Gram positive pathogens (complete) Flashcards
(182 cards)
1
Q
Are Staphylococcus normal flora
A
yes, but they can be opportunistic pathogens
2
Q
What are the nine groups of Gram positive pathogens we study
A
- Staphylococcus Aureus
- Streptococcus Pyogenes (A)
- Streptococcus pneumoniae
- Bacillus Anthracis
- Clostridium (perfringins, dificile, tetani, and botulinum)
- Listeria monocytogenes
- Corynebacterium diptheriae
- propionibacterium acnes
- Actinomyces species
3
Q
Staphylococcus is motile or nonmotile?
A
non-motile
4
Q
how does Staphylococcus interact with oxygen (anarobe, aerobe)
A
facultative aerobe
5
Q
What does Staphylococcus look like under a microscope
A
cocci in irregular clusters (grapes)
6
Q
What is the most common organism found on the skin
A
Staphylococcus epidermis
7
Q
Where is Staphylococcus aureus typically carried in 30-50% of the healthy population
A
nose and perineum
8
Q
How can you tell between Staphylococcus aureus and Staphylococcus epidermis
A
Staphylococcus Areus is
coagulase positive, mannitol positive
Staphylococcus Epidermis
coagulase negative, mannitol negative
9
Q
which is more virulent Staphylococcus Aureus or Staphylococcus epidermis
A
Staphylococcus Aureus
10
Q
How many bacteria are required for disease to result from a staph infection
A
only a few hundred bacteria
11
Q
what are the three things about Staphylococcus that cause pathogenicity
A
- It’s ability to evade phagocytosis
- Production of enzymes
- production of toxins
12
Q
What are the three categories of Staphylococcus diseases
A
Noninvasive disease
Cutaneous disease
Systemic disease
13
Q
What is a non-invasive Staphylococcus disease
A
food poisoning that results from ingested food contaminated with enterotoxin
14
Q
What are examples of cutaneous Staphylococcus disease
A
scalded skin syndrome
impetigo
folliculitis
furuncles
15
Q
How does Staphylococcus defend itself against phagocytosis
A
Protein A
Bound Coagulase:
16
Q
how does Protein A help Staphylococcus defend against phagocytosis
A
Protein A onthe bacterial surface binds antibodies by the Fc end. This inhibits opsonization and complement
17
Q
how does bound coagulase help Staphylococcus defend against phagocytosis
A
converts blood protein fibrinogen into fibrin molecules, which make blood clots, the Staphylococcus hides from the phagocytes in the clots
18
Q
What are the 5 enzymes created by Staphylococcus that attribute to its virulence
A
Cell-free coagulase hyaluronidase staphylokinase lipases B-lactamase
19
Q
What does Cell-free coagulase do for Staphylococcus
A
triggers fibrin formation, which helps the Staphylococcus hide from phagocytes
20
Q
What does hyaluronidase do for Staphylococcus
A
breaks down hyaluronic acid, which allows the bacteria to spread between cells
21
Q
what does staphylokinase do for Staphylococcus
A
dissolves fibrin threads in blood clots, which allows Staphylococcus aureus to free itself from clots
22
Q
what do lipases do for Staphylococcus
A
digests lipids, allows Staphylococcus to grow on the skins surface and in oil glands
23
Q
what do B-lactamases do for Staphylococcus
A
Breaks down penicilins, makes them resistant to beta-lactams
24
Q
What are the 4 toxins produced by Staphylococcus
A
Cytolytic toxins
exfoliative toxins
Toxic shock syndrome toxins
Enterotoxins
25
What are the two cytolytic toxins created by Staphylococcus and what do they do
alpha-toxins- pore forming toxins
| PVL - beta pore forming toxin that lyses leukocytes
26
What do the exfoliative toxins of Staphylococcus cause
they cause the patients skin cells to separate from each other and slough off the body
27
What does the toxic shock syndrome toxin of Staphylococcus cause
it causes toxic shock syndrome, which is caused by the creation of a superantigen
28
What do enterotoxins of Staphylococcus cause
they stimulate intestinal muscle crampings, naseua, and intense vomiting (staph food poisoning)
29
Does Staphylococcus aureus cause food poisoning
yes
30
Does Staphylococcus cause colitis
yes
31
what is colitis (caused by Staphylococcus )
overgrown Staphylococcus aureus in the bowels (caused by broad-spectrum antibiotic treatment), when they produce enterotoxin B you get damage to intestinal mucosa, cramps, pain, diarrhea, and fever
32
What are the 4 skin diseases caused by Staphylococcus aureus
impetigo
furuncles (boils) (infected hair follicle)
Carbuncler (many boils)
Scalded skin syndrome
33
What are the 5 systemic diseases caused by Staphylococcus
```
Toxic shock syndrome
Bacteremia
Endocarditis
Pneumonia
Osteomyelitis
```
34
What causes Toxic shock syndrome
the TSS toxin (from Staphylococcus ) being absorbed into the blood, and being used as a superantigen, which causes T-cells to produce far too many cytokines
35
what are the symptoms of toxic shock syndrome
high fever, rash, vomiting, diarrhea
| renal, liver, and blood involvement
36
What is bacteremia
bacteria in the blood
37
What is endocarditis
when bacteria attack the lining of the heart
38
what is pneumonia
inflammation of the lungs in which the alveoli and bronchioles become filled with water
39
what is osteomyelitis
inflammation of the bone marrow and surrounding bone
40
What is the drug of choice to treat staph infections
Methicilins
41
Are any Staphylococcus organisms resistant to methicilins? what are they called
yes, MRSA (methicilin resistant staph. aureus)
42
What is the drug used for MRSA
vancomycin
43
how are staph infections prevented
1. proper food prep and storage
2. hand antisepsis
3. proper cleansing of wounds, catheters, and needles
44
Which type of bacteria is tracked by phage typing
Staphylococcus
45
What is the arrangement of cocci in streptococcus
cocci arranged in pairs or chains
46
how does streptococcus interact with oxygen
aerotolerant anaerobes
47
What is the system of classification often used for streptococcus
lancefield classification
48
What are the two groups of streptococcus that are common pathogens of humans
Group A and Group B strep
49
What is used to determine the group of streptococcus organisms
the bacterias C antigens
50
What is the name for the only organism in Group A strep
streptococcus pyogenes
51
what does strep pyogenes cause on blood agar plates
it forms white colonies surrounded by beta-hemolysis on blood agar
52
What does strep pneumoniae cause on blood agar plates
it does alpha hemolysis
53
do pathogenic strains of streptococcus pyogenes often form capsules
yes
54
When do Group A strep generally cause disease
1. normal microbiota are depleted
2. large inoculum enable strep to establish themselves before antibodies are formed against them
3. specific immunity is impaired
55
What does protein M of streptococcus pyogenes do
it interferes with opsonization and lysis of the bacteria, and helps the bacteria attach to keratinocytes of the host
56
What does a hyaluronic acid capsule do for streptococcus pyogenes
it camoflages the bacteria
57
What are the enzymes produced by streptococcus pyogenes, and what do they do?
Streptokinases
Deoxynucleases
C5a
They facilitate the spreading of streptococcus through the tissues
58
What are the toxins released by streptococcus pyogenes and what do they do
they are pyrogenic toxins, and they induce macrophages and T-helper cells to release cytokines
59
What do streptolysins do
they lyse RBCs, WBCs and platelets
60
What are the 6 diseases caused by group A strep
1. Pharyngitis (strep throat)
2. Scarlet fever
3. Pyoderma (impetigo)
4. Erysipelas
5. streptococcal Toxic Shock syndrome
6. Necrotizing Fasciitis
61
Scarlet fever is caused by a toxin of streptococcus pyogenes, what else is caused by that toxin
puerperal sepsis (an infection of the uterus)
62
What is scarlet fever
a rash that begins on the chest and spreads across the body, it is caused by erythrogenic toxin
63
What is pyoderma (impetigo)
confined, pus-producing lesions, usually on the face, arms or legs
64
What is erysipelas
lymph node involvement with pain and inflammation (bright red face-mask shaped inflammation)
65
What is streptococcal toxic shock syndrome
bacteremia and severe multisystem infections
66
What is necrotizing fasciitis
Flesh eating strep
| strep that spreads in the deep tissues along fascia, it destroys tissues including fat and muscle. 50% mortality
67
What are two post-streptococcal diseases? (poststreptococcal sequelae) and what cause them
Rheumatic fever and glomerulonephritis
| cross reactive antibodies
68
Which age group is the most common carrier and infected by streptococcus pyogenes
Children 1-15
69
How is Group A strep transmitted
by respiratory droplets, direct and indirect contact
70
How is Group A strep diagnosed
hemolysis, bacitracin sensitivity, gram morphology, catalase tests
71
What is used to treat Group A Strep
penicilliin G
72
how is group A strep prevented and controlled
isolation, early and complete treatment
73
What is the other name for the alpha-hemolytic streptococci
the viridans group
74
Where are the viridans group of streptococci normally found
the mouth, pharynx, GI tract, genital tract, and urinary tract
75
Which group of strep play a significant role in dental caries, and dental plaque production
Alpha-hemolytic Streptococci (The viridans group)
76
What can the alpha-hemolytic strep (viridans group) cause when they enter the blood
meningitis, and endocarditis
77
Which group of Strep mostly forms pairs of cocci
streptococcus pneumoniae
78
What happens when streptococcus pneumoniae is grown on blood agar? and then on blood agar in anaerobic conditions
it forms alpha-hemolytic colonies, then in anaerobic conditions it produces beta-hemolytic colonies
79
Where does streptococcus pneumoniae normally colonize
the mouoth and pharynx (pathogenic in the lungs)
80
What was the leading cause of human death before antibiotics
streptococcus pneumoniae
81
What percent of bacterial pneumonia is caused by streptococcus pneumoniae
60-70%
82
Which bacteria causes the majority of otitis media
streptococcus pneumoniae
83
in streptococcus pneumoniae, pathogenesis is tied to what
a large polysaccharide capsule
84
how does the polysaccharide capsule of streptococcus pneumoniae's polysaccharide capsule aid in pathogenicity
it binds factor H which inhibits the alternative complement pathway, and protects the bacteria from phagocytosis
85
What does the protein adhesin of streptococcus pneumoniae aid in its pathogenicity
it helps the cells bind to epithelial cells of the pharynx
86
What type of protease does streptococcus pneumoniae release
secretory IgA protease (destroys IgA)
87
What does the streptococcus pneumoniae toxin, pneumolysin do
a toxin released when the bacteria is lysed the lyses epithelial cells and suppresses digestion of the phagocytized bacteria
88
What are the 6 diseases caused by streptococcus pneumoniae
```
pneumococcal pneumonia
sinusitis
otitis media
bacteremia
endocarditis
pneumococcal meningitis
```
89
What is pneumococcal pneumonia
bacteria multiply in the alveoli, damaging it, and causing an inflammatory response
90
What is sinusits
streptococcus pneumoniae bacteria in the sinuses
91
what is otitis media
streptococcus pneumoniae bacteria in the middle ear
92
What is pneumococcal meningitis
when streptococcus pneumoniae bacteria spread to the meninges of the CNS
93
how is streptococcus pneumoniae diagnosed
gram stain of sputum smears, growth, optochin sensitivity, and bile solubility
94
How is streptococcus pneumoniae treated
penicillin or cephalosporins
95
how is streptococcus pneumoniae prevented
```
pneumovax 23 (adults)
pneumococcal conjugate vaccine (PCV) 7-valent
```
96
What is the structure of enterococcus
short chains or pairs without a capsule
97
where is enterococcus normally found
the human colon, rarely pathogenic here (pathogenic in the lungs, urinary tract, and blood)
98
What is enterococcus resistant against
B-lactams, sulfonamides, aminoglycosides, tetracyclines, and erthyromycins (some are even resistant to vancomycin)
99
What is VRE
Vancomycin resistant enterococcus
100
what is the structure of Bacillus
Bacilli that can occur singly, in pairs, or in chains
101
What makes bacillus particularly difficult to get rid of
it forms endospores
102
What is bacillus anthracis
Anthrax, a strict pathogen of humans and animals
103
How do humans contract bacillus anthracis
1. inhalation of spores
2. ingestion of spores
3. inoculation of spores into the body via a break in the skin
104
how long can anthrax spores survive
decades, possibly centuries
105
What is responsible for the virulence of anthrax
a 3 component toxin and a protein capsule
106
What are the two plasmids which house the virulence factors of anthrax
pXO1 and pXO2
107
What are the three forms of anthrax disease in humans
inhalation (pulmonary)
Gastrointestinal
Cutaneus
108
What is woolsorters disease
a pulmonary anthrax infection, induces capillary thrombosis and cardiovascular shock
109
How does one get gastrointestinal anthrax
ingestion of spore contaminated meat
110
What is a sign of cutaneus anthrax infections
Echar lesions (black, necrotic skin lesions)
111
how fatal are cutaneus anthrax infections
usually not fatal
112
how is bacilli diagnosed
large, non-motile, bacilli in the lungs or skin
113
how is bacilli anthracis treated
with ciproflaxin, penicilin, or tetracycline
114
how is bacilli anthracis prevented
control the disease in animals
| vaccination (requires multiple doses and boosters)
115
besides bacilli anthracis, what are other important bacilli
bacilli cereus - food poisoning in rice, beans, and potatoes
| Bacili subtilis - produces bacitracin
116
what produces bacitracin
bacilli subtilis
117
are clostridium bacteria aerobic or anaerobic
anaerobic
118
do clostridium bacteria produce endospores like bacillus
yes
119
Where are clostridium found
soil, water, and the GI tract of humans
120
What are the 4 different types of clostridium
clostridium perfringins
clostridium dificile
clostridium tetani
clostridium botulinum
121
what are the two main diseases caused by clostridium perfringins
```
food poisoning (enterotoxin)
Gas gangrene
```
122
how is gas gangrene caused by clostridium perfringins
endospores enter the tissues in a traumatic event, they germinate and cause necrosis,
123
what are the two toxins of clostridium perfringins that cause gas gangrene
lecithinase and pore-forming toxin
| it is when there is necrosis that is accompanied by gas build up in the tissues
124
how is gas gangrene diagnosed
easily, just by its symptoms
125
how is gas gangrene treated
removing dead tissue, large doses of penicillin, and hyperbaric chamber
126
how is gas gangrene prevented
proper cleaning of wounds, but it is difficult to prevent because clostridium perfringins is so common in the environment
127
Where is clostridium dificile normally found
part of the intestinal microbiota
128
What leads to an infection of clostridium dificile
when patients are treated with broad spectrum antibiotic drugs
129
what are the two degrees of infections of clostridium dificile
```
minor = self-limiting explosive diarrhea
major = pseudomembranous colitis
```
130
what is pseudomembranous colitis
swollen colon that can perforate, leading to massive internal infection by fecal bacteria and death
131
how is a clostridium dificile infection treated
discontinuing antimicrobials, and restoring normal bowerl flora (fecal transplants)
132
What is botulism, and what bacteria is it caused by
botulism is flaccid paralysis, it is caused by clostridium botulinum
133
how does one contract botulism
by ingesting toxin from clostridium butulinum
134
why shoudn't infants younger than one consume honey
because it could contain the botulism toxin
135
What is the most potent poison known to man
botulism toxin
136
how is botulism treated
administration of the polyvalent antitoxin
137
how is botulism prevented
proper food preparation and storage (botulism toxin is destroyed by heat)
138
how does botulism cause flaccid paralysis
the toxin enters into a motor nerve terminus, and cleaves the SNARE proteins responsible for fusing the vesicle (containing ACH) with the terminal membrane. (doesn't allow the muscle to receive the neurotransmitter from the nerve)
139
What are the 3 forms of butulism
food-borne botulism
infant botulism
wound botulism
