Microbiological Organisms, Symbiosis, Bacteria Flora, Forms of Disease

Unit1

bacteria (prokaryotic)

smallest, most versatile, independently living cells, single-celled organisms. “live on their own” NO HOST NEEDED

archaea prokaryotic

prokaryotic but different from bacteria

fungi

eukaryotic organisms
protozoans
single celled, eukaryotic organisms, molds and yeasty

helminths

multicellular eukaryotic parasitic worms, huge worms

viruses

not considered living- cannot reproduce without a host, NEEDS A HOST, “Hijackers”

prions

infectious proteins; smaller than viruses

archaea

all except … cause disease in humans
some archaea normal flora PROKARYOTIC

symbiotic relationships

Microorganism and human interactions

virus or prion

if it has no cell its is a ….

commensalistic symbiotic relationships

do not harm humans or provide benefit to humans ( Neither harm nor benefit humans)

fungi, protozoa, helminths

if it has a nucleus…

bacteria or archae (prokaryotic)

if no nucleus…

mutualistic symbiotic relationships

benefit humans and other organisms in the environment
form base of food chain/

where both the microorganism and the human host benefit

cyanobacteria

photosynthetic; autotrophic
convert carbon dioxide and water to glucose and oxygen

are autotrophic organisms that use photosynthesis to convert carbon dioxide and water into glucose(sugar) and oxygen.

“Cyanobacteria eat sunlight and breathe out oxygen.”

CO₂ + H₂O + sunlight → sugar + oxygen

decompose wastes

human, animal, industrial, water wastes, surface runoff
sewage treatment removes bacteria and solids to clean water

Microorganisms decompose human, animal, and industrial wastes, and sewage treatment uses bacteria to remove solids and harmful microbes, resulting in cleaner water.

“Microbes clean our mess so water stays safe.”

recycle chemicals

C, H, O, N converted to forms usable by organisms
return to soil and atmosphere

digestion

some normal flora bacteria
synthesize some vitamins- vitamins K and B12
E. coli, Klebsiella, Citrobacter- large intestine

parasitic or pathogenic symbiotic relationships

infectious disease agents
disease agent uses host for all or part of life cycle
harm humans and/ or other host species

( where microorganism benefits while the host is HARMED)

pathogenic

disease causing bacteria

parasitic

viruses, fungi, protozoans, helminths

Microorganism flora on body

normal, transient, opportunistic
characterized as houseguests- come and go

normal flora

microorganisms adapted to body
on body and/ or in organ system tracts opening to outside all the time
most commensal, some mutualistic
no normal flora below epithelium
normal flora establishes conditions on body that inhibit or control opportunists
100 trillion on skin, in oral cavity, intestines- 1 to 2 lbs.
Escherichia (E.) coli in digestive tract
Staphylococcus aureus on skin
normal flora may be susceptible to broad spectrum antibiotics that opportunists resist

transient flora

temporarily present on body
not adapted to body
transient flora can be removed with washing, cleaning, and disinfecting

opportunistic flora

potentially disease causing
may become resident
any microorganism including normal and transient flora can become opportunistic
evade surface defenses
enter tissue below epithelial membranes

normal floral E. coli

causes urinary tract infections- UTI
E. coli moves from anus to urethra to bladder to ureters to kidney
opportunist Neisseria meningitidis
resident flora in pharynx in up to 40% individuals sampled

C diff

asymptomatic
may or may not be sick
may or may not spread to others and cause disease

3 ways disease causing bacteria damage host

damage tissue directly
release exoenzymes into tissue
produce toxins
bind cell receptors
hypersensitivity reactions
Streptococcus pneumoniae
produces thick external capsule
makes bacterium more difficult to phagocytize
causes ongoing inflammatory response
allergic reactions
excessive immune response to normally harmless allergens

bee stings, some foods, pollen, antibiotics

4 forms of disease

diseases that have always infected humans and probably always will in the future
Strep throat- Streptococcus pyogenes, Ebola hemorrhagic fever, influenza A, arborvirus diseases

Strep throat Streptococcus pyogenes

diseases that have caused serious problems in the past but are now controlled by immunizations
measles, polio, diphtheria
diseases that are characterized as “emerging diseases”
recently recognized diseases or disease outbreaks that have been occurring more frequently
mostly zoonotic- spread from animals to humans

Ebola hemorrhagic fever

ongoing epidemic in central Africa- 2019
Ebola transmitted by contact with contaminated body fluids/ blood
proper PPE reduces transmission
originally described in 1976- Ebola river in Congo

influenza A

bird flu H5N1, H7N9 (2013), H5N2 (2015), H7N8 (2016)
swine flu H1N1
human flu H3N2

arborvirus diseases

diseases transmitted by mosquitos
Zika virus, Dengue virus, west Nile virus

Diseases that are characterized as “neglected tropical diseases” poor

diseases that are always present in poor regions of the world
receive less attention, less funding and less discussion
can be very painful and stigmatizing but are usually not fatal

Guinea worm

Dracunculus- worm
causes disease symptoms in humans

Cyclops- copepod

contains Dracunculus larvae
ingested by us with water

Guinea worm disease

… reduced with clean water
… almost eliminated from the world
river blindness

Onchocerca

transmitted by black flies
tropical west Africa, South America, Central America, Mexico, Caribbean
damage from hypersensitized inflammatory response against dead worms
control black flies to control disease

yaws

Treponema subspecies- cause of syphilis
transmitted person to person by contact- infects children
skin lumps, ulcers, cartilage, bone
endemic in 15 countries- cure with antibiotics

(kids + skin, spread by contact skin, affects children, cause skin and bone damage)

soil parasites-ascaris

transmitted by ingestion of eggs in fecal contaminated food and water ( spread by contaminated food and water)

Streptococcus pneumoniae

Sometimes harmless

• It can live in the nose and throat without causing disease

• In that situation, it behaves like normal flora

• or It becomes bad (pathogenic) when:

  • It moves to places it shouldn't be (lungs, blood, brain)

  • The immune system is weakened

  • The capsule helps it evade immune defenses

  Then it can cause:

  • Pneumonia

  • Meningitis

  • Ear and sinus infections

is normally harmless in the upper respiratory tract but becomes pathogenic when it invades sterile tissues, causing disease

strep throat- Streptococcus pyogenes

spreads easily among humans, has no effective vaccine, and infection does not produce lasting immunity. ALWAYS HERE

neglected tropical disease

guinea worm, cyclops, river blindness, yaws, soil parasite

emerging diseases

ebola hemorrhagic fever, influenza A, arbovirus diseases,

protozoa

virus

bacteria

helminth