Transcript The Profession of Medical Assisting

CHAPTER
46
Microbiology and
Disease
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46-2
Learning Outcomes
46.1
Explain the medical assistant’s role in microbiology.
46.2
Describe how microorganisms cause disease.
46.3
Describe how microorganisms are classified and
named.
46.4
Discuss the role of viruses in human disease.
46.5
Discuss the symptoms of HIV/AIDS and hepatitis.
46.6
Discuss the role of bacteria in human disease.
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46-3
Learning Outcomes (cont.)
46.7
Discuss the role of protozoa in human disease.
46.8
Discuss the role of fungi in human disease.
46.9 Discuss the role of multicellular parasites in human
disease.
46.10 Describe the process involved in diagnosing an
infection.
46.11 Identify general guidelines for obtaining specimens.
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46-4
Learning Outcomes (cont.)
46.12 Carry out the procedure for transporting specimens
to outside laboratories.
46.13 Describe two techniques used in the direct
examination of culture specimens.
46.14 Carry out the procedure for preparing and
examining stained specimens.
46.15 Carry out the procedure for culturing specimens in
the medical office.
46.16 Describe how to perform an antimicrobial sensitivity
determination.
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46-5
Introduction
• Microorganisms
• Medical assistant
– Everywhere in the
environment
– Identification of
microorganisms
– Cause disease if
– Proper collection
techniques
• Pathogenic in
nature
• Displaced from
their natural
environment
– Testing procedures
– Quality control
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46-6
Microbiology and the Role of the
Medical Assistant
• Microbiology – study of microorganisms
• Microorganisms
– Resident normal flora
– Pathogens
• Medical assistant
– Assist the physician
– Preparing specimens
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46-7
Apply Your Knowledge
What role does the medical assistant play in
relation to microbiology?
ANSWER: The medical assistant may assist the
physician in obtaining specimens, obtain specimens
herself, prepare specimens for direct examination or
transport to a reference laboratory, and possibly
perform microbiologic procedures.
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46-8
How Microorganisms Cause Disease
• Extensive variety of pathogens
• People normally are able to avoid infection
• Cause disease in variety of ways
• May remain localized or become systemic
• Transmitted directly or indirectly
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46-9
Classification and Naming of
Microorganisms
• Classification by structure
– Subcellular
– Prokaryotic
– Eukaryotic
• Standardized naming
– Genus ~ biologic classification
– Species of organism ~ distinct type of
microorganism
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46-10
Classification and Naming of Microorganisms
(cont.)
• Standardized naming
– Genus
• Category of biologic classification
• Example – Staphylococcus
– Species of organism
• Represents a distinct type of microorganisms
• Examples – Staphylococcus aureus and
Staphylococcus epidermidis
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46-11
Apply Your Knowledge
1.
How do microorganisms cause disease?
ANSWER: Organisms cause disease by using nutrients needed by
cells and tissues, damaging cells directly, causing to body’s
defenses to attack the cell, or producing toxins.
2. Describe the classifications of microorganisms and give
an example of each.
ANSWER: Microorganisms are classified as:
Subcellular organisms – viruses
Prokaryotic organisms – bacteria
Eukaryotic organisms – protozoans, fungi, and parasites
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46-12
Viruses
• Smallest known infectious
agents
• Subcellular microorganism
– Have only nucleic acid
surrounded by a protein coat
Hepatitis Virus
– Must live and grow in living cells of other
organisms
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46-13
Significant Bloodborne Pathogens
• Medical assistants must understand
– How HIV and hepatitis cause infection
– Risk factors
– Progression of the infections
– Treatments
– Special precautions
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46-14
AIDS/HIV Infection
• HIV – virus
• HIV infection  AIDS
• The HIV virus destroys
– Helper T cells
– Neurons
• Patients develop opportunistic infections
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46-15
AIDS/HIV Infection (cont.)
• Risk factors
– Unprotected sexual
activity
– Sharing needles
used by IV drug
users
– Passes from
mother to fetus or
infant
• Risk in the medical
community
– Percutaneous
exposure
– Mucocutaneous
exposure
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46-16
AIDS/HIV Infection (cont.)
• Progression of the infection
– Initial infection ~ may occur years before
symptoms
– Incubation period
• Virus becomes inactive
• Lasts 8 to 15 years
– Full-blown AIDS
• 200 or less helper T cells / mL blood
• Opportunistic infections and neurological
deterioration
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46-17
AIDS/HIV Infection (cont.)
