Chapter 4: Prokaryotic Diversity

microbes that colonize the body without normally causing disease; normal flora that inhabit a healthy body

a microorganism that does not normally cause a disease but if given the opportunity, will
caused by illness, change in environment, suppressed immunity, etc.
can be certain normal flora
sometimes our normal flora shift from mutualistic to parasitic

skin
ears, nose, throat (nasopharynx)
mouth
upper respiratory tract
gastrointestinal tract (GI tract)
urogenital tract (bladder; bladder is sterile)
places with a warm, moist environment with lots of food (eat our dead cells, secretions, and our waste products)

relationship that exists between two different species that live in close association

neither organism benefits from relationship

one organism benefits and the other is unaffected in relationship

both organisms benefit from relationship

one benefits (parasite) while the other is harmed in relationship

proteins that kill other bacteria
Example: normal flora release chemicals that kill other bacteria
Bacteriocins that are released by E.coli that kills Salmonella species

microbe against microbe
normal flora provide competition for food and space w/incoming pathogens-limits opportunistic pathogens that grow
some normal flora release chemicals that kill other bacteria (bacteriocins)

1. The organism gains access to a site it does not normally inhabit
2. The populations at a site are altered so the dominate population is suppressed - opportunists grow
3. The host's immune response is down/suppressed

some provide particular vitamins to us
Ex: E. coli (found in the gut, normal flora) provides us with vitamin K (used to make clotting factors in blood)
- provides competition for food and space with incoming pathogens - limits opportunistic pathogens to grow
- normal flora stimulation to immune system-keeps us ready to respond, it keeps genes for making HDM (host defense mechanisms) always on
- some normal flora release bacteriocins that kill other bacteria

antibiotic associated diarrhea (severe diarrhea)
inflammation of the colon
causes pseudomembranes colitis
more susceptible if taking broad spectrum antibiotics such as (ampicillins, chloramphenicol, Tetracycline, etc)
kills off all good and bad bacteria

normal flora of gut
primarily of urogenital tract/bladder
99% of UTI's are caused by gram-negative enterics gaining access to urinary tract
catheter insertion can also be a cause
organism gains access to the bladder, where bacteria does not normally inhabit

normal flora of nasopharynx
causes otitis media, bronchitis, sinusitis when it gains access to tissue below mucous membranes
damage to mucous membranes is usually by viral infection (affects tissues)
children 5 and under (and their parents) are primary carriers
the host's immune response is suppressed due to viral infection which lets S. pneumoniae get into tissues

inflammation of peritoneum cavity
caused when poop bacteria gains access to peritoneal cavity
100 million bacterial cells in poop the size of quarter
rapid onset of symptoms/death occur within 24 hours
poop gets into site it does not normally inhabit
mainly happens to gunshot/stab victims
IV antibiotic fluids are used to protect patients and flush out the infection

normal flora of vagina
caused vaginal yeast infection when pH balance is off
under healthy conditions, Lactobacillus species are dominant and they are like acidic pH (pH of 6) which keeps C. albicans from overgrowing
when pH changes to basic in that area, lactobacillus will die which allows C. albicans to overgrow creating inflammation/irritation

Increased pH can happen from sex, hormone fluctuations, douching and other hygiene practices

Clostridium difficile
mild case: lactobacillus shifts out of dominance in the gut, enterics overgrow which causes disruption of metabolic activities and can damage the gut lining depending which ones overgrow; kills gram - bacteria

severe diarrhea- cause by Clostridium difficile which causes pseudomembranes colitis; more susceptible if taking broad spectrum antibiotics that kill good and bad bacteria

thin layer of microbial growth on surface of some object
special problem in in-dwelling medical devices (artificial joints, stints, pacemakers, etc) - staphylococcus epidermidis (normal flora of skin) can affect these and cause inflammation

are antibiotic resistant naturally and sometimes the products designed to fight them contain Triclosan (broad spectrum antibiotic); more likely for bacteria to develop resistance

biofilm is found on plaque on teeth

1. Cell morphology-size and shape
2. Staining characteristics- Gram stain reaction
3. Atmospheric requirements-O2 and CO2
4. Nutritional Requirements-CHNOPS
5. Genetic composition-similar DNA/genes and rRNA
6. Pathogenicity- used for strain designation, not genus/species

1. Chlamydia species: energy parasites; obligate intracellular pathogens because they can't make their own ATP
2. Rickettsia: energy parasite; obligate intracellular pathogens because it can't produce ATP; transmitted by tick bites
3. Mycoplasma: no cell wall; has to live inside another cell or die due to osmotic variations, cause atypical or walking pneumoniae

prokaryotic; extremophiles; found in extreme environments
have glycocalyces capsules (formation biofilms, made out of polysaccharides or polypeptides); adhere cells to one another and inanimate objects
have fimbriae; also have fimbriae structures called hami (function to attach archaea to surfaces)
do not have peptidogylcan
cellular membrane can be single layer of phospholipids
specialized polysaccharides and proteins
square cells, can be rod-shaped, blobby