E. coli makes vitamin B12 other organisms digest complex foods
restore good microbe balance
Genitourinary tract : urethra
has many organisms because it is in such close proximity with the outside world - S. Epidermidis, Enterococcus
if these go up into the bladder they can cause UTI
Composition of vaginal microflora changes
with menstrual cycle (change of nutrients and pH)
pH of vagina
4.5 (acidic) acid tolerant Lactobacillus acidophilus grows there
Antibiotic kills normal flora
leaves room for Candida albicans (yeast) to grow - not killed by antibiotics
cause diseases in compromised host
How do commensal organisms enhance the function of our immune system?
Genetically engineered to produce proteins (from pathogenic species) on their cell surface. modified species elicit immune response. eg. S. Salivarius, Lactococcus/bacillus
Bacterial proteins eg. catalase act as immunoglobulins,
Function of immunoglobulins
modify the secretion of host proteins eg. cytokines and tumor necrosis factor TNF
Function of cytokines
binds to cells in the immune system and regulate extent and duration of responses by those cells
How do non-commensal organisms **** up our intestine?
gram negative non-commensal pathogens produce a protein called Enterotoxin
how does enterotoxin harm us?
they damage the intestine and causes diarrhea
twist to enterotoxin
may protect against colorectal cancer by activating calcium channels in intestinal epethelial cells
increase in membrane conductance for calcium turns on a pathway that provides resistance for colon cancer
shows that the presence of normal flora challenges immune system and keeps it active Gnotobiotic animal - germ free/all microbial species are known. These animals have poorly developed immune systems, low cardiac output, thin intestinal walls.