unit 6 seminar: microbe-human interactions: infection and disease

Unit 6 Seminar:Microbe-Human Interactions:

Infection and Disease

Evelyn I. MilianInstructor

Microbiology

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?

Evelyn I. Milian - Instructor 2


Normal Microbiota in the Human Body


Normal microbiota = normal biota, resident microbiota, normal microflora, indigenous microflora: The microorganisms normally present in 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 in 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.


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.




Click on the link or copy and paste into your web browser:http://io9.com/5910477/meet-a-few-of-the-100+trillion-lifeforms-that-call-your-body-home

Read the introduction, then click on the purple words ‘click through’ in the 3rd paragraph.

Click on the body parts and bacteria to learn more about these normal microbiota.

Normal Microbiota

FIELD TRIP!!!


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.




Most of the resident microbiota in the human body are commensal; in other words, they feed on excreted cellular wastes and dead cells without causing harm.

Each square centimeter of your skin contains about 3 million bacteria, and your large intestine contains 400 to 1000 kinds of bacteria outnumbering your own cells many times.


Sterile (Microbe-Free) Sites and Fluids in the

Human Body

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.

8Evelyn I. Milian - Instructor


The Origins of Microbiota in Newborns

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.



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?



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

Prebiotics: Nutrients that encourage the growth of beneficial microbes.



Food Production Using Beneficial Bacteria

Yogurt is a probiotic food (pro = for, bios = life).

Probiotics are live microbes administered to the body to exert a beneficial effect, including prevention of overgrowth of bad microbes.

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 (disease-causing microorganisms).



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:browse-all&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)



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)



Benefits of Probiotics According to Scientific Studies

Boost your immune system, decreasing the incidence of common diseases such as cold, flu and intestinal infections

Lactose tolerance: better lactose digestion Decreased symptoms of constipation and

Irritable Bowel Syndrome Decrease in antibiotic-associated diarrhea Decreased incidence of some allergies in

infants Decreased incidence of vaginal infections

in women Reduced duration of infectious diarrhea in

children



What is an opportunistic infection?


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.

Opportunistic infection: An illness caused by an opportunistic pathogen.


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.


Predisposing Factors for Infections

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Other predisposing factors that make the body more susceptible to infection and disease are: climate, fatigue, inherited traits, and lifestyle.

Evelyn I. Milian - Instructor


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; Healthcare-associated Infections (HAI). http://www.cdc.gov/hai/



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.

Evelyn I. Milian - Instructor


Control of Nosocomial Infections 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.



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.

Bauman, Robert W. (2012). Microbiology with Diseases by Body System. Third Edition. Pearson Education, Inc.-Benjamin Cummings. CA, 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. (2011). Campbell Biology. Ninth 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. (2011). 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.


unit 6 seminar: microbe-human interactions: infection and disease

Documents

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resident microbiota

normal microflora

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human cells

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normal conditions

normal microbiotafield