Microbes that live with us in a stable relationship.  Inhabit healthy people.  Commensalistic relationship.

• bacteria
• yeast
• archaea
• protozoa
• mite

Microbes that live on us indefinately.

• Permanent Population (more or less)
• Species and population size may vary from person to person
• Can change over time

Microbes that we pick up from our enviornment

• Can be eliminated

(Opportunists)

• Cause disease only under certain circumstances
• Depends on the condition of the host

1. Breakdown of immune system (HIV, elders, babies, patients, cancer
2. Medical treatment (antibiotics)
3. Injury (burns, wounds, surgery)

(Parasites)

Not part of normal microflora.

Organisms capable of causing disease in host

• New pathogens can appear over time

Two kinds of organisms living together (host and microbe)

Relationship involving host and microbe.

Positive effect on host

Positive effect on microbe

Example: Ruminats (cows) and microbes that ferment cellulose

Relationship involving host and microbe.

Neutral effect on host

Postive effect on microbe

Example:  Humans and their normal microflora

Relationship involving host and microbe.

Negative effect on host

Positive effect on microbe

Example: Humans and the influenza virus

Hostile enviornment

• Dry, salty, extreme temperatures, inhibitory substances produces (fatty acids in oils, lysozyme in perspiration)
• Only a few types of microbes but in large numbers
• Approx. 100,000 microbes per/cm²

Staphylococcus epidermidis (most common)

Others: Staphylococcus aureus (wound infections) and Propionbacterium acnes (produces irritating fatty acids- ance)

Advantages: Provide competition for pathogens.

Disadvantages:  Opportunistic disease, body odor (fermentation in pores, hair follicles; production of acids, alcohols, and gases)

(nose, mouth, throat)

Excellent enviornment

• Warm, moist, lots of nutrients, lots of oxygen
• Many types of organisms (more than 80 species and high in numbers)

Strepococcus mutans

• Converts sucrose into glucan and lactic acid
• Lactic acid erodes tooth enamel

S. mitis, S. salivarius (also forms lactic acid)

Advantages: Provides competition for pathogens

Disadvantages: Cavaties, gum disease, bad breath

Excellent enviornment

• Warm, moist, protected enviorment, lots of nutrients for fermentation (anaerobes)
• Many types of organisms
• More than 400 species, very high populations

Most common

• Bacteroides
• Bifidobacterium (90% of the normal flora of infants)
• Coliforms (like e.coli)

Advantages:  Provides competition for pathogens. Produces Vitamin B and K

Disadvantages:  Gas (approx. liter/day), disease

Excellent enviornment

• Warm, moist, protected enviornment, however- lacks a lot of nutrients

Most common:

• Lactic acid bacteria (lower pH)
• Yeast

Advantages:  Competition for other pathogens

Disadvantages:  Opportunistic disease, vaginal yeast infections

The ability of an organism to gain entry into the host's tissue and cause disease

Any organism having pathogenicity

Degree of pathogenicity

• High virulence vs. avirulent

Growing of a pathogen in/on a host

Any change from general state of good health

• Unstable for host

Spreading of Disease

Low level of cases in certain geographic areas

• Chicken pox

Spreading of Disease

Large increase in humber of cases of an illness

• Influenze, e. coli, salmonella

Beyond what is expected

Spreading of Disease

Spread of epidemic worldwide

• AIDS

Pathogen's normal enviorment (permanent home)

• Only reservoir for some pathogens
• Some pathogens only suited for human body
• Carrier-

1. Special type of reservoir
2. Host that continues to shed pathogen after recovery from disease

• Both domestic and wild
• Zoonosis

1. Rabies
2. Human disease caused by pathogen with animal reservoir
3. Human = "dead end host"

Water, soil, house dust

• Less than ideal conditions for pathogen

• Pathogen leaves reservoir to enter host
• Pathogen goes from host to host
• Two types:

1. Direct Method: physical contact
2. Indirect Method: intermediate participant

Droplets: Tiny particals or mucus and saliva expelled from respiratory host.

• cough, sneeze, laugh, talk
• most common way human diseases are transmitted

Body Contact:  Pathogen must be deposited directly on body of new host.