• Diagnosis
– Rapid HIV test
– Confirmatory blood tests
• Enzyme-linked immunosorbent assay (ELISA)
• Western Blot Test
• Immunofluorescent antibody (IFA)
– Positive results in two of three positive –
accurate diagnosis
– Home test available
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46-18
AIDS/HIV Infection (cont.)
• Symptoms
– Peripheral nervous
systems
– Systemic
– Respiratory
– Oral
– Skin-related
– Kaposi’s sarcoma
– Gastrointestinal
– Central nervous
symptoms
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46-19
AIDS/HIV Infection (cont.)
• Prevention
– Sexual contact
• Avoid high-risk sexual activity
• Take safety precautions
– IV drug use ~ avoid sharing or reusing
needles
– Medical procedures ~ Standard Precautions
– Education ~ accurate information
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46-20
AIDS/HIV Infection (cont.)
• Chronic disorders – early diagnosis and
treatment key
• Drug Treatment
– Goals
– Treatment guidelines
– Initiating treatment ~ delayed vs. early
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46-21
Hepatitis
• Viral infection of the
liver
• Hepatitis A
– Fecal-oral route
– Vaccine available
• Hepatitis B
– Bloodborne
– Vaccine available
• Hepatitis C
– Bloodborne
– Prevent spread
• Hepatitis D – occurs
only in people infected
with the HBV
• Hepatitis E – fecaloral route
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46-22
Hepatitis (cont.)
• Risk factors include
– IV drug use
– Travel
– Hemophilia or receiving blood transfusions
prior to implementation of screening
– Hemodialysis
– Multiple sexual partners or living with
someone with Hepatitis B or C
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46-23
Hepatitis (cont.)
• Risk in medical community
• Progress of the infection
– Prodromal stage
– Icteric, or jaundice, stage
– Convalescent stage
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46-24
Hepatitis (cont.)
• Diagnosis
• Symptoms
–
–
–
–
–
–
–
Jaundice
Decreased appetite
Fatigue
Nausea and vomiting
Joint pain / tenderness
Stomach pain
General malaise
– Investigation of
• Risk factors
• Exposure incidents
– Blood tests
• Antigen-antibody
systems
• Determine stage of
disease
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46-25
Hepatitis (cont.)
• Preventive measures
– Avoid contact with contaminated substances
– Use Standard Precautions
– Vaccination ~ HBV infections
– HBIG for postexposure inoculation
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46-26
Apply Your Knowledge
Which statements are true and which are false?
ANSWER:
T Risk factors are the same for HBV and HCV.
____
Right!
___
F Hepatitis A is spread via contaminated blood or body fluids.
the fecal-oral route.
F Helper T cells are red blood cells and are a key component of
____
immune system.
white blood cells
T Percutaneous exposure occurs through a puncture wound or
____
needlestick.
T
Viruses are the smallest known pathogens.
F
Viruses are a complex life form but can only live in another
organism’s cells.
simple
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46-27
Bacteria
• Single-celled prokaryotic organisms
• Reproduce rapidly
• Classification
– Shape
– Ability to retain dyes
– Ability to grow
with / without air
– Biochemical reactions
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46-28
Classification and Identification
• Shape
– Coccus – spherical, round, or ovoid
– Bacillus – rod-shaped
– Spirillum – spiral-shaped
– Vibrio – comma-shaped
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46-29
Classification and Identification (cont.)
• Ability to retain certain dyes
– Gram stain
– Acid-fast stain
• Ability to grow in presence
or absence of air
– Aerobes
– Anaerobes
– Facultative
• Biochemical reactions – differentiation
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46-30
Bacteria (cont.)
• Special groups of bacteria
– Mycobacteria
– Rickettsiae
– Chlamydiae
– Mycoplasmas
• Bacterial pathogens
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46-31
Bacteria (cont.)
• Drug resistance
• Risk factors
– MRSA
– Elderly
– VRE
– Invasive procedures
– VISA
– Prior use of
antimicrobials
– VRSA
– ESBLs
– Repeated contact with
healthcare system
– PRSP
– Severity of illness
– Underlying conditions
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46-32
Bacteria (cont.)
• Preventing antibiotic resistance in
healthcare settings
1. Prevent infection
2. Diagnose and treat infection appropriately
3. Use antibiotics carefully
4. Prevent transmission of infections
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46-33
Apply Your Knowledge
How are bacteria classified and identified?
