Microbiology II Flashcards
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?
food fluids fingers flies feces
(but really it’s just feces)
What are two pathologically important features of Gram negative rods?
Sharing of virulence factors
(through conjugation, etc)
Antibiotic resistance
Where are gram negative rods found?
ubiquitous
dirt, water, GI flora
T/F
Gram negative bacteria can cause cancer
True
How many species of Enteric Gram negative rods are there?
What is their metabolic category?
over 500
Facultative anaerobes
T/F
Enteric Gram negatives are highly fastidious.
False
they are non-fastidious but sensitive to drying
All of the Gram- Enterics are have a _______ cycle.
Oro fecal
What type of infection is Campylobacter?
Zoonotic
Where can Helicobacter live?
Stomach
*causes cancers and ulcers
What are the Serotype terms for:
Flagella
Capsules
Endotoxins (LPS)
H-antigens
K-antigens
O-antigens
*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.
Adhesive factors Endocytosis (invade cells) Macrophage Taxi Capsules (phagocytic resistance) Phase variation Antibiotic Resistance Toxins
T/F
All Gram- Enterics have endotoxin, and some have exotoxin.
True
What are the specific adhesion molecules on Fimbrae called?
Adhesins
T/F
All Gram- Enterics initiate actin assembly and internalize into attached cells
False
some do
*Bacterial-directed endocytosis
Which Gram- Enterics enter mucosal epithelium?
Which of these use macrophage taxis?
E. coli (EIEC)
Shigella
Salmonella
Yersinia
(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
Macrophage
Hageman Factor (coagulation)
Platelets (coagulation)
Complement (mast cell degranulation/pro-inflammatory mediators)
TNF-alpha stimulated endothelial cells to produce:
NO
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) then, Multiple organ shutdown ARDS
*bacteriamia
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?
Actin-directed pseudopodia
What is the result of a local Shigella infection of the colon?
dysentery
What type of toxin do some strains of Shigella dysenteriae produce?
Shiga toxin
(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:
S. dyssenteriae
S. flexneri
S. sonnei
The Shigella bacteria cause a _____ LPS caused by invasion of bacteria into the endothelium.
Local
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?
mucus
pus
blood
EHEC 0157:H7 has _____ toxin and can act _____.
Shiga-like
Systemically
What causes Typhoid Fever?
Salmonella typhi
macrophage taxis rupture and releases lots of bacteria
*systemic
Where is Salmonella typhi found in carriers?
Gallbladder (maybe gallstones)
feces
*typhoid Mary
How many Salmonella serotypes are there?
over 2000
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:
S. typhi
S. typhimurium
S. enterica
T/F
Salmonella is acid sensitive
True
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?
Cytolytic exotoxin
What is a curved Gram- rod and has enterotoxin causing ribosylation (increases cAMP)?
Vibrio cholerae
What zoonotic infection has Shiga-like toxin?
Campylobacter jejuni
What causes ulcers and is a spiral Gram- rod?
Helicobacter pylori
What causes cystic fibrosis and is a big problem in burn victims and has a poor response to antibiotics?
Pseudomonas aeruginosa
What’s a key periodontal bug that is Gram- rod anaerobe?
Bacteroides
What Gram- rod comes through skin, oral mucosa, and grows in macrophage?
Brucella abortus
What fragile Gram- rod with a capsule binds ciliated bronchi and is not enteric?
Bordetella pertusis
What Gram- rod causes Plague?
Yersinia pestis
Mortality rates:
Bubonic plague
Pneumonic plague
75%
100%
T/F
Y. pestis uses macrophage taxis
True
What are the toxic agents used by Y. pestis?
LPS
Superantigen
What are 2 sources of Passive Immunity?
Mother
Injection of antibody
Why is passive immunity temporary?
IgG half life 21 days
What is an important mild antibody?
slgA
(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?
Cholera
Vibrio cholerae
What type of toxin does Cholera release?
What does it do?
A-B exotoxin
pumps salts and water into colon
*rice water stools
What is the treatment for Cholera?
Water/electrolyte matching
When is the “window of susceptibility” for babies?
3-5 months
What are the 2 major pathogenic Neisseria species?
N. meningitidis
N. gonorrhoeae
Neisseria meningitidis and gonorrhoeae are both?
Gram- diplococci
aerobic or microaerophilic
T/F
Both pathogenic Neisseria species cause purulent infections
True
Where is Neisseria meningitidis commonly found in healthy individuals?
What is the medical slang for this species?
nasopharynx
meningococcus
What are the 2 diseases caused by Neisseria meningitidis?
meningitis
meningococcemia
What are the major virulence factors of N. meningitidis?
Fimbrae (nasopharynx)
Capsule
IgA protease (very clever)
What two benefits does N. meningitidis get from having a capsule?
Anti-phagocytic
Antigenic differences between strains
How is N. meningitidis spread?
Natural carriers?
respiratory droplets and prolonged contact
humans only
What percentage are asymptomatic and carrying N. meningitidis?
10%
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) 20 yrs
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+
T/F
Viral meningitis is much more severe than bacterial.
False
Viral much more common much less severe
On gross examination of CSF, what is indication of bacterial meningitis?
Cloudy
The 3 species that cause bacterial meningitis in children (H. influenza, N. meningitidis, S. pneumococcus) all have _____ and live _____
capsules
back of throat
Where does the human reservoir for N. meningitidis reside?
Carrier rate?
Nasopharynx
10%
T/F
N. meningitidis is very hardy.
False
Very fragile, drying kills, hard to grow
What are meningits and meningococcemia both caused by?
Systemin LPS
Meningococcemia is often accompanied with a…..
rash
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?
15%
15%
What is the Fatality rate for Meningococcemia?
Serious outcomes like brain damage?
40%
50%
Common name for N. meningitidis
Common name for N. gonorrhoeae
meningococcus
gonococcus
What are the major virulence factors for N. gonorrhoeae?
Fimbrae attachment to mucosal epithelium* Gene conversion and Phase Variation Incorporates host surface receptors IgA protease* LPS* Penicillin resistance
Is N. gonorrhoeae encapsulated?
no capsule
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?
PID
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
False
Name 3 important Virulence factors for N. gonorrhoeae.
Fimbrae
LPS
IgA protease
Inflammation from gonorrhea is local/systemic and leads to _______
Local LPS
Pus (pyogenic)
Gonorrhea in women:
% asymptomatic
% untreated
50
10-20
*leads to PID 1 million/yr
Where does adhesive scarring occur in PID?
Fallopian tubes
Is there a vaccine for gonorrhea?
NO
extreme antigen variation makes it difficult
What are the 3 very small Gram- bacteria that cause human disease?
Rickettsia
Chlamydia
Mycoplasma
What are Rickettsia and Chlamydia’s effects on tissues?
Obligate Intra-cellular (invaders) Attacks endothelium Energy parasites (steal ATP)
What are Mycoplasma’s effects on tissue?
Extra-cellular
Attacks epithelium
What toxins does Mycoplasma have?
Super Antigen
and no LPS
What are 2 results of a Rickettsia infection?
Spotted Feve
Typhus
What are 2 results of a Chlamydia infection?
Eye infection
STD
T/F
Rickettsia is an obligate intracellular parasite.
True
Why must Rickettsia live inside cells?
Lack enzymes required to produce AA’s
What is the main reservoir for Rickettsia?
Arthropods
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?
Typhus
What is the only Rickettsial Typhus that can cause explosive epidemics?
How is it spread?
Louse-born
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 Scrub typhus Epidemic typhus Murine typhus
R. rickettsii ticks
O. tsutsugamushi mites
R. prowazekii Louse
R. typhi fleas
*skip scrub/murine
What do all the arthropod transmitted Rickettsia’s have in common?
small
G-
Obligate intracellular parasites
Rickettsia is an obligate _______ bacteria.
Gram?
Shape?
Intracellular
G-
coccobacilli
What kind of parasite is the Rickettsia bacteria?
Energy parasite
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.
reservoir
vector
LPS in Rickettsia is systemic and causes what symptoms?
Headache, fever, chill
Rash
What are the 3 biotypes in the serological taxonomy of Rickettsia?
Spotted fever group
Scrub typhus group
Typhus group
How does Typhus differ from Typhoid?
Typhus - caused by Rickettsia
Typhoid - “typhus like” caused by Salmonella typhi
(typhoid mary)
*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
Describe Chlamydia
Obligate intracellular parasite no cell wall two lipid bilayer/LPS G- energy parasite
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?
STD
blindness (trachoma)
What is the primary reservoir for Trachoma?
What is the pathological progression?
children
eyelids turn inward and scar
How is Chlamydia symptomatically similar to Gonorrhea?
symptomatic in men
asymptomatic in women
(generally)
* also a cause of PID
T/F
Chlamydia and Rickettsia are energy parasites
true
T/F
Chlamydia has a peptidoglycan wall and LPS
False
No peptidoglycan, but has LPS
What does Chlamydia infect and what type of inflammation does it cause?
Mucosal epithelium
Local (and chronic)
Chlamydia pneumonia has an association with atherosclerosis, is community acquired, and is very rare.
False
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
T/F
There is a vaccine for C. trachmatis
False
What is the most common bacterial STI in the USA?
Chlamydia trachmatis
What are the smallest known self-replicating organisms?
Mycoplasma and Ureaplasma
Describe Mycoplasma
No LPS Gm+ Very common No cell wall sterols
What is the major Mycoplasma pathogen?
M. pneumonia
Where does M. pneumonia live?
Surface of respiratory epithelium
*destroys ciliated cells
What type of inflammation does M. pneumonia elicit?
How?
Local
super antigen
What is “walking pneumonia”?
atypical, mild
T/F
Mycoplasma species have been implicated in genitourinary tract diseases, PID, and STI’s
True
What are Koch’s 4 postulates to determine causality of agent?
- Found in all cases
- grown
- cause disease when introduced
- reisoloation from inoculated host and identified as identical to original causative agent
What causes diphtheria and where is it found?
Corynebacterium diphtheriae
skin, upper respiratory, GI
What are 3 defining characteristics of C. diphtheriae?
G+
non-spore forming
Rods (bacilli)
What kind of toxin does C. diptheriae make and how is it spread?
A-B exotoxin
(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
Throat
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?
Pseudomembrane
Suffocation
*difficult to dislodge without making underlying tissue bleed
How is diphtheria treated?
How avoided?
anti-toxin
toxoid (modified immunogenic toxin)
Besides C. diphtheriae, what causes a pseudomembrane to form?
Candidiasis
T/F
Diphtheria is non-invasive.
True
*toxin invades
Two major ways to die from diphtheria?
Suffocation
Heart
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
T/F
A minimum amount of metabolism goes on in endospores.
False
NO metabolic processes
Structure of endospore:
Dehydrated core with DNA
thick Peptidoglycan
Keratin-like protein
What are 2 of the most common and important spore forming bacteria?
Bacillus
Clostridium
Describe Clostridium: metabolism Gram Shape spore forming? where found
Obligate anaerobe G+ Bacilli (rods) spore forming ubiquitous
What are the 4 Clostridium human pathogens?
C. tetani
C. botulinum
C. perfringens
C. difficile
*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
T/F
Botulism causes “true” food poisoning.
True
T/F
Perfringens is an infection food poisoning
True
What is the worldwide mortality rate for tetanus?
For infants?
20-50%
90%
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)
T/F
The immune system can respone to C. tetani and C. botulinum.
False
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?
Gas gangrene
Food poisoning
What type of exotoxin does C. perfringen produce?
mostly Cytolytic
*huge number
What is the mode of most C. perfringens food poisoning?
left out meat
What Clostridium is associated with broad spectrum antibiotics?
C. difficile
*has 2 exotoxins
What is another G+ spore forming pathogen other than Clostridium species?
Bacillus anthracis
*this is a HUGE G+
What are the 3 types of pathologies caused by Bacillus anthracis?
Mortality rates?
Cutaneous anthrax (20%) Pulmonary anthrax (90%) GI anthrax (50%)
What type of toxin is released by Bacillus anthracis?
two potent A-B exotoxins
Edema Toxin
Lethal Toxin
*uses Macrophage taxis
What is the Bacillum species that causes true food poisoning, mostly by re-heated fried rice?
Bacillum cereus
What are the 2 most important species of Mycobacterium affecting humans?
M. tuberculosis
M. leprae
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)
T/F
1/3 of the world is infected with TB
True
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
T/F
TB grow fast
False
T/F
TB is an Obligate Aerobe
True
Why is milk pasteurized?
TB is sensitive to heat
What are some morphological features of M. tuberculosis?
Poor staining Gram+
lipid rich
Acid Fast
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?
1.2 million
What are 3 major problems in wiping out TB?
complacency
poor compliance
multi-drug resistance
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
T/F
M. tuberculosis has resistance to enzymes, pH, drying
True
How is TB detected in the US?
PPD skin test
IFN-gamma release assay
How is the vaccine (BCG) for TB made?
from M. bovis
makes cross reactive immunity
(false + PPD screens)
