Introduction to Antimicrobial Drugs

–Antibacterial –Antiviral –Antifungal –Antiprotozoan –Anthelmintic Classification by Susceptible Organism

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

Agent Classification Narrow- spectrum: Causative agent known through culture Extended- spectrum : Specific causative agent not known

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%)

Cephalosporins 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)

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