Download Basic Microbiology: Understanding Your Enemies

Train the Trainer
(Infection Control & Microbiology Training)
Basic Microbiology:
Understanding Your Enemies
Introduction
The Bermuda Triangle
¾ Microorganisms cause infectious disease
¾ Essential to understand how
microorganisms interact with their
environment
¾ Need to understand how microorganisms
are transmitted before you can choose
which detergent / disinfectant to use
AGENT
HOST
The Agent
¾ Where does it
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come from?
Comes from students, patients, staff, visitors
Public: Respiratory secretions, feces, wounds,
other body fluids
Staff: mouth, nose, hands
Visitors: Respiratory secretions, hands
ENVIRONMENT
The Agents
Incubation Period
Infection and Incubation Time
True or False: Incubation Time is the time from the
moment of inoculation (exposure) to the development of
the clinical manifestations (symptoms) of a particular
infectious disease.
TRUE: It’s the time from exposure to the time when
symptoms appear. Allows us to ask:
“When did I get this?”
“Who did I get this from?”
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D
D
D
D
D
D
D
Next Slide
The Host
D
Infection doesn’
doesn’t always lead to disease
The time from infection to the onset of symptoms
ranges from hours to years
Salmonella:
Influenza:
Common Cold:
Chicken Pox:
Hepatitis B:
Scabies:
Tuberculosis:
HIV:
6 - 48 hrs
1 – 2 days
2 – 5 days
14 – 16 days
50 - 150 days
2 – 6 weeks
6 months - 2 years
3 - 10 years
The Environment
How do we get these together?
¾ Why are they susceptible?
¾ Overcrowding
¾ Age
¾ Shared equipment (toys, medical instruments &
¾ Developing or Decreasing Immunity
devices, sports equipment)
¾ Poor cleaning & disinfection practices
¾ Poor hand hygiene (staff, visitors and students)
¾ Breaks
in the natural defenses
¾ Other illnesses (asthma, allergies etc)
Environmental Reservoirs
¾ Association between reservoirs and
outbreaks
¾ Protocols should include careful cleaning
of wet surfaces and equipment to prevent
the build up of Biofilms
¾ Examples:
z
z
z
z
z
Faucet aerators, Shower Heads
Sinks, Drains
Flower Vase Water
Ice Machines
Hydrotherapy Baths
Chain of Infection
¾ Microorganisms are carried with the
human / animal / insect body (Reservoir)
¾ Microorganisms released from body by
coughs, sneezes, feces, blood, saliva
¾ Inanimate objects, environmental
surfaces, food, water become
contaminated which leads to potential
transmission of disease
Chain of Infection
Transmission
Chapped Skin – Open Wound
Transmission
True or False: Infectious diseases are transmitted in
the same way.
FALSE: There are 4 main routes of transmission.
Contact
Airborne
Vehicle
Vector
Next Slide
How do Microorganisms Spread?
¾ Transmitted from person to person
through human contact, air currents, on
animals or insects, in food, in water or on
inanimate objects
¾ The human hand is capable of
transporting microorganisms from one
person to another, from one contaminated
object to another, or from a contaminated
object to another person
Five Routes of Transmission
¾ Contact Transmission
z
Most common divided into two subgroups
• DirectDirect-contact transmission – body surface to body
surface
• Indirect –contact transmission – contaminated
intermediate object
¾ Droplet transmission
z
Five Routes of Transmission
¾ Common vehicle transmission
z
Through contaminated items such as food
water
¾ Vectorborne transmission
z
Mosquitoes, flies, rats
Coughing, Sneezing, procedures
¾ Airborne transmission
z
Smaller evaporated droplets that remain suspended
for a long time
SARS
Norwalk
Influenza
MRSA
VRE
Norwalk
Chicken Pox
Pink Eye
Athelete’s Foot
Plantar Warts
Measles
Mumps
Rubella
Colds
Cross-Infection & Nosocomial
Disease
¾ Cross Infection refers to the process
¾
¾
West Nile
Virus
Malaria
where microorganisms are transmitted
from one person to another, causing
illness
¾ Nosocomial Diseases are infections which
are acquired by a patient after admittance
to a health care facility but were not
present or in an incubative stage at the
time of admission (generally 3 days)
FACTS
¾
Hand Hygiene
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¾
Hand Hygiene
¾ Recognized
as the best way of stopping
the spread of organisms in this setting
¾ Soap and water
z
z
No indication for antimicrobial soap
1010-15 seconds of lathering
¾ Alcohol
z
more research into concentration required to
kill all viruses
How Environmental Services
can STOP transmission
Environmental services professionals can prevent
the spread of infectious agents among patients
and healthcare workers by protecting themselves
in the following ways:
• Wearing gloves while handling any form of
hospital waste to include biohazard bags,
infectious waste containers, and trash bags of
any color
Play a major role in the transmission of
pathogenic microorganisms to
susceptible hosts
Hands acquire known or potential
pathogens by contact with objects and
animate and inanimate surfaces
Strict adherence to HH is more likely to
prevent the spread of infections than
procedures exceeding routine cleaning
of the environment
Hand Hygiene
¾ Towelettes
z
Must be alcohol based if used for hand
hygiene
¾ Children
z
z
z
z
after toileting
before and after eating
after pets, sand, dirt, art, ……..
