ISBN: 978-0-8153-6514-3 Microbiology: A Clinical Approach, by Tony Srelkauskas © Garland...

ISBN: 978-0-8153-6514-3Microbiology: A Clinical Approach, by Tony Srelkauskas © Garland ScienceMicrobiology: A Clinical Approach © Garland Science

CHAPTER 1WHAT IS MICROBIOLOGY AND WHY IS

IT IMPORTANT?

© WHO / TDR / Crump


The Importance of Microorganisms

medical and most populous group of organisms and are found everywhere on the planet

play a major role in recycling essential elements

source of nutrients and some carry out photosynthesis

benefit society by their production of food, beverages, antibiotics and vitamins

causative agents of some important diseases

What is Microbiology?

generally defined as the study of organisms too small to be clearly seen by the unaided eye (i.e., microorganisms)

these organisms are relatively simple in their construction and lack highly differentiated cells and distinct tissues

Members of the Microbial World

procaryotic cells lack a true membrane-delimited nucleus

eucaryotic cells have a membrane-enclosed nucleus, are more complex morphologically and are usually larger than procaryotic cells


Procaryotes

most are single-celled most have peptidoglycan in cell wall can survive broad range of

environments most are non-pathogenic and play

major role in nutrient recycling

…….. Eucaryotes

animals, plants and eucaryotic microorganisms

microorganisms include protists (unicellular algae, protozoa, slime molds and water molds) and fungi

most are larger than procaryotic cells

…….. Viruses

acellular smallest of all microbes (smallest is

10,000 times smaller than a typical bacterium)

Importance of Microorganisms

first living organisms on planet live almost everywhere life is possible more numerous than any other kind

of organisms global ecosystem depends on their

activities influence human society in many

ways


WHY IS THIS IMPORTANT?

Microbiology is more relevant than ever in today’s world.

Infectious diseases are a leading health-related issue, especially in a society where the elderly population is increasing.

New infectious diseases continue to emerge and be identified all the time.

Microbiology impacts every facet of daily life

Discovery of Microbes

Antony Van Leeuwenhoek (1632-1723) first person to observe and

describe microorganisms accurately

Developed early microscope First to observe

microbes:“animalcules”

ISBN: 978-0-8153-6514-3Microbiology: A Clinical Approach, by Tony Srelkauskas © Garland Science

………….. .. PasteurPasteur


………….. .. PasteurPasteur

• Pasteur laid the foundation of aseptic techniques, techniques that prevent contamination by unwanted microbes. These techniques are based on Pasteur’s idea that microbes can be killed by heat and that procedures can be designed to inhibit the access of airborne microbes to nutrient environment.

• He disapprove the idea that microorganisms spontaneously generated from non-living matter.


The Golden Age of Microbiology (1857-1914)

•Many disease producing organisms were discovered•Microbial metabolism studies undertaken•Microbiological techniques refined•A better understanding of the role of immunity and ways to control and prevent infection by microbes


The Role of Microorganisms in Disease

• was not immediately obvious• establishing connection depended on development of techniques for studying microbes• once established, led to study of host defenses - immunology


Recognition of the Relationship between Microorganisms and Disease

Agostini Bassi (1773-1856):showed that a disease of silkworms was caused by a fungus

M. J. Berkeley (ca. 1845):demonstrated that the great Potato Blight of Ireland was caused by a water mold

Heinrich de Bary (1853):showed that smut and rust fungi caused cereal crop diseases

Louis Pasteur (1860s - 80s) :showed that the pébrine disease of silkworms was caused by a protozoan

Aseptic techniques

…….. Pure Culture Technique

Phases of antibiotic development

Pre Antibiotic Era-No antibiotic

Antibiotic era - penicillin

“New” Diseases

Resurgence of “old” diseases

Microbial resistance to drugs

Emergent Diseases and the Post-Antibiotic Era

Experts agree that decades of antibiotic use and abuse have contributed to the emergence of antibiotic-resistant organisms in both hospital and community settings.

