Antibiotics Part 1 Chapter 38 - STUDENT PDF

Antibiotics Part 1 Exploring the critical role of antibiotics in modern medicine. KR by Katie Robinson Microbial Infection Ubiquitous Microbes Beneficial or Harmful Defense Mechanisms Microorganisms are everywhere. Can be harmful or beneficial Physical, physiologic...

Antibiotics Part 1 Exploring the critical role of antibiotics in modern medicine. KR by Katie Robinson Microbial Infection Ubiquitous Microbes Beneficial or Harmful Defense Mechanisms Microorganisms are everywhere. Can be harmful or beneficial Physical, physiologic, and under normal circumstances. phagocytic defenses protect the body. Bacteria Gram Positive Gram Negative Community-associated Infections Definition Examples Infections acquired Infections not linked to without prior healthcare settings. hospitalization or medical procedure. Prevalence Common in general population, not healthcare-related. Health Care–Associated Infections Contracted in Facility Difficult to Treat Common Infection Previously Known As Not present on Caused by drug- Methicillin-resistant Nosocomial infections admission, occur after resistant, virulent Staphylococcus aureus 48 hours microorganisms (MRSA) Infection Prevention Handwashing Antiseptics Disinfectants Effective way to prevent spread of Inhibit growth but do not Kill organisms, used only on microorganisms. necessarily kill microbes. nonliving objects. Antibiotics Overview Medications Identification Used to treat bacterial Culture suspected infections infection to identify causative organism Susceptibility Determine potential antibiotic susceptibilities before therapy Types of Antibiotic Therapy Empiric Therapy Definitive Therapy Prophylactic Therapy Treat infection before culture results. Tailor treatment to identified Prevent infection, as in surgery organism. or trauma. Therapeutic Response Decrease in signs and symptoms of infection. Fever, elevated white blood cell count reduced. Redness, inflammation, drainage, and pain improve. Antibiotic Therapy Issues 1 Superinfection 2 Secondary Infection C. difficile infection, Emergence of new formerly infections during pseudomembranous treatment colitis 3 Resistance 4 Food-Drug Interactions Antibiotic-resistant bacteria can develop Certain foods may impact antibiotic effectiveness Allergic Reactions Severe Reactions Anaphylactic Reactions Pregnancy Factors Difficulty breathing, rash, hives, Penicillins and sulfonamides can Certain host factors can impact and GI intolerance. trigger life-threatening reactions. antibiotic therapy. Antibiotic Classes Sulfonamides Penicillins Interfere with bacterial Disrupt cell wall synthesis metabolism Cephalosporins Macrolides Similar mechanism to penicillins Inhibit bacterial protein synthesis Mechanism of Action Cell Wall Synthesis Protein Synthesis DNA Replication Metabolic Disruption Antibiotics interfere with Antibiotics disrupt the Antibiotics block the Antibiotics act as construction of bacterial bacterial machinery for replication of bacterial metabolites to disrupt cell walls. making proteins. genetic material. critical bacterial processes. Actions of Antibiotics Bactericidal Bacteriostatic Kill bacteria Inhibit bacterial growth Sulfonamides Overview One of the First Antibiotics Often Combined Common Combinations Sulfonamides were among the Commonly used in combination Sulfamethoxazole combined with earliest antibiotic groups with another antibiotic. trimethoprim, known as Bactrim. discovered. Sulfonamides: Mechanism of Action Bacteriostatic Action Selective Targeting Human Cell Sparing Prevent folic acid synthesis. Affect organisms that synthesize Do not affect human cells or own folic acid. certain bacteria. Sulfonamides Indications Broad Spectrum Urinary Tract Infections Effective against gram- Treatment of UTIs positive and gram- caused by susceptible negative bacteria. strains. Susceptible Bacteria Includes _Enterobacter_, _E. coli_, _Klebsiella_, _Proteus_, and _S. aureus_. Sulfonamides Indications (Cont.) Pneumocystis jiroveci Pneumonia Co-trimoxazole used for treatment. Upper Respiratory Tract Infections Sulfonamides commonly used. Staphylococcus Infections SMX-TMP used for community-acquired MRSA. Sulfonamides: Adverse Effects Blood Integumentary Hemolytic, aplastic Photosensitivity, anemia, agranulocytosis, exfoliative dermatitis, thrombocytopenia Stevens-Johnson, necrolysis Sulfonamides: Adverse Effects (Cont.) GI Other Nausea, vomiting, diarrhea, pancreatitis Hepatotoxicity, convulsions, crystalluria, toxic nephrosis, headache, peripheral neuritis, urticaria, cough Beta-Lactam Antibiotics Penicillins Cephalosporins Carbapenems Monobactams Penicillins Overview Natural Penicillins Penicillinase-resistant Derived from Penicillium Resistant to beta- fungi lactamase enzymes Aminopenicillins Extended-spectrum Expanded spectrum of Increased coverage activity against Gram-negative bacteria Penicillin Types Natural Penicillins Penicillinase-resistant Penicillin G and Penicillin V Nafcillin, Cloxacillin, Oxacillin, Dicloxacillin Aminopenicillins and Extended-spectrum Amoxicillin Ampicillin Carbenicillin Piperacillin Broad-spectrum Broad-spectrum Extended-spectrum Extended-spectrum aminopenicillin aminopenicillin penicillin antibiotic. penicillin antibiotic. antibiotic. antibiotic. Beta-Lactamase Inhibitors Bind with Beta-Lactamase Clavulanic Acid Tazobactam and Sulbactam Prevent breakdown of penicillin. Also known as clavulanate. Additional beta-lactamase inhibitors. Combination Agents Ampicillin/Sulbactam Amoxicillin/ Ticarcillin/Clavulanic Piperacillin/ Clavulanic Acid Acid Tazobactam Unasyn combines ampicillin and Augmentin combines Timentin combines Zosyn combines sulbactam. amoxicillin and ticarcillin and clavulanic piperacillin and clavulanic acid. acid. tazobactam. Penicillins: Mechanism of Action Cell Wall Entry Protein Binding Penicillins enter bacteria Bind to penicillin-binding via cell wall. proteins inside cell. Cell Wall Disruption Selective Toxicity Disrupt normal cell wall Penicillins do not kill other synthesis, leading to cell cells in the body. lysis. Penicillins: Indications Gram-positive Bacteria Prevention and Treatment Treat infections caused by Streptococcus, Effective for preventing and treating susceptible Enterococcus, and Staphylococcus. bacterial infections. Penicillins: Adverse Effects Allergic Reactions 0.7-4% of patients experience allergic reactions. Cross-Reactivity Increased risk of allergy to other beta-lactams. Reaction History Determine type of prior antibiotic reaction. Penicillins: Adverse Effects (Cont.) Common Adverse Effects Less Common Adverse Effects Nausea, vomiting, diarrhea, abdominal pain Other adverse effects are less common Penicillins: Interactions Many Interactions Penicillins can interact with NSAIDs, oral contraceptives, warfarin, and others. Cephalosporins Overview Semisynthetic Bactericidal Categorized Antibiotics structurally and Possess broad-spectrum, Divided into groups by pharmacologically related to killing action against bacteria antimicrobial activity penicillins Cephalosporins Generations First Generation Second Generation Third Generation Fourth Generation Narrow spectrum, good Expanded spectrum, Broad spectrum, Expanded Gram- for Gram-positive improved Gram- enhanced Gram- negative coverage, bacteria negative coverage negative activity increased stability Cephalosporins: First Generation Gram-Positive Coverage Gram-Negative Coverage Good coverage against gram-positive bacteria. Poor coverage against gram-negative bacteria. Formulations Examples Available in parenteral Cefadroxil, Cephradine, and oral forms. Cefazolin, Cephalexin. Cephalosporins: First Generation Surgical Prophylaxis Staphylococcal Infections Oral Administration Cefazolin used for surgical Effective against susceptible Cephalexin available in oral (PO) infection prevention staphylococcal infections formulation Cephalosporins: Second Generation Gram-Positive Gram-Negative Coverage Coverage Good coverage against Better coverage against gram-positive bacteria. gram-negative bacteria than first generation. Examples Cefaclor, Cefprozil, Cefoxitin, Cefuroxime, Cefotetan. Cephalosporins: Second Generation Surgical Prophylaxis Anaerobe Coverage Parenteral and Oral Used for abdominal or colorectal Cefoxitin kills anaerobic bacteria. Cefuroxime available as Zinacef surgeries. (IV/IM) and Ceftin (PO). Cephalosporins: Third Generation Potent Against Gram- Less Active on Gram- Examples Negatives Positives Cefotaxime, Ceftazidime, Most effective against gram- Less effective against gram- Cefdinir, and more. negative bacteria. positive bacteria. Cephalosporins Third Generation Ceftriaxone (Rocephin) IV and IM, long half-life, once-a-day dosing. Hepatic Elimination Elimination is primarily hepatic. CNS Penetration Easily passes meninges, treats CNS infections. Ceftazidime Uses IV and IM Forms Gram-Negative Coverage Available in intravenous and intramuscular formulations. Excellent spectrum against difficult-to-treat organisms. Pseudomonas Coverage Resistance Concerns Particularly useful for infections caused by Increasing resistance is limiting the usefulness of Pseudomonas spp. ceftazidime. Cephalosporins: Fourth Generation Broader Spectrum Indications Broader antibacterial activity, especially against Uncomplicated and complicated UTI, e.g. Cefepime gram-positive bacteria. (Maxipime). Cephalosporins: Fifth Generation Ceftolozane (Zerbaxa) Ceftaroline (Teflaro) Contains beta-lactamase inhibitor, enhances gram Broader spectrum of antibacterial activity, effective negative activity. against MRSA. Cephalosporins: Adverse Effects Similar to Penicillins Cross-Sensitivity Mild diarrhea, cramps, rash, Potential allergy if also itching, redness, swelling. allergic to penicillins. Carbapenems Broadest Action Reserved Use Broadest antibacterial For complicated action of any antibiotics. infections in acutely ill patients. Infusion Time Seizure Risk Must be infused over 60 May cause drug-induced minutes. seizures, reduced with proper dosage. Carbapenems (Cont.) Imipenem/cilastatin Meropenem (Merrem) (Primaxin) Another carbapenem Treats bone, joint, skin, antibiotic option. and soft tissue infections. Ertapenem (Invanz) Doripenem (Doribax) Also a carbapenem The fourth carbapenem antibiotic for various antibiotic mentioned. infections.