……..
Education on sneezing and coughing
• never too early to start!
How Environmental Services
can STOP transmission
• Change gloves between patient rooms to
avoid transfer of microorganisms from one
patient to another
• Wear proper personal protective equipment
when cleaning up spills of potentially infectious
material
• Change gloves immediately after contact with
blood and/or body fluids, soiled linen, or
contaminated equipment
How Environmental Services
can STOP transmission
• Wash hands before and after
eating, smoking, applying
cosmetics, or preparing food
Knowing The Bugs!
• Stay home to rest when feverish
and sick with a cold, flu, or other
infection
Bacteria, Viruses, Fungi, Spores
Bacteria vs Virus
Major Groups Of Microbes
True or False: A virus is a more virulent bacteria.
Virus: Are “dead” unless living in someone else’s living
cell. It takes over the resources of a host cell (like
humans) and makes the host cell make more virus!
Bacteria: One-celled living organisms. All bacteria are
surrounded by a cell wall. They can reproduce
independently. They inhabit virtually every environment on
earth. Some are good (break down organic waste, make
yogurt & cheese). Some are not so good (cause disease).
¾ Bacteria (Gram
(Gram +ve
+ve
& Gram -ve)
ve)
¾ Viruses (enveloped & nonnon-enveloped)
¾ Fungi
¾ Protozoa
¾ Bacterial Spores
¾ Prions
Next Slide
Computer Keyboards May Harbor
Harmful Bacteria
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Harmful bacteria can survive for prolonged periods on
keyboards & keyboard covers
VRE & MRSA evident 24 hrs after contamination
PSAE evident only up to 1hr
More contact with contaminated keyboard increase
likelihood of transmitting bacteria to hands (MRSA: 42%
- 92%, VRE: 22% to 50%, PSAE: 9% to 18%)
Hand Hygiene important helps cut down on transmission
Cleaning & Disinfection of keyboards & keyboard covers
helps decrease contamination
Infection Control Today
Computer Keyboards May Harbor Harmful Bacteria;
Experts Advise to Use Disinfectant and Wash Your Hands
April 2005
Bacteria
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Microscopic, oneone-celled organisms that are
invisible to the naked eye (400 million bacteria
grouped together would be the size of a grain
of sugar)
Classified by shape: round, rod and spiral
Classified by Gram Straining
Vegetative forms relatively easily killed by
chemical germicides
Round Shaped Bacteria
¾
Rod-Shaped Bacteria
¾
Examples: E. Coli &
Salmonella
choleraesuis (food
poisoning), Klebsiella
spp. (pneumonia),
Mycobacterium spp.
(tuberculosis)
The Gram Stain
¾ Developed in
the late 1800’
1800’s by Dr. Gram,
a pathologist
¾ Originally being developed to stain kidney
cells
¾ Gram positive organisms are purple (S.
aureus)
¾ Gram negative organisms are red (S.
choleraesuis, Pseudomonas spp.)
