Flashcards in Microbiology II Deck (205):
What is the gram type and shape of the major flora in the gut?
Gram negative rods
What are the 5 F's that infect the gut with the bacilli Enterobacteriaceae?
(but really it's just feces)
What are two pathologically important features of Gram negative rods?
Sharing of virulence factors
(through conjugation, etc)
Where are gram negative rods found?
dirt, water, GI flora
Gram negative bacteria can cause cancer
How many species of Enteric Gram negative rods are there?
What is their metabolic category?
Enteric Gram negatives are highly fastidious.
they are non-fastidious but sensitive to drying
All of the Gram- Enterics are have a _______ cycle.
What type of infection is Campylobacter?
Where can Helicobacter live?
*causes cancers and ulcers
What are the Serotype terms for:
*these are determined by agglutination
What is meant by Antigen Variation?
Bacteria evade adaptive response by changing epitopes
*referring to Gram- Enterics
How does Phase Variation in Gram- Enterics protect them from Antibody-mediated death?
They change the expression of major features (Antigens), like capsule and flagella.
Name 6 virulence factors for Gram- Enterics.
Endocytosis (invade cells)
Capsules (phagocytic resistance)
All Gram- Enterics have endotoxin, and some have exotoxin.
What are the specific adhesion molecules on Fimbrae called?
All Gram- Enterics initiate actin assembly and internalize into attached cells
Which Gram- Enterics enter mucosal epithelium?
Which of these use macrophage taxis?
E. coli (EIEC)
(these two taxi)
How do macrophage taxi Gram- Enterics survive?
Block endosome-lysosome function and escape the death chamber
E. coli (EPEC variant) does what to intestinal cell walls?
Attaches to brush border and causes malabsorption
What 4 things does LPS directly activate?
(this is our innate immune response)
Hageman Factor (coagulation)
Complement (mast cell degranulation/pro-inflammatory mediators)
TNF-alpha stimulated endothelial cells to produce:
Gram - bacteria can, in large numbers, cause sepsis, which entails:
*this is caused especially by what bacteria?
Hypovolemic shock (CV)
Intravascular coagulation (causing internal bleeding)
Multiple organ shutdown
What are the 3 major classes of A-B Exotoxins produces by Gram - Enterics?
2 Robosylation of regulatory proteins (gut)
1 cleave rRNA and block protein synth
What is the equation for disease causing potential?
Virulence x Dose / Host resistance
Why is Shigella's infectious dose very small?
Very acid resistant
How does Shigella infect the colon?
By invading epithelial "M" cells and dividing inside.
How does Shigella move laterally once inside these epithelial cells?
What is the result of a local Shigella infection of the colon?
What type of toxin do some strains of Shigella dysenteriae produce?
(A-B cleaves rRNA)
*damages intestinal epithelial cells
What can Shiga toxins do if they get into blood?
HUS - Hemolytic Uremic Syndrome
(damage glomerular endothelial cells & renal failure)
What encodes a Shiga-like Toxin?
Entero-hemorrhagic E. coli (EHEC)
*similar to S. dysenteriae
List Shigella species from most pathogenic to least:
The Shigella bacteria cause a _____ LPS caused by invasion of bacteria into the endothelium.
What is the immune response to M-cell invasion by Shigella?
Ulcers, which causes dyssenteric symptoms
What is stool filled with in dysentery caused by Shigella?
EHEC 0157:H7 has _____ toxin and can act _____.
What causes Typhoid Fever?
macrophage taxis rupture and releases lots of bacteria
Where is Salmonella typhi found in carriers?
Gallbladder (maybe gallstones)
How many Salmonella serotypes are there?
How is Salmonella different from Shigella?
Doesn't tolerate stomach acid as well
*need large dose for infection
How do most Salmonella species act in the gut?
Invade epithelial cells and destroy.
Usually isolated infection
Why is Salmonella typhi particularly infectious?
Evades macrophage destruction by using taxis
What is the definition of bacteremia?
Bacteria in blood
List Salmonella species from most to least virulent:
Salmonella is acid sensitive
What type of virulence factors can be transferred to normal Gi flora?
What are 2 types of pathogens that transfer such genes?
adhesions and endotoxins
Shigella and V. cholera
Name 4 pathogenic E. coli that have gained virulence factors from Shigella or V. cholera?