ANSWER: They are classified by their shape, their
ability to retain certain dyes, their ability to grow in the
presence or absence of air and biochemical reactions.
Good Job!
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46-34
Protozoans
• Single-celled eukaryotic organisms
• Found in soil and water
• Leading cause of
death in developing
countries
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46-35
Fungi
• Eukaryotic organisms with rigid cell wall
• Yeasts
– Single-celled
– Reproduce by budding
• Molds
– Large, fuzzy, multi-celled
organisms
– Reproduce by spores
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46-36
Multicellular Parasites
• Organisms that live on or in another
organism
– Use it for nourishment
– Detrimental to host
• Parasitic worms
• Parasitic insects
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46-37
Apply Your Knowledge
Matching:
ANSWER:
A Yeast or mold
___
___
C Tapeworm/lice
A. Fungus
B. Protozoan
C. Multicellular
parasite
B, C Poor sanitation promotes
spread
___
B Single-celled, much larger than bacteria
A reproduce by budding or spores
___
B Found in soil and water
___
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46-38
How Infections Are Diagnosed
1. Examine the patient
– Presumptive diagnosis
– May or may not need additional tests
2. Obtain specimen(s)
3. Examine the specimen
– Wet mount
– Smear
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46-39
How Infections Are Diagnosed (cont.)
4. Culture the specimen
– Placed on a growth medium and allowed to
incubate
– Identifies microorganism
5. Determine antibiotic sensitivity
6. Treat the patient
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46-40
Apply Your Knowledge
What is the process for diagnosing an infection?
ANSWER: There are six steps for diagnosis and
treatment of an infection:
1. Examine the patient
4. Culture the specimen
2. Obtain specimen(s)
5. Determine sensitivity
3. Examine specimen directly
6. Treat patient
Super!
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46-41
Specimen Collection
• Must be collected correctly
• Collection devices
– Use container appropriate
for specimen
– Sterile swabs
• Collection and transport
systems
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46-42
Guidelines for Specimen Collection
• Avoid causing harm
• Collect from
appropriate site
• Obtain specimen at
correct time
• Use appropriate
devices
• Obtain sufficient
quantity
• Obtain specimen prior
to therapy
• Label correctly
• Include requisition
form
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46-43
Specimen Collection (cont.)
• Throat culture specimens
• Urine specimens
• Sputum specimens
• Wound specimens
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46-44
Transporting Specimens to an
Outside Laboratory
•
Three objectives
– Follow proper
collection procedures
– Prevent deterioration
of specimen
– Protect anyone
handling specimen
• Transportation
methods
– Regularly scheduled
pickups
– As-needed pickups
– Mail ~ etiologic agent
label
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46-45
Apply Your Knowledge
1. What are the general guidelines for specimen collection?
ANSWER: They are to
• Avoid causing harm, discomfort, or undue embarrassment
• Collect from appropriate site
• Obtain specimen at correct time
• Use appropriate collection devices
• Obtain sufficient quantity of specimen
• Obtain specimen prior to the start of antimicrobial therapy
• Label specimen correctly.
Impressive
!
2. What are the objectives for transporting a specimen to
an outside laboratory?
ANSWER: They are to follow proper collection procedures and use
the proper collection device, prevent deterioration of the specimen
during transport, and protect anyone that will handle the specimen
from exposure.
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46-46
Direct Examination of Specimens
• Enables physician to initiate treatment
immediately
• Wet mounts
– Quick identification of microorganisms
– Determining motility
• KOH mounts
– Potassium hydroxide dissolves keratin
– Fungal infections
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46-47
Preparation and Examination of Stained
Specimens
• Prepare a smear on a glass slide
• Gram’s stain
– Moderate-complexity test
– Series of staining and
washing steps
– Iodine used to “set” stain ~ mordant
– Gram-positive
– Gram-negative
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46-48
Apply Your Knowledge
1. What are the methods for preparing a slide for
direct examination by the physician?
ANSWER: Wet mount and KOH mount.
2. How does the examination of stained
specimens facilitate patient care?
ANSWER: Stained specimens enable the physician to
provide a quick, tentative diagnosis and differentiate
between types of infections.
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46-49
Culturing Specimens in the Medical Office
• Place a sample of specimen on a culture
medium
– Medium ~ nutrients
– Place in incubator for
growth
– A colony develops
as microorganism
multiplies
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46-50
Culture Media
• Liquid, semisolid, or solid containing
agar
• Types
– Selective
– Nonselective
•
Special culture units
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46-51
Inoculating a Culture Plate
• Transfer some of the specimen onto a
culture plate
• Label the plate correctly
• Qualitative analysis – determination of
type of pathogen
• Quantitative analysis – number of bacteria
present in sample
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46-52
Inoculating a Culture Plate (cont.)
