PowerPoint® to accompany
Medical Assisting
Chapter 46
Second Edition
Ramutkowski Booth Pugh Thompson Whicker
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Introduction to Microbiology
Objectives:
461 Define microbiology.
462 Describe how microorganisms cause diseases.
463 Describe how microorganisms are classified and
named.
464 Explain how viruses, bacteria, protozoans,
fungi, and parasites differ and give examples of
each.
465 Describe the process involved in diagnosing an
infection.
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Introduction to Microbiology
Objectives (cont.)
466 List general guidelines for obtaining specimens.
467 Describe how throat cultures, urine, sputum,
wound, and stool specimens are obtained.
468 Explain how to transport specimens to outside
laboratories.
469 Describe two techniques used in the direct
examination of cultures specimens.
4610 Explain how to prepare and examine stained
specimens.
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Introduction to Microbiology
Objectives (cont.)
4611 Describe how to culture specimen in the
medical office.
4612 Explain how cultures are interpreted.
4613 Describe how to perform an antimicrobial
sensitivity determination.
4614 Explain how to implement quality control
measures in the microbiology laboratory.
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Introduction
When microorganisms
are pathogenic in
nature or displaced
from their natural
environment, they
cause infections and
disease.
You will learn:
Processes in identifying
microorganisms
Culture medias used
Antimicrobial testing
Quality control
You must understand different life forms of microorganisms,
how they may be identified, and how to teach proper
collection techniques for common specimens.
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Microbiology and the Role of the
Medical Assistant
Microbiology – study of
microorganisms (simple
forms of life visible only
through a microscope
usually single celled)
Found everywhere
Cause infections
Mild
Severe
6
How Microorganisms Cause
Disease
By using up nutrients or
other materials needed by
cells and tissues they
invade
By damaging body cells by
reproducing inside the
cells
By making body cells targets
of body’s own defenses
Resulting in:
Fever
Tiredness
Aches
Weakness
Skin reactions
Gastrointestinal upset
Transmitted from one person to another
by direct touching or by vectors,
droplets, or contaminated food or drink.
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Classifications of
Microorganisms
Classifications:
Subcellular – DNA or RNA surrounded by a
protein coat
Prokaryotic – simple cell structure no nucleus
or organelles
Eukaryotic – complex cell structure with
nucleus and specialized organelles
8
Naming of Microorganisms
Types of microorganisms:
Viruses
Bacteria
Protozoans
Fungi
Multicellular parasites
Named by first word refers to genus (biologic
classification between family and species) and
second word refers to particular species
Staphylococcus aureus
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Viruses
Smallest known infectious agents
Cannot be seen by regular microscope
Consist of only nucleic acid surrounded by a
protein coat
Causes:
Colds
Influenza
Croup
Hepatitis
Hepatitis Virus 10
Bacteria
Singlecelled prokaryotic
organisms
Reproduce quickly
Major cause of diseases
Many different types and
ways to identify them
Rapid reproduction is why
untreated infections can be
dangerous
Bacillus bacterial
classification
11
Bacteria Classification
Shape – coccus, bacillus, spirillum, virbrio
Ability to retain certain dyes
Ability to grow in presence or absence of air
Biochemical reactions
Spirillum bacterial
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classification
Protozoans
Single celled eukaryotic organisms – larger
than bacteria
Found in soil and water
Cause:
Malaria
Amebic dysentery
Trichomonus vaginalis
Protozoan
Trichomonus vaginalis
13
Fungi
An eukaryotic organism – rigid cell wall
Grow mainly as singlecelled
Reduce by budding
Yeasts
Molds
Cause superficial infections
Athlete’s foot
Ringworm
Thrush
Yeast a single
celled fungi
14
Parasites
Organism that lives on or in
another and uses that organism
to provide nourishment
Infections caused by parasites
are called infestations
Worms
Insects ticks
15
Apply Your Knowledge Answer
How is bacteria classified?
Shape – coccus, bacillus, spirillum, virbrio
Ability to retain certain dyes
Ability to grow in presence or absence of air
Biochemical reactions
16
Diagnosing Infections
Step 1 – Examine the patients signs and
symptoms
Step 2 – Obtain Specimens
Step 3 – Examine the Specimens Directly
Step 4 – Culture the Specimen
Step 5 – Determine the Culture’s Antibiotic
Sensitivity
Step 6 – Treat the Patient as Ordered
17
Specimen Collection
If specimen is collected
incorrectly, the organism
will not grow in culture
and then cannot be
identified.
If a specimen contains
contaminants that are
identified as causing the
infection, the patient may
be treated incorrectly.
18
Specimen Collection Devices
Sterile swabs
Absorbent material on the
tip
Collection and transporting
systems
Contains a polyester swab
and a small thinwalled vial
of medium in a plastic
sleeve
19
Throat Culture Specimens
Avoid touching any
structures in the mouth
Get the specimen from
the throat area only
Clinical medical
assistants must know
how to obtain a throat
culture specimen
correctly
20
Other Specimens
Urine
Obtain cleancatch midstream specimen to
prevent contaminants
Sputum
Instruct patient to cough up mucus from the
lungs
Wound
Use a swab
Stool
Use clean paper plate or waxed paper
21
Transporting Specimens
Many offices do not
perform microbiologic
testing.
You may send culture
specimens to outside
labs.
There are three main
objectives.
22
Transporting Specimens (cont.)
Three main objectives:
1. Follow proper collection procedures and
use correct device.
2. Maintain the samples in a state close to
their original as possible.
3. Protect anyone who handles the
specimen container from exposure to
potentially infectious material.
23
Methods of Transportation
Regularly scheduled daily pickups by the lab
As needed pickup by the lab
Through the mail
24
Direct Examination of
Specimens
Physician may examine
specimens under the microscope
to detect microorganisms.
Two types of procedures:
Wet mounts permits quick
identification
Potassium Hydroxide (KOH)
mounts – suspects a fungal
infection of the skin, nails, or
hair.
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