Soft Tissue Infections I: Strep and Staph - Kozel Flashcards
1
Q
What is the most common bug in non-bullous impetigo?
A
S. aureus
2
Q
What is the second most common cause of non-bullous impetigo?
A
strep pyogenes
3
Q
T/F: impetigo can be caused by an infection of more than one bug
A
true
4
Q
What is this?
Begins as erythematous papules that turn to vesicles then pustules then rupture. Dries to HONEY COLORED crusts, heals without scarring
A
impetigo
5
Q
What bug and toxin causes bullous impetigo?
A
S. aureus producing exfoliating toxin
6
Q
What is an ulcerative pyoderma that is a deeper form of impetigo?
A
Ecthyma
7
Q
What gives you echtyma>?
A
insect bites or minor traumas
8
Q
T/F: ecthyma can be caused by the same bugs as impetigo
A
true
9
Q
T/F: ecthyma scars
A
false
10
Q
T/F: a cutaneous abscess is restricted to the epiderm
A
false; goes to the dermis and deeper
11
Q
What is pyoderma in a hair follicle?
A
folliculitis
12
Q
What is an inflammatory nodule extending into subcutaneous tissue; follows folliculitis
A
furuncle (boil)
13
Q
What is a coalescent process involving multiple follicles
A
carbuncle
14
Q
what bug causes folliculitis, carbuncles, and furuncles
A
S aureus
15
Q
Bacillus anthracis, treponema pallidum, Haemophilus ducreyi, F. tularensis, M ulcerans and M marinum all present with what type of lesion?
A
chancriform
16
Q
T/F: Erysipelas and cellulitis both describe diffuse, superficial spreading skin infections
A
true
17
Q
T/F: cellulitis is associated with pus
A
false
18
Q
what layers of tissues does cellulitis involve?
A
upper derm and subQ fat
19
Q
When doing your preliminary physical exam of cellulitis, what are you going to notice? Think latin!
A
Rubor, tumor, calor, dalor!
20
Q
What bugs cause cellulitis?
A
Group A strep and sometimes S. aureus
21
Q
What differentiates erysipelas from cellulitis?
A
lymphatic involvement
22
Q
What is characterstic about the appearance of erysipelas?
A
sharp, painful demarcation of the rash
23
Q
What bug is basically the only thing that causes erysipelas?
A
S. pyogenes
24
Q
What tissues does necrotizing fasciitis affect?
A
all tissue between skin and muscle
25
T/F: necr. fasc. is often polymicrobial
true
26
T/F: necr. fasc. can result in systemic toxicity
true
27
What are the four most common bugs causing necrotizing fasciitis?
S pyogenes
S aureus
V vulnificus
Aeromonas hydrophila
28
Synergistic necrotizing cellulitis
Clostridial anaerobic cellulitis
are subtypes of (blank)
subcutaneous tissue infections
29
What is readily visible in a systemic bacterial infection?
skin rash
30
Bacteremia ,Leptospirosis (Weil’s disease), Rat-bite fever – Annular erythema – Lyme disease,
Rocky mountain spotted fever are all examples of rash producing (blank)
systemic infections
31
scarlet fever is induced by (blanks) released by group A strep
toxins
32
scarlet fever follows what initial presentation
pharyngitis
33
What toxin is responsible for scarlet fever?
SpeA of strep pyogenes
34
What toxin is responsible for scalded skin syndrome? What bug?
exfoliating toxin of staph
35
What bug and toxin causes toxic shock syndrome?
staph aureus, TSST-1 super ag
36
A violaceous lesion will present with infection of what bug after contact with infected fish, marine animals, swine, or poultry?
E. rhusiopathiae
37
Cat scratch disease shows what types of lesions?
pustular
38
What bug infects surgical wounds?
serratia marcesens
39
What bug infects cuts from FRESH ONLY water?
Aeromonas
40
What bug infects cuts from FRESH AND SALT water?
Vibrio parahaemolyticus
41
What bug infects cuts from SALT WATER ONLY?
Vibrio vulnificus
42
What bug infects battlefield injuries?
A. baumanii
43
What bug infects post human bite or fist fights?
E. corrodens
44
what is the name for pus within a muscle?
pyomyositis
45
What causes pyomyositis 90 percent of the time?
S. aurues
46
where in the world do we commonly see pyomyositis?
the tropics
47
Myonecrosis or gas gangrene happens after contamination with soil or other material containing (blank)
spores
48
What is the most common bug causing gas gangrene?
Clostridium perfringens
49
What is the discoloration associated with gas gangrene?
yellowish-bronze
50
T/F: most streptococci are facultative anaerobes
true
51
strep is catalase (pos/neg)
negative
52
what are the three ways that strep is classified?
hemolytic patterns, lancefield grouping, and bch properties
53
(B/ a and g) hemolytic strept are classified by lancefield groups
B
54
(B/a and g) hemolytic strep are classified by bch properties
alpha and gamma hemolytic
55
What type of hemolysis is partial and turns the agar green?
alpha
56
What type of hemolysis is complete creating a clear zone?
beta
57
what type hemolysis doesn't actually cause hemolysis?
gamma
58
Streptolysins O and s are associated with which hemolytic group?
beta
59
S. salivaris and S. mitis are what type of hemolytic group?
alpha
60
The normal flora of the mucous membranes is what (a/b) hemolytic
alpha
61
C carbohydrate is found in what hemolytic group?
Beta
62
Group A includes (blank) and most human pathogens
strep pyogenes
63
Groups B C F G H KL are found on what types of bugs?
normal flora of mucous membranes, occasionally on pathogens
64
Groups E M N CHOs are found where?
in most lower animals
65
Group D ag is found on what specific bug?
enterocccus faecalis
66
T/F: strep with C carbohydrate are only B hemolytic
false; can by a b or g
67
What bug causes this: pharyngitis, pyoderma, rheumatic fever
strep pyogens
68
What bug causes this: neonatal sepsis and meningitis
s. agalactiae
69
What bug causes this: puerperal sepsis and endocarditis
Strep anginosus and equi
70
What bug causes this: endocarditis, UTI
enterococcus, strep bovans, s. equinus
71
What bug causes this: penumonia, otitis media, meningitis
strep pneumoniae
72
What bug causes this: subacute endocarditis
S. mutans, salivaris, or mitis
73
T/F: Strep pneumoniae has no serological group
true
74
S. anginosus and equi are what group?
group C
75
What streps are in the Viridans group?
mutans, salivaris, and mitis
76
Which strep groups are Beta hemolytic>?
A, B, C, D
77
Which strep groups are alpha hemolytic?
D, S. pneumoniae, and viridans
78
which groups of strep may be non-hemolytic?
D and Viridans
79
(blank) is a Polymer of rhamnose and N-acetyl-glucosamine
lancefield CHO or C CHO
80
The M protein subdivides group (blank) into over 100 types
group A
81
(blank) induces type-specific protective immunity to GAS
M protein
82
What three extracellular enzymes are present in S. pyogenes?
streptolysin O, DNase, hyaluronidase
83
Impetigo, Erysipelas, Cellulitis, myositis and necr. fasc. are caused by group (A/D) strep
A
84
What is the function of lipoteichoic acid?
adhesion to epithelial cells
85
F protein/strept fibronecting binding protein binds to what type of epithelial cells?
nasopharyngeal
86
(M protein/hyaluronic acid capsule) is essential for early colonization and adhesion to nasal mucosa
hyaluronic acid capsule
87
T/F: M protein is involved in both adherence and avoiding phagocytosis
true
88
What step pyogenes virulence factor is a target for vaccine development?
M protein
89
Erythrogenic toxin and scarlet fever toxin are two types of (blank) toxin
strep pyrogenic exotoxins aka Spe
90
Spe super-ags stimulate the release of which cytokines?
IL1, IL2, IL6, TNFa, IFNg
91
(Spe/Spa) is coded by the lysogenic bacteriophage
Spe
92
(blank) activates steps in inflammation and septic shock, e.g., complement cascade, cytokine secretion, coagulation cascade in GAS
lipoteichoic acid
93
streptolysin O is what class of protein?
porin
94
Streptolysin O is oxygen (labile/stable)
labile
95
Streptolysin (O/S) is antigenic
O is antigenic
| S is non-antigenic
96
Streptolysin (O/S) is oxygen stable
S
97
(Streptokinase/streptornase) converts plasminogen to plasmin and lyses blood clots
streptokinase
98
(Streptokinase/streptornase) reduces viscosity of abscess material
streptornase
99
T/F: Hyaluronidase function as a virulence factor by avoiding phagocytosis
false; causes tissue damage
100
A strawberry tongue with enlarged fungiform papillae, red cheeks with a pale area around the mouth and a fine, red and rough textured rash that blanches upon pressure is classic for what non-purulent strep based disease?
Scarlet fever
101
Are live streptococci necessary to cause AGN or rheumatic fever?
no, can be secondary to the first infection
102
Is prior sensitization necessary for both AGN and rheumatic fever?
ONLY FOR RHEUMATIC FEVER; you can get AGN from your first exposure to streptococci
103
What is the site of infection of rheumatic fever?
pharynx
104
what is the site of infection of AGN?
skin!
105
is it common for an infant to get rheumatic fever? AGN?
rare for rheumatic fever, not uncommon for AGN
106
T/F: prophylaxis is mandatory in rheumatic fever
true
107
T/F: there is no prophylaxis for AGN
true
108
Describe the M protein types for rheumatic fever and for AGN?
rheumatic fever: rheumatogenic strains
| AGN: nephritogenic strains
109
Are complement levels decreased in rheumatic fever or AGN? why does this make sense?
AGN; you are getting kidney damage from large molecule depostion--all that complement is stuck in the kidneyu
110
What is mechanism for rheumatic fever?
cytotoxic Ab
111
what is the mechanism for AGN?
immune complex disregulation
112
What does the quick strep test detect?
lancefield carbohydrate ag
113
```
Describe the status of strep pyogenes for the following tests:
Gram stain
Hemolysis
Catalase production
Bacitracin sensitivity
Lancefield group
```
```
Gram pos
B hemolytic
Catalase neg
Bacitracin sensitive
Lancefield will tell what type of B hemoltic strep
```
114
What are the systemic effects of SpeA toxin?
Fever, rash, and systematic effects
115
What is the mechanism of the SpeA toxin?
```
Superag causing cyotkine release of :
IL1
IL2
IL6
TNFa
IFNg
```
116
Serological tests for GAS are used for a (blank)-type diagnosis
retrospective
117
The anti-streptolysin O assay is (neg/pos) in skin infections
negative
118
Anti-streptolysin O is useful for diagnosis of (rheumatic fever/AGN)
rheumatic fever; NOT HELPFUL for AGN
119
Anti-DNase assay is (neg/pos) in skin infections
positive
120
Anti-DNase assay is useful for Dx of (rheumatic fever/AGN)
AGN
121
T/F: anti streptolysin O and anti-DNase imply immunity to the infection
FALSE
122
strep pharyngitis is