140
how is food borne botulism usually contracted
in home-canned food, or preserved fish
141
is infant botulism usually fatal
nope
142
how do the symptoms of wound botulism differ from that of food-borne botulism
they don't just the means of contraction
143
How is botulism diagnosed
the symptoms are diagnostic, confirmed by culturing the organism from food, feces or the wound
144
how is botulism treated
antibodies against the botulism toxin
| antimicrobial drugs to kill clostridia in infant botulism
145
how is botulism prevented
proper canning of food
| infants under 1 shouldn't have honey
146
how does clostridium tetani interact with air
it is an obligate anaerobe
147
where can clostridium tetani be found
soil, dust, GI tract of humans
148
When does tetanus result
when the bacterial endospores germinate and produce toxin
149
what are the symptoms of tetanus
spasms and contractions, death due to inability to exhale
150
Which bacteria causes lockjaw (spastic paralysis)
clostridium tetani
151
how is tetanus treated
cleaning of the wound to remove endospores, administration of antitoxin and antibiotics
152
how is tetanus prevented
vaccination TDaP, or Td
153
How does tetanus cause spastic paralysis
the tetanus toxin blocks the release of glycine, making it so the muscles can't relax
154
What is the hallmark of an anaerobic infection
foul odor
155
What is deceiving about the name of the anerobe bacteroides fragilis
it is actually one of the easiest anaerobes to grow
156
What is the most commonly isolated anaerobic bacterium, especially from the blood
bacteroides fragilis
157
What are the virulent features of bacteroides fragilis
- attachment pili
- polysaccharide capsule
- modified or absent lipid A
- enzymes
158
What makes listeria monocytogenes problematic
its ability to live within cells
159
What are the toxins and enzymes of listeria monocytogenes like
it doesn't produce any toxins or enzymes
160
Does listeria monocytogenes produce endospores
nope
161
how is listeria monocytogenes able to live inside cells, and move from one to another
it's able to live inside cells by its ability to escape from phagocytic vessicles. Then once inside cells it builds an actin tail (actin polymerization) which helps it propel itself through that cell and into others.
162
What is the thing that helps listeria monocytogenes escape from vesicles
LLO listeriolysin O - it is pore forming
163
What about the conditions that listeria monocytogenes can grow in is different from many other bacteria
it can grow at refrigerator temperatures
164
where do most infections of listeria monocytogenes in humans come from
contaminated milk or meat
165
What is the problem with a pregnant woman being infected with listeria monocytogenes
it can be transferred to the baby prenatally or postnatally, which can cause meningitis, and still-births
166
How is listeria monocytogenes treated, and prevented
it is treated with ampicillin, and it is prevented with pasteurization and proper cooking
167
how is a listeria monocytogenes infection diagnosed
presence of the bacteria in the blood or cerebrospinal fluid (gram staining isn't effective because so few cells are required to cause disease)
168
What is the name of the bacteria that causes diptheria
cornyebacterium diptheriae
169
how is diphtheria transmitted from person to person
respiratory droplets or skin contact
170
What are the signs and symptoms of diptheria
- pseudomembrane (dead cells and fluid that accumulates) in the respiratory tract, or on the skin (in the case of cutaneous diptheria)
- Bull neck (swelling in cervical lymph nodes)
171
Which bacteria can often be seen on a micrograph in V-shapes
cornyebacterium diptheriae
172
besides the respiratory tract, what else can diptheria toxin harm
the heart and CNS
173
how is diptheria diagnosed
clinical and serological tests
174
how is diptheria treated
antitoxin, then penicillin or erythromycin
175
how is diptheria prevented
toxoid vaccination
176
What is the bacteria that causes most of our acne
propionibacterium acnes
177
can propionibacterium acnes cause more than just acne
yes, it can also be an opportunistic pathogen
178
Why is actinomyces an important bacteria to study
because it is a major component of dental plaque and is associated with gingivitis and root caries
179
how is antinomyces treated
with amoxicillin
180
What is nocardia
a soil saprophyte that cause nocardiosis
181
what is nocardiosis
a TB-like pulmonary disease that can progress to form abscesses and can show on the back of the patient
182
What is streptomyces
a non-pathogenic bacteria that produces most of our antibiotics
