Chapter 38 - The Red Zone
advertisement
CHAPTER 38 Antibiotics Part 1 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Infections: Sites of Origin Community-associated infections An infection that is acquired by a person who has not been hospitalized or had a medical procedure (such as dialysis, surgery, catheterization) within the past year Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 2 Infections: Sites of Origin (cont’d) Healthcare-associated infections Contracted in a hospital or institutional setting Were not present or incubating in the patient on admission to the facility More difficult to treat because causative microorganisms are often drug resistant and the most virulent One of top ten leading causes of death in the U.S. MRSA most common Previously known as nosocomial Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 3 Healthcare-Associated Infections: Prevention Hand washing Antiseptics Disinfectants Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 4 Healthcare-Associated Infections: Prevention (cont’d) Disinfectant Kills organisms Used only on nonliving objects Antiseptic Generally only inhibits the growth of microorganisms but does not necessarily kill them Applied exclusively to living tissue Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 5 Antibiotics Medications used to treat bacterial infections Ideally, before beginning antibiotic therapy, the suspected areas of infection should be cultured to identify the causative organism and potential antibiotic susceptibilities Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 6 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 7 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 8 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 9 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 10 Antibiotic Therapy Empiric therapy: treatment of an infection before specific culture information has been reported or obtained Definitive therapy: antibiotic therapy tailored to treat organism identified with cultures Prophylactic therapy: treatment with antibiotics to prevent an infection, as in intraabdominal surgery or after trauma Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 11 Antibiotic Therapy (cont’d) Therapeutic response Decrease in specific signs and symptoms of infection are noted (fever, elevated WBC, redness, inflammation, drainage, pain) Subtherapeutic response Signs and symptoms of infection do not improve Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 12 Antibiotic Therapy (cont’d) Superinfection Pseudomembranous colitis Host factors Genetic host factors G6PD deficiency Slow acetylation Allergic reactions Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 13 Antibiotics: Classes Sulfonamides Quinolones Penicillins Aminoglycosides Cephalosporins Tetracyclines Macrolides Others Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 14 Antibiotic Therapy: Mechanism of Action Interference with cell wall synthesis Interference with protein synthesis Interference with DNA replication Acting as a metabolite to disrupt critical metabolic reactions inside the bacterial cell Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 15 Actions of Antibiotics Bactericidal: kill bacteria Bacteriostatic: inhibit growth of susceptible bacteria, rather than killing them immediately; will eventually lead to bacterial death Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 16 Antibiotics: Sulfonamides One of the first groups of antibiotics Sulfadiazine Sulfamethoxazole Sulfisoxazole Often combined with another antibiotic Sulfamethoxazole combined with trimethoprim (a nonsulfonamide antibiotic), known as Bactrim, Septra, or co-trimoxazole (SMX-TMP) This combination is used commonly Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 17 Sulfonamides: Mechanism of Action Bacteriostatic action Prevent synthesis of folic acid required for synthesis of purines and nucleic acid Do not affect human cells or certain bacteria—they can use preformed folic acid Only affect organisms that synthesize their own folic acid Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 18 Sulfonamides: Indications Effective against both gram-positive and gram-negative bacteria Treatment of UTIs caused by susceptible strains of: Enterobacter spp., Escherichia coli, Klebsiella spp., Proteus mirabilis, Proteus vulgaris, Staphylococcus aureus Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 19 Sulfonamides: Indications (cont’d) Pneumocystis jirovecii pneumonia (PJP) Co-trimoxazole Upper respiratory tract infections Other uses Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 20 Sulfonamides: Adverse Effects Body System Blood Integumentary Adverse Effects Hemolytic and aplastic anemia, agranulocytosis, thrombocytopenia Photosensitivity, exfoliative dermatitis, Stevens-Johnson syndrome, epidermal necrolysis Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 21 Sulfonamides: Adverse Effects (cont’d) Body System GI Other Adverse Effects Nausea, vomiting, diarrhea, pancreatitis Convulsions, crystalluria, toxic nephrosis, headache, peripheral neuritis, urticaria Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 22 Beta-Lactam Antibiotics Penicillins Cephalosporins Carbapenems Monobactams Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 23 Penicillins Natural penicillins Penicillinase-resistant penicillins Aminopenicillins Extended-spectrum penicillins Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 24 Penicillins (cont’d) Natural penicillins penicillin G, penicillin V potassium Penicillinase-resistant drugs cloxacillin, dicloxacillin, nafcillin, oxacillin Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 25 Penicillins (cont’d) Aminopenicillins amoxicillin, ampicillin Extended-spectrum drugs piperacillin, ticarcillin, carbenicillin Usually used with other drugs; rarely used alone Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 26 Penicillins (cont’d) First introduced in the 1940s Bactericidal: inhibit cell wall synthesis Kill a wide variety of bacteria Bacteria produce enzymes capable of destroying penicillins These enzymes are known as beta-lactamases As a result, the medication is not effective Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 27 Penicillins (cont’d) Chemicals have been developed to inhibit these enzymes: Clavulanic acid Tazobactam Sulbactam These chemicals bind with beta-lactamase and prevent the enzyme from breaking down the penicillin, thus making the drug more effective Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 28 Penicillins (cont’d) Penicillin–beta-lactamase inhibitor combination drugs Ampicillin + sulbactam = Unasyn Amoxicillin + clavulanic acid = Augmentin Ticarcillin + clavulanic acid = Timentin Piperacillin + tazobactam = Zosyn Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 29 Penicillins: Mechanism of Action Penicillins enter the bacteria via the cell wall Inside the cell they bind to penicillin-binding protein Once bound, normal cell wall synthesis is disrupted Result: bacteria cells die from cell lysis Penicillins do not kill other cells in the body Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 30 Penicillins: Indications Prevention and treatment of infections caused by susceptible bacteria, such as: Gram-positive bacteria Streptococcus spp., Enterococcus spp., Staphylococcus spp. Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 31 Penicillins: Adverse Effects Allergic reactions occur in 0.7% to 4% of cases Urticaria, pruritus, angioedema Those allergic to penicillins have a fourfold to sixfold increased risk of allergy to other betalactam antibiotics Cross-reactivity between penicillins and cephalosporins is between 1% and 4% Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 32 Penicillins: Adverse Effects (cont’d) Common adverse effects Nausea, vomiting, diarrhea, abdominal pain Other adverse effects are less common Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 33 Penicillins: Interactions MANY interactions! NSAIDs Oral contraceptives Warfarin Others Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 34 Cephalosporins First generation Second generation Third generation Fourth generation Fifth generation (not yet marketed) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 35 Cephalosporins (cont’d) Semisynthetic derivatives Structurally and pharmacologically related to penicillins Bactericidal action Broad spectrum Divided into groups according to their antimicrobial activity Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 36 Cephalosporins: First Generation Good gram-positive coverage Poor gram-negative coverage Parenteral and PO forms Examples cefadroxil cephradine cefazolin cephalexin Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 37 Cephalosporins: First Generation (cont’d) Used for surgical prophylaxis, and for susceptible staphylococcal infections cefazolin (Ancef and Kefzol): IV or IM cephalexin (Keflex): PO Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 38 Cephalosporins: Second Generation Good gram-positive coverage Better gram-negative coverage than first generation Examples: cefaclor cefprozil cefoxitin cefuroxime loracarbef cefotetan Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 39 Cephalosporins: Second Generation (cont’d) cefoxitin (Mefoxin): IV and IM Used prophylactically for abdominal or colorectal surgeries Also kills anaerobes cefuroxime Zinacef is parenteral form; Ceftin is PO Surgical prophylaxis Does not kill anaerobes Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 40 Cephalosporins: Third Generation Most potent group against gram-negative bacteria Less active against gram-positive bacteria Examples ceftibuten cefotaxime ceftazidime cefdinir ceftizoxime ceftriaxone ceftazidime Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 41 Cephalosporins: Third Generation (cont’d) ceftriaxone (Rocephin) IV and IM, long half-life, once-a-day dosing Elimination is primarily hepatic Easily passes meninges and diffused into CSF to treat CNS infections Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 42 Cephalosporins: Third Generation (cont’d) ceftazidime (Ceptaz) IV and IM forms Excellent gram-negative coverage Used for difficult-to-treat organisms such as Pseudomonas spp. Eliminated by renal instead of biliary route Excellent spectrum of coverage Resistance is limiting usefulness Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 43 Cephalosporins: Fourth Generation Broader spectrum of antibacterial activity than third generation, especially against gram-positive bacteria Uncomplicated and complicated UTI cefepime (Maxipime) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 44 Cephalosporins: Fifth Generation Ceftobipriole (not available) Broader spectrum of antibacterial activity Effective against a wide variety of organisms MRSA Pseudomonas spp. Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 45 Cephalosporins: Adverse Effects Similar to penicillins Mild diarrhea, abdominal cramps, rash, pruritus, redness, edema Potential cross-sensitivity with penicillins if allergies exist Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 46 Carbapenems Very broad-spectrum antibacterial action Reserved for complicated body cavity and connective tissue infections May cause drug-induced seizure activity This risk can be reduced with proper dosage All given parenterally Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 47 Carbapenems imipenem/cilastatin (Primaxin) Used for treatment of bone, joint, skin, and soft-tissue infections; many other uses Cilastatin inhibits an enzyme that breaks down imipenem meropenem (Merrem) ertapenem (Invanz) doripenem (Doribax) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 48 Monobactams aztreonam (Azactam) Synthetic beta-lactam antibiotic Primarily active against aerobic gram-negative bacteria (E. coli, Klebsiella spp., Pseudomonas spp.) Bactericidal Parenteral use only Used for moderately severe systemic infections and UTIs Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 49 Macrolides erythromycin (E-mycin, E.E.S, others) azithromycin (Zithromax) clarithromycin (Biaxin) dirithromycin Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 50 Macrolides: Mechanism of Action Prevent protein synthesis within bacterial cells Considered bacteriostatic Bacteria will eventually die In high enough concentrations, may also be bactericidal Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 51 Macrolides: Indications Strep infections Mild to moderate URI and LRI Haemophilus influenzae Spirochetal infections Streptococcus pyogenes (group A beta-hemolytic streptococci) Syphilis and Lyme disease Gonorrhea, Chlamydia, Mycoplasma Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 52 Macrolides: Indications (cont’d) azithromycin and clarithromycin Recently approved for mycobacterium aviumintracellular complex infection (opportunistic infection associated with HIV/AIDS) clarithromycin Recently approved for use in combination with omeprazole for treatment of active ulcer disease associated with Helicobacter pylori infection Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 53 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 54 Ketolide telithromycin (Ketek) Only drug in this class Better antibacterial coverage than macrolides Active against gram-positive bacteria, including multi–drug-resistant strains of S. pneumoniae Associated with severe liver disease Use is limited Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 55 Tetracyclines demeclocycline (Declomycin) oxytetracycline tetracycline doxycycline (Doryx, Vibramycin) minocycline tigecycline (Tygacil) Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 56 Tetracyclines (cont’d) Natural and semisynthetic Obtained from cultures of Streptomyces Bacteriostatic—inhibit bacterial growth Inhibit protein synthesis Stop many essential functions of the bacteria Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 57 Tetracyclines (cont’d) Bind (chelate) to Ca2+ and Mg2+ and Al3+ ions to form insoluble complexes Thus, dairy products, antacids, and iron salts reduce oral absorption of tetracyclines Should not be used in children under age 8 or in pregnant/lactating women because tooth discoloration will occur if the drug binds to the calcium in the teeth Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 58 Tetracyclines: Indications Wide spectrum Gram-negative and gram-positive organisms, protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme disease, acne, others Demeclocycline is also used to treat SIADH by inhibiting the action of ADH Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 59 Tetracyclines: Adverse Effects Strong affinity for calcium Discoloration of permanent teeth and tooth enamel in fetuses and children, or nursing infants if taken by the mother May retard fetal skeletal development if taken during pregnancy Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 60 Tetracyclines: Adverse Effects (cont’d) Alteration in intestinal flora may result in: Superinfection (overgrowth of nonsusceptible organisms such as Candida) Diarrhea Pseudomembranous colitis Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 61 Tetracyclines: Adverse Effects (cont’d) May also cause: Vaginal candidiasis Gastric upset Enterocolitis Maculopapular rash Other effects Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 62 Nursing Implications Before beginning therapy, assess drug allergies; renal, liver, 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 63 Nursing Implications (cont’d) It is ESSENTIAL to obtain cultures from appropriate sites BEFORE beginning antibiotic therapy Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 64 Nursing Implications (cont’d) 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 Assess for signs and symptoms of superinfection: fever, perineal itching, cough, lethargy, or any unusual discharge Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 65 Nursing Implications (cont’d) For safety reasons, check the name of the medication carefully because there are many drugs that sound alike or have similar spellings Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 66 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 67 Nursing Implications (cont’d) Sulfonamides Take with 2000 to 3000 mL of fluid/24 hr Assess RBCs prior to beginning therapy Take oral doses with food Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 68 Nursing Implications (cont’d) Penicillins Take oral doses with water (not juices) as acidic fluids may nullify drug’s antibacterial action Monitor patients taking penicillin for an allergic reaction for at least 30 minutes after administration Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 69 Nursing Implications (cont’d) Cephalosporins Assess for penicillin allergy; may have cross allergy Give orally administered forms with food to decrease GI upset, even though this will delay absorption Some of these drugs may cause a disulfiram (Antabuse)-like reaction when taken with alcohol Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 70 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 71 Nursing Implications (cont’d) Tetracyclines Avoid milk products, iron preparations, antacids, and other dairy products because of the chelation and drug-binding that occurs Take all medications with 6 to 8 ounces of fluid, preferably water Because of photosensitivity, avoid sunlight and tanning beds Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 72 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 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. 73
