Transcript Document

Microbiology
Unit 6 Seminar:
Microbe-Human Interactions:
Infection and Disease
Evelyn I. Milian
Instructor
2011
Microbiology: Unit 6 Seminar – Microbe-Human Interactions
FIELD TRIP!!! – Websites and Questions Assigned

USprobiotics.org. Probiotics Basics. *** Watch the video!
http://www.usprobiotics.org/basics.asp
 Centers for Disease Control and Prevention; Healthcare-associated
Infections (HAI). http://www.cdc.gov/hai/
 Questions assigned:
1. Define “normal microbiota” and explain why normal microbiota is
critical to animals and humans.
2. Do you know anyone taking probiotics? Do you feel “probiotics” are a
good idea for the general population? Do you think the effects of
probiotics are real or psychosomatic in nature?
3. What is an opportunistic infection? Give an example and explain who
would be most at risk for this type of infection.
4. Explain why nosocomial infections are a significant challenge to the
medical community. Why is it so difficult to prevent transmission of
these diseases to patients?
5. Patients that contract a nosocomial infection may suffer considerably,
depending on the illness. Should they be compensated for their
suffering? If so, who should be financially responsible?
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Normal Microbiota in the Human Body

Normal microbiota = normal biota, resident microbiota,
normal microflora, indigenous microflora: The microorganisms
normally present on the body of an organism (the host; such
as the human or another animal) without causing disease
under normal conditions.
 Millions of microbes are normally present in the human body. Microbes
on the human body outnumber human cells at least ten to one!!!
 Bacteria were once classified as plants, which gave rise to use of the
term flora (or microflora) for microbes, now replaced by microbiota.
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Transient microbiota: The microorganisms that are present
in a host for a short time (days, weeks, or months) under
certain conditions, without causing a disease.
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Normal Microbiota: The Human as a Habitat

Roles of normal microbiota in the human body:
1. Normal microbiota protect the host by competing with pathogens:
 Microbial antagonism: competition between microbes; for example, the
normal microbiota compete for nutrients with harmful microorganisms and
produce substances that prevent their overgrowth (acids, bacteriocins).
2. Normal microbiota produce growth factors such as folic acid and
vitamin K.
3. Help us digest foods.
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Microbiology: Unit 6 Seminar – Microbe-Human Interactions
Normal Microbiota in the Human Body

The body provides a wide range of
habitats and supports a wide range
of microbes.

Most areas of the body in contact
with the outside environment harbor
resident microorganisms, while most
internal organs and tissues, and their
fluids are generally microbe-free.
•
Normal microbiota are adapted to the prevailing
conditions of each of these body regions.

Under some circumstances, normal microbiota
can make us sick or infect people we contact.
 Example: When some normal microbiota leave
their normal habitat in our body to reach another
site, they can cause disease, especially in
debilitated or immunocompromised people.
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Microbiology: Unit 6 Seminar – Microbe-Human Interactions
Sterile (Microbe-Free) Sites
and Fluids in the Human Body
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Some regions of the
body lack normal
microbiota either
because these regions
provide conditions
unsuitable for
microorganisms, are
protected by host
defenses, or are
inaccessible to
microorganisms.
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Microbiology: Unit 6 Seminar – Microbe-Human Interactions
Normal Microbiota
Many bacterial species live
on the surface of your body
or inside it. Mutualistic
microbes in the human
body help prevent growth
of pathogens, produce
vitamins, and help us
digest foods.
Some of the most common
bacteria that are members
of the normal microbiota in
humans are Escherichia
coli (in the large intestine),
Staphylococcus spp. (in
skin, mouth and other
areas) and Streptococcus
spp. (various species in
mouth, large intestine and
other areas).
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Microbiology: Unit 6 Seminar – Microbe-Human Interactions
The Origins of Microbiota
in Newborns
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A vaginal birth exposes
babies to the biota of the
mother’s reproductive tract.

From the moment of birth,
the infant will begin to
acquire microbes from its
environment, including
food, family members, and
health care personnel.
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Microbiology: Unit 6 Seminar – Microbe-Human Interactions
PROBIOTICS

What are probiotics?

Do you know anyone taking probiotics?

Do you feel probiotics are a good idea
for the general population?

Do you think the effects of probiotics
are real or psychosomatic in nature?
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Probiotics: Live Microbial Cultures for Good Health!

Probiotics: Live microbes (mainly
bacteria) administered to the body
with the purpose of exerting a
beneficial effect.
 Examples: bifidobacteria, lactobacilli
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Prebiotics: Nutrients that encourage
the growth of beneficial microbes.
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Food Production Using
Beneficial Bacteria
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Yogurt is a probiotic food
(pro = for, bios = life).
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Probiotics are live microbes
administered to the body to
exert a beneficial effect,
including prevention of
overgrowth of bad microbes.
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Yogurt contains live lactic
acid bacteria (LAB) which
are beneficial for the human
intestine. They produce
lactic acid and bacteriocins
that inhibit the growth of
certain pathogens (diseasecausing microorganisms).
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Probiotics: The Scientific Basis

Walker R., Buckley, M. (2006). Probiotic Microbes: The Scientific
Basis. A Report of the American Academy of Microbiology; American
Society for Microbiology.
 http://academy.asm.org/index.php?option=com_content&view=article&id
=233:probiotic-microbes-the-scientific-basis-june-2006&catid=40:browseall&Itemid=79
 “In theory, microorganisms could be used to combat pathogenic
microorganisms and the diseases they cause. They could also
conceivably be used to prevent infectious diseases and immune
dysfunction. Some probiotic formulations have been subjected to more
scientific scrutiny than others, and many of these applications show
considerable promise for alleviating certain illnesses. Many combinations
of therapies are being evaluated for the treatment and prevention of
various diseases and conditions.” (Walker & Buckley, 2006)
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Probiotics: The Scientific Basis

“In identifying prospective probiotic organisms for use
in humans, particular attention must be placed on the
safety of the organism for a variety of individuals,
including the immunocompromised, the very young,
and the aged. A number of in vitro tests systems and in
vivo models are now available for studying probiotics
prior to their use in human subjects, although relevance
of the resulting data may not be predictable.”

