microbio chapter 20 (G-) Flashcards
Gram - Bacteria
- constitute largest group of human bacterial pathogens
- due in part to lipid A on outer membrane
- most grow at mesophilic conditions
Neisseria gonorrhoeae (gonococcus)
- also called gonococcus
- causes gonorrhea
- gonococci attach to genital, urinary, and digestive tract
Gonorrhea in men
painful urination and pus filled discharge
Gonorrhea in women
often asymptomatic but can trigger pelvic inflammatory disease
- infection in children can occur during childhood
Common case of Gonorrhea
occurred in Colorado when people were having sex for drugs
How can Gonorrhea stick in our urinary tract when urine runs through it?
Gonorrhea cells contain Opa which is an intimate attachment outer membrane protein that allows it to adhere to our urinary tract
What is the function of Opa and in which bacteria is it found?
Opa is an intimate attachment outer membrane protein that allows gonorrhea cells to adhere to the urinary tract
What is the significance of gonorrhea adhering in the urinary tract?
- it is a hard place to get antibiotics to stick and an immune response to occur
- antibiotics do NOT stick well so they are not effective
- this allows a good environment for bacteria to grow
What is the best antibody for gonorrhea?
slgA
What does gonorrhea have to combat slgA
gonorrhea has proteases that cleave the antibody
LOS in gonorrhea
- outer membrane lipopolysaccharide
- inhibits C3b binding on to bacterial membrane
- limits C5 convertase production
- limits C3b binding to surface (does not bind to CR1)
- triggers inflammation
Diagnosis of gonorrhea
Gram- diplococci in pus from inflamed penis
- if asymptomatic genetic probes can be used
Treatment of gonorrhea
broad spectrum antimicrobial drugs
Prevention of gonorrhea
sexual abstinence
Communal immunity of gonorrhea
- little to no long-term immunity due to changing surface proteins
- infection can occur in same individual many times
- fairly communal
Enterobacteriaceae
- in the intestinal microbiota of most animals and humans
- ubiquitous in soil, water, and decaying systems
- most common Gram-pathogens of humans
Escherichia coli
- coliform opportunistic Enterobacteriaceae
- most common and important of the coliforms
- virulent strains have virulence plasmids
- gastroenteritis is a common disease
- common cause of non-nosocomial urinary tract infection
E. coli 0157:H7
- pathogenic strand
- most prevalent in developed countries
- causes diarrhea, hemorrhaging, hemolytic uremic syndrome
- ~2100 hospitalizations per year
- undercooked meat is the problem
Jack n the Box E. coli
they served undercooked burgers to many children, and they went to the hospital
- many died
- many had irreversible kidney damage
- occurred in 1993
E. coli toxins
- has a Shiga like toxin from Shigella
- believed to be passed through transduction
- contains SLT gene
SLT gene
- an A-B toxin
- A= modifies rRNA in ribosomes bringing translation to a halt
- causes diarrhea/vomiting
Truly pathogenic Enterobacteriaceae
- salmonella
- shigella
- yersinia
- almost always pathogenic due to virulence factors
- produce a type 3 secretion system
Type 3 secretion system
- introduce proteins that inhibit phagocytosis, rearrange cytoskeleton, or induce apoptosis
- acts as a syringe to push in A-H protein
Type 3 secretion system process
- A-H protein is put into cell and cell is tricked into taking it in
- A-H protein modifies membrane of phagosome with bacteria - phagosome cannot bind with lysosome
- a separate type 3 secretion releases more A-H protein
- cell with salmonella has to die in order to release bacteria
- adjacent cell can uptake salmonella that is released from dying cells
Salmonella exposure
Salmonella is constantly exposed to our immune system as it is released from cell to cell
Salmonella
- ~2M cases/year
- very low death rate
- Gram -, motile bacilli
- can be found in intestines and feces of birds, reptiles, and mammals
- most human infections are due to consuming food with animal feces contamination
- poultry and eggs are a common source
- causes salmonellosis and typhoid fever
Salmonella in our cells vs test tube
when salmonella A-H protein cells are grown in human cells, many proteins expressed in humans that do not appear in test tubes
Salmonellosis
- salmonella cells attach to epithelial cells in small intestine
- bacteria triggers endocytosis
- A-H protein prevents binding to a lysosome so bacteria grows in phagosome
- salmonella kills host cell which induces fever, diarrhea, and cramping
- bacteria can move into bloodstream
Salmonella’s O side chain
- has a longer O side chain that affect MAC complex
- it signals MAC complex away from inner membrane
- binds to C9 to disrupt completion of MAC
- MAC can bind to O-side chain but it is too far to make holes in the membrane
Mary Mallon cook
- asymptomatic carrier of Salmonella
- was a cook and would pass on infection to others
- was quarantined but found work again
- eventually quarantined until her death in 1938
- confirmed to cause 55-122 typhoid fever cases
Yersinia
normal pathogen of animals
1. Yersinia enterocolitica
2. Yersinia pseudotuberculosis
3. Yersinia pestis
Yersinia enterocolitica
causes inflammation of the intestinal tract
Yersinia pseudotuberculosis
similar to enterocolitica but less severe
Yersinia pestis
causes bubonic and pneumonic plague
- nearly 75% mortality rate
- killed 1/3 of European population in 14th century
Transmission of Y. pestis
- natural hosts pass on disease to an amplifying
- either host would make direct contact with a human through biting
- human would become infected with bubonic plague or pneumonic plague
- people with pneumonic plague could pass it as an airborne condition
Great fires of London
Destroyed many hay houses and people resorted to bricks. This limited the number of areas for rodent hosts to live.
Buboe
- causes by Y. pestis
- causes high fever with painful swollen lymph nodes
- caused by sub-cutaneous hemorrhaging and death of tissue (gangrene)
- death often within a week
Why is the bubonic plague also called the black death?
It causes lymph nodes to swell and hemorrhage. This creates blockages in the lymphatic system that hold blood up. Blood eventually begins to turn black causes blackening of the skin.
Virulence factors of Y. pestis
- virulence plasmids confer a Type 3 secretion that inject YopE and YopH which inhibit phagocytosis by degrading actin filaments
- YopM: inhibits recruitment of additional phagocytes
- Fra1: glycocalyx capsule makes it harder to engulf
- Pla: degrades C3b to decrease phagocytosis and C5a so decreased number of phagocytes in area
- decreases opsonization and anaphylatoxin
Diagnosis of Yersinia pestis
characteristics symptoms
- diagnosis and treatment must be rapid to avoid death
Treatment of Yersinia pestis
many antimicrobial drugs are effective
Bubonic plague
first biological welfare
