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Immune System Infectious Diseases 1 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Introduction Immune system: Body’s built-in defense system Identifies and kills foreign bodies Antibiotics help when invading organism gets out of hand Antibiotic means “against life” 2 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Introduction (Continued) Antibiotic: natural or synthetic substance that inhibits or destroys microorganisms Normal flora: bacteria residing in human body (mutually beneficial) Antibiotics don’t differentiate between normal flora and pathogens Will destroy/ inhibit normal flora What would result of this be? 3 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Gram Stain Hans Christian Gram developed Gram stain procedure in 1883 Allows scientists to determine shape and appearance of bacteria 4 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. How do Antibiotics Work? Most of the bacterial world falls into one of two categories, Gram+ and Gram-, based on differences in the cell wall structure of bacterial cells. Penicillin works only against Gram Positive Bacteria by interfering with the structure of a strong cell wall molecule called peptidoglycan. When the structural integrity of the bacterial cell wall is compromised, the cell loses its protection and ultimately dies. 5 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Why Do We Need Antibiotics Other Than Penicillin? There are many types of harmful bacteria that are considered Gram-negative. Gram-negative bacteria has a cell wall that has an extra layer of protection that interferes with the drug reaching the peptidoglydan. Therefore other antibiotics have been developed to work against Gram- cells. Some drugs, called broad-spectrum antibiotics, 6 even work against both types of cells. Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. History of Antibiotics 1930s first antibiotic, sulfa (sulfanilamide) discovered Cure staphylococcus infections: bacteriostatic Mass production: WWII Used often without regard for possibility of resistance 7 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. History of Antibiotics (Continued) Patients take drug— feel better—stop taking drug Remaining microbes build immunity to drug; infection reappears; bacteria more resistant to antibiotic 8 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. History of Antibiotics (Continued) Antibiotic resistance is another problem that has led to the need for different types of antibacterial drugs. Once a certain antibiotic becomes widely used, bacteria quickly develop resistance to being harmed by it, so new antibiotics have to be found to kill these tougher bacteria. 9 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. History of Antibiotics (Continued) Penicillin agents - around since 1940s; very effective; bactericidal effect toward gram-positive bacteria 100 individual drugs available to combat range of infections 10 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Modern Antibiotics Some microbes produce an enzyme that breaks down antibiotics. They are called Penicillinase-producing microbes. Newer antibiotics developed to inhibit these penicillinase enzymes. Amoxicillin + clavulanate = Augmentin (strengthens penicillin) Ampicillin + sulbactam = Unasyn 11 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Penicillins Common Adverse Reactions: Diarrhea Hypersensitivity (skin rash, itching, hives, anaphylaxis) Yeast infections (prevent with probiotic such as Lactobacillus or acidophilius) Amoxicillin 2 gm taken 1 hr prior to dental appt/ surgery standard for prevention of bacterial endocarditis in patients with cardiac valve disorders/ disease. Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Cephalosporins Similar structure to penicillins If person has allergy to penicillin, 3-7% will have allergy to cephalosporins Divided into generations based on antibacterial activity Less affected by stomach acids Can be taken with meals Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Fluoroquinolones Broad-spectrum antibacterials Can cause phototoxicity reactions (skin burning, redness, rash) – use with sunscreen or avoid sun during treatment. Do not take any products with calcium, iron, zinc, magnesium, or dairy products within 6 hours before or 2 hours after taking (will decrease absorption of fluoroquinolones) CONTRAINDICATED in < 18 yo – joint, cartilage, tendon problems Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Tetracyclines Alternate antibiotic for those allergic to PCN Causes photosensitivity DO NOT give to children: tooth discoloration Do not give with dairy products or antacids: decreases absorption of tetracyclines Take on empty stomach Used for long term treatment or prevention of acne Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Macrolides Also used in those allergic to PCN Azithromycin may be taken on empty stomach or with food, but NOT antacids Drugs: clarithromycin, azithromycin, & erythromycin Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Aminoglycosides Strongest agents in use today Bactericidal for many gram-negative microorganisms Narrow range between therapeutic and toxic levels 17 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Aminoglycosides (Continued) Almost always given IV Patient’s blood levels of antibiotic at peak and trough levels drawn for evaluation, can cause toxic reactions Ototoxicity (hearing damage) Nephrotoxicity (kidney damage) Drugs: gentamycin, tobramycin, neomycin, streptomycin 18 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Sulfonamides Primarily used in UTI’s Can cause phototoxicity & hypersensitivity reactions Contraindicated in patients with sulfa allergies and nursing mothers ( can cause brain damage in child) 19 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Miscellanesous Antibiotics Vancomycin Given IV for severe staphlococcus infections Can cause ototoxicity and nephrotoxicity Metronidazole (Flagyl) Given IV and PO Avoid alcohol while taking (and 3 days after finished) – antabuse type reaction Metallic taste Used for anaerobic bacteria and parasites 20 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Antituberculosis Drugs Must be taken for full course of treatment (from 6 months to years, depending on test results) Usually give in regimen of 3 drugs at once Given with vitamin B6 to prevent side effect of peripheral neuropathy Examples: Isoniazid & Rifampin 21 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. Antimalarial drugs Malaria Symptoms: fever, chills, sweating, headache, nausea Most often transmitted by mosquito bite Incubation period — 1 week to 1 month Suffix: ine Ex. Chloroquine, Mefloquine 22 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved. HIV/AIDS Drugs Transmitted by body fluids containing virus Virion does not cause death; renders host too weak to fight off infections Treatments for both HIV and AIDS Aimed at controlling progression of disease but cannot cure it HIV drug treatment consists of regimen of multiple drug combinations 23 Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved.