Exam 2 Flashcards
(133 cards)
1
Q
What are the main virulence factors of N. meningitidis
A
- Fimbrae, to attach to nasopharynx
- capsule, antiphagocytic and different serotypes
- IgA protease, to destroy IgA of course
- LPS blebs, systemic inflammation if in blood
2
Q
How is N. meningitidis spread
A
Via respiratory droplets among individuals with prolonged contact
3
Q
What are the natural carriers of N. meningitidis
A
Only humans
4
Q
What is the asymptomatic carrier rate of N. meningitidis
A
~10% of individuals
5
Q
Who is most susceptible to N. meningitidis
A
Babies, elderly, late teens, and those who live in crowded conditions
6
Q
Which of the virulence factors do all invasive strains of N. meningitidis have
A
Anti-phagocytic capsule
7
Q
What makes an individual susceptible to N. meningitidis
A
Lack opsinizing antibodies to the particular strain, and further compromised by respiratory damage (smoking, infection)
8
Q
What diseases can N. meningitidis cause, and which is the most severe
A
meningitis (10% fatality) and meningococcal sepsis (40% fatality)
9
Q
How does meningococcal sepsis cause damage
A
Bacteria blebs off outer membrane which activates monocytes to produce large quantities of cytokines. This causes systemic inflammation, with decreased blood pressure, disseminated intravascular coagulation, etc “septic shock”
10
Q
What is meningitis
A
N. meningitides make their way to the brain and set up home there, where their endotoxin triggers a massive immune response with local and systemic inflammation
11
Q
What are the methods for prevention of meningococcal disease
A
antimicrobial prophylaxis of persons in close contact with a carrier, and vaccination
12
Q
What are some viruses that cause lymphocytic meningitis
A
coxsackie and polio
13
Q
What are the main causes of acute purulent meningitis in neonates
A
Strep. pneumoniae, H. influenza
14
Q
What are the main causes of acute purulent meningitis in children
A
H. influenza, N. meningitidis, Strep pneumoniae
15
Q
What are the main causes of acute purulent meningitis in adults
A
N. meningitidis, strep. pneumoniae
16
Q
What are the main causes of acute purulent meningitis in elderly
A
Strep. pneumoniae
17
Q
Viruses and bacteria can both cause meningitis and encephalitis, which is more common and which is more deadly
A
Viral is more common, bacterial is more deadly
18
Q
Where is Neisseria normally found
A
It is a normal, hardy, oral species
19
Q
Are the pathogenic Neisseria bugs hardy?
A
nope! very fragile actually and drying kills it
20
Q
Is Neisseria gam positive or negative
A
Negative, it’s got LPS
21
Q
What is the appearance of Nesseria under the microscope
A
Pairs, “the official bacteria of starbucks” because it looks like a coffee bean
22
Q
What are the main virulence factors of N. gonorrhoeae
A
- Fimbrae (attachment and escape phagocytosis) 2. Ag-variation of pili structure (gene conversion and phase variation) 3. Surface receptors for host protein (camo) 4. IgA protease 5. LPS 6. Penicillin resistance (beta-lactimase) 7. Intracellular (hide)
23
Q
Why does N. gonorrhoeae remain a local infection
A
It doesn’t have a capsule
24
Q
What is the natural reservoir for N. gonorrhoeae
A
humans, particularly the asymptomatically infected person (usually a woman)
25
What could happen if a N. gonorrhoeae infection is left untreated
10-20% of untreated women develop pelvic inflammatory disease, which can result in scarring, sterility, and ectopic pregnancy
26
What risk do newborns have in contracting a N. gonorrhoeae infection
They can get gonorrhoeae in their eyes via the whole birthing process, so they are often treated with antimicrobial drops in their eyes
27
Why is there no vaccine for N. gonorrhoeae
Because it has so many variable surface antigens (epitopes)
28
Can you get N. Gonorrhoeae from a toilet seat
extremely unlikely since it is a very fragile bug; needs mucosal contact
29
What are the top 4 STI's in the US
1. HPV 2. Chlamydia 3. Trichamoniasis 4. Gonorrheae
30
Where does N. Gonorrhoeae live and replicate
In mucosal cells, usually in the genital tract, occasionally oral or eyes (newborns). They also pass through to the lamina propria
31
Can you be reinfected with N. Gonorrhoeae
Absolutely. The antigenic variation and phase variation means that we have poor immunity to them
32
What type of infection does N. Gonorrhoeae cause
A local, pyogenic infection. Thanks, LPS!
33
What type of cells are killed by N. Gonorrhoeae
ciliated columnar cells = ulcerant
34
Can you ever get rid of N. Gonorrhoeae infection without antibiotic treatment
Yes, it often 'self cures' in 2-3 weeks.
35
What does rickettsia, chlamydia, and mycoplasma have in common
They are all very small, gram negative coccobacilli and all steal from their host
36
What type of environment does N. Gonorrhoeae like
Microaerophilic
37
What do rickettsia and chlamydia steal from their host
They are intracellular obligate parasites that steal ATP and amino acids
38
What does mycoplasma steal from its host
It is an extracellular parasite that steals host cholesterol and lipids to strengthen its cell membrane.
39
What type of infection does Rickettsia cause
Systemic infections by infecting endothelial cells, with capillary blockage and fever caused by LPS
40
What type of infection does chlamydia cause
local infection IN mucosal epithelium
41
What type of infection does mycoplasma cause
Local infection ON mucosal epithelium, and releases a super-ag that is the main cause of epithelial damage
42
What is the cell wall situation with rickettsia, chlamydia, and mycoplasma
Rickettsia has a cell wall and LPS, chlamydia has LPS but no cell wall, and mycoplasma has no LPS and no cell wall
43
What diseases do rickettsia cause
Spotted fever, Typhus, Q fever (systemic LPS)
44
What diseases does chlamydia cause
eye infection (not so much in the US), STI chlamydia
45
What diseases does mycoplasma cause
pneumonia and urethritis
46
What is the main reservoir for Rickettsia
animals and arthropods
47
What is the main vector for Rickettsia
arthropods
48
What is the reservoir for R. prowazekii
Human
49
What disease does R. prowazekii cause
Epidemic typhus, which spreads human to human in crowded, poor sanitary conditions by body lice.
50
What is endemic (murine) Typhus
A common but mild disease caused by rickettsia typhi with urban rodents as its main reservoir
51
What are the three majors species of Chlamydia
C. trachomatis, pneumoniae, psittaci
52
What disease does C. trachomatis cause
STI, and another strain causes trachoma
53
Which species of Chlamydia is best adapted to humans as the host
C. trachomatis. C. psittaci is a bird bacteria, and C. pneumonia is very mild
54
How are C. trachomatis eye infection strains spread
From eye-to-eye by tears, hands and flies, repeat infection leads to permanent inflammation and in-turning of the eyelids resulting in blindness
55
How does chlamydia STI compare to gonorrhoeae STI
4x more chlamydia STI than gonorrhoeae, both untreated lead to PID, and chlamydia is not treated with penicillin because it has no cell wall
56
What is the main disease that Mycoplasma pneumonia causes
walking pneumonia. Other species cause mild UTI and genital diseases
57
What type of environment does Mycoplasma like
Common inhabitants of mucosa; they are facultative
58
What is the main pathology of mycoplasma
It produces a toxin which decreases ciliary action and epithelial sloughing leading to poor mucus clearance
59
What type of bacteria is Corynebacterium
Gram positive, non-spore-forming rod (bacilli)
60
Where is Corynebacterium found
It is ubiquitous in plants and animals
61
Where does Corynebacterium colonize humans
Skin, URT, and GI. All can be opportunists
62
What makes Corynebacterium diphtheriae pathogenic
It is infected by a virus that carries the genetic information for an AB exotoxin
63
What type of infection is diphtheria
Local infection, systemic disease
64
What is a main sign of a C. diphtherium infection
The production of a psuedo-membrane of a thick, proteinaceous matrix, that causes bleeding when dislodged
65
What does the AB exotoxin in C. diphtheriae do
It causes a major decrease in protein synthesis and primarily affects heart tissue, causing permanent heart damage and/or death
66
What is a toxoid
a toxin that has been modified so that it is no longer pathogenic, but is still immunogenic
67
What is an anti-toxin
something (antibody) that neutralizes a toxin
68
What type of bacteria form spores
Some gram positive, but never gram negative, bacteria like Clostridium and Bacillus
69
What is a spore
Dehydrated, multi-shelled structure that allows the bacterium to exist in 'suspended animation' for an incredible period of time
70
How does a spore keep a bacterium alive for so long
The structure of a spore protects the DNA from desiccation, heat, radiation, enzymes, and chemicals
71
What type of bacteria are Clostridium
Gram positive, obligate anaerobic bacilli capable of forming spores
72
What Clostridium species are human pathogens
C. tetani, botulinum, perfringens, difficile
73
What is the main pathology of Clostridium tentani
It produces an AB exotoxin that blocks inhibitory neuron release of glycine causing spasmodic paralysis
74
What is the main pathology of Clostridium botulinum
It produces an AB exotoxin that blocks the release of acetyl choline causing flaccid paralysis
75
What is the lethal dose of C. tetani or botulinum
roughly 0.1 microgram
76
How does one get a C. tetani infection
a dirty wound. Spores get way into a wound, where there are nice anaerobic necrotic conditions which prompt it to germinate
77
How does one get a C. botulinum infection
By eating food that was improperly canned and thus allowed C. botulinum to germinate, or it will also germinate in the gut of an infant.
78
How does C. Perfringens cause gas gangrene
Spores get into a deep wound, germinate, and then produce massive amounts of cytolytic exotoxins and digestive factors
79
How does C. perfringens cause food poisoning
Not a true food poisoning, one eats food (typically meat) that has been left out for too long. In the small intestine, they release a toxin that causes cramping and diarrhea
80
How does C. difficile cause pseudomembrane colitis
After receiving antibiotic therapy, the C. difficile overgrows and produces 2 exotoxins. It forms a pseudomembrane that blocks the colons function
81
How serious is C. difficile infection
it has a 10-15% mortality, partially because many people who get it are already sick. But deaths have 2x in the past 10 years thanks to a particularly virulent strain
82
What type of bacterium is Bacillus anthracis
gram positive, spore forming, facultative bacillus
83
What are the main sites of infection for Bacillus anthracis
Cutaneous, pulmonary, gastrointestinal
84
What is the main pathology of Bacillus anthracis
Macrophage taxis, Edema AB exotoxin, Lethal AB exotoxin
85
What is the mortality rate of anthrax
cutaneous: 20% GI: 50% Pulmonary: 90% mortality
86
Who is most at risk for a Bacillus anthracis infection
Primarily grazing animals, and those who handle them
87
What type of bacterium is Mycobacterium tuberculosis
Acid-fast, aerobic slender rod
88
What is the main virulence factor of Mycobacterium tuberculosis
Lipid rich wall/coat that is resistant to disinfectants, detergents, common abx, and traditional stains
89
What is the typical treatment for a Mycobacterium infection
Because the body can't rid itself of Mycobacterium by itself, a long, multi-drug course of antibiotics is necessary
90
What cell does Mycobacterium tuberculosis typically infect
Macrophages; it evades phagocytosis with its waxy coat
91
What is the main reservoir for Mycobacterium
humans
92
What are the disease stages of M. tuberculosis infection
Latent infection, in which you are infected but not infectious, and active disease in which you are infected and infectious
93
What are problems with getting rid of a M. tuberculosis infection
Compliancy is traditionally poor, and so multi-drug resistant strains have been bred.
94
Who normally develops active tuberculosis disease
Those with a compromised immune system
95
What tissue does Mycobacterium leprae normally infect
Schwann cells in the periphery and cool parts of the body
96
What slows the progression of a Mycobacterium Leprae infection
Launching a Th1 response (tuberculoid, humoral) to isolate the bacteria in granulosas
97
Why doesn't a Th2 response work well against Mycobacterium leprae or tuberculosis
Because antibodies and c' are ineffective against it, and CD8 doesn't help either
98
What is the main transmission route for M. tuberculosis
Respiratory from person to person, M. bovis can spread from cows or dust to a person
99
How hardy is M. tuberculosis
It is resistant to chemicals and drying (5% phenol for 24 hrs) and heat sensitive (30 minutes at 62 C) this is the basis for pasteurization and sterilization protocols
100
How long does it take M. tuberculosis to double
10-20hrs (sloooooow)
101
How many people have died from TB in the last century
1.5 billion! that's 5% of all deaths
102
Who is at risk for TB
Alcoholics, crowding, poverty, homeless, prisons, drug abuse, HIV, Immune therapy, health workers
103
What are the classic signs of tuberculosis disease
chronic, bloody, productive cough, fever and night sweats, weight loss
104
What diagnostic techniques are used to confirm M. tuberculosis infection
PPD skin test or TST(cheap), lung X-ray, Sputum smear stain and culture, PCR (expensive machine)
105
Why doesn't the USA routinely recommend TB vaccination
Because TB is rare in the US, and then the PPD skin test would be worthless. Cost vs Risk
106
What is DOT
Directly Observed Therapy. This was designed to improve compliance with abx courses
107
What is the most popular TB vaccine
BCG: Attenuated M. Bovis, designed to stimulate CD4 cells, is 80% effective
108
What is the difference between parasitism and saphrophytism
A parasite's host is live, a saprophyte's host is dead
109
What is the different between commensalism and mutualism
Mutualism both parties benefit, commensalism only one benefits while the other is neutral
110
What type of organism is Candida
It is a fungus, eukaryotic mono cellular
111
What makes fungal infections tricky to treat
They are eukaryotes, like us, so they have very mechanisms drugs can target without damaging the patient
112
What are the sterols used in cell walls
Yeasts use: ergosterol and zymosterol. Animals use: cholesterol
113
What is the main virulent factor of fungi
C3b protease; enzyme that destroys proteins, like Ab and C'
114
What is candida's cell wall made of
Beta 1-4 N-AGM (chitin)
115
What are the 7 fungal pathologies
1. mycotoxicoses 2. hypersensitivities 3. superficial mycoses 4. cutaneous mycoses 5. subcutaneous mycoses 6. systemic mycoses 7. opportunistic mycoses
116
What causes mycotoxicoses
a variety of toxins, all gained by eating mushrooms and result in liver damage. Rare
117
What are fungal Hypersensitivities
Hay fever and asthma are IgE response to fungi, contact dermatitis to fungal products. Common
118
Where are superficial mycoses
in the outermost skin layers, hair. No immune response. Common
119
What cause cutaneous mycoses
Dermatophytes cause skin and nail infections. common
120
What causes subcutaneous mycoses
Fungi/spores that get into a wound. Serious. Rare
121
Who is susceptible to opportunistic mycoses
Young, old, immunocompromised individuals, oral appliance (dentures), IV catheter
122
What are the common opportunistic mycoses species
from common to rare: candida, cryptococcus, aspergillosis, pneumocystis
123
What is systemic mycoses
Typically a lung infection from a HUGE dose that overwhelms host immunity. Clinically similar to TB. Rare-ish
124
What is the most common fungal opportunist and what diseases does it cause
Candida albicans causes thrush and yeast infections
125
How many forms can candida take
3: single cell, non-seperated single cells "pseudohyphae", true hyphae
126
What prompts candida to switch forms
pH. it is yeast in acidic environments and switches to hyphae in basic environments
127
What is the most pathological form of candida
hyphae form. it secretes ammonia and may help it "jailbreak"
128
What is the best immune response to candidiasis
Th1 response; Ab's, C' are of no value because it has protease
129
What is the pseudomembrane in candidiasis composed of
Dead PMNs, live PMNs, fibrin, and fungal cells. It is easily wiped off
130
What is a common treatment for thrush
Painting it with crystal violet or gentian violet
131
What does skin do in a fungal infection
It often hyper-proliferates to increase protective keratin layer and to hopefully slough off the fungal colonization
132
What causes rocky mountain spotted fever
Rickettsia rickettsii. This is the most frequent and severe rickettsial disease in the US. Spread by ticks
133
What causes scrub typhus
Orientia tsutsugamuchi
