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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”

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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?

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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

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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.
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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,
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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

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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
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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.
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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

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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

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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

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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
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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)

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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

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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

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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

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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
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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
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Copyright © 2007, 2004 by Saunders, an imprint of Elsevier Inc. All rights reserved.