Transcript File

Chapter 43
Basic Microbiology
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2014 Cengage
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Learning.
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Reserved.
be scanned,
May not
copied
be scanned, copied
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posted
duplicated,
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or posted
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to a publicly
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accessible
in wholewebsite,
or in part.
in whole or in part.
The Medical Assistant’s Role in
the Microbiology Laboratory
• Obtain and test specimens
• Prepare slides and cultures
• Allow cultures to grow at least 12 hours
before examining for identification
• Sensitivity identifies which antibiotic(s)
will kill microorganism causing infection
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
The Medical Assistant’s Role in
the Microbiology Laboratory
• Normal flora: natural bacteria
• Pathogen: disease causative
microorganism
• Use technique to avoid laboratory error
• Use sterile supplies
• Deliver culture to laboratory in
reasonable amount of time
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
The Medical Assistant’s Role in
the Microbiology Laboratory
• Identification of organisms done
successfully within 24 to 72 hours
• Many test kits available
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology
• Classification
– Taxonomy deals with classification of living
organisms
– Kingdoms: plants, animals, protists
– Lower protists, or prokaryotes (blue-green algae
and bacteria)
– Higher protists, or eukaryotes (protozoa, algae,
fungi)
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology
• Nomenclature
– System for naming bacteria
– Genus
• First name; capitalized
– Species
• Second name; not capitalized
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology
• Nomenclature
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Bacteriologists and microbiologists
Parasitology
Virology
Mycology
Reference laboratory
Report certain types of bacteria and yeasts to
Department of Public Health
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology
• Cell structure
– DNA
(deoxyribonucleic
acid)
– Lower protist
Basic bacterial cell >>
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Autoclave
– Used to sterilize equipment
– Many laboratories no longer use autoclaves because of use
of presterilized and disposable equipment
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Microscope
– Used to view organisms that cannot be seen with
naked eye on prepared slide
– Delicate instrument
– Cared for properly as stated by manufacturer
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Safety hood
– Aerosols can be released into air when culturing
– Potentially dangerous if inhaled
– Use of hood mandatory when performing culture
on specimen with potential aerosol
– Used to minimize odors
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Incubator
– Constant temperature of 35–37°C
– Grows aerobic or anaerobic organisms
– Temperature requirements must be met for
adequate growth
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Anaerobic equipment
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Absence of oxygen to grow anaerobic bacteria
Use of candle jar
Gas pack jar
Specimens sent to reference laboratories
Gram stain used to observe gross morphological
features of bacteria
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Inoculating
equipment
– Loop used to inoculate
organisms
– Needle used when
performing stab culture
Inoculating loop>>
Inoculating needle>>
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Incinerator
– Quickest method of sterilization
– Electrical incinerator or Bunsen burner
• Media
– Host of substances
– Used to foster growth of bacteria
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Equipment
• Refrigerator
– Used to store materials
– Temperature of 2–8°C
– Never store food or drink with specimens, kits,
media
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Safety When Handling
Microbiology Specimens
• Personal protective equipment
– PPE worn at all times
– Laboratory coat or apron, safety goggles, gloves
– May need to work behind shield or use safety
hood
– Never eat, smoke, drink, or put objects into mouth
– Do not touch contact lenses or apply makeup
– Wash hands
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Safety When Handling
Microbiology Specimens
• Work area
– Use strong germicide before and after daily use or
immediately after spills
– Dust-free and clean at all times
– Uncluttered
– Avoid body burns or files
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Safety When Handling
Microbiology Specimens
• Specimen handling
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Look for leaks and contamination on containers
Wear gloves
Use appropriate container
Handle all specimens as if contaminated
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Safety When Handling
Microbiology Specimens
• Disposal of waste
and spills
– Separation of
biohazardous wastes
(red bags)
– Disinfect spills with
5% phenol or 10%
bleach solution
<<Biohazard symbol
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Quality Control
• All equipment with temperature controls
monitored daily
