Download INFECTIONS

Chapter 9
Drugs for Bacterial,
Viral, and Fungal
Infections
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When the body’s immune system is
unable to combat and control an
invasion by a microorganism, it
requires assistance
Chemotherapeutics
– Fight organisms such as bacteria, viruses,
fungi
– Control or eliminate infection
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Antibiotics
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Bacteria
Unicellular microorganisms
Can synthesize proteins and carry out
cellular metabolism, but they need
nourishment for these activities from
the host
Some bacteria are beneficial
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Bacteria
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Bacteria that exist in the
gastrointestinal system are helpful to
their human host
– Assist in the digestion of foods
– Limit the growth of other microorganisms
– Limit excess production of some stomach
acids
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Types of Antibiotics
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Bacterial infections must be diagnosed
and treated by a physician
Variety of classification systems
Two in this book:
– Spectrum of Activity
– Method of Control
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Antibiotics
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Spectrum of Activity
– Narrow spectrum
– Broad spectrum
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Methods of Control
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Bactericidal
– Kills bacteria
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Bacteriostatic
– Prevents further replication
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Basic Mechanisms of
Antibacterial Drugs
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Must be selectively toxic without causing
excessive damage to normal cells
Four primary mechanisms of action for
antibacterial drugs:
– Inhibition
– Inhibition
– Inhibition
– Inhibition
of
of
of
of
bacterial cell wall and function
protein synthesis
DNA/RNA function
folic acid synthesis
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Penicillin
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Discovered in 1928 (Alexander Fleming’s
laboratory), where mold was mistakenly
introduced to bacteria being grown.
Initially, the scientist was going to
discard the contaminated Petri dish but
noticed that the bacteria in the dish were
dying around this contaminated area.
Drug company in the United States
decided to start making it and later
discovered ways to produce penicillin in
the laboratory.
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Inhibits specific enzymes that allow
construction of bacteria’s cell wall
Is effective in selectively destroying
bacteria without affecting host cells
Oral and injectable
Treat ear infections, pneumonia, skin
infections
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Adverse effects
– Allergic reactions
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Rash, itching, swelling, anaphylactic,
disrupted GI function
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Adverse Effects of Antibiotics
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Hypersensitivity
Diarrhea, GI distress, nausea/vomiting,
itching, swelling, skin rashes, or difficulty
breathing
In some, an anaphylactic reaction
resulting in severe bronchoconstriction
and cardiovascular collapse
Some of the antibiotics may produce a
photosensitivity reaction
Birth control pill problems
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Minor Skin Infections
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Triple antibiotic ointments
Topical application of multiple
antibiotic therapies to destroy any
microbes that may exist on or around
the infected area.
– Inhibit cell wall activity, protein synthesis,
and/or DNA synthesis
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Example: Neosporin
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Antibiotic Resistance
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Becoming more common
Strains of bacteria are developing
resistance to certain antibacterial drugs
Mutations due to taking only a portion of
prescribed dosage
Overprescribing
Researchers continually working to
develop new drug
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Antiviral Medications
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Virus holding DNA or RNA invades the
body via airborne or opening in skin
Finds host cell and replicates
Ranges from benign to fatal
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Examples of Viral
Infections
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Common Cold
Flu
Herpes
Warts
Mononucleosis
Hepatitis
HIV
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Oral Medications
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Inhibit viral DNA replication
Table 9-2, pg 127
The sooner the patient takes the
prescription medication, the quicker
the symptoms will subside
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Table 9-2: Examples of
Prescription Antiviral
Medications
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Viral Vaccines
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Entire or partial virus is inactivated in
lab setting so that is cannot replicate
Injected into human host
Body produces antibodies in
preparation for a live viral invader
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Table 9-3: Vaccines
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Antifungal Agents
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Fungus – a plantlike microorganism
– Exist in air or soil
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Opportunistic and occur on epidermis
To develop, multiply, and sustain life
– Warmth, darkness, moisture
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Proper hygiene can reduce possibility
of fungal infections
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Tinea Infections
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Capitis
– Scalp
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Corporis
– Trunk
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Cruris
– “Jock itch”
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Pedis
– Athlete’s foot
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Onychomycosis
– Nails
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Tinea Infections (cont.)
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Community showers
Direct contact
Length of infection increases problems
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Fungal Infections
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Some find way into body and multiply
Due to inadequate care of cutaneous
infection
Or when fungal spores become
airborne and are inhaled
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Oral and Topical
Medications
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OTC used first, prescriptions can be
prescribed by physician
1 week to 1+ months to completely
control infection
Meds impair cell membrane synthesis,
cell cannot function normally and dies
Table 9-4, pg 128
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Adverse Effects of
Antifungal Agents
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Very safe, few side effects
Allergic reactions
Observe area being treated
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What to Tell the Athlete
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Page 129
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