CLINICAL LAB SCIENEC

Microbiology
CHAPTER 15
LEARNING OBJECTIVES
On completion of this chapter, the reader will be able to:
• Describe the three major
morphological shapes of bacteria.
• List the major classifi cations of
pathogens that may infect the
body.
• Describe the types of infections
where antibiotics are indicated.
• Describe the types of infections
where antibiotics are NOT
indicated.
• Compare direct and indirect tests
for infections.
• Perform decontamination of a
microbiology laboratory work area.
• Explain physical conditions
where a person would more
easily contract an infection.
• Give the reasons why it would
be important to collect a pure
culture of an organism and
not a mixed specimen.
KEY TERMS
Antibiotic therapy
Bacteria
Bacterial incinerator
Crystal violet stain
Decolorizer
Direct method
Fungi, yeasts, and molds
Gene probes
Gram negative
Gram positive
Gram stain
Immunocompromised
Immunosuppressive drug therapy
Indirect method
Iodine stain
Meningitis
Petri dish
Pus
Ringworm
Safranin
Viruses
Introduction
Throughout history, many theories have been proposed for infections by various
organisms that could not be observed, much less understood. Raging fevers and
hallucinations were sometimes ascribed to demonic possession or unclean blood,
resulting in the letting of blood, which further served to exacerbate any infectious
process. Nothing was known of the immune system, although those genetically
fortunate enough to survive certain infections then maintained immunity to
later contact with the diseases in others. Chance observations of colonies of an
unknown growth, found on various products and in liquids, were not thought to
be related to any sort of disease process. From outward appearances, they were
thought to be mere physical changes in the materials.
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