• Handshake, kissing (saliva exchange), sexual intercourse
• Vertical transmission

Transmission of pathogen from mother to infant (either before of after birth)

Formites: Inanimate object transfer; pathogen must still be infectious (Door handles, toilet seats, phones, cups, money)

Fecal-Oral Route:  Untreated water supplies, daycare centers, poor hygiene

Arthropod Vector:  Insects transferring pathogens

• Mechanical- Pathogen is on insect (Ex: flies)
• Biological- Insect participates in pathogen's life cycle- biting transmission (Ex: mosquitoes, ticks, fleas, lice)

Indirect method of transmission

• Pathogen suspended in air; inhaled
• Pathogen that can withstand drying for long periods of time

• Infections acquired in the hospital
• #1 hospital acquired infection:

STAPHYLOCOCCUS

5% of patients

90,000 deaths anually

Grouping that is smaller that 'species', larger than strain

• species > type > strain

More than 200 different types of viruses

Types of colds include:

• Rhinovirus 25 - 50%
• Coronavirus 10 - 15%

Others:

• adenovirus, echovirus, myxovirus, coxsackievirus, unknown virus

Respiratory Droplets

Direct Contact

Formites

Infection and Disease:

• Mucus membrane of nose and throat
• Sneezing, coughing, congestion, sore throat

Prevention

• Wash hands frequently

The 'flu'

Three types: A, B, C

   -Mutates frequently

Reservoir: Humans (A, B, C) + Animals (A) Birds, Pigs, Seals

Respiratory Droplets

Direct Contact

Formites

Infection and Disease:

   -Upper respiratory tract, lungs, systemic

   -Chills, fever, headache, muscle aches, coughs

   -Vomiting/diarrhea are NOT typical symptoms!

Treatment:

   -Relenza, Tamiflu; shorten the duration

Prevention:

   -Wash hands

   -Vaccination

• 70 - 90% protection (typically)
• Composed of 3 strains
• Designed by top scientists at the end of flu season

Flu Season: November through March

More contact through this period because most people are indoors

Agent:

   -Varicella-Zoster Virus (VZV)

   -1 virus, 2 diseases

Reservoir

   -Humans

Respiratory Droplets

Direct Contact

1st infection = Chicken pox

   -fluid-filled vessels

Latent in neurons near spinal cord

Reactivation = Shingles

   -blisters

   -very painful due to nerve activation

• Vaccination: 70 - 80% effective
• Must be given every 10 years for maximum propection
• Will protect against shingles

"Stomach Flu"

Many different types of virus

Agents:

• Rotavirus
• Norwalk Virus
• Norovirus
• Coxsackievirus

Reservoir:

•  Humans

Transmission:

Fecal-Oral Route

Infection and Disease:

• In intestines
• Diarrhea, nausea, vomitting, fever, cramps, headache, malaise

Prevention:

• Wash hands frequently
• Personal Hygiene

Liver inflammation caused by an infectious disease

Reservoir:

   -Humans

Transmission:

   -Direct Contact

   -Fecal-Oral Route

Infection and Disease:

   -Infects Liver

   -Fever, anorexia, nausea, vamitting, diarrhea, jaundice

Prevention:

   -Hand washing

   -HAV Vaccine

Reservoir:

   -Humans

   -Chimpanzees (not found in nature)

Transmission:

   -Direct Contact (Blood to blood; intercourse)

Infection and Disease:

   -Infects liver; causeds tussue degeneration

   -Abdominal discomfort, etc...

   -Can cause liver cancer

Prevention:

   -HBV Vaccine

   -Avoid infected blood

AIDS

HIV_-1   Most common

HIV_-2

Reservoir:

   -Humans

Transmission:

   -Direct Contact (blood, intercourse, vertical transmission)

- Targets T-Cells (immune cells)

- Retrovirus (RNA > DNA + Provirus)

- Can remain dormant, or can replicate

     -End result is a descrease in T-Cells

- Fever, malaise, headache, weight loss, secondary infections

Treatment:

- AZT or Retrovir

- Protease inhibitors

- No Vaccine

Prevention:

- Education, Blood Screening, Safe Sex

Streptococcal Disease

Group A Strep

Gram Positive Cocci

Reservoir:

   -Humans

Virulence Factors:

