MICR 201 Microbiology for Health Related Sciences

Microbiology- a clinical approach by Anthony Strelkauskas et al. 2010

Chapter 1: What is Microbiology and Why does it matter?

Think of your future professional goal. Write down three reasons why you think it is

important to take this class and do well in this class.

Keep this note. We will revisit it later on in the quarter.

Why does microbiology matter to you?

“Infectious disease is one of the few genuine adventures left in the world. The dragons are all dead and the lance grows rusty in the chimney corner…About the only sporting proposition that remains unimpaired by the relentless domestication of a once free-living human species is the war against those ferocious fellow creatures, which lurk in dark corners and stalk us in the bodies of rats, mice and all kinds of domestic animals; which fly and crawl with insects, and waylay us in our food and drink and even in our love.”

Hans Zinsser was an American bacteriologist known for work on typhus and a poet.

Hans Zinsser, 1934:

Map for chapter 1

The following case studies illustrate how microbiology is part of our everyday lives:◦ 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

Case studies chapter 1

Microbiology has relevance to everyday life. We are not sterile and we do not live in a

sterile environment; we interact with microbes all the time.

Travel allows the movement of infectious diseases around the world in a relatively short period of time (less than 48h for respiratory infectious diseases).

Keep in mind

http://learn.genetics.utah.edu/archive/sars/images/world_spread.gif

Travel rapidly spreads infectious diseases

Infectious diseases Treatment of infectious diseases Beneficial use of microbes

Relevance of microbiology to health care

Only a small fraction of all microbes cause disease◦ Many more microbes form part of our normal

microbiota (trillions...)◦ Microbial agent that causes disease is called a

pathogen◦ Potential to cause disease is referred to as

virulence◦ Some microbes become pathogens only under

certain circumstances and are called opportunistic pathogens

Infectious diseases have been around as long as humans lived

Infectious diseases (1)

Infectious diseases (2)

Oil painting by Nicolas Poussin, 1630

Advances in public health awareness and intervention lessened the effects of infection

However, infectious diseases still account for a large percentage of health care◦ Among top ten causes of death

Lower respiratory tract infections, diarrhea, tuberculosis, HIV/AIDS (http://www.who.int/mediacentre/factsheets/fs310/en/index.html)

Healthcare professionals need to understand how pathogens cause disease

Infectious diseases (3)

• Sanitation• Antibiotics• Vaccination

New threats◦ Antibiotic resistance◦ Emergence of new pathogens

Swine flu◦ Bioterrorism

Infectious diseases (4)

A fundamental understanding of microbiology has never been more relevant.

Most pathogens can be looked at from the following 3 perspectives:◦ Epidemiology◦ Pathogenesis◦ Host defense

Infectious diseases (5)

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

◦ Exit (Get out) and be transmissible

Epidemiology (1)

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 (2)

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 (3)

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

Epidemiology (4)

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

Pathogenesis (1)

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 (2)

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 (1)

Defense

Healthy

Host defense (2)

Defense

Healthy

Defense

Primary pathogen

Defense

Opportunistic pathogen

Infectious Disease

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

Host defense (3)

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

Treatment of infectious diseases

Prevention

Are toxic chemicals and therefore must act selectively.◦ They must kill the disease-causing

microorganisms but not harm the patient. Antibiotics (antibacterial) Anti-viral drugs Anti-fungal drugs Anti-parasitic drugs

Antimicrobics

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

Immunizations◦ Requires that we understand immune mechanisms

and that we design vaccines that will successfully stimulate protection.

◦ An ability to ensure the safety of vaccines◦ Public health control of the immunization of children

Prevention of infectious diseases

Bioremediation and recycling◦ Oil spill clean up

Insect control◦Bacillus toxin and caterpillars

Biotechnology◦ Recombinant drugs like insulin◦ Gene therapy with virus vectors

Microbiology isn’t just about infectious diseases

Microbiology is very relevant to our everyday lives.

We are exposed to potentially dangerous pathogens on a daily basis.

These pathogens possess virulence factors that allow them to persist in the host, evade host defenses, and cause disease.

Pathogens must accomplish five tasks to be successful in causing disease. They must get in, stay in, defeat the host defenses, damage the host, and be transmissible.

Microbiology is not just about infection and disease. In many cases, microbes can be very beneficial to humans.

Chapter 1 key concepts

Virulence can be defined asA. Opportunistic infectionB. Adequate nutritionC. Degree of pathogenicityD. Limited rates of growth

Epidemic outbreaks of disease are fostered by all of the following exceptA. Poor hygieneB. Decreased birth ratesC. Poor nutritionD. Poor socioeconomic conditions

Test questions (1)

Treatment of disease relies on which of the following?A. AntisepticsB. DisinfectantsC. AntibioticsD. None of the above

Which of the following uses of microbes is not beneficial to man?A. Insect controlB. Crop fertilizationC. Mineral decompositionD. All of the above are useful

Test questions (2)