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:
46-1 Define microbiology.
46-2 Describe how microorganisms cause diseases.
46-3 Describe how microorganisms are classified and
named.
46-4 Explain how viruses, bacteria, protozoans,
fungi, and parasites differ and give examples of
each.
46-5 Describe the process involved in diagnosing an
infection.
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Introduction to Microbiology
Objectives (cont.)
46-6 List general guidelines for obtaining specimens.
46-7 Describe how throat cultures, urine, sputum,
wound, and stool specimens are obtained.
46-8 Explain how to transport specimens to outside
laboratories.
46-9 Describe two techniques used in the direct
examination of cultures specimens.
46-10 Explain how to prepare and examine stained
specimens.
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Introduction to Microbiology
Objectives (cont.)
46-11 Describe how to culture specimen in the
medical office.
46-12 Explain how cultures are interpreted.
46-13 Describe how to perform an antimicrobial
sensitivity determination.
46-14 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
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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.
7
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
Single-celled 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
classification
12
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 single-celled
 Reduce by budding


Yeasts
Molds
 Cause superficial infections



Athlete’s foot
Ringworm
Thrush
Yeast a singlecelled 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 thin-walled 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 clean-catch midstream specimen to
prevent contaminants
Sputum

Instruct patient to cough up mucus from the
lungs
Wound

Use a swab

Use clean paper plate or waxed paper
Stool
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.
25
Stained Specimens


Enables the doctor to differentiate between
types of infections.
The medical assistant should be able to prepare
a specimen slide and perform a Gram’s stain.
26
Culturing Specimens



You will need on-the-job training or
additional courses to culture certain
specimens.
More common to send these specimens to
outside labs.
Culturing involves placing a sample of
specimen on a culture medium.
27
Culturing Specimens (cont.)



Culture media – liquid,
semisolid, or solid
forms
Medium called – agar
Special culture units –
used to perform rapid
urine cultures (Unicult)
28
Culturing Specimens (cont.)
Inoculating a culture plate
Transferring some of the specimen onto the plate
Label the plate:
 Patient’s name
 Doctor’s name
 Source of sample
 Date and time of inoculation
 Your initials
29
Culturing Specimens (cont.)



Streak the plate with the specimen swab for:
 Qualitative analysis – type of pathogen
 Quantitative analysis – number of
pathogen present in the specimen
Incubating Culture plates – to allow bacteria
to grow (incubator set at 35 to 370 C)
Allow to grow for 24 to 48 hours.
30
Interpreting Cultures


This step is performed by physicians,
microbiologists, or technicians who have
been properly trained.
They will look for:



Characteristics of colony growth
Relative number of colony growth
Changes in the media surrounding the colonies
31
Determining Antimicrobial
Sensitivity




Taking a sample of the isolated pathogen and
suspending it in a liquid medium and
streaking it on a culture plate.
Small disks of filter paper with antimicrobial
agents are placed on top.
Plate is incubated at 370 C for 24 hours.
The antimicrobial that inhibited microbial
growth will be effective in treating the
infection.
32
Quality Control in the Office


Ongoing system to
evaluate the quality of
medical care being
provided.
Provides an objective
means to define,
monitor, and correct
potential problems.


All media, staining
solutions, and
reagents should be
evaluated
frequently.
Equipment must
also be in proper
running order.
33
Impact of CLIA’ 88



All labs must incorporate the appropriate
policies and procedures to comply with
CLIA’ 88
Proper documentation of lab policies and
procedures, materials, and lab personnel
qualification and training.
Proficiency testing program monitors quality
of laboratory’s test results
34
Apply Your Knowledge -Answer
How are pathogens tested to see if they
can be treated effectively by
antimicrobial agents?
Small disks of filter paper with antimicrobial agents are
placed on top of the inoculated culture plate, and if the
antimicrobial agents stop the growth of the pathogens,
it will be effective in treatment of the infection.
35
Summary
Medical Assistant
Developing your clinical skills will be an asset to the
office and will allow you to advance your career.
Quality control in the microbiology laboratory is an
important factor in ensuring high-quality
medical care.
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End of Chapter
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