Factive)
- 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
- Fluoroquinolones: (con’t)
- Indications
- Lower respiratory tract infections
- Bone and joint infections
- Infectious diarrhea
- Urinary tract infections
- Skin infections
- Sexually transmitted diseases
- Anthrax
- 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
- Fluoroquinolones:
- Adverse Effects (cont'd)
- Body System Adverse Effects
- Integumentary Rash, pruritus, urticaria, flushing, photosensitivity
- Other Fever, chills, blurred vision, tinnitus
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Miscellaneous Antibiotics
- clindamycin (Cleocin)
- metronidazole (Flagyl)
- nitrofurantoin (Macrodantin)
- dapsone
- linezolid (Zyvox)
- Quinupristin, dalfopristin (Synercid)
- daptomycin (Cubicin)
- 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
- 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
- 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
- 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
- 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
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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
- Avtiviral meds
- Drug Treat
- Oseltamvir phosphjate (Tamiflu) Flu
- Amantidine Influenza Ribavirin (Virazole) RSV, Hepatitis C
- 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
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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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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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