   -M Protein

   -Capsules

   -Streptokinas

   -Exotoxins

Fever, sore and red throat, malaise, swelling of the lymph nodes

• Flesh eating bacteria
• Infects skin lesions
• Inflammation and destruction of skeletal muscles and fat tissue

• Toxin circulates throughout the body
• Rash, sore throat, ever, chills, headache, strawberry colored tongue

Post streptococcal diseases

• Toxins damage the kidney
• Fever, hypertension (high blood pressure), blood incline
• In severe cases can lead to permanent kidney damage

• Infects immune system (mechanism not known)
• Swollen joints, chest pains, fatigue, shortness of breath
• Can cause inflammation and lesions on heart valves, joints, and nervous system

Treatment: Penicillin or Erythromycin

Prevention: Hand washing, proper disposal and cleansing of facial tissues and handkerchiefs, cleaning medicated wounds

"consumption"

Mycobacterium tuberculosis

   -Not gram positive or gram negative (acid fast)

   -Bacilli

First identified by Robert Koch

1.  Bacteria infects lungs

• White blood cells incase the bacteria (phagocytosis)
• Bacteria continues to replicate in white blood cells

2.  Immune cells are sent and combine with infected cells to create tubercles

• Tubercles- hard lesions that show up on chest x-rays
• If lesions liquify they can spread disease to other parts of the body

Symptoms: Fever, fatigue, weight loss, cough that often results in bloody sputum

Diagnosis: 

- Acid fast staining of patient's sputum

- Tuberculin test

• Protein form M. tuberculosis inserted under the skin
• If a raised area forms, the patient has been exposed

Treatment: 

• Isoniazid and Rifampin (doesn't work on drug resistant strains)
• Additional drugs have been developed

Prevention:

• Better public health
• Vaccine (not often given because of side effects)

Bacterial Pneumonia

Two major causative agents:

   -Streptococcus pneumoniae

   -Mycoplasma pneumonia

Pneumoccoccus

• Gram Positive cocci
• Virulence factor: capsule
• Serious, life threatening infection
• Labored breathing, high fever, chest pains
• Most strains are antibiotic resistant
• Vaccine (not routinely administered)

Primary atypical pnewmonia ("walking pneumonia")

• Bacterium without a cell wall (no gram stain)
• Intracellular parasite
• Mild disease
• Low fever, fatigue, persistant dry cough
• Some antibiotics effective

Anthrax - Soilbourne disease

Reservoir:  Plant eating animals; cattle, goats, sheep, deer

Transmission:

   -Airbourne

   -Formites

   -Ingestion

Virulence Factors:

   - Exotoxin

   - Extremely fast growth

Cutaneous anthrax:  infected would forms a blackened ulcer

Inhalation anthrax:  (respiratory) inhalation of bacterial spores

Treatment:

   -Antibiotics (if given early)

Prevention:

   -Vaccine (given to domestic animals, military, veteranarians; possible side effects)

Lyme Disease - Arthropodbourne Disease

Reservoir:  Small rodents, deer

Transmission

   -Ticks (not all ticks carry lyme disease)

Virulence Factors

   -unknown-

Infection and Disease

   -Headache, stiff neck, muscle aches, fatigue, rash

   -If untreated; chronic arthritis

   -75% of time a bullseye rash forms; lymph nodes, bloodstream

Treatment:  Antibiotics (most effective in early stages)

Prevention:  Avoid and remove ticks within 24 hours

Sexually transmitted Disease/Infection

Virulence Factor:  Ability to grow intracellularly in phagocytes

Infection and Disease:

   -Men: Slight discharge or no symptoms

   -Women:  Slight discharge or no symptoms; inflammation/scarring of fallopian tubes which is the leading cause of female infertility/ectopic pregnancies

• Most common reportable STD

• Protozoa, fungi (yeasts or mold)
• Typically difficult to treat
• Antimicrobial drugs are toxic to humans

Yeast infections

- Oppotunistic pathogen

- 10% of nosocomial disease

- No satisfactory treatment

     -Speacial cream sold commercially

     -Prevention: Keep skin slean and dry

     -Probiotics to balance microflora while on antibiotics

- Vaginal: Itching, burning discharge

- Thrush: Milklike curds on tongue, mucous membranes

• Yeast
• In soil, pidgeon droppings
• Disease in immunocompromised
• Respiratory tract > bloodstream, meninges (headaches, stiffneck, paralysis)