• Qualitative
• Quantitative
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46-53
Culturing Specimens (cont.)
• Incubating culture plates
• Interpreting cultures
– Characteristics of colonies
– Relative number
– Changes to media around colonies
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46-54
Determining Antimicrobial Sensitivity
• Appropriate antimicrobial
• An outside lab reports
– Sensitive
– Intermediate
– Resistant
• Inoculate and place antimicrobial discs
• Incubate and evaluate
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46-55
Apply Your Knowledge
1. What is the process for culturing a specimen?
ANSWER: Selective culture media allows the growth of
only certain kinds of bacteria. Unselective culture media
support the growth of most organisms.
2. The office received a culture sensitivity report
on a bacteria that said it was resistant to an
antimicrobial. What does this mean?
ANSWER: It means that the bacteria was not killed by
the antimicrobial and that there was an overgrowth of
the bacteria.
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46-56
In Summary
46.1
As an office medical assistant, you may assist the
physician with several microbiologic procedures that
aid in diagnosing and treating infectious diseases.
46.2
Microorganisms can cause disease by using up
nutrients or other materials needed by the cells and
tissues they invade, damaging body cells, and
producing toxins.
46.3
Microorganisms are classified on the basis of their
structure. Specific microorganisms are named in a
standard way.
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46-57
In Summary (cont.)
46.4
Viruses are among the smallest known infectious
agents causing common diseases, including the
common cold, influenza, chickenpox, croup,
hepatitis, and warts.
46.5 The initial symptoms of AIDS are usually severe flulike symptoms followed later by systemic, respiratory
oral, gastrointestinal, nervous system, and skin
complaints.
The general symptoms of hepatitis include jaundice,
diminished appetite, fatigue, nausea, vomiting, joint
pain or tenderness, stomach pain, and general
malaise.
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46-58
In Summary (cont.)
46.6 Bacteria are single-celled prokaryotic organisms that
reproduce very quickly.
46.7 Protozoans are single-celled eukaryotic organisms
found in soil and water.
46.8
Fungi are eukaryotic organisms including molds and
yeasts.
46.9
Multicellular parasites include roundworms,
tapeworms, flatworms, ticks, lice, and mites.
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46-59
In Summary (cont.)
46.10 The steps involved in diagnosing an infection are to:
examine the patient; obtain one or more specimens;
examine the specimen directly either by wet mount or
smear; culture the specimen; and determine the
culture’s antibiotic sensitivity.
46.11 The general guidelines for obtaining specimens are to:
– obtain the specimen with great care to avoid causing the
patient harm, discomfort, or undue embarrassment;
– collect the material from a site;
– obtain the specimen at the proper time;
– use appropriate collection devices;
– obtain a sufficient quantity of the specimen; and
– obtain the specimen before antimicrobial therapy begins.
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in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
46-60
In Summary (cont.)
46.12 When transporting specimens to outside
laboratories, the medical assistant should:
– Follow proper collection techniques using specific
containers provided by the laboratory;
– Maintain the samples in a state as close to their
original as possible; and
– Protect anyone who handles a specimen container
from exposure to potentially infectious material.
46.13 Direct examination of culture specimens is
accomplished in two ways: wet mounts and KOH
mounts.
© 2014 by McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution
in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
46-61
In Summary (cont.)
46.14 To prepare a stained specimen, the medical assistant
must first prepare a smear, fix the sample to the slide
so it does not wash off during the staining process,
and follow a specific staining procedure.
46.15 To culture a specimen, the medical assistant should
place a sample of the specimen on or in a specialized
culture medium and allow it to grow in an incubator for
24 to 48 hours.
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in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
46-62
In Summary (cont.)
46.16 Performing an antimicrobial sensitivity test involves
taking a sample of the isolated pathogen,
suspending it in a small amount of liquid medium,
and streaking it evenly on the surface of a culture
plate.
Small disks of filter paper containing various
antimicrobial agents are placed on top of the
inoculated agar plate.
The plate is then incubated at 37º C, and the results
are evaluated the following day.
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in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.
46-63
End of Chapter 46
Each organism's
environment, for the
most part, consists of
other organisms.
~ Kevin Kelly
© 2014 by McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution
in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.