¾ Based on cell wall composition
Examples:
Staphylococcus
(cause wound
infections, food
poisonings) &
Streptococcus (strep
throat)
Spiral Shaped Bacteria
¾
Examples:
Treponema pallidum
(venereal disease,
syphilis)
The Gram Stain
¾ Determination
is done through a chemical
process where bacteria are stained with
dyes and other substances, rinsed clean,
then stained again with another dye
¾ Final staining indicates if the bacteria is
gram +ve
+ve (bacteria stains purple / blue) or
gram –ve (bacteria stain red)
Gram Stain
¾ Gives a quick
look at the specimen
¾ Can interpret quality of specimen
¾ Can help direct antibiotic therapy
¾ Not so helpful if lots of normal flora
present
¾ Quite significant on sterile body sites
Elements of Survival & Growth
¾ Bacteria are selfself-sufficient
if they have the
basic elements of survival
z
z
z
z
z
Water
Food
Oxygen
Temperature
pH level
Water & Food
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¾
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Oxygen
¾ Oxygen requirements vary by type of
bacteria
¾ Aerobic bacteria require oxygen to survive
(Salmonella, Pseudomonas)
¾ Anaerobic bacteria grow only in
environments without oxygen (Clostridium
difficile)
¾ Facultative anaerobic bacteria can survive
in either environment (Salmonella)
Water is essential for survival
Structure of bacteria is primarily comprised of
water & protein
Water “holds”
holds” the structure of bacteria together
Water transports food into cell & removes waste
Both organic & inorganic materials are utilized
as food
Requirements of food types and quantity needed
varies by bacteria type
Temperature & pH
¾ Temperature affects the reproduction
cycle
¾ Bacteria that affect humans thrive at
normal body temps 98.6 F
¾ pH level refers to amount of acid or alkali
present in an environment
¾ Optimal growth environment for bacteria is
usually pH 7 or neutral
Bacteria – Tough Enemies
¾ Bacteria reproduce by process called
Binary Fission
¾ Single Cell divides into two cells, these
new cells split into 2 more cells etc, etc
¾ The whole process can occur as rapidly as
every 15 minutes
¾ Under ideal conditions, one cell can
generate an entire colony of over 1 million
bacteria in under 5 hours
Laboratory Testing
¾ Most human pathogenic bacteria take 24
hours to grow enough on the laboratory
media to be visible and to be able to
distinguish single colonies with the naked
eye.
¾ Sensitivity testing from a pure culture can
be anywhere from 4 – 24 hours later.
¾ Full identification can also take up to 24 –
48 hours.
Viruses
¾ Classified as
either DNA virus or RNA
virus
¾ New research shows there is a small
group of viruses that contain both DNA &
RNA
¾ Viruses are also classified by shape, size
& other structural characteristics for
example
z
Enveloped or NonNon-enveloped Viruses
Bacteria – Tough Enemies
¾ Bacteria can develop an immunity or
resistance to antibiotics designed to kill
them
¾ Hence the requirement for new treatment
options
¾ However, resistance to antibiotics does
not necessarily mean a bacterium is
resistant to disinfectants
Viruses
¾ Viruses are even smaller than bacteria
and cannot be seen under an ordinary
microscope
¾ Viruses cannot live independently and are
not self sufficient
¾ Viruses are referred to as obligate
parasites meaning they are dependent on
cells of a living host to replicate & multiply
Enveloped Viruses
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¾
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Envelop refers to the
Lipoprotein outer layer of
some viruses derived from
plasma membrane of the
host cell
Considered easier to kill
than even Vegetative
Bacteria
Examples: HIV, Herpes,
Hepatitis B & C, Influenza,
Coronavirus
Non-Enveloped Viruses
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NonNon-enveloped
viruses lack the
lipoprotein coat
Considered hardier
and more resistant
Examples: Polio,
Norovirus, Rhinovirus,
Rotavirus, Parvovirus
Fungi
Fungi
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UniUni-cellular or multimulti-cellular plants
Can cause many diseases in humans & animals
Grow on dead and decaying matter
Can be as small as a single cell or as large as a
mushroom
Common forms are yeast and molds including
mildew
Most fungi are harmless or “nonnon-pathogenic”
pathogenic”
Mycobacteria
¾ Vegetative bacteria:
¾
Examples:
Trichophyton
mentagrophytes
(Athlete’
(Athlete’s foot) used
as surrogate to
achieve disinfectant
claims
¾ Gram positive rods, nonnon-spore forming,
nonnon-motile, slightly curved, forming
strands and cords, acidacid-fast staining,
aerobic, slowslow-growing,
¾ More resistant to chemical germicides
than other types of vegetative bacteria
¾ Mycobacterium terrae is surrogate for High
Level disinfection claim
Mycobacteria
¾
¾
Examples: M.