Antibiotic era

We have all heard of the Pre-Antibiotic Era, prior to the 1940’s when millions of people died from common bacterial infections because antibiotics were not used to treat them.

In the last 50 years we have enjoyed the luxury of knowing that bacterial infections can almost always be cured by using antibiotics. We are now in the Antibiotic Era.

Post-Antibiotic Era

As we enter the 21st Century, we are gradually slipping into the Post-Antibiotic Era, a time when antibiotics no longer work because bacteria have become resistant to all the antibiotics.

The change will not come as suddenly as the start of the Antibiotic Era, because the change to antibiotic resistant germs has been slow, up until now.

New strains are rapidly developing

In the next 5-10 years we will start noticing the change much more dramatically.


OVERVIEW


CASE STUDIES FROM DAILY LIFE The following case studies illustrate how

microbiology is part of our everyday lives: ( Ref. pg3-7) Special Delivery Ivan Goes to Chicago Hamburger Havoc The Hospital Can Be Dangerous Did You Wash Your Hands Mary, Mary, Quite Contrary It’s For the Birds


MICROBIOLOGY & INFECTIOUS DISEASE

Today microbiology is mentioned frequently in the news.

It affects many facets of our daily lives, including: The air we breathe The food we eat The hospitals where we go for treatment of illness

and injury The natural disasters which sometimes occur

without warning


THE RELEVANCE OF MICROBIOLOGY TO HEALTH CARE

There has always been disease. For generations, little could be done to treat or

prevent disease. Advances in public health awareness lessened the

effects of infection. Infectious disease utilizes a large percentage of

health care. Health care professionals need to understand how

pathogens cause disease.


…THE RELEVANCE OF MICROBIOLOGY TO HEALTH CARE

The discovery of antibiotics began to prevent serious infection.

Vaccination and better sanitation practices reduced the incidence of infectious diseases.

For a time, most infectious diseases were thought to be under control.


…THE RELEVANCE OF MICROBIOLOGY TO HEALTH CARE

Diseases once thought to be under control are reappearing Pathogens are showing increasing resistance to

antibiotics. New diseases are emerging and organisms that were

thought to be harmless have been discovered to cause disease in certain circumstances.

Interest in bioterrorism has progressed from fiction to fact.

A fundamental understanding of microbiology has never been more relevant.


INFECTIOUS DISEASE

Only a tiny fraction of microorganisms cause infections.

A microorganism that causes an infection is called a pathogen.

Only a fraction of pathogens affect humans.


…INFECTIOUS DISEASE

The potential of a pathogen to cause disease is referred to as its degree of virulence.

Pathogens can be categorized based on their degree of virulence.

Many bacteria and some fungi are part of the normal microbial flora of the body. They naturally colonize the skin and mucosal surfaces. Most of the time, these organisms are completely

harmless.


…INFECTIOUS DISEASE

Some of these organisms provide important products and services to the body.

Under certain circumstances, these organisms become pathogenic.

When this happens, the organisms are called opportunistic pathogens and typically possess a mild degree of virulence.


...INFECTIOUS DISEASE

Some pathogens are always highly virulent. Highly virulent pathogens are always

associated with disease. Most pathogens can be looked at from the

following 3 perspectives: Epidemiology Pathogenesis Host defense


EPIDEMIOLOGY

Epidemiology is the study of factors determining the frequency and distribution of disease.

In epidemiology, pathogens are studied by how well they meet the five requirements of infection: Entry (Get in) Establishment (Stay in) Defeat the host defense Damage the host Be transmissible


...EPIDEMIOLOGY

In epidemiology, pathogens are classified by the transmission mechanisms they use. Such as: Air Food or water Insect vectors Person-to-person contact

Pathogens can also be classified according to their geographic distribution Some are found worldwide, others are restricted to

certain geographic areas.