(one gained from an unknown source)
ETEC - Enterotoxigenic E. coli
EHEC - Enterohemorrhagic E. coli
EPEC - Enteropathogenic E. coli
EIEC - Enteroinvasive E. coli
E. coli outbreak's pts are often hospitalized with what condition?
HUS (hemorrhagic uremic syndrome)
What causes most (75%) UTI's?
What allows them to survive in the urinary tract?
E. coli (uropathogenic strains)
Specialized adhesions (fimbrae)
At what point can a UTI cause systemic LPS?
Once it reaches the kidney
Aside from LPS, what do E. coli strains of UTI's secrete?
What is a curved Gram- rod and has enterotoxin causing ribosylation (increases cAMP)?
What zoonotic infection has Shiga-like toxin?
What causes ulcers and is a spiral Gram- rod?
What causes cystic fibrosis and is a big problem in burn victims and has a poor response to antibiotics?
What's a key periodontal bug that is Gram- rod anaerobe?
What Gram- rod comes through skin, oral mucosa, and grows in macrophage?
What fragile Gram- rod with a capsule binds ciliated bronchi and is not enteric?
What Gram- rod causes Plague?
Y. pestis uses macrophage taxis
What are the toxic agents used by Y. pestis?
What are 2 sources of Passive Immunity?
Injection of antibody
Why is passive immunity temporary?
IgG half life 21 days
What is an important mild antibody?
(blocks colonization of gut viruses and toxins)
*protects from Vibrio cholerae
What Gram- curved rod is Non-invasive, and does not fully penetrate enteric endothelium?
What type of toxin does Cholera release?
What does it do?
pumps salts and water into colon
*rice water stools
What is the treatment for Cholera?
When is the "window of susceptibility" for babies?
What are the 2 major pathogenic Neisseria species?
Neisseria meningitidis and gonorrhoeae are both?
aerobic or microaerophilic
Both pathogenic Neisseria species cause purulent infections
Where is Neisseria meningitidis commonly found in healthy individuals?
What is the medical slang for this species?
What are the 2 diseases caused by Neisseria meningitidis?
What are the major virulence factors of N. meningitidis?
IgA protease (very clever)
What two benefits does N. meningitidis get from having a capsule?
Antigenic differences between strains
How is N. meningitidis spread?
respiratory droplets and prolonged contact
What percentage are asymptomatic and carrying N. meningitidis?
Who is susceptible to N. meningitidis?
Those lacking opsonizing antibodies to anti-phagocytic capsules
*moves from nasopharynx into blood - bacteremia
What can bacteremia from N. menigitidis lead to?
meningococcal sepsis (septic shock)
'blebs' - lots of endotoxin from meningococcal outer membrane > cytokine > systemic inflammation > decrease BP > Disseminated Intravascular Coagulation
When are the peaks for death by menigococcal sepsis?
3 months (vast majority of deaths)
What is the difference between meningitis and meningococcal septicemia?
Bacteria cross to the brain and local endotoxin causes damage
What results in capillary blockage and damage during sepsis?
Disseminated Intravascular Coagulation
What are the 3 most serious brain infections in children that cause meningitis?
Are they Gram+/-?
H. influenza G-
N. meningitidis G-
Strep pneumococcus G+
Viral meningitis is much more severe than bacterial.
Viral much more common much less severe
On gross examination of CSF, what is indication of bacterial meningitis?
The 3 species that cause bacterial meningitis in children (H. influenza, N. meningitidis, S. pneumococcus) all have _____ and live _____
back of throat
Where does the human reservoir for N. meningitidis reside?
N. meningitidis is very hardy.
Very fragile, drying kills, hard to grow
What are meningits and meningococcemia both caused by?
Meningococcemia is often accompanied with a.....
Both meningitis and meningococcemia are both ultimatley caused by....
Blebbed endotoxin released by N. meningitidis
What is the fatality rate for bacterial meningitis?
% with serious outcomes like brain damage?
What is the Fatality rate for Meningococcemia?
Serious outcomes like brain damage?
Common name for N. meningitidis
Common name for N. gonorrhoeae
What are the major virulence factors for N. gonorrhoeae?
Fimbrae attachment to mucosal epithelium*
Gene conversion and Phase Variation
Incorporates host surface receptors
Is N. gonorrhoeae encapsulated?
Why is gonorrhea so difficult to get rid of?
Half women have no symptoms
less that 10% men have no symptoms
What is a consequence of untreated gonnorhea?