tuberculosis
(tuberculosis), M.
bovis, M. leprae
(leprosy)
Mycobacterium terrae
is surrogate for High
Level disinfection
claim
Protozoa
¾ A very diverse group comprising some
50,000 eukaryotic organisms that consist
of one cell
¾ Most of them are motile and heterotrophic
¾ Infected animals & humans shed protozoa
in feces in the form of an oocyst
(Cryptosporidium) or cyst (Giardia)
¾ These protozoans can remain dormant for
long periods in the oocyst/cyst form. They
become active upon entering a host.
Protozoa
¾
Bacterial Spores
Cryptosporidium and
Giardia are protozoan
parasites affecting the
gastrointestinal tract
of humans and
animals.
¾ Produced by certain types of GramGram-
positive bacteria
¾ Heat & stain resistant, metabolically
inactive bodies formed within the
vegetative cells of bacteria
¾ Sporidcidal activity for highhigh-level
disinfectant claim (chemical sterilant)
Spores
¾
Examples of spores:
z
z
z
¾
Clostridium difficile
Bacillus subtilis
Bacillus anthracus
Outbreak Scenario
Spores of Bacillus
subtilis & Clostridium
sporogenes are
surrogates in tests
Norovirus, Norwalk
Norovirus
Critical Characteristics
Norovirus Transmission
¾ “OralOral-fecal”
fecal”
¾ Mouth
route
Gut (Replication)
Anus
¾ Hands
¾ Air
¾ Environmental surfaces
¾ Food
¾ Water
HANDS
ES
¾ Multiple modes of transmission
¾ Stable in the environment
FOOD
H2O
AIR
¾ Highly contagious
¾ Resistant to routine
disinfection methods
¾ Asymptomatic infections
¾ Limited immunity
Norovirus Infection
¾ 2424-48 hour incubation period
¾ 1212-60 hour duration of illness
¾ “Winter vomiting disease”
disease”
¾ “Stomach flu”
flu”
¾ Vomiting
¾ Diarrhea
¾ Nausea
¾ Abdominal cramps
¾ Headache, muscle aches
¾ “Lurgy”
Lurgy”
¾ A “mild”
mild”
Norovirus Infection Symptoms
and short lived illness
¾ Fever
¾ Dehydration in young and
elderly victims
¾ Up to 30% may be asymptomatic
Evidence for airborne transmission of NorwalkNorwalk-like virus
(NLV) in a hotel restaurant;
PJ Marks; Epidemiol.
Epidemiol. Infect. 2000, 124: 481481-487
Widespread environmental contamination with NLV
detected in a prolonged hotel outbreak of gastroenteritis;
JS Cheeseborough;
Cheeseborough; Epidemiol Infect 2000, 125: 9393-98
¾
71%
91%
56%
¾ Hotel restaurant with 126 patrons
¾ Patron (
) vomited at table
¾ 52 of 83 survey responders ill
z
63% overall attack rate
50%
¾ Attack rates higher at closer tables
40%
¾ Consistent with airborne
25%
transmission of NLV
Norovirus Transmission
RTRT-PCR environmental surface testing +
z
z
z
z
z
z
z
z
z
Carpets (known vomiting)
Carpets (no vomiting)
Toilet rims/seats
Toilet handles, taps, basins
Horizontal surfaces below 1.5 m
Horizontal surfaces above 1.5 m
Phones, door handles, etc.
Soft furnishings
Total
5/8 (62%)
9/12 (75%)
8/11 (73%)
13/39 (39%)
11/29 (37%)
6/12 (50%)
7/29 (24%)
2/10 (20%)
61/144 (42%)
ENVIRONMENTAL
ENVIRONMENTAL SPREAD
SPREAD OF
OF VIRUSES
VIRUSES
AND
ITS
CONTROL
AND ITS CONTROL
VIRUS RELEASE
CLEANING
¾ Food (39%)
¾ Hands (12%
“person to person”
person”)
(3%)
¾ Environmental surfaces (fomites)
¾ Air (aerosolization with vomitus)
vomitus)
¾ 46% unknown or no data available
CONTAMINATION
¾ Water
MMWR 2001; 50: RRRR-9
SURVIVAL
TRANSFER TO OTHER
VEHICLES
DISINFECTION
STERILIZATION
INOCULATION
INFECTION
(DISEASE)
INTERRUPTION
Antibiotic Resistant Organisms
(AROs)
¾ Antibiotic resistant strains do not mean
Antibiotic Resistant Organisms
(AROs)
¾ There are differing opinions
within the
scientific community as whether over use
of disinfectants can lead to chemical
resistance. A literature search showed
that there are several published studies
that suggest disinfectant chemistries such
as Quats that leave an active residual on
the surface can lead to resistance.
chemical resistance. These bacteria have
developed resistance to antibiotics
pertaining to human clinical situations.
This does not imply that these strains are
resistant to chemical disinfection.
Chemical are now tested against antibiotic
resistant strains such as VRE, MRSA etc.
These are shown on the label claims.
Vancomycin Resistant
Enterococci (VRE)
¾ Enteric,
Gram +ve
+ve cocci
¾ Enterococcus sp. normal flora in GI &
female genital tract
¾ Transmission via fecalfecal-oral route by
contact (direct & indirect)
¾ Healthy people are unlikely to get VRE
¾ Critically patients, patients with urinary
catheters, patients with underlying disease
¾ Hospital Acquired Infection (HAI)
Methicillin Resistant
Staphylococcus Aureus (MRSA)
¾ Gram
+ve
+ve cocci, normal flora on skin, in
nose or groin area (opportunistic)
¾ Incubation Time: 4 – 10 days, but can be
up to several months
¾ Transmission by contact (direct or indirect)
¾ Concern for elderly or patients with serious
health problems
¾ Causes urinary tract infections or wound
infections (Surgical Site Infections)
Pseudomonas aeruginosa
¾
¾
¾
¾
Gram –ve bacillus (opportunistic, thrives in moist
conditions)
Incubation Time: dependant on infection (Ex.
eye infection 24 – 72hrs)
Transmission by direct contact with
contaminated water (vehicle), Infected solutions
such as soap, IV (vehicle), contact (direct &
indirect),
Risk of disease to immunocompromised patients
Influenza Virus
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Influenza types A, B & C
Enveloped virus
Incubation Time: 1 – 4 days (infectious 3 – 5
days of clinical onset)
Transmission by direct contact through droplet
infection, airborne spread among crowded
populations in enclosed spaces
Virus may persist for hours in dried mucous & be
transmitted by direct contact (occasionally
fomites)
Human Immunodeficiency Virus
(HIV)
¾ HIV
is classified as an enveloped virus
¾ Incubation Time: 6 months to 7 years
¾ Transmitted from person to person
through direct exposure to infected body
fluids (blood, semen) sexual contact,
sharing unclean needles etc.;
transplacental transfer can occur
¾ Drying of virus in the environment causes
rapid reduction
Clostridium difficile
Mycobacterium tuberculosis
¾ Gram
+ve
+ve rod
¾ Incubation Time: 4 – 12 weeks
¾ Transmission by airborne particles
(inhalation)
¾ Higher risk of infection among
Health Canada MSDS – Infectious
Substances
¾ Anaerobic,
Gram +ve rod, spore forming
(Opportunistic)
¾ Commonly part of normal flora in gut
¾ Incubation Time: Not Known
¾ Transmission by direct contact (fecal-oral
route), indirect contact of contaminated
surfaces
¾ Risk of infection increases for patients on
prolonged antibiotic therapy, elderly,
immunocompromised patients
Health Canada MSDS – Infectious
Substances
¾
¾
¾
Listed by infectious agent
Include information on characteristic of
organism, mode of transmission, reservoir etc
http://www.hchttp://www.hc-sc.gc.ca/pphbsc.gc.ca/pphb-dgspsp/msdsdgspsp/msdsftss/index.html#menu
Conclusions
What YOU need to know
¾
¾
“Coughs and
Sneezes Spread
Diseases”
Diseases”
“If Its Moist and Its
not Yours, Don’
Don’t
Touch It”
It”
Handwashing
¾ Contaminated
hands are
probably the
single most
common vector
for the spread of
Infectious disease
Stay Healthy–Wash Your Hands
Virox Technologies
Inc.
Engineering
Revolutionary
Disinfectants for the
War Against
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