• Microscopes cleaned and kept dust-free
• Before use, expiration date checked on
all testing kits
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Quality Control
• Media of all types should not be used
past shelf life and should be stored at
proper temperatures
• Check specific list of bacteria to use on
various media to test for growth
• Laboratory manual updated periodically
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Quality Control
• All chemicals or reagents with Material
Safety Data Sheets (MSDS) should be
available to reference
• Document all quality control testing in
proper laboratory logs
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Collection Procedures
• Check to see if culture was:
– Collected properly
– Delivered within a reasonable period of time
– Collected in sufficient quantity
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Collection Procedures
• All specimens taken from site of
infection
• Place in appropriate container
• Deliver to laboratory
• Rejecting specimens
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Collection Procedures
• Factors determining successful isolation
of causative pathogens
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Proper collection from infection site
Collection of specimen during infection period
Sufficient amount of specimen
Appropriate specimen container
Appropriate transport medium
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Collection Procedures
• Factors determining successful isolation
of causative pathogens
– Specimen labeled properly
– Specimen delivered to laboratory in minimal
amount of time
– Specimen collected before administration of
antibiotics
– Specimen inoculated onto proper media and
placed in correct atmosphere to ensure growth
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Urine
– Obtaining clean-catch specimen
– Use of catheterization
• Nose
– Nasal-pharyngeal swab collects specimen
– Place swab in sterile tube for transport to
laboratory
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Throat
– Specimens taken using culturette
– Use sterile tongue depressor to hold patient’s tongue
down
– Avoid swabbing sides of mouth and tongue
– Take specimen directly from affected area
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Wound
– Use of sterile needle or swab to aspirate pus-filled
fluid from wound
– Use of anaerobic transport medium
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Sputum
– Patient coughs deeply and expectorates into
sterile container
– Should be morning specimen
– Use of special sterile container
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Stool
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Ova and parasites
Bacterial cultures
Keep at between room and body temperature
Non-sterile containers
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Cerebrospinal fluid (CSF)
– Lumbar puncture
– Fluid dispersed in several departments of clinical
laboratory
– Use of incubator
– Refrigeration can kill meningitis-causing bacteria
– STAT order for processing
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Specific Collection Requirements
for Cultures
• Blood
– Development of septicemia
– Cultures collected by same means as regular
blood collection
– Variety of collection devices available
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Foodborne Illnesses
• Bacterial infections and parasites
• 48 million cases of “food poisoning”
each year contracted from:
– Raw or undercooked meats and seafood
– Contaminated food handlers
– Unwashed produce
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Foodborne Illnesses
• Symptoms: mild to severe diarrhea,
nausea, vomiting, abdominal pain,
fever, headaches, flu-like symptoms
• Diagnostics: stool cultures, blood tests,
following the symptoms
• Treatments: antibacterial medications
and treating symptoms
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Bacterial Shapes
Bacilli
Cocci
Spirilla
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Dyes (stains)
– Derived from coal tar
– Basic dyes carry a positive ion
– Acidic dyes carry a negative ion
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Simple stain
– Uses single stain on fixed slide for given period of
time
– Shows arrangement and structure of bacterial cell
– Takes no more than 3 minutes to stain
– Does not give much information
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Differential stain
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Stain result varies
Common differential stain is Gram stain
Developed in 1884 by Dr. Hans Christian Gram
Differentiates bacteria by Gram stain ability of
being negative or positive
– Retain or lose color through decolorization
– Use of gentian or crystal violet reagents
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Differential stain
– Identifies Gram-positive and Gram-negative
bacteria
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Staphylococcus
Streptococcus
E. coli
Proteus
– Morphological arrangement, shape, and Gramstain characteristic help identify bacteria
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Acid-fast stain
– Specific stain
– Allows microscopic examination of acid-fast
mycobacteria
– Use of heat or powerful dye
– Ziehl-Neelsen stain
– Kinyoun stain
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Special techniques
