Disease and Bacteria

A white blood cell eating bacteria.Small Pox

What is an Infectious Disease?

Slide # 2

1. Disease- a condition in which the body does not function normally.

2. Infectious disease: disease caused by the presence and activity of a microbial agent.

3. Epidemic- A local outbreak of a disease concentrated in one area.

4. Pandemic-A worldwide outbreak of a disease

Robert Koch

1. German physician interested in how disease was spread

2. Founder of modern microbiology and bacteriology

3. Identified the causative agents of Tuberculosis (Mycobacterium tuberculosis), Anthrax (Bacillus anthracis) and Cholera (Vibrio cholera).

4. Received Nobel Prize in medicine in 1905

5. Developed Koch’s postulates:

Koch’s Postulates

Step 1: Association- The organism and the disease are observed together consistently

Step 2: Isolation - The organism can be isolated from the diseased.

Step 3: Inoculation - The isolated organism causes the disease in a healthy individual

Step 4: Re-isolation - The organism can be re-isolated from the infected

1. What causes infectious (contagious) disease?

a. Pathogen- any disease causing agent

b. Examples of Pathogen and Disease:

Virus -HIV causes AIDS

Bacteria -Streptococcus causes Strep throat

Protist - Plasmodium causes Malaria

Fungi -fungi cause athlete’s foot & ringworm

Pathogens Are Infectious AgentsSlide # 3

1. Airborne: spread through coughing & sneezing. Enter through the nose, mouth, and move to lungs.

2. Contaminated food or water; enter mouth & go to stomach & intestines.

3. Bites from vectors such as mosquitoes, ticks, & fleas that transfer pathogens.

4. Enter through openings in the skin (wounds & when you touch your eyes.)

5. Body fluids – which can be exchanged through sexual activities, pregnancy, & drug needles.

How do you get an Infectious PATHOGEN? Slide # 4

How to Prevent the Spread of Diseases 1. Good Hygiene- washing hands & keeping

hands away from eyes, nose and mouth.

2. Proper cooking & water treatment.

3. Controlling Vectors- spraying for mosquitoes, fleas, ticks, etc.

4. Abstinence from sexual activity.

5. Vaccinations- weak or dead strain of a pathogen that is injected into a person so the body can learn how to recognize and fight off the pathogen.

Slide # 5

How are Diseases Treated?

1. Bacterial disease is treated with antibiotics.

2. Viral infections do not have a cure. Viral infections must “run their course” until the body learns how to get rid of it.

3. Over-the-counter medicines only treat symptoms

Slide # 6

Not All Bacteria Are “Bad Guys”1. Live in human intestines (&

other organisms) and help in digestion

2. Decomposers in Ecosystems

3. Work in the nitrogen cycle (nitrogen fixation)

4. Used to clean up oil spills (consume the oil)

5. Used to make food (yogurt, cheese, etc)

Bacteria and Disease1. Bacteria cause disease in one of two ways:

a. Damage cells or tissues directly by breaking them down for food (ex. Mycobacterium tuberculosis)

Mycobacterium tuberculosis causes tuberculosis. The bacteria feed on lung tissue, causing damage to the lungs. Thus, infected humans experience difficulty breathing, and cough up blood and lung tissue, until death results.

Slide # 7

2. Release toxins (poisons) that travel through the body and interfere with the normal activity of the body. (ex. Streptococcus, or strep throat, and Corynebacterium diphtheriae, which causes diphtheria)

Corynebacterium diphtheriae

Streptococcus

Bacteria and DiseaseSlide # 8

Binary Fission: Asexual Reproduction

Chromosome (DNA)

Cell membrane

Cell wall

Chromosome duplicates & separates

Divides into 2 cells

Cell grows; chromosomes move

Growth and Reproduction: Conjugation

1st step

2nd step

3rd step 4th step

Result: No additional cells; cells genetically different

Controlling Bacteria1. Sterilization occurs by exposing bacteria to extreme

heat. Boil or cook food thoroughly.

2. Disinfectants are chemical solutions that kill bacteria. Examples include bathroom cleaners, soaps, detergents, Lysol, etc.

3. Overuse of disinfectants may increase the likelihood that bacteria will become resistant to disinfectants and become more dangerous and difficult to kill.

Slide # 9

Food Storage and Processing1. Refrigeration: slows the growth of bacteria,

but does not kill them

2. Pasteurization

3. Boiling, frying, or steaming sterilizes many kinds of food.

4. Using preservatives when canning food for long periods is effective.

5. Using everyday chemicals such as salt, vinegar, or sugar preserves foods.

Slide # 10

Preventing Disease

1. Antibiotics are compounds that block the growth and reproduction of bacteria.

2. One side effect of antibiotics: may cause diarrhea b/c antibiotics can kill beneficial bacteria.

3. Overuse of antibiotics is creating antibiotic resistance and bacteria are becoming difficult to kill. Creates “super bugs.”

Slide # 11

EOC Practice Why is Sendai virus used as

a vaccine against HPIV-1? A It alters the protein coat

of HPIV-1. B It makes cells chemically

unrecognizable to HPIV-1. C It forms a protective

barrier againstHPIV-1 D It triggers the production

of antibodies that fight HPIV-1What do vaccines do?

They cause the body to produce antibodies to fight the targeted disease.

Correct answer: D