Pelvic Inflammatory Disease
Why are newborns routinely treated with anti-microbial eye ointment?
Prevent gonococcal eye infections
(if bad can lead to blindness)
N. gonorrhoeae is very hardy
Name 3 important Virulence factors for N. gonorrhoeae.
Inflammation from gonorrhea is local/systemic and leads to _______
Gonorrhea in women:
*leads to PID 1 million/yr
Where does adhesive scarring occur in PID?
Is there a vaccine for gonorrhea?
extreme antigen variation makes it difficult
What are the 3 very small Gram- bacteria that cause human disease?
What are Rickettsia and Chlamydia's effects on tissues?
Obligate Intra-cellular (invaders)
Energy parasites (steal ATP)
What are Mycoplasma's effects on tissue?
What toxins does Mycoplasma have?
and no LPS
What are 2 results of a Rickettsia infection?
What are 2 results of a Chlamydia infection?
Rickettsia is an obligate intracellular parasite.
Why must Rickettsia live inside cells?
Lack enzymes required to produce AA's
What is the main reservoir for Rickettsia?
What is the mechanism of Rickettsia infection from vector to host?
Infected arthropod defecates while biting, bacteria enter blood
What can many of the pathologies associated with Rickettsia be traced to?
LPS flooding bloodstream systemically
What is the most common and important Rickettsial disease worldwide?
What is the only Rickettsial Typhus that can cause explosive epidemics?
How is it spread?
R. prowazekii > lice > clothes
What is the most common Rickettsia in the United States?
R. rickettsii, species of bacteria transmitted by ticks causing Rocky Mountain Spotted Fever
Organism and Vector causing the following:
Rocky Mountain Spotted Fever
R. rickettsii ticks
O. tsutsugamushi mites
R. prowazekii Louse
R. typhi fleas
What do all the arthropod transmitted Rickettsia's have in common?
Obligate intracellular parasites
Rickettsia is an obligate _______ bacteria.
What kind of parasite is the Rickettsia bacteria?
Steals AA's and ATP
*Chlamydia also does this
What does Mycoplasma steal from its host?
lipids and cholesterol to strengthen its membrane
Ticks are both the _____ and the ______ for Rickettsia.
LPS in Rickettsia is systemic and causes what symptoms?
Headache, fever, chill
What are the 3 biotypes in the serological taxonomy of Rickettsia?
Spotted fever group
Scrub typhus group
How does Typhus differ from Typhoid?
Typhus - caused by Rickettsia
Typhoid - "typhus like" caused by Salmonella typhi
*typhus/typhoid - think fever/rash
What does Rickettsia prowazekii cause?
What is its reservoir?
epidemic typhus in close quarters via lice
humans (and some rodents)
*DDT extremely effective against
Obligate intracellular parasite
no cell wall
two lipid bilayer/LPS
What are the 3 major species of Chlamydia that affect humans?
C. trachomatis (STD)
C. pneumoniae (bronchitis & pneumonia)
C. psittaci (pneumonia)
*psittaci is mostly bird pathogen, occasionally human
What 2 diseases does Chlamydia trachomatis cause?
What is the primary reservoir for Trachoma?
What is the pathological progression?
eyelids turn inward and scar
How is Chlamydia symptomatically similar to Gonorrhea?
symptomatic in men
asymptomatic in women
*also a cause of PID
Chlamydia and Rickettsia are energy parasites
Chlamydia has a peptidoglycan wall and LPS
No peptidoglycan, but has LPS
What does Chlamydia infect and what type of inflammation does it cause?
Local (and chronic)
Chlamydia pneumonia has an association with atherosclerosis, is community acquired, and is very rare.
More than 50% population has serologic evidence of previous infection
What is the common route of infection for C. psittaci?
Birds to dust to lung
*generally only affecting immunocompromised
There is a vaccine for C. trachmatis
What is the most common bacterial STI in the USA?
What are the smallest known self-replicating organisms?
Mycoplasma and Ureaplasma
No cell wall
What is the major Mycoplasma pathogen?
Where does M. pneumonia live?
Surface of respiratory epithelium
*destroys ciliated cells
What type of inflammation does M. pneumonia elicit?
What is "walking pneumonia"?
Mycoplasma species have been implicated in genitourinary tract diseases, PID, and STI's
What are Koch's 4 postulates to determine causality of agent?