– Used when flagella, spore, capsule, or nuclei of
cells present
– Organisms in living state, without staining
– Wet-mount preparation
– Hanging drop preparation
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Potassium hydroxide (KOH) preparation
– Used for study of fungi and spores
– Fragments of human hair, skin, or nails placed on
slide with drop of 10% KOH and coverslip
– KOH clears debris
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microscopic Examination of Bacteria
• Potassium hydroxide (KOH) preparation
– Set slide at room temperature for a half hour
before examination for debris settlement
– Direct examination of specimens
– Use of phase or dark-field microscope
– Dispose of properly (live organisms)
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Culture Media
• Inoculate material on proper culture
medium for growth and identification
• Reliability of results
• Aerobic bacteria grow only in oxygen
• Anaerobic bacteria live and grow in
absence of oxygen
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Culture Media
• Transport media for reference
laboratory
• Media solid, liquid, or semisolid
substance
• Agar: solid form of media
• Semisolid media: made by adding less
agar
• Liquid media: in broth form stored in
tubes
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Culture Media
• Media nutrients to support growth of
bacteria
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Vitamins
Sugar
Salt
Minerals
Amino acids
Addition of special products
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Culture Media
• Media classification
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Basic
Differential
Selective
Enriched
• Check known organisms for quality
control and for contaminants
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology Culture
• Inoculating the media
– Roll swab onto upper quadrant of agar plate
– Use loop to inoculate sputum or liquid
– Inoculum spread back and forth in sweeping
motion with flamed loop or needle
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology Culture
• Inoculating the media
– After inoculating agar plate, turn upside down and
place in proper environment for growth
– Liquid broths and agar slant tubes have screw
caps
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology Culture
• Other types of streaking
– Lawn streak used to place organism over entire
area of agar plate for sensitivity testing
– Colony count used to plate urine cultures
– Laboratories have slightly different ways of
performing basic streaks
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Microbiology Culture
• Primary culture
– After media incubated for 24 to 48 hours, initial or
primary culture read
• Subculture
– More than one pathogen grows in culture
– To identify each organism, separate bacteria to
other media
– Separate pathogenic bacteria from normal flora
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Rapid Identification Systems
• Streptococcus screening
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Rapid strep testing
Many rapid test kits available
Rapid identification important
Latex agglutination test based on antigen and
antibody agglutination
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Rapid Identification Systems
• Streptococcus screening
– Read and understand directions before starting
test
– Never use outdated materials
– Observe all safety guidelines and precautions
– Use correct swab in taking throat cultures
– Always run positive and negative control along
with actual test
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Sensitivity Testing
• Often ordered on
pathogenic
organisms
recovered from
culturing process
• Culture and
Sensitivity (C&S)
Culture plate showing
antibiotic discs on
bacteria>>
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Parasitology
• Parasitic infections becoming more
common
• Different geographic areas have
different types of parasites
• Common methods of fecal specimen
examination for parasitic identification is
direct wet-mount slide
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Parasitology
• Specimen collection
– Wide-mouth containers with tight lid to prevent
leakage
– Container in biohazard transport bag to avoid
contamination
– Laboratory user’s manual for specific instructions
– Strictly follow laboratory procedure
– Label specimen correctly
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Parasitology
• Common parasites
– Giardiasis lamblia
• Spread through fecal to oral route
– Enterobius vermicularis
• Nematode (round worm)
• Pinworms
• To diagnose: adult worm or ova has to be located in
specimen
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Parasitology
• Common parasites
– Trichomonas vaginalis
• Found five times more often in women than in men
• Transmitted sexually
• Recovery of trichomonad
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Parasitology
• Common parasites
– Hookworm
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Infection through hair follicles, pores, open wounds/sores
Poor hygiene and warm moist climates
Concern is anemia
Diagnostic tests: stool cultures and CBC
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Mycology
• Extensive field
• Candida has several species that cause
yeast infections in body
• Dermatophytes cause infections on hair,
skin, nails
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.