...EPIDEMIOLOGY

Providing the best care for infected individuals and protection of others involves a clear understanding of the 5 requirements for infection.

Knowing how an organism gains entry and how it spreads are vital to care for infected individuals It allows for the implementation of strategies to limit

spread. It also helps in understanding of the spread of disease.


...EPIDEMIOLOGY

Epidemics are caused by a variety of factors, including the following: Poor socioeconomic conditions Ignorance of how infections occur Poor hygiene Natural disasters


PATHOGENESIS

Virulence factors are required for a pathogen to do the following: Persist in the patient Cause disease Escape or defeat host defenses


...PATHOGENESIS

Pathogens employ a variety of methods to accomplish infection.

Bacterial pathogens can: Produce digestive enzymes Produce toxins

Viral pathogens can kill the host cells. Sometimes, damage associated with an

infection is due to over active host defenses.


…PATHOGENESIS

Symptoms can be associated with particular types of infection: Coughing – respiratory infection Diarrhea – digestive infection Nervous system dysfunction – central nervous

system


HOST DEFENSE

Infection is a complex and competitive struggle.

It can be characterized as pathogens versus host defense.

The outcome of this struggle depends on the success or failure of the host defense.

Failure of the host defense = infection!


....HOST DEFENSE

Many pathogens have developed methods to defeat host defenses. Some directly attack host defenses Some change their looks (a form of camouflage) Some hide


TREATMENT OF INFECTIOUS DISEASES

Many potent and successful tools are available to defeat infection. These include: Antibiotics Disinfectants and antiseptics

Antibiotics are toxic chemicals and therefore must act selectively. They must kill the disease-causing microorganisms

but not harm the patient.


…TREATMENT OF INFECTIOUS DISEASES

Treatments are easier for bacterial infections than for fungal and viral diseases.

Fungal cells are very similar to human cells so very few chemicals are selectively toxic.

Viruses are intracellular parasites so either: They must be attacked before entry into a host cell.

orThe infected host cells must be killed to kill the virus.



The best treatment of disease is prevention. Prevention involves public health measures

and immunization.



Public health measures include: Disinfection of water supplies Monitoring food supplies Proper hygiene and sanitation Proper waste removal and treatment Insect and pest control


..TREATMENT OF INFECTIOUS DISEASES

Immunization requires that we understand immune mechanisms and that we design vaccines that will successfully stimulate protection.

Immunization also requires: Public health control of the immunization of

children Design and development of new vaccines An ability to ensure the safety of vaccines


MICROBIOLOGY ISN’T JUST ABOUT INFECTIOUS DISEASE

Some microbes are very beneficial to humans as they are able to: Recycle vital elements in soil. Convert elements in the environment into usable

forms.

Return CO2 into the atmosphere.


BIOREMEDIATION AND RECYCLING

Microbes have been routinely used for bioremediation since 1988.

Microbes can be used: To recycle waste water during sewage treatment. To clean up and decontaminate toxic waste

including chemical and oil spills. In the production of enzymes that are subsequently

used in cleaning solutions.


INSECT CONTROL

Bacteria are extensively used to control pests. They can be applied as part of crop dusting. Bacterial genes can be engineered into the plants

themselves.

Using bacteria in these ways is seen as being safer than using chemicals.


BIOTECHNOLOGY

Bacteria and viruses are often used for many new technologies. Bacteria can be engineered to produce drugs. Viruses can be used for gene therapy strategies.


Bibliography

Microbiology, A clinical Approach -Danielle Moszyk-Strelkauskas-

Garland Science 2010

http://en.wikipedia.org/wiki/Scientific_method

http://www.brighthub.com/science/medical/articles/21169.aspx ( L Pasteur & theory of Biogenesis)

ISBN: 978-0-8153-6514-3 Microbiology: A Clinical Approach, by Tony Srelkauskas © Garland...

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Transcript of ISBN: 978-0-8153-6514-3 Microbiology: A Clinical Approach, by Tony Srelkauskas © Garland...