Skin infections - numerous fungi

Acquired from enviornment

• Ringworms
• Athlete's foot
• Jock itch

Valley Fever

• Occurs in dry regions of SW U.S.
• Regional to South California, Neveda, New Mexico, Texas and Mexico
• Organism in Soil; inhaled
  • "Flu-like" illness (fever, body aches, fatigue)
  • Can progress to meningitis

Many life stages

Malaria

- Caused by Sporozoan; non-motile

• In 2002; 1337 cases in U.S./150 million cases in Africa
• 41% of world lives in areas with Malaria
• 0.7 to 2.7 million die each year

Transmission

• Vector: Mosquitoes
• Blood transfusions, contraminated needles (1963-1999: 93 cases of transfusion malaria)

• Inside blood cells
• Leads to blood cells lysea (mass destruction)
• Leads to cycles of high fever, chills, sweats every 48 hours (correlates with the reproduction of pathogen)

Treatment:  Antimicrobial drugs

Prevention: 

• Control of mosquito populations
• No Vaccine
• Netting owuld/could reduce Malaria by 75%

Toxoplasmosis

- Sporozoan, Zoonosis

Transmission:  Fecal-oral route

• Cat feces (cats = essential part of life cycle; large number infected)
• Soil
• Undercooked Meat

• Healthy adults: mild/no symptoms (about 90% of people)
• Immunocompromised
  • Seizures, brain lesions
    • Fatal
• Pregnant Women
  • Infection of fetus
    • Miscarriage, mental retardation, blindness, deafness

• Wash hands/good hygiene
• Throughly cook meat
• Avoid cat feces

Cryptosporodiosis

• Transmission
  • Fecal-Oral route
    • Water supplies, freash fruit/veggies
• Infection and Disease
  • Instestines
    • Diarrhea, gas, cramps (swimming pools)
• Prevention
  • Boil water (10 minutes), filter/treat water
    • Resistant to Chlorine
  • Good hygiene/sanitation

Giardiasis - Flagellate

"Beaver fever"

• Transmission
  • Fecal-oral route (contaminated water, daycares)
• Infection and Disease
  • In intestines
    • Diarrhea, gas, cramps (50%), no symptoms (50%)
• Prevention
  • Boil water (10 minutes), filter/treat water
    • Resistant to Chlorine
  • Good hygiene/sanitation

Amoebiasis - Amoeba

• Transmission
  • Fecal-oral route (contaminated food/water)
• Infection and Disease
  • In Instestines
    • Bloody diarrhea, fever, cramping, abdominal pain
• Prevention
  • Good hygiene/sanitation

Response the same against ALL microbes/groups of microbes

• In place from birth

• Dry, salty, acidic
• Covers body's exterior (forms barrier)
• Cells tightly joined and constantly shed

• Epityillal surfaces that line nose and throat
• Mucus plus movement of cilia

Low pH

• Stomach (HCl acid)
• Vagina (Lactic acid)

Tears, Saliva

• Destroys peptidoglycan
• Greatest effect on Gram⁺ bacteria

• Antiviral substance (produced by virally infected cells)

"Cell Eating"

• Performed by phagocytes (i.e. macrophages)
  • White blood cells
• Kill pathogens, remove debris by ingestion

• Limits extent of injury/infection
  1. Dialation of blood vessels
  2. White blood cells begin phagocytosis

• Abnormally high body temperature
• Increases cell metabolism
• Stimulates phagocytosis

The Immune System

• Slowest to respond
• Most complicated
• Most powerful
• SPECIFIC

• Chemical substance capable of stimulating immune system and provoking immune response
• Examples: pathogen proteins, milk proteins, bee venom, bacterial toxins, flagella, pollen...
  • Recognising non-cell cells; what's mine and what's not

lymphocytes - white blood cells

1. T-Cells - Cell Medicated Immunity (CMI)
   • Responsible for cell-mediated immunity
2. B-Cells - Antibody Mediated Immunity (AMI)
   • Responsible for antibody-mediated immunity

• Located on T and B cells
• Recognize specific antigen
  • "lock and key" situation