1. Found in all cases
3. cause disease when introduced
4. reisoloation from inoculated host and identified as identical to original causative agent
What causes diphtheria and where is it found?
skin, upper respiratory, GI
What are 3 defining characteristics of C. diphtheriae?
What kind of toxin does C. diptheriae make and how is it spread?
(inhibits protein synth)
only spreads when lysed by virus
(the infection has an infection)
Where does the A-B exotoxin of C. diptheriae preferentially spread systemically?
Where is it locally?
B-subunit binds heart and nerve cells
How is C. diptheriae usually transmitted?
Respiratory droplets of asymptomatic, immune carriers
What is the distinctive thick, grayish white exudate caused by C. diphtheriae that adheres firmly to tissue?
What does this cause in advanced cases?
*difficult to dislodge without making underlying tissue bleed
How is diphtheria treated?
toxoid (modified immunogenic toxin)
Besides C. diphtheriae, what causes a pseudomembrane to form?
Diphtheria is non-invasive.
Two major ways to die from diphtheria?
Why does Corynebactirum diphtheriae infections increase when vaccination rates go down?
Bacteria is found everywhere
USSR - Russia breakup lag in public health
What type of bacteria form spores?
Gram positive (some)
NEVER Gram negative
A minimum amount of metabolism goes on in endospores.
NO metabolic processes
Structure of endospore:
Dehydrated core with DNA
What are 2 of the most common and important spore forming bacteria?
What are the 4 Clostridium human pathogens?
*these are all G+ spore formers and strict anaerobes
What is special about the A-B exotoxin secreted by C. tetani and C. botulinum?
They are the most potent toxins known
Botulism causes "true" food poisoning.
Perfringens is an infection food poisoning
What is the worldwide mortality rate for tetanus?
What is the mechanism of the Clostridium tetani toxin?
Blocks neurotransmitter release of Inhibitory Synapses
What is the main way we contract C. botulinum?
spores in Food
*infants and honey, home canning ("true")
What is the mechanism of the Clostridium botulinum toxin?
Blocks RELEASE of neurotransmitter acetylcholine at the NMJ
*this prevents contraction (flaccid paralysis)
The immune system can respone to C. tetani and C. botulinum.
they are so powerful immune system never sees it at lethal dose
Why do infants have less tolerance for C. botulinum?
Stomachs higher pH
What two pathologies do Clostridium perfringens cause?
What type of exotoxin does C. perfringen produce?
What is the mode of most C. perfringens food poisoning?
left out meat
What Clostridium is associated with broad spectrum antibiotics?
*has 2 exotoxins
What is another G+ spore forming pathogen other than Clostridium species?
*this is a HUGE G+
What are the 3 types of pathologies caused by Bacillus anthracis?
Cutaneous anthrax (20%)
Pulmonary anthrax (90%)
GI anthrax (50%)
What type of toxin is released by Bacillus anthracis?
two potent A-B exotoxins
*uses Macrophage taxis
What is the Bacillum species that causes true food poisoning, mostly by re-heated fried rice?
What are the 2 most important species of Mycobacterium affecting humans?
Why is B-cell immunity no good against Mycobacterium?
Because they get INTO cells
Describe the pathology/immune response in M. tuberculosis.
Infects macrophage (mostly)
Immunity isolates into lung granulomas
Describe the pathology/immune response of M. leprae.
Infects Schwann cells
Immunity only slows disease progression
either Tuberculoid (strong) or Lepromatous (weak)
1/3 of the world is infected with TB
Where does Mycobacterium tuberculosis usually live?
Man, cows, birds, soil, milk, deer, etc.
What is unique about the membrane of M. tuberculosis?
High lipid content
(60% dry weight)
TB grow fast
TB is an Obligate Aerobe
Why is milk pasteurized?
TB is sensitive to heat
What are some morphological features of M. tuberculosis?
Poor staining Gram+
What is the infection rate of TB in US and worldwide?
10 million US
2 billion world
What does it mean to be Infected Latent?
Infected but not infectious
How many die/yr from TB?
What are 3 major problems in wiping out TB?
What is THE virulence factor in TB?
Lipid (waxy) membrane
*has Mycolic Acid
(relatively impervious barrier to enzymes, etc)
Why are antibodies of no use fighting TB?
It wants to be in macrophage
*only way to deal is put it in Granuloma jail
M. tuberculosis has resistance to enzymes, pH, drying
How is TB detected in the US?
PPD skin test
IFN-gamma release assay