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Chapter Objectives

After reading this chapter, the student will be able to:

  1. Describe the difference among the following types of microorganisms: bacterial, viral, and fungal.

  2. Explain the role of the physician in prescribing medications to alleviate infections.

  3. Understand the different categories of antibiotic drugs and how each works.

  4. Describe the problems associated with antibiotic resistance.

  5. Explain the types of antiviral medications available and how they are used.

  6. Understand the treatment options for topical fungal infections.

  7. Describe the use of the Internet as a source of information about microorganisms.

Chapter Outline

  • Antibiotics

    • Bacteria

    • Types of Antibiotics

    • Adverse Effects of Antibiotics

    • Antibiotic Resistance

  • Antiviral Agents

    • Scenarios from the Field

    • Oral Medications

    • Vaccines

  • Antifungal Agents

    • Oral and Topical Medications

    • Adverse Effects of Antifungal Agents

    • What to Tell the Athlete

    • Discussion Topics

    • Chapter Review

At certain times, we become susceptible to different types of infections caused by bacteria, viruses, or fungi. Typically, the body’s immune system is strong enough to repel or destroy invading microorganisms. Situations do occur, however, when the body’s immune system is not able to combat and control an invasion by one or more of these microorganisms. When microbes overload the natural immune system, the body requires assistance to control the invasion. During these instances, chemotherapeutics (chemical agents that fight organisms such as bacteria, viruses, and fungi) are prescribed to control or eliminate the infection. In this chapter, we will study three categories of chemotherapeutic agents—antibiotics and antiviral and antifungal agents—and discuss their mechanisms of action in fighting invading microorganisms.



Bacteria are classified according to their general structure and makeup. They are small unicellular microorganisms (about the size of mitochondria) contained within a cell wall. Their genetic material is not contained in a true nuclear membrane. Bacteria cells lack the processes of mitosis and meiosis, and their genetic organization is simpler than that of cells in multicellular plants and animals.11 Bacteria can maintain cellular metabolism. However, they require nutrients and prefer to steal the necessary amino acids, sugars, and other products they need to sustain life from their host. By understanding the needs of bacteria, we can begin to appreciate how they compete with their human host for these nutrients.

Some bacteria are beneficial to humans. For example, the bacteria in the gastrointestinal (GI) system assist in the digestion of food and help limit the growth of other microorganisms and excess production of some stomach acids. These helpful bacteria, the normal flora of the GI system, should not be destroyed on a regular basis. However, they are sometimes casualties of antibacterial treatment. It is sometimes necessary to restore these normal GI flora after an antibiotic regimen.

Types of Antibiotics

Bacterial infections must be diagnosed and treated by a physician. Treatment of a bacterial invasion is typically accomplished by a ...

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