• features of Bacteria

single cell;

cell wall enable survivial in wide range of environment;

reproduce by cell division. divide and grow without being inside a host;

example: pneumonia (lung); otitis media (middle ear lobe); meningitis; cystitis (bladder)

treatment: antibiotics usually successful but now has resistance

extremly small;

non-cellular agent, need host cell to live and reproduce;

protein coat contain either DNA or RNA;

inert outside living cell;

replicate using host cell's metabolism process.

Bacteriophage=virus that infect bacteria

Example: common cold; AIDs; cold sores; hepatitis

treatment: do not respond to antibiotics; a few antiviral agent available but toxic to cells.

well-defined microorganism with true nucleus;

inclue simple plants like yeast (single cell) and mold ( multicellular);

cell wall;

contribute to decomposition;

vast majority fungi is not pathogenic (alcohol, dough raiser);

fungal disease often affect surface of body

ex: ringworm; athlete's foot; candidiassis (vainitis, esophagitis, thrust) cause superinfection by disrupt flora; histoplasmosis (midwest- a systemic infection characterize by feaver, night sweats, malaise, cough, lympamegaly); coccidiomycosis (valley fever in south west)

treatment: do not respond to antibiotic, a limited number of antifungal agents are available.

single cell (protozoa) live in areas with large supply of water, and many disease cuased by protozoa are contracted by drinking from contaminated water supplies.  seen with increasing frequency in developed countries due to poor nutrition and sanitary conditions)

ex:

1. antamoeba histolytica (amebic dysentery) causes severe diarrhea
2. toxoplasmosis: toxoplasma gondii widely distributed. result from contact with infected cat feces. infection is short-lived and asymptomatic. it can cause congenital abnormalities in fetus.
3. cryptosporidium: causes enteritis (inflamtion of the mucosal lining of small interesting. primary symptom is diarrhea.

such as roundworm, flatworms.

microscopic in size although not microorganisms in many stages of life cycle. often need different host for each stage of development.

ex disease:

1. schistosomiasis-infection of blood and visceral organs.
2. trichinosis.

1. pneumococcus

2. meningococcus

3. haemophilus influenza

4. klebsiella pneumoniae

5. streptococcus pyogenes

6. staphyloccocus aureus

7. Escherichia coli

8. Gonococcus

9. bacteroides fragilis

1. clostridium difficile

2. C. botulinum

3. C. tetani

4. C. perfringens

5. Several other clostridia

6. bacteroides fragilis

7. several other bacteroides

8. Actinomyces bovis

9. some streptococci

10. other members of the normal flora

1. staphylococcus aureus

2. S. epidermidis

3. Streptococcus pyogenes

4. gonococcus

5. pseudomonas aeryginosa

6. pneumococcus

1. bacillus anthracis

2. bacillus cereus

3. clostridium difficile

4. C. botulinum

5. C. tetani

6. C. perfringens

1. capsule-found in numerous bacteria [for protection]
2. cellwall-found in all bacteria except one [this coponent forms the basis for distinguishing bacteria based on the gram stain]
3. fimbriae (pili)-found in various bacteria [for attachment]
4. Flagella-found in many types of bacteria [for longevity]
5. Endotoxin (LPS) found only in gram-negative bacteria.

• help indentify bacteria as being either gram-negative or gram-positive [based on differences in cell composition]
• gram-positive: bacteria appears purple/blue
• gram-negative-bacteria appear pink/red
• gram stain reagents:crystal violet, gram's idodine, ethanol [decolorizer], safranin [counterstain]

• lyme disease: deer tick
• rocky mountain spotted fever:dog tick
• malaria: mosquito
• west Nile infection: mosquito
• the plague: flea
• Leishmaniasis-sand fly

epidemiology: sources and communicability

define Non-communicable infections. give example

non contagious disease.

• not transmitted by direct person-to-person or animal-to-person contact.
• caused by patient's normal flora (ex. peritonitis fro ruptured appendix, endocarditis from streptococci bacteria disseminating from oropharynx into blood)
• those caused by the ingestion of performed toxin (ex. botulisms and staphylococcal food poisoning)
• infections caused by certain organisms common in nature (ex. gas gangrene, Legionnair's disease and certain fungi)

contagious

• spread by person-to-person, animal-to-person, or vector-to-person contact.
• require that an organism be able to multiply in or on the body and to leave the body in a form directly infectious to other (ex. influenza virus, common cold viruses, STD pathogen)
• or indirectly infectious after development in a living vector (ex. malaria: require the presence of a biting mosquito).

Endemic

Epidemic

Pandemic

endemic: the disease is present at a low but faily constant level in a population.

epidemic: a level of infection above that usually found in a population (e.g. West Nile viral infection in NYC; a few years ago, it was Hantavirus in the southwest)

Pandemic: Widespread disease in a region or worldwide with high attacj rate (e.g. cholera outbreaks; also, to some extent, AIDS.)

• Infection: multiplication of the organism in a host.
• disease: clinically apparent reponse of the host to infection characterized by typica, [sometimes atypical] disease manifestations

infection is more comon than disease, healthy people play a role in disease propagation by serving as a carrier

the infectious agent established itself as part of a patient's indigenous micro-flora, or causes low-grade, chronic disease after occuring as an acute, recoverable infection.

ex. S. aureus: carriage in anteriors nare

S. typhi: chronic gall bladder infection follow by typhoid fever leads to fecak excreatuib if organism.

evasive factors: capsules, receptors, enyme, flagella.

invasive factors: ensyme, exotixin, endotoxins, adhersive surface structures.

a. direct contact with infected individual or by direct contact with inanimate objects or materials, or vectors.

b. Reservoirs: referes to only mammalian carriers of infectious agents such as Human and Animal (zoonoses)

Zoonoses: diseases that occur primarily in the wild and domestic animal and can be transmitted to human. ex. swine, rabbies by bats, skunks, foxes, cats and dog.

• indirect contact with infected animal (from bites)
• ingestion of contaminated food and water
• contact with contaminated hides, furs or feathers.
• consumption of infected animal product
• insect vectors

congenital

spread from mother to fetus through placental barrier