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Introduction to Antimicrobial Drugs. Classification by Susceptible Organism. Antibacterial Antiviral Antifungal Antiprotozoan Anthelmintic. Mechanism Of Action. Inhibition of bacterial cell wall synthesis Inhibition of protein synthesis Inhibition of nucleic acid synthesis
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Classification by Susceptible Organism • Antibacterial • Antiviral • Antifungal • Antiprotozoan • Anthelmintic
Mechanism Of Action Inhibition of bacterial cell wall synthesis Inhibition of protein synthesis Inhibition of nucleic acid synthesis Inhibition of metabolic pathways Disruption of cell membrane permeability Inhibition of viral enzymes
Direct Exam Of Tissue & Secretions Gram stain Morphology Use of special reagents, stains Cultures Common organisms and identification
Diagnosis Of Infection Signs and symptoms fever, increased WBC, pain, inflammation, erythema Microscopic exam of fluids CSF, urine, blood Identification of organism culture, sensitivity
Empiric Therapy The antibiotic selected is one that can best kill the microorganisms known to be the most common cause of infection
Empiric Therapy Selection Patient Characteristics age, immune function, other disease states, pregnancy, renal/hepatic function Site of Infection Drug Characteristics efficacy, side effects, tissue penetration, cost
Prophylactic Therapy The antibiotic given when there is likelihood of microorganisms being present and used to PREVENT infection
Antimicrobial Resistance Production Of Drug-inactivating Enzymes Mrsa Vre Tb
General Considerations • ID of the pathogen • Drug susceptibility • Drug spectrum • Drug dose • Period of time to affect the pathogen • Site of infection • Patient assessment
Narrow-spectrum: Causative agent known through culture Extended-spectrum: Specific causative agent not known Agent Classification
General Side Effects • Hypersensitivity • Toxicity to various organs: kidney, liver, skin, bone marrow • Suprainfection
General Nursing Implications • Assess results of C&S or that culture has been done before starting antibiotic • Instruct client to take all medication • Use another type of Bc • Monitor blood levels • Peak • Trough
Continued: • MONITOR CBC (WBC and differential) • If severe diarrhea, instruct client to drink buttermilk/yogurt to replace flora • Know difference: • Bacteriostatic • Bactericidal
Nursing Process • Assessment • Nursing Diagnosis • Planning • Intervention • Evaluation
Antibiotics Affecting The Bacterial Cell Wall • PENICILLINS: • Derived from fungus • Beta-lactam drugs • Bactericidal • Penicillin G: narrow spectrum • Aminopenicillins: broad-spectrum • Commonly destroys gram + • Streptococcus, staphylococcus
Major Side Effects • Most common SE are GI • Rash on abdomen, scalp, or arms…usually first sign of allergy • Hematologic reactions: decreased hemoglobin, prolonged bleeding • NSAIDS: protein-bound/compete • Decreased effect of BCP
Combination Products • Clavulanic acid, tazobactam, sulbactam • Bind to enzyme’s active site and allow antibiotic to reach target site • Augmentin,Unasyn
Cephalosporins • Introduced in 1960’s • Similar to penicillins, bactericidal • 4 generations of drug, each with different spectrum • If allergic to penicillins, may be allergic to cephalosporins (1-18%)
1st generation Gram + Skin infections take with food to decrease GI upset 2nd generation gram + and gram - low cost broad range of organisms Cephalosporins
3rd generation Works best against Gram - severe infections and immuno-compromised patients SE: bleeding, no alcohol Ceftriaxone (Rocephin) 4th generation Active against Gram + , - highly resistant to to destruction by beta-lactamases (both 3rd and 4th) Vancomycin (Vancocin) Cephalosporins
Antibiotics Affecting Protein Synthesis • Aminoglycosides • Macrolides
Aminoglycosides • Action: severe infections • Potential for serious AE • ototoxicity, nephrotoxicity • Not given orally due to their poor absorption • Low dose: bacteriostatic • High dose: bactericidal • Use primarily for Gram - • Monitor peak and trough • Gentamicin
Macrolides • Bacteriostatic and high doses is bactericidal • Common AE: GI upset, hepatotoxicity • Interacts with warfarin, cyclosporin, carbamazepine • Common drugs: erythromycin, clarithromycin, azithromycin
Tetracyclines • Inhibit the growth of bacteria, does not kill them • Uses: Gram +, -, broad spectrum • Contraindicated for use in children under 8, pregnant or nursing women • Major AE: GI upset, hepatotoxicity, stained teeth, superinfections
Miscellaneous Antibiotics • Fluoroquinolones • Sulfonamides
Fluoroquinolones • Very broad-spectrum antibiotic. • Kill rather than inhibit. • Cipro is most active against aerobic gram - organisms. • Not indicated for children under 18 or pregnant women. • Adverse effects: arthropathy, GI upset, HA, • Give on an empty stomach.
Sulfonamides • Bacteriostatic • Primarily used to treat UTI because of high concentrations in kidneys • Major AE: nephrotoxicity, photosensitivity, allergic reactions • Encourage increase fluid intake, take on empty stomach • Sulfamethoxazole-trimethoprm(SMZ-TMP)-Bactrim)
Antimycobacterials • Used to treat or prevent TB infection • Used in caution with liver disease or severe renal impairment • AE: hepatitis, peripheral neuropathy • Review diet and alcohol restrictions
Antiviral • Acyclovir: • Treats herpes-viruses; herpes simplex, herpes zoster, Epstein Barr virus, CMV • Effective against actively replicating viruses • AE: N/V, anorexia, nephrotoxic
Antifungal • Amphotercin (Fungizone) • Wide spectrum of activity against many fungi • Can cause anemia, hypokalemia, hypomagnesemia. • AE: nephrotoxicity