“Today, hundreds of probiotic foods and dietary
supplements that offer a variety of health benefits are
available to the consumer.” (Walker & Buckley, 2006)
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Benefits of Probiotics According to Scientific Studies

Boost your immune system, decreasing
the incidence of common diseases such
as cold, flu and intestinal infections.
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Lactose tolerance: better lactose digestion
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Decreased symptoms of constipation and
Irritable Bowel Syndrome
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Decrease in antibiotic-associated diarrhea
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Decreased incidence of some allergies in
infants
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Decreased incidence of vaginal infections
in women
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Reduced duration of infectious diarrhea in
children
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What is an opportunistic infection?
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Pathogen: A microbe that causes disease.
 True pathogen (primary pathogen): A microorganism
capable of causing disease in healthy persons with normal
immune defenses.
 Opportunistic pathogen: A microorganism that does not
usually cause disease but can become pathogenic under
certain circumstances. Opportunistic pathogens are not
considered pathogenic to a normal healthy person and do
not generally possess well-developed virulence properties.
 Some members of the normal microbiota can become
opportunistic pathogens; they take advantage of particular
opportunities to reproduce and cause disease.
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Opportunistic Infections

Conditions that create opportunities for opportunistic
pathogens include:
1) Failure of the host’s normal defenses: for example, in
individuals with weakened defenses (immuno-compromised)
because of malnutrition, another disease, immunosuppressive
drugs, etc.
2) Entrance of the organisms into unusual body sites.

Example: The bacterium Escherichia coli is a normal harmless
resident of the human large intestine, but it can cause disease if
it gains access to other body sites, such as the urinary tract,
lungs, spinal cord, or wounds.
3) Disturbances in the normal microbiota: for example, by
taking antibiotics. Some antibiotics kill not only the harmful
microorganisms, but also part of the normal microbiota.
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Predisposing Factors for Infections
Other predisposing factors that make the body more susceptible to
infection and disease are: climate, fatigue, inherited traits, and lifestyle.
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What are nosocomial infections?

Explain why nosocomial infections are a significant
challenge to the medical community.

Why is it so difficult to prevent transmission of these
diseases to patients?

Patients that contract a nosocomial infection may suffer
considerably, depending on the illness. Should they be
compensated for their suffering? If so, who should be
financially responsible?

Centers for Disease Control and Prevention; Healthcareassociated Infections (HAI). http://www.cdc.gov/hai/
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Microbiology: Unit 6 Seminar – Microbe-Human Interactions
Nosocomial Infections (Healthcare-associated Infections)
A
nosocomial infection is an infection acquired
or developed in a hospital or other medical facility.
 A nosocomial infection does not show any evidence of
being present or incubating at the time of admission to a
hospital or other medical facility.
 According to the CDC (Centers for Disease Control and
Prevention), 5 - 15% of all hospital patients acquire a
nosocomial infection; 2 to 4 million cases per year.
 Patients in hospitals are compromised hosts, they are
more susceptible to infection than the general population.
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Nosocomial infections result from the interaction of several factors.
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Control of Nosocomial Infections
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Using aseptic techniques:
handling contaminating materials
carefully, frequent and careful hand
washing, wearing gloves.
Educating staff members about
basic infection control measures.
Using isolation rooms and wards.
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Tracking Disease in the Population: Public Health Organizations

Centers for Disease Control and Prevention (CDC): a
branch of the U.S. Dept. of Health and Human Services
(with headquarters in Atlanta, GA).
 Collects and analyzes epidemiological information in the
United States.
 Publishes “Morbidity and Mortality Weekly Report” (MMWR).
 Website: www.cdc.gov

World Health Organization (WHO): international agency
in Geneva, Switzerland.
 Coordinates and sets up programs to improve health in more
than 100 member countries.
 Publishes “Weekly Epidemiological Record”.
 Website: www.who.int/en/
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References

Audesirk, Teresa; Audesirk, Gerald & Byers, Bruce E.
(2005). Biology: Life on Earth. Seventh Edition. Pearson
Education, Inc.-Prentice Hall. NJ, USA.

Black, Jacquelyn G. (2005). Microbiology, Principles and
Explorations. Sixth Edition. John Wiley & Sons, Inc. NJ,
USA. www.wiley.com/college/black.

Campbell, Neil A.; Reece, Jane B., et al. (2008). Biology.
Eighth Edition. Pearson Education, Inc.-Pearson Benjamin
Cummings. CA, USA.

Cowan, Marjorie Kelly; Talaro, Kathleen Park. (2009).
Microbiology A Systems Approach. Second Edition. The
McGraw-Hill Companies, Inc. NY, USA.
www.mhhe.com/cowan2e

Dennis Kunkel Microscopy, Inc. (2010).
http://www.denniskunkel.com

Mader, Sylvia S. (2010). Biology. Tenth Edition. The
McGraw-Hill Companies, Inc. NY, USA.

Tortora, Gerard J.; Funke, Berdell R.; Case, Christine L.
(2010). Microbiology An Introduction. Tenth Edition.
Pearson Education, Inc.-Pearson Benjamin Cummings; CA,
USA. www.microbiologyplace.com.
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