Infectious Disease - Basics of Microbiology Flashcards
(575 cards)
1
Q
What are the 2 types of organisms?
A
prokaryotes and eukaryotes
2
Q
What type of organism is bacteria?
A
prokaryotes
3
Q
what are the characteristics of prokaryotes?
A
very old form of life
no membrane bound organelles
no nucleus
nuclear material
free inside cell
bacteria are prokaryotes
4
Q
what are the characteristics of eukaryotes?
A
more modern form of life
membrane bound organelles
nucleus
plant and animal cells
protozoa
fungi
5
Q
What makes bacteria unique?
A
they are prokaryotes and a very old form of life
6
Q
What color are gram positive organisms on a gram stain?
A
purple
7
Q
What color are gram negative organisms on a gram stain?
A
red
8
Q
what is the difference between gram positive and gram negative organisms?
A
the contents of their cell wall gram positive have a very thick cell wall allowing for it to take up the gram stain and they have lipoteichoic acids gram negative have a much thinner cell wall/periplasm and an outer membrane
9
Q
what is unique to gram negative bacteria?
A
their outer membrane
10
Q
what is peptidoglycan?
A
major structural component of bacterial cell walls
polymer sheets of sugars and peptides
sheets cross-linked to other sheets
11
Q
what are peptidoglycans composed of?
A
sugars (NAG & NAM)
peptides - attach to NAM****; 3-5 aa long
12
Q
what is the quaternary structure of peptidoglycan?
A
sugar/peptide backbone makes chains that cross link with peptide cross bridges
13
Q
Why is peptidoglycan a target for some antibiotics?
A
human cells don’t have peptidoglycan
14
Q
what is the difference in the peptidoglycan in gram positive vs negative?
A
gram positive = up to 40 sheets; composes 50% or more of the cell wall
gram negative = very few sheets; only 5-10% of cell wall
15
Q
why do gram positive bugs stain purple?
A
because of the thick peptidoglycan layer in their cell wall traps the dye
16
Q
Which bacteria have unique cell walls?
A
mycoplasma
mycobacteria
chlamydia
17
Q
characteristics of mycoplasma
A
no cell wall does not gram stain cell membrane has sterols for extra stability
18
Q
characteristics of mycobacteria
A
cell wall has MYCOlic acid does not gram stain well special stain used (Ziehl-Neelsen)
19
Q
What makes the cell wall of chlamydia special?
A
lacks muramic acid
20
Q
What are the characteristics of the cell membrane in bacteria?
A
lipoprotein bilayer electron transport and ox phos enzymes and carrier molecules (bacteria lack mitochondria)
21
Q
what is a unique feature of gram + bacteria that drives immune rxns?
A
LTA - lipoteichoic acid
22
Q
what is LTA?
A
major surface antigen that drives immune rxns
23
Q
LTA has induced what abnormalities in animal studies?
A
arthritis uveitis meningeal inflammation cascades resulting in septic shock and multi organ failure
24
Q
what does LTA induce release of?
A
cytokines
25
LTA binds _____ and activates \_\_\_\_\_\_\_\_\_.
antibodies; complement cascade
26
What are the 2 unique features of gram negative bacteria?
periplasm outer membrane
27
what is periplasm? what does it contain?
space btwn cell membrane and outer membrane contains many enzymes
28
What is the main factor driving an immune response for gram + bacteria?
LTA
29
what are the most important enzymes in the periplasm?
ß-lactamases - inactivates Antibiotics
30
what is special about the enzymes found in the periplasm?
they allow the gram neg bacteria to resist antibiotics that have a ß-lactam structure
31
what is the most important component of the outer membrane of gram neg bacteria?
LPS - lipopolysaccharide
32
What is a major immune trigger for gram negative bacteria?
LPS
33
what are the components of LPS?
polysaccharide lipid A O antigen
34
lipid A
highly toxic triggers cytokine release
35
O antigen
target for antibodies
36
what are bacterial capsules?
sticky, gelatinous layer secreted by the bacteria that helps it to attach to host cells and protects against phagocytosis
37
what are capsules composed of?
mainly water with some polysaccharide
38
what is the exception for bacillus anthracis capsule?
capsule is protein = d-glutamate
39
what is d-glutamate?
major virulence factor that allows unimpeded growth
40
where is d-glutamate found?
capsule of bacillus anthracis
41
What is the quelling rxn used for?
detects capsule - mainly used to detect if strep pneumonia was the cause of a bacterial lung infection
42
How is the quelling rxn performed?
take rabbit antiserum and add it to bacterial slide capsule swells when visualized under the microscope
43
what are the + quelling rxn encapsulated bugs?
strep pneumonia H. influenza N. meningitidis E. Coli Salmonella Klebsiella Group B strep (agalactiae)
44
how does the body defend itself against encapsulated bacteria?
1. B-cells secrete capsular antibodies (IgG) - antibodies bind capsule to tag it for phagocytosis via Fc receptors 2. antibodies that bind to capsule can activate the complement cascade
45
what happens when the complement cascade gets activated?
formation of MAC --\> Cell death formation of C3b --\> opsonin
46
Loss of what will cause recurrent encapsulated bacterial infections?
loss of antibodies/b-cells or complement
47
patients without what organ are at a higher risk for infection from encapsulated bacteria?
spleen (i.e. sickle cell) asplenia = risk of sepsis from encapsulated bacteria; loss of splenic phagocytes
48
what is the basis for bacterial vaccines?
capsular polysaccharides
49
why is the polysaccharide capsule conjugated to an immune stimulator protein?
polysaccharides in capsule are weakly immunogenic
50
what is a glycocalyx?
"sugar coat" made of polysaccharides
51
what does bacteria use a glycocalyx for?
to adhere to surfaces (catheters)
52
what is the difference between the bacteria that use a capsule vs glycocalyx?
bacteria with distinct, firmly attached gelatinous layer = capsule bacteria with irregular, slimy fuzz layer = glycocalyx
53
major bacteria that uses a glycocalyx coat
S. epidermis - forms biofilm on catheters
54
Pili and fimbria are structurally similar to \_\_\_\_\_
flagella
55
what are pili/fimbria?
appendage/arm of bacteria, made of proteins
56
ordinary pili allows for adherence to \_\_\_\_\_\_
surfaces
57
\_\_\_\_\_ _____ attach to another bacteria for conjugation
sex pili
58
What is important about the pili of E. coli?
allows to attach in the urinary tract causing UTIs/pyelonephritis
59
what bacteria have pili with antigenic variation?
Neisseria Gonorrhea
60
What is antigenic variation?
bacteria change the makeup of the proteins of their pili
61
what are plasmids?
small DNA molecule within a cell, physically separated
62
What are flagella?
long protein arms that bacteria use to move
63
What are ribosomes?
site of protein synthesis
64
what are the subunits for bacterial ribosomes?
50S & 30S
65
Why do some antibiotics target bacterial ribosomes? (i.e. tetracyclines bind 30S subunit)
bacterial ribosomes differ from eukaryotic ribosomes which allows to selectively target the bacterial ribosome subunit
66
MOA aminoglycosides
interferes with 30S protein synthesis
67
some bacteria can enter a dormant state called \_\_\_\_\_\_\_\_\_
a spore "spore forming bacteria"
68
how are spores advantageous?
can survive a long period of starvation resistant to dehydration, heat, chemicals
69
are spores metabolically active?
no they are like a seed that has the potential to grow in the right conditions
70
what are the components of a spore?
coat - outermost cortex/core wall - innermost dipicolinic acid
71
what is the function of the spore coat?
impermeable to many chemicals and antibacterial agents
72
what are the spore components made out of?
coat = keratin-like protein cortex/core wall = peptidoglycans
73
dipicolinic acid may help with _________ \_\_\_\_\_\_\_\_\_\_
heat resistance
74
why is it difficult to kill a spore?
because their keratin-like coat is impermeable to many chemicals and antibacterial agents
75
what is found in large amounts within a spore?
dipicolinic acid
76
what are the major spore forming bacteria? (5)
Bacillus anthracis Bacillus cereus Clostridium perfringens Clostridium tetani Clostridium botulinum
77
what are the 3 methods used to identify bacteria?
shape color after staining special tests
78
what are the 3 common bacterial shapes?
cocci - sphere bacilli - rod coccobacillus - mixture
79
what are the patterns seen for cocci?
diplococci - pairs streptococci - chains staphylococci - bunches/clusters
80
why/how do streptococci form chains?
each new bacteria forms away from the older bacteria so that you get them forming away from each other to get these long curved chains
81
most cocci are gram \_\_\_\_
positive
82
what are the 2 main gram positive cocci?
streptococcus and staphylococcus
83
what are the gram negative cocci bacteria?
Neisseria (meningitidis/gonorrhea) Moraxella catarrhalis
84
rods are also called what?
bacilli
85
most rods and coccobacillus are gram \_\_\_\_\_
negative
86
what are the few gram positive rods?
Corynebacterium (diphtheria) Clostridium Listeria Bacillus (anthrax, cereus)
87
what are some other less common bacteria shapes?
branching/filamentous spirochetes vibrio
88
Main bacteria that have a branching/filamentous shape
actinomycetes nocardia
89
Branching/filamentous bacteria look like \_\_\_\_\_
fungi
90
what are the main spirochetes?
Treponema (syphilis) Borrelia (Lyme disease) Leptospira (leptospirosis)
91
what 2 bacteria are described as being pleomorphic and an obligate intracellular pathogen?
Rickettsia Chlamydia
92
What are pleomorphic bacteria?
bacteria that can take on many shapes
93
What are the common bacterial stains?
gram stain Giemsa Ziehl-Neelsen Silver India ink - crypto coccus (fungi)
94
what are the simple stains used to visualize bacteria?
methylene blue safranin crystal violet
95
what are the steps of a gram stain?
fixation crystal violet iodine (all bacteria look purple) decolorization - gram Positive are Purple safranin - gram Positive still Purple, gram negative are red/pink
96
what color is gram positive on a gram stain? why?
Positive = Purple they retain crystal violet in cell walls to look purple
97
what color is gram negative on gram stain? why?
red = do not retain crystal violet in cell walls - take up safranin counter stain
98
why is gram positive purple?
thick cell wall of peptidoglycan in gram positive bacteria
99
What bugs do not gram stain well?
treponema (syphilis) - too thin to see mycobacteria (tuberculosis) - mycolic acids in cell wall mycoplasma - no cell wall intracellular bacteria
100
what are the main intracellular bacteria?
Rickettsia - obligate intracellular Chlamydia - obligate intracellular; no muramic acid cell wall Legionella - mostly intracellular
101
what is the stain used for mycobacteria called?
acid fast
102
what is muramic acid?
1 of the 2 components of peptidoglycan
103
What is the Giemsa stain?
mixture of methylene blue, eosin, and Azure B
104
How does the Giemsa stain work?
enters cells and stains nucleic acids
105
What is the Giemsa stain used for?
protozoa - plasmodium & trypanosomes intracellular bugs -chlamydia, rickettsia, borrelia (sometimes intracellular)
106
Giemsa stain is used for what purpose?
to get inside the cells
107
What is the Ziehl-Neelsen stain?
acid-fast stain used to detect mycobacterium (esp. TB), nocardia
108
What is carbolfuschin?
used in the acid-fast stain to visualize mycobacterium (esp. TB) also used for nocardia
109
How does the acid fast stain work?
carbolfuschin stains everything purple then acid solvent is used to decolorize anything that is not an acid fast bug
110
The silver stain is used for what 3 organisms?
Pneumocystis pneumonia (HIV/AIDS) Legionella H. Pylori
111
contaminated water w/ outbreaks in nursing homes is characteristic of what bacteria?
Legionella
112
Gastric ulcers are caused by what bacteria?
H. Pylori
113
What stain is used for fungi and yeast?
india ink
114
what is different about India ink?
it is a negative stain, meaning it makes the background very dark not the organisms and the unstained organisms stand out in contrast to the dark background
115
India ink is used primarily to detect what bacteria?
cryptococcus neoformans
116
When stained with India ink, what pattern will you see if the is cryptococcus neoformans present?
the large polysaccharide capsule creates halos
117
what is cryptococcus neoformans?
a fungi that exists as a yeast
118
What special color is associated with each of the following bacteria? staph aureus pseudomonas aeruginosa serrate actinomyces
staph aureus - golden, yellow pseudomonas aeruginosa - blue-green (pyocyanin) serrate - red actinomyces - yellow-orange
119
when actinomyces "Cement" together what are they called?
sulfur granules
120
what does "aureus" mean?
gold
121
growth plates generally use what substance?
agar
122
what is needed for a growth plate?
agar in Petri dish nutrients added to support growth - sugar, water, salts, amino acids
123
what is agar?
semi-solid substance made from seaweed
124
why is agar used on growth plates?
because bacteria usually don't consume/decompose it so it will be there indefinitely to grow on top of
125
what are the two types of culture media?
non-selective & selective
126
what are non-selective culture media's used for?
general purpose, can grow many bugs
127
nutrient agar is what type of culture media?
non-selective
128
what is the most commonly used non-selective media?
blood agar
129
which type of culture media contain toxic substances?
selective culture media
130
What grows on Thayer-Martin media?
Neisseria
131
what is a disadvantage to using selective media?
contains toxic substances
132
what does it mean for a culture medium to be enriched?
special nutrients added so many bugs will grow
133
what does it mean for a culture medium to be differential?
different bugs grow with different patterns
134
What is blood agar enriched with?
sheeps blood
135
Why is blood agar considered a differential medium?
because some use alpha hemolysis and some use beta hemolysis
136
what type of culture media is blood agar?
enriched - blood differential - hemolytic patterns
137
what type of culture media is eosin methylene blue?
selective - only gram neg. differential - lactose fermenters
138
what do fastidious bacteria require?
special nutrients, won't grow on standard media
139
what are 2 important fastidious bacteria?
H. Influenza Legionella
140
what type of culture media is blood agar?
contain mammalian blood - usually 5% sheep blood non-selective enriched - blood differential - hemolysis pattern
141
What hemolysis patterns are seen on blood agar?
alpha, beta, gamma
142
why is there a zone a white around the beta hemolytic bacteria?
because they are completely hemolyzing all the blood cells that are around them
143
What are the different patterns of hemolysis on blood agar?
beta = lysis alpha = partial gamma = no lysis
144
why is blood agar so useful for identifying bacteria?
because it distinguishes a lot of different kinds of streptococcus
145
most gram positive bacteria are of what shape?
cocci
146
cocci are split into what 2 groups?
catalase (+) clusters - staph catalase (-) chains - strep
147
How do you distinguish between different types of strep?
see hemolysis pattern on blood agar
148
What strep are beta hemolytic?
s. progenies (group A) s. agalactiae (group B)
149
what strep are alpha hemolytic?
s. pneumonia s. viridans
150
what strep are gamma hemolytic?
enterococcus (group D) s. bovis
151
what gram negative rod is beta hemolytic?
pseudomonas
152
what is unique about pseudomonas beta hemolysis?
it produces greenish-metallic appearing colonies
153
what pigments are produced my pseudomonas creating the unique color on blood agar?
pyoverdin and pyocyanin (blue)
154
what staph is beta hemolytic?
staph aureus
155
what is chocolate agar?
variant of blood agar contains RBCs that are lysed by heating contains NAD (factor V) & hemming (factor X)
156
what bacteria is chocolate agar used to identify?
H. Influenzae \*\*\* very important to know
157
Why is H. Influenzae considered a fastidious organism?
Because it needs factor V (NAD) and factor X (hemin)
158
In what scenario would H. Influenzae grow on bood agar?
If s. Aureus is present
159
Where does the NAD needed for chocolate agar come from?
Inside RBCs
160
What is thayer-martin media selective for?
Neisseria (think M looks like N)
161
When testing for Neisseria why is it important to have a media that is selective?
Neisseria often come from sites with lots of other flora (throat, genitalia)
162
How is Thayer-martin media selective for neisseria?
It is enriched with vancomycin, colistin (polymyxin), & nystatin
163
What are the actions of vancomycin, colistin (polymyxin), & nystatin?
Vancomycin - kills most gram positive organisms Colistin - kills most gram negatives (except Neisseria) Nystatin - kills fungi
164
What agar is selective for Bordetella pertussis?
Bordet-Gengou Agar Aka Potato Agar
165
What does Bordetella pertussis cause? Why is it so rare?
Whooping cough; vaccines
166
Why is Bordet-Gengou agar aka potato agar?
Prepared from potatoes - high in starch which is favorable to pertussis bacteria
167
What 2 media are used to detect Corynebacterium diphtheriae?
Loffler’s media - selective Tellurite media - differential
168
What is another name for Tellurite media?
Cysteine-Tellurite agar
169
What does C. Diphtheriae look like on tellurite media?
C. Diphtheriae reduces K+ tellurite to tellurium producing gray-black colored colonies
170
What media is special for mycobacterium tuberculosis?
Lowenstein-jensen agar
171
What is lowenstein-jensen agar enriched with?
Eggs Flour Glycerol Salt
172
what stain is used for M. tuberculosis?
Ziehl-Neelsen stain (acid-fast)
173
why is it important to treat suspected patients for tb before lab cultures come back?
because M. tuberculosis is slow growing, it can take several weeks for visible colonies to appear
174
what is Eatons agar used to detect?
mycoplasma pneumonia
175
why its mycoplasma unique?
no cell wall - poorly visualized with gram stain
176
what is Eatons media enriched with to grow m. pneumonia?
cholesterol
177
why is m. pneumonia considered fastidious?
because it requires cholesterol to grow
178
why is Eatons agar rarely used in the modern era?
because it takes days to weeks to grow
179
how is mycoplasma pneumonia diagnosed?
serology (antibody testing) PCR (bacterial DNA) Cold agglutinins (IM antibodies)
180
What is MacConkey's agar selective for ?
gram negative bacteria
181
how is MacConkey's selective for gram negative?
contains bile salts as inhibitors of gram positive bacteria growth
182
how is MacConkey's differential for lactose fermenters?
lactose fermenters produce an acid that turns the agar pink; non-lactose fermenters are colorless
183
what shapes are gram negative bacteria categorized into?
diplococci coccbacillus rods comma (oxidase +)
184
what does sorbitol MacConkey agar detect?
E. coli O157:H7 strains (shiga-like toxin)
185
How does E. coli O157:H7 look on sorbitol MacConkey agar compared to other E. coli?
O157:H7 cannot ferment sorbitol and other E. coli can O157:H7 grows colorlessly and other E. coli produce pink colonies
186
buffered charcoal yeast extract is used to detect what bacteria?
Legionella (only 1 L in name - charcoaL)
187
why is it important to culture legionella?
can contaminate water supplies and cause an outbreak
188
what is another way to test for legionella?
urinary antigen test - only works for a "type 1 infection" (negative result is not definitive)
189
what is Sabouraud's agar selective for?
fungi
190
what inhibits bacterial growth in sabouraud's agar?
acid or antibiotics
191
If something is growing on Sabourauds agar what are they trying to tell you?
that it's a fungi
192
what are the 4 different bacterial growth environments?
obligate anaerobes - no O2 obligate aerobes - O2 only facultative anaerobes - both intracellular
193
what are the 2 biochemical methods used to generate ATP inside cells?
respiration fermentation
194
how does respiration produce ATP?
ETC requires O2 \*\*\*
195
how does fermentation produce ATP?
sugars --\> acids does NOT require O2\*\*\*\*
196
Does respiration or fermentation make more ATP?
respiration
197
what 2 enzymes present in aerobic organisms allows then to survive in environments with a lot of O2?
superoxide dismutase & catalase
198
what does superoxide dismutase do?
catalyzes superoxide (O2-) radical to O2 od hydrogen peroxide
199
what does catalase do?
converts hydrogen peroxide (H2O2) to oxygen and water
200
why do obligate aerobes need O2 to generate ATP?
because O2 is the final electron acceptor during respiration
201
what 3 bacteria are the main obligate aerobes?
pseudomonas aeruginosa mycobacterium tuberculosis nocardia (opportunistic infections)
202
what is the benefit of being an obligate aerobe?
can make a lot of ATP
203
obligate anaerobic bacteria are common among the normal flora or what?
gut and mouth
204
obligate anaerobes _____ (do/do not) cause communicable diseases?
do not
205
obligate anaerobes often live near ______ surfaces
mucosal
206
99% of fecal flora are obligate \_\_\_\_\_\_\_
anaerobes
207
when will an obligate anaerobe cause infection?
when the surface breaks down i.e. abscesses
208
what type of antibiotic will not work on anaerobes and why?
aminOglycosides require O2
209
what method do obligate anaerobes use to make ATP?
fermentation
210
what are the byproducts of fermentation?
gases - CO2 & H2 short chain FA's - acetic acid, isobutyric acid etc. causes a foul smell that you get from pustules
211
3 main obligate anaerobes
actinomyces - gums, dental abscess bacteroides - abdominal abscess clostridium
212
what are the 3 types of clostridium?
botulinum perfringens tetani
213
what are two key anaerobic infections?
abdominal abscesses/perforations aspiration pneumonia
214
What anaerobic bacteria is the cause of abdominal abscesses/perforations?
Bacteroides fragilis
215
what is the treatment for b. fragilis?
metronidazole w/ gram neg. agent
216
b. fragilis \_\_\_\_\_(is/is not) resistant to many antibiotics
is
217
what happens in aspiration pneumonia?
when you aspirate vomit, mouth anaerobes enter the lungs
218
what 3 bacteria commonly cause aspiration pneumonia?
peptostreptococcus fusobacterium prevotella
219
what is the treatment for aspiration pneumonia?
clindamycin
220
what antibiotic is used on anaerobic infections above the diaphragm?
clindamycin (lungs)
221
what antibiotic is used on anaerobic infections below the diaphragm?
metronidazole (abscesses/perforations)
222
what are facultative anaerobes?
can live w/o O2 but use it when it's available
223
what type of organism can perform respiration and fermentation?
facultative anaerobe
224
what is the Pasteur effect?
if a facultative anaerobe is in an environment with O2, fermentation is inhibited
225
what 3 common bacteria are facultative anaerobes?
staph strep E.coli
226
How do obligate intracellular bacteria get ATP?
depend on host cell
227
how come obligate intracellular bacteria do not gram stain well?
because they live inside other cells so it is difficult to get them on a slide
228
what are 3 disadvantages of intracellular bacteria
cannot synthesize their own ATP do not gram stain well difficult to grow - need cell culture
229
what are the 2 most important obligate intracellular bacteria to know?
Rickettsia Chlamydia
230
What does Rickettsia cause and how is it Dx'd?
Rocky Mountain spotted fever Dx'd clinically or w/ Ab tests
231
How is Chlamydia Dx'd?
DNA testing
232
what are facultative intracellular bacteria?
they can live inside other cells if they need to
233
what bacteria are facultative intracellular?
mycobacterium legionella salmonella neisseria listeria brucella francisella yersinia pestis
234
what facultative intracellular bacteria use macrophages?
mycobacterium legionella listeria brucella francisella yersinia pestis
235
besides macrophages, what cell does listeria use? what about brucella?
listeria - monocytes brucella - neutrophils
236
what facultative intracellular bacteria uses intestinal cells?
salmonella
237
what facultative intracellular bacteria uses urethral epithelial cells?
neisseria
238
what does the bacterial growth curve look like in the lag phase?
its a flat line because the bacteria are not dividing
239
what happens in the growth phase of the bacterial growth curve?
aka exponential phase/log phase bacteria have started to multiply
240
what is the generation/doubling time in reference to the bacterial growth curve?
time it takes for the # of cells to double
241
during what phase of the bacterial growth curve do antibiotics have their greatest effect?
growth phase
242
what happens in the stationary phase of the bacterial growth curve?
bacteria are continuing to grow but they are also starting to die bc there is a lack of nutrients amt of death = amp of growth total # of bacteria doesn't change
243
what does the stationary phase look like on the bacterial growth curve?
flat line amt of death = amt of growth
244
what happens during the death phase of the bacterial growth curve?
the number of bacteria dying exceeds the number that are growing and the number of bacteria decreases and the growth curve shows a downhill slope
245
what is so important about bacterial gene transfer?
key for evolution of antibiotic resistance
246
why would antibiotics stop working leading to development of antibiotic resistance?
the bacteria have evolved and now have genetic resistance to a given antibiotic
247
what are the 3 key mechanisms by which which bacteria transfer genes?
transformation conjugation transduction
248
what is the easiest method of bacterial gene transfer?
bacterial transformation
249
what is bacterial transformation?
direct uptake of DNA from the surrounding environment allows fo evolution of DNA over time
250
what mechanism is used when transferring genes to introduce them to bacteria for replication?
bacterial transformation
251
what is bacterial conjugation'?
when one bacteria cell directly transfers genetic information to another cell using an appendage called a pilus
252
what are sex pili?
what bacterial cells use to transfer genetic info during conjugation
253
How is the DNA transferring in bacterial conjugation?
via plasmids
254
what are plasmids?
small DNA molecules within a cell that are physically separated from chromosomal DNA
255
plasmids can replicate \_\_\_\_\_
independently
256
what can the genes found in plasmids code for?
antibiotic resistance toxins
257
how is it proven that conjugation takes place between two bacteria?
transformation vs. conjugation experiment where 2 different strains that require 2 different amino acids for growth were put together w/ DNAase and they grew proves that genetic material must have been transferred through conjugation bc the DNAase destroyed any leaked DNA
258
what do high frequency strains of bacteria do?
they take plasmids and incorporate it into their DNA
259
Why are high frequency strains of bacteria important?
because when they conjugate with a bacteria that doesn't have the plasmid they tend to transfer their entire genome along with the plasmid
260
what are high frequency strains used for?
gene mapping
261
What is the site of origin of genetic transfer for high frequency strains?
plasmid
262
What is Lancefield grouping?
system to classify streptococci based on C carbohydrates in the cell wall that allow agglutination with particular antisera
263
Lancefield Group A
Strep pyogenes
264
Lancefield Group B
Strep agalactiae
265
Lancefield Group D
enterococcus
266
what are the hemolysis patterns seen on blood agar?
β = lysis - will have a white ring around the bacteria because of hemolysis α = partial γ = no lysis
267
what is the catalase test used for?
to differentiate staph from strep
268
what are the gram + rods?
clostridium corynebacterium listeria bacillus
269
what are the gram + cocci and how do you distinguish them?
1. catalase (+) staph 2. coagulase (+) S. aureus 3. novobiocin sensitive - S. epidermidis 4. novobiocin resistant - S. saprophyticus 1. catalase (-) strep 2. blood agar hemolysis β --\> bacitracin test α --\> optochin test γ --\> bile-esculin agar bacitracin sensitive - S. pyogenes (group A) bacitracin resistant - S. agalactiae (group B) optochin sensitive - S. pneumonia optochin resistant - S. viridans bile & NaCl - enterococcus bile only - Strep. bovis
270
what is the algorithm for gram positive bacteria?
272
what 2 gram positive bacteria resemble fungi?
actinomycesnocardia
273
what gram positive bacteria is catalase +, coagulase +?
staph aureus
274
strep grows in \_\_\_\_\_\_
chains
275
staph grows in \_\_\_\_\_
clusters
276
What system classifies only streptococci?
lancefield grouping
277
what are the different forms of cocci?
diplococci - pairsstreptococci - chainsstaphylococci - clusters
278
what is the catalase test?
differentiates staph from strepH2O2 on slide + bacteria--\> bubbles = catalase +
279
what does the catalase enzyme do?
produced by bacteria that use oxygenbreaks down H2O2 into H2O and O2 = bubbles
280
how do you know that staph is aerobic?
because it has catalase and only organisms that use oxygen will have catalase
281
what is chronic granulomatous disease?
loss of function of NADPH oxidase - phagocytes cannot generate H2O2 to kill bacteria
282
what is the importance of NADPH oxidase?
respiratory burst - phagocytes use NADPH oxidase to generate H2O2 from O2
283
how come people with CGD can still clear catalase negative infections?
catalase negative bacteria generate their own H2O2 which the phagocytes use for respiratory burst despite the loss of functions of NADPH oxidase
284
what 5 organisms cause almost all CGD infections?
staph aureus\*pseudomonasserratianocardiaaspergillus\*all catalase +
285
why do ppl with CGG get recurrent catalase + bacterial infections?
no NADPH oxidase = no H2O2 = no resp. burst = recurrent infections
286
what is the coagulase test used for?
differentiates staph aureus from other staph
287
how is the coagulase test done?
add rabbit plasma to tube with bacteriacoagulase causes fibrin clots (clumping)clumping = coagulase +no clumping = coagulase negative
288
what is the novobiocin sensitivity test used for?
differentiates S. saprophyticus from S. epidermidis
289
how is the novobiocin sensitivity test done?
plate bacteria on agar with novobiocin "disk"measure clearance zone around diskresistant = growth near edge of disksensitive = large zone of clearance around disk
290
what is the bacitracin sensitivity test used for?
differentiates group A strep from group B strep
291
what does bacitracin interfere with?
peptidoglycan synthesis
292
how is the bacitracin sensitivity test done?
plate bacteria on agar with bacitracin disk and measure the clearance zone
293
how do all antibiotic sensitivity tests work?
plate bacteria with antibiotic disk and measure the zone of clearance around the diskresistant = no zonesensitive = large zone
294
what is the optochin sensitivity test used for?
differentiate S. pneumonia from S. viridans strep
295
what bacteria is optochin sensitive?
S. pneumonia
296
ethylhydrocupreine
optochin
297
what is bile-esculin agar selective for?
group D strep - enterococcus and strep bovismedia turns dark brown/black
298
why does bile-esculin agar only grow group D strep?
bile salts inhibit most gram positive bacteria but group D strep can hydrolyze esculin and the media will turn brown/black
299
how can you differentiate the 2 group D strep?
NaCl media - differentiates enterococcus from non-enterococcus group D bacteria
300
how does NaCl media differentiate enterococcus?
enterococcus is salt tolerant and can grow in high salt concentrations so if the bacteria grows on NaCl you know its enterococcus and if not it is strep bovis
301
what is mannitol salt agar (MSA) used for?
differentiates staph species
302
what is used in MSA to differentiate staph?
high [salt] + mannitol + pH indicator (phenol red)mannitol fermenters make acid --\> phenol red turns yellow
303
what color is s. aureus on MSA?
yellowmannitol fermenter = acid = phenol red turns yellowmost other staph do not ferment mannitol
304
what are the shapes of gram negative bacteria?
diplococcicoccobacillusrodscomma shape
305
what are the gram negative coccobacillus?
haemophilus influenzapasteurellabordetella pertussisbrucellayersinia pestis
306
what are the gram negative diplococci?
Neisseria meningitidis (maltose fermenter)Neisseria gonorrhea (non-maltose fermenter)
307
gram negative rods can be further divided into what?
lactose fermenter & lactose non-fermenter
308
what gram negative rods are "fast" lactose fermenters?
klebsiellaE. coliEnterobacter
309
what gram negative rods are "slow" lactose fermenters?
citrobacterserratia
310
what gram negative rods are oxidase (+) lactose non-fermenters?
pseudomonasH. pylori
311
what gram negative rods are oxidase (-) lactose non-fermenters?
shigellasalmonellaproteus
312
what are the comma shape gram negative bacteria?
campylobacter (grows in warm temps 42ºC)vibrio (grows in alkaline environments)
313
which neisseria species can metabolize maltose?
meningitidis
314
what agar is used to test for lactose fermentation?
MacConkey's
315
how is MacConkey's agar selective for gram negative bacteria?
contains bile salts to inhibit the growth of gram positive bacteria
316
what color will gram negative bacteria that can ferment lactose be when placed on MacConkey's agar?
pinklactose fermentation produces acid turning the agar pinknon-lactose fermenters are colorless
317
what are "slow" fermenters?
citrobacter and serratia can initially appear as non-lactose fermenting due to slow growth, longer incubation will show growth and turn media pink
318
the oxidase test is for what enzyme?
cytochrome oxidase
319
how does the oxidase test work?
bacterial colonies on paper discs w/ indicator that will change color in the presence of oxidase
320
what are the 2 groups of oxidase + gram negative bacteria?
lactose non-fermenting rodscomma shaped
321
how can you differentiate oxidase negative gram negative rods?
hydrogen sulfide testing (H2S)
322
what bacteria are distinguished using H2S?
salmonella and proteus produce H2Sshigella does NOT produce H2S
323
what test is used to look for production of hydrogen sulfide?
triple sugar iron (TSI) testorganisms that produce H2S will turn TSI media black
324
what are virulence factors?
bacterial features that allow evasion of host defensesprotein AIgA proteaseM protein
325
what is protein A?
key virulence factor for staph Aureuspart of the peptidoglycan cell wallinhibits phagocytosis
326
how does protein A help the bacteria evade the immune system?
inhibits phagocytosis by binding Fc of IgG preventing opsonization and phagocytosis by macrophages and prevents complement activation
327
what is IgA protease?
enzymes that cleave IgA, allows for colonization of mucosal surfaces
328
IgA is important for what?
mucosal infections (GI, Resp)
329
IgA protease is an important virulence factor for what bacteria?
s. pneumoniah. influenzaneisseria gonorrhoeae & meningitidis
330
what helps s. pneumonia get into the respiratory tract?
IgA protease
331
What is the M protein?
surface molecule of group A strep (s. pyogenes)
332
how does the M protein work?
prevents phagocytosis by interfering with the complement system:binds to factor H (protects our own cells from complement activation)breaks down C3-convertase, prevents opsonization by C3b
333
M protein causes the Sx seen in what illnesses?
strep throatrheumatic fever
334
what is thought to be the bases of rheumatic heart disease?
M protein shares properties with myosin-\> autoimmune damage to the heart in pts that have had a bacterial infection w/ s. pyogenes
335
what are the post-strep complications that M protein is responsible for?
rheumatic heart diseaseglomerulonephritis\*different subtypes of M protein
336
endotoxin vs. exotoxin
endotoxin - component of the outer cell membrane of gram neg. bugsexotoxin - proteins synthesized by some bacteria
337
endotoxins are found only in gram ______ bacteria
negativegram positive bacteria do not have an outer cell membrane
338
LPS
lipopolysaccharidewhat makes up endotoxin
339
how is endotoxin released into the tissues?
when the cell dies
340
what is an important distinction regarding how bacterial toxins get into the blood?
endotoxin - cell dies and releases contents - NOT SECRETEDexotoxin - secreted
341
what are bacterial toxins made of?
endo - fat/sugarexo - protein
342
what key features do all endotoxins have?
Lipid A coreO antigen
343
what does lipid A do?
responsible for most of the toxicitytrigger the immune system and the secretion of cytokines causing hypoTN/edema etc.
344
O antigen
terminal end sugars that vary among bacterial strainsdo not cause disease by themselvestarget for the immune system, part of the way immune system targets and kills the endotoxin
345
how come people with gram neg. infections can get very sick?
endotoxin can lead to fever and shock by triggering the release of TNF and IL-1 which are key immune components of sepsis and shock
346
what 2 cytokines are important components of sepsis and septic shock?
TNFIL-1
347
why can't you vaccinate against endotoxin?
because it generates a weak Ab response
348
endotoxin is heat \_\_\_\_\_\_\_
stable - can tolerate high temps
349
what are the 3 ways that endotoxin/LPS can activate the immune system?
macrophagescomplementtissue factor
350
how does LPS activate macrophages?
binds to receptor CD14 aka endotoxin receptor
351
once macrophages are activated by LPS what do they secrete?
IL-1: feverTNF: fever & hypoTNNO: hypoTN
352
what happens when LPS activates the complement system?
C3a and C5a get released
353
how will a patient present with a gram neg. infection that has activated complement via LPS?
C3a: hypoTN & edemaC5a: neutrophils chemotaxis & edema
354
what are anaphylatoxins?
toxins that cause anaphylaxiscomplement proteins C3a and C5a
355
C3a
hypoTNedema
356
C5a
neutrophil chemotaxisedema
357
How does endotoxin cause coagulation problems and DIC?
endotoxin directly activates TF (tissue factor) leading to coagulation problems and DIC
358
what is lipooligosaccharide?
LOSmake up endotoxin of some gram neg. bacteria (non-enteric)
359
what is the most important example of a gram neg. bacteria whose endotoxin is made up of LOS? how is this different than LPS?
N. meningitidislacks O-antigen
360
what are the systemic reactions a person can develop from endotoxin?
meningococcemiagram (-) sepsis
361
how do you get meningococcemia?
N. meningitidis gets in the bloodstream and causes hypoTN and go into shock because of the endotoxin LOS
362
how do you get gram negative sepsis?
bacteria in blood streami.e. - bacteria (E.coli) in bloodstream from a UTIendotoxin causes shock
363
what are exotoxins?
proteins that are secreted by bacteria to cause disease Sx
364
what is the structure of exotoxins?
two component "A-B" polypeptideA = active = toxicB = binding = binds to cell surface
365
what are the different categories of exotoxins?
protein synthesis inhibitorsincrease fluid secretion (diarrhea)inhibit phagocytosisinhibit neurotransmitter release (botulinum)lyse cell membranessuperantigens
366
Which bacteria produce exotoxins that inhibit protein synthesis?
Corynebacterium diphtheriaPseudomonas aeruginosaShigellaEnterohemorrhagic E. Coli (EHEC)
367
what 2 exotoxins work by ADP ribosylation?
Diphtheria toxinExotoxin A (pseudomonas aeruginosa)
368
Corynebacterium diphtheria exotoxin
diphtheria toxin
369
pseudomonas aeruginosa exotoxin
exotoxin A
370
How do diphtheria toxin and exotoxin A inhibit protein synthesis?
ADP ribosylationaddition of ADP-ribose to proteins makes them dysfunctional
371
What are the S/Sx of diphtheria?
sore throat with membraneswollen nodes
372
how does the diphtheria toxin work?
Inactivates EF-2 (elongation factor 2) which is necessary for protein synthesisLETHAL TOXIN\*\*\*\*
373
How did diphtheria become largely eradicated?
DPT vaccine (diphtheria-pertussis-tetanus)
374
how does diphtheria toxin inactivate EF-2?
toxin stimulates a reaction so that NAD will be converted to nicotinamide and an ADP ribosyl group will be transferred to EF-2 resulting in no protein synthesisLETHAL TOXIN\*\*\*\*only takes a small amount of toxin to completely shut down protein synthesis
375
what types of infection does pseudomonas aeruginosa cause?
skinsepsispneumonia
376
what is the mechanism for exotoxin A
same as diphtheria toxinexotoxin A ADP ribosylates EF-2 = no protein synthesis
377
Shigella exotoxin
shiga toxin
378
what does shigella cause?
infectious diarrhea
379
how does shiga toxin halt protein synthesis?
binds to 60S ribosome in cells and removes a specific adenine residue from rRNA in the 60S ribosomal subunit
380
What is the main way that shigella can cause illness?
invasion of GI mucosal cells is the main cause of disease
381
Do all strains of shigella produce the shiga toxin?
No, there are non-toxigenic strains that still cause significant disease by invading the GI mucosal cells
382
How does shigella mainly cause disease?
invasion of GI mucosal cellsshiga toxin causes disease but not the main mechanismall strains of shigella cause disease this way, it is known because of the non-toxigenic strains that still cause significant disease
383
Enterohemorrhagic E. Coli (EHEC) exotoxin
shiga-like toxin
384
what is the mechanism of shiga-like toxin?
same as shiga toxinbinds to 60S ribosome in cells and removes a specific adenine residue from rRNA in the 60S ribosomal subunit
385
what does EHEC cause?
bloody diarrhea
386
what is the classic serotype of E. coli?
O157:H7 - causes EHEC
387
How does E. Coli O157:H7 cause disease?
do not invade host cellsattach to intestinal epithelial cells and secrete proteins into host cells & toxin effects
388
What is the difference in mechanisms between shigella and EHEC?
shigella causes disease mainly by bacteria invading GI mucosal cellsEHEC causes disease mainly by the shiga-like toxin (inflammation) it produces because it is not invasive
389
Shiga and shiga-like toxin can lead to what?
cytokine release --\> systemic circulation --\> hemolytic uremic syndrome (HUS)
390
what is one of the worst complications of EHEC?
HUS - acute Renal failure, hemolytic anemia
391
What bacteria produce exotoxins that increase fluid secretion?
Enterotoxigenic E. coli (ETEC)Bacillus anthracis (anthrax)Vibrio cholera
392
How is fluid secretion in the GI tract regulated?
CFTR - cystic fibrosis regulator proteinGs protein in GI tract stimulates AC to increase cAMP which activates CFTR to secrete more Cl-cells in the GI tract secrete chlorideamount of Cl- secreted = amt of water in GI tract
393
How do toxins increase Cl- secretion to cause diarrhea?
activate Gs or AC =\> CFTR secretes more Cl- =\> more H2O in GI tract =\> diarrhea
394
ETEC exotoxins
LT - heat labile toxinST - heat stable toxindifferentiated by heat stability
395
how does ETEC heat labile toxin work to increase fluid secretion?
activates adenylyl cyclase =\> increase cAMP =\> increase water in gut =\> diarrhea
396
how does ETEC heat stable toxin work to increase fluid secretion?
activates guanylyl cyclase =\> increase cGMP =\> stimulate Cl- secretion =\> inhibit NaCl absorption =\> increase water in gut =\> diarrhea (watery)
397
What 3 proteins does bacillus anthracis make?
PA - protective AgLF - lethal factorEF - edema factoronly cause toxicity in pairs
398
Edema toxin is made up of what 2 proteins produced by bacillus anthracis? how does it work to increase fluid secretion?
PA + EFmimics adenylyl cyclase
399
where are the main sites of disease for anthrax?
skin - most commonlungs - necrotizing pneumoniaGI - ulcers
400
What is important about the skin and GI lesions caused by anthrax?
they have an edematous border that may be cause by edema factornecrotic looking lesions surrounded by an area of swollen skin tissue caused by edema factor and increased fluid secretion related to the exotoxin
401
How does cholera toxin increase fluid secretion?
permanently activates Gs =\> increase cAMP
402
what does cholera toxin cause?
voluminous "rice-water" diarrhea
403
where is cholera commonly found?
areas without clean water
404
What ends up causing death in people with cholera?
profound dehydrationelectrolyte lossesshock
405
what is the mainstay of treatment for cholera?
aggressive volume repletionthe body will clear the infection in time but you have to give enough fluids to compensate for the loss caused by the cholera toxin until the body eliminates it
406
what toxin inhibits phagocytosis?
pertussis toxin secreted by Bordetella pertussis
407
What does pertussis toxin cause?
whooping cough
408
how does pertussis toxin inhibit phagocytosis?
inhibits Gi proteins - inhibiting the inhibitor = over activation of AC which increases cAMP in neutrophils causing impaired recruitment of neutrophils to control infection
409
what bacteria produce neurotoxins?
Clostridium tetaniClostridium botulinum
410
clostridium tetani and botulinum toxins work by disruption of what?
SNARE proteins - vesicles can't release their neurotransmitter
411
what do SNARE proteins do?
allows vesicles in the neuron to "dock" and unload their neurotransmitter
412
Clostridium tetani exotoxin
tetanospasmin
413
How does tetanospasmin work?
works on inhibitory interneurons in the spinal cord called Renshaw cells inhibiting the inhibitory cells causes overactive neurological activity = muscle ridigity
414
what does Tetanus cause?
rigid paralysis
415
how does botulinum toxin work?
prevents Ach release at NMJ =\> no muscle contraction =\> muscle flaccidity
416
what does botulinum toxin cause?
flaccid paralysis
417
what bacteria produce exotoxins that lyse cell membranes?
Clostridium perfringensStrep pyogenes
418
what does clostridium perfringens cause when infecting wounds?
gas gangrene
419
clostridium perfringens exotoxin
α-toxin
420
what is alpha toxin?
phospholipase C enzyme that degrades phosphatidylcholine and sphingomyelin
421
what does alpha toxin cause?
myonecrosis - muscle breakdowndecline in muscle blood flow =\> occlusive plugs (platelets, leukocytes, fibrin) =\> low oxygen environment =\> C. perfringens thrives (anaerobic)
422
how does alpha toxin cause disease?
lysing cell membranes and allowing the degradation of muscle cells to occur
423
strep pyogenes causes what?
strep throat which can lead to sequelae like rheumatic fever and glomerulonephritis
424
strep pyogenes exotoxin
streptolysin O aka cytolysin because it lyses cells
425
strep pyogenes will show what kind of hemolysis?
β hemolysis from streptolysin O or streptolysin S toxin
426
what are ASO antibodies used for?
anti-streptolysin Oelevated following strep infectioncan be useful in suspected rheumatic heart disease or post-strep glomerulonephritis to see if they have ever had strep throat
427
how are toxins used as a basis for many vaccines?
turn the toxin into a toxoid - an inactivated bacterial toxinused to prevent diphtheria and tetanus
428
What is in the DTaP combined immunization?
diphtheria toxoidtetanus toxoid"acellular" pertussis - inactivated toxin plus some bacterial elements
429
what toxins are plasmid-encoded?
E. coli heat labile toxin
430
what toxins are bacteriophage-encoded?
\*\*\*corynebacterium diphtheriastrep pyogenes erythrogenicE. coli shiga-like toxinbotulinum toxincholera toxinbacteriophage gives bacteria DNA and allows them to acquire a new ability to synthesize exotoxins
431
what are superantigens?
exotoxins that activate a massive number of T-cells
432
how are superantigens different from regular antigens?
a normal Ag is processed and presented by an APC on MHC to trigger a T-cell receptor and activation of a single T-cella superAg is NOT processed, it directly connects the MHC complex to the TCR and triggers many T cells to be activated
433
what cytokines are released in large amounts from superantigens?
IFN-γ and IL-2 causing massive vasodilation and shock
434
what bacteria can synthesize toxins that act as superantigens?
staph aureus - toxic schock syndrome toxin (TSST-1)strep pyogenes - pyrogenic exotoxin A or C
435
what bacteria can cause toxic shock syndrome?
staph \>\> strep
436
what is toxic shock syndrome? initial Sx?
the body's reaction to a superantigenfevershock (hypoTN)diffuse red rash (looks like sunburn)diarrhea - unique for TSS
437
why is TSS more common with staph?
staph normally present in the vagina can cause TSS after having a tampon in
438
what is strep TSS associated with?
necrotizing fasciitis
439
how doe TSS progress?
after weeks - desquamation of palms and solesmulti-organ system failure
440
how can you differentiate between TSS and sepsis?
diffuse sunburn type rashpresence of diarrhea
441
women using tamponssurgical wound with packing
staph + packing = TSSclassic scenarios for toxic shock syndrome
442
what do all clostridia have in common?
all form sporesall obligate anaerobesall form toxins(tetani, botulinum, perfringens, difficile)
443
Where are c. tetani spores found and how does this relate to how they enter the body?
found in the soilenter body through penetrating injury - barefoot on rusty nail or splinter
444
how does c. tetani cause disease?
spores from soil enter the body through an open wound --\> spores germinate into bacteria --\> tetanospasmin is produced --\> travels to sp. c. --\> blocks glycine and GABA release by inhibitory neurons (renshaw cells)inhibit the inhibitor --\> overactive
445
what are renshaw cells?
inhibitory spinal cord interneurons
446
what type of paralysis does c. tetani cause?
spastic
447
classic Sx for tetanus
lockjaw = trismusRisus sardonicus - forced grin d/t spastic facial muscles (evil smile)
448
What is the treatment for tetanus?
wound debridementmetronidazoletetanus immune globulin - binds circulating toxinBenzo's or neuromuscular blockers until toxin wears off
449
is there a vaccine for tetanus?
yes, DTaP. toxoid vaccine
450
botulinum produces heat-\_\_\_\_\_\_ spores
resistantcan survive up to 100ºc -- cook your food!!
451
how does botulinum cause disease?
works at NMJ preventing Ach release = no muscle contractions = floppy baby syndrome (flaccid paralysis)
452
some variants of ______ toxin are carried by bacteriophages
botulinumDNA not found in the bacteria itself but found in a virus that infects the bacteria and delivers the ability to synthesize toxin
453
3 types of botulism
foodinfantwound
454
how do adults get botulism?
ingestion of toxin from undercooked food, canned food\*\*multiple sick adults after a meal
455
how do infants get botulism?
ingestion of spores --\> growth in intestine\*\*contaminated honey
456
why should you worry about botulism in canned food?
anaerobic environment promotes growth
457
what is the incubation period for botulism before Sx present?
12-48 hrs
458
what are the Sx of botulism?
3 D's:DiplopiaDysphagiaDysphonia
459
Dx of botulism
often clinical, but spores and toxins can sometimes be detected in stool
460
Tx of botulism
antitoxin - blocks circulating toxin --\> cannot block toxin already in nerves (like tetanus) --\> supportive care --\> toxin washout
461
where is c. perfringens found?
soil
462
what does c. perfringens do?
infects dirty wounds (soil) --\> gas gangrenecauses food poisoning
463
what is gas gangrene?
aka clostridial myonecrosistraumatic wound compromises the vasculature creating a favorable environment for anaerobic growth (w/o good blood supply --\> less O2 --\> anaerobic growth
464
what toxin is produced by c. perfringens that is involved in the pathogenesis of clostridial myonecrosis?
α-toxin
465
what does the α-toxin produced by c. perfringens do?
destroys muscle tissue and causes hemolysis = favorable anaerobic environmentlecithinase - degrades phospholipids in cell membranes helping it to break down muscle tissue and cause hemolysis
466
what is lecithinase
(α-toxin)phospholipase that acts on lecithin
467
S/Sx gas gangrene
severe pain at injury site within 24 hoursskin tense and tendersystemic toxicity - fever, hypoTN, shock
468
Dx gas gangrene
gas at injury site on imaginingcrepitus
469
Tx gas gangrene
surgical debridementbroad spectrum antibiotics
470
C. perfringens food poisoning pathogenesis
undercooked meats --\> ingest spores --\> produce enterotoxin --\> LATE ONSET watery diarrhea
471
how long after ingestion of c. perfringens spores will you see watery diarrhea?
8-22 hrs, late onset
472
what is special about the watery diarrhea that c. perfringens causes?
LATE ONSET b/c spores have to germinate and produce toxin
473
what is the difference between food poisoning caused by c. perfringens, S. aureus, and B. cereus
c. perfringens causes a late onset watery diarrhea b/c of spore ingestionS. aureus and B. cereus cause early onset watery diarrhea from ingestion of preformed toxin
474
How does GI flora help defend ingestion of c. diff?
normal GI flora prevent overgrowth of c. diff
475
what does c. diff cause?
antibiotic-associated colitis
476
antibiotic-associated colitis
antibiotics alter normal gut flora, creating a favorable environment for c. diff
477
what population commonly gets antibiotic-associated colitis?
hospitalized patients on antibiotics --\> exposed to c. diff
478
what are the toxins ordered by c. diff?
Toxin A: enterotoxin --\> watery diarrheaToxin B: cytotoxin --\> cell necrosis/fibrin deposition\*\*\*Toxin B stronger
479
is c. diff invasive?
no, disease caused by toxins A/B
480
how do the toxins of c. diff cause disease?
toxins bind GI cells and are internalized --\> destroy cytoskeleton of GI cells --\> pseudomembrane of the colon
481
what does c. diff colitis cause?
massive watery diarrhea \*\*look for recent antibiotic use
482
what will you see on endoscopy in c. diff colitis?
pseudomembrane formation = white-yellow plaquesmucosal ulcerations, fibrin, inflammatory cells
483
Dx c. diff colitis
stool detection of Toxin A and B
484
c. diff colitis aka
pseudomembranous colitis
485
Tx c. diff colitis
metronidazoleORAL vancomycin
486
Tx for severe, recurrent c. diff colitis infections
surgerystool transplant - introduce stool with healthy bacteria
487
what is metronidazole used to Tx?
anaerobes below the diaphragm
488
why is oral vancomycin rarely used and why is it used to Tx c. diff colitis?
it is poorly absorbed but in c. diff this is good so that it stays in the colon and kills the c. diff bacteria
489
what are the special features of corynebacterium diphtheria?
produces exotoxinunique lab diagnostic techniques
490
how does the diphtheria exotoxin cause disease?
β-prophage (lysogenic phage) --\> incorporates DNA into bacteria --\> synthesis of exotoxin --\> inactivates EF-2 (necessary for tln)
491
diphtheria exotoxin is synthesized and secreted from DNA that ______ part of the bacterial genome
is not
492
what carries the DNA for diphtheria exotoxin?
a phage called β-prophage = lysogenic phage
493
how does diphtheria exotoxin inactivate EF-2?
Adp-Ribosylation of EF-2 ---\> no protein synthesis
494
what are the characteristics of corynebacterium?
gram + rodscurved"Chinese character" distribution
495
In order to culture corynebacterium, what special medium is used?
Loeffler's or Tinsdale (tellurite plate)
496
corynebacterium will grow _______ on tinsdale media and ________ on loeffler's media
black coloniesmetachromatic (blue/red) granules
497
Dx corynebacterium
Elek test for toxin detection
498
how does the Elek test work?
plate unknown bacteria on agar plate w/ diphtheria antitoxin-impregnated filter paper underneathif unknown bacteria secretes diphtheria toxin you can visualize precipitation @ 45º angles
499
Sx of diphtheria
sore throat, fever, LADgray-white membrane in pharynx
500
why is diphtheria a serious illness?
b/c absorption/dissemination of toxin can cause:myocarditis = heart failure, arrhythmias, heart blockCNS disease = neuropathiesrenal disease = renal failure
501
how do children often die from diphtheria?
myocarditis and heart failure
502
you can vaccinate for diphtheria with a _____ vaccine
toxoid
503
Tx for acute diphtheria infection
penicillindiphtheria antitoxin (passive immunization)diphtheria toxoid (active immunization)
504
listeria is found in \_\_\_\_\_
soil
505
what is unique about how listeria moves?
tumbling motilitymoves inside cells from cell to cell to avoid extracellular responsetakes over host cell machinery and polymerizes actin to move, generating "actin rockets"
506
what type of organism is listeria?
facultative intracellular
507
what population is susceptible to listeria?
people with poor cell-mediate immunity:neonatesHIVorgan transplant
508
how is listeria ingested in adults?
contaminated food: likes cold tempundercooked meat, unwashed vegetables\*\*\*\*unpasteurized cheese/milk
509
how do neonates get infected with listeria?
transplacental or vaginal transmission
510
what does listeria cause?
gastroenteritis - N/V/D, self-limitedmeningitis
511
bacteremia will be present in the ______ if a pregnant woman is infected with listeria
3rd trimester
512
listeria in pregnancy will present as...
flu-like illness - fever/chills
513
is listeria infection in pregnancy serious?
no - often resolves spontaneously and rarely caused fetal demise/newborn infection
514
listeria can cause meningitis in what 2 populations and why
elderly and newborns both have poor cell-mediated immunity
515
what is granulomatosis infantiseptica?
infection of a baby from mom in pregnancy = severe in utero infection from listeria
516
S/Sx granulomatosis infantiseptica
baby develops disseminated abscesses and/or granulomasskin lesions - papules/ulcersmost babies stillborn or die soon after birth
517
what organs are involved in granulomatosis infantiseptica
liverspleenlungskidneysbrain
518
what is the distinctive inflammatory pattern seen in the placenta with babies who have granulomatosis infantiseptica
chorioamnionitis - inflammation of the chorionvillitis - inflammation of the villiabscess formation
519
mom w/ flu-like illness in 3rd trimester and miscarries
granulomatous infantiseptica from listeria
520
what does bacillus anthracis cause?
anthrax - skin or pulmonary diseaselargely eradicatedweapon of bioterrorism
521
what does bacillus cereus cause?
food poisoning
522
why is bacillus anthracis used as a weapon of bioterrorism?
spores can be released into a populated area and cause widespread disease
523
bacillus anthracis is the only bacteria with a ________ capsule
polypeptide
524
most bacteria have a ______ capsule
polysaccharide
525
b. anthracis capsule contains \_\_\_\_\_
D-glutamate
526
how does a polypeptide capsule benefit b. anthracis?
D-glutamate limits/prevents phagocytosis
527
b. anthracis is found in \_\_\_\_
soil
528
what animals are susceptible to b. anthracis? as a result, what occupation is at risk?
cattlesheephorsesfarmers
529
spores from _____ can be used as bioterrorism weapon
b. anthracis
530
what toxins does b. anthracis produce?
edema toxinlethal toxin
531
how does edema toxin cause disease?
edema factor activates AC --\> increases cAMP --\> fluid secretion
532
what are the active components of the toxins produced by b. anthracis?
edema factorlethal factor
533
how does lethal toxin cause disease?
lethal factor is a protease that inhibits cell signaling and causes apoptosis
534
how does b. anthracis cause cutaneous disease?
spores enter skin through cut/abrasion --\> bacteria vegetate and grow --\> PAINLESS black ulcers surrounded by edemacan progress to bacteremia and death
535
in anthrax cutaneous disease, what causes the edema seen surrounding each ulcer formed?
edema factor
536
what is the treatment for anthrax cutaneous disease?
ciprofloxacindoxycyclineclindamycin
537
in b. anthracis cutaneous disease, ulcers are formed surround by edema. what causes this edema?
edema factor
538
what form of anthrax is most dangerous?
pulmonary disease
539
woolsorters' disease
anthrax pulmonary disease
540
how does anthrax cause woolsorters' disease?
inhalation of spores into lungs --\> flu Sx that rapidly progress
541
where did woolsorters' disease get it's name?
ppl that work on wool from farm animals would inhale the spores and become sick
542
in woolsorters' disease, what do the flu Sx rapidly progress to?
pulmonary hemorrhagemediastinitisshockdeath
543
classic finding of pulmonary anthrax on CXR
widened mediastinum from mediastinitis
544
treatment for pulmonary anthrax
difficult to treat = multi-drug regimenantitoxin
545
what is the classic cause for a widened mediastinum? How can you distinguish this cause from pulmonary anthrax?
aortic dissectionpulmonary anthrax = flu Sx & possible anthrax exposure
546
what does b. cereus cause?
food poisoning from enterotoxins
547
what organism is classically ingested from undercooked/reheated rice?
b. cereus
548
reheated rice syndrome
b. cereus food poisoning
549
pathogenesis of b. cereus food poisoning
bacteria in uncooked rice --\> heat-resistant spores survive cooking --\> cooked rice at room temp allows bacteria to multiply --\> direct ingestion of enterotoxin
550
what are the 2 types of b. cereus food poisoning?
emetic = vomit no diarrheadiarrheal = diarrhea no vomit
551
pathogenesis of b. cereus emetic food poisoning
direct ingestion of toxin: Cereulide --\> abdominal cramps, N/V w/o diarrhea
552
how long after ingestion of b. cereus will Sx of emetic food poisoning develop? how does this compare to the diarrheal type?
emetic = 1-5 hrsdiarrheal = 8-16
553
b. cereus emetic food poisoning classically occurs in what type of food?
rice dishes
554
Sx of b. cereus diarrheal food poisoning will show _______ after ingestion
8-16 hours
555
Sx of b. cereus diarrheal food poisoning
abdominal crampsdiarrheaNO VOMITING
556
the toxins that cause b. cereus diarrheal food poisoning are heat \_\_\_\_
labile - destroyed by heat - COOK FOOD
557
how can you reduce risk of illness w. b. cereus diarrheal food poisoning?
cook food thoroughly
558
what foods are commonly associated with b. cereus diarrheal food poisoning?
meatvegetablessauces
559
where is actinomyces found normally?
oral florafemale genital tract
560
does actinomyces like O2?
no it is an anaerobe
561
why was actinomyces first considered a fungi?
because it clusters into long filaments resembling fungiclassified as branching filamentous
562
what does actinomyces cause?
head/neck abscesses (normal oral flora, gets into soft tissue =\> abscess)IUD infections in women
563
what procedure is actinomyces infection usually preceded by? how will they present?
dental work/orofacial traumafacial mass present on examoften yellow center (suffer granules)often draining puss
564
what is the treatment for actinomyces abscesses?
penicillindrainage
565
what shape is nocardia?
branching filamentous (like actinomyces), resembles fungi
566
what other bacteria besides mycobacteria is acid-fast?
nocardia
567
what does nocardia produce that is used for identification?
urease
568
does nocardia like O2?
yes - obligate aerobeloves lungs = pulmonary infection
569
nocardia is found in ____ but it can be ingested by \_\_\_\_\_\_
soilinhalation
570
nocardia is a very rare cause of infection but it can potentially cause what 2 illnesses?
pneumoniaskin infection
571
the infection that nocardia causes is dependent on what factor?
immune system functionimmunocompromised = pneumoniaimmunocompetent = skin infection
572
how does nocardia cause pneumonia?
inhalation of bacteria in immunocompromised patients (HIV/AIDS)
573
immunocompromised patientbranchingacid-fast
classic nocardia infection scenario
574
nocardia skin infection often invades the skin during what 2 activities? why?
gardeningfarmingfound in soil
575
nocardia in immunocompetent patients causes what?
skin infection
576
DOC for nocardia
TMP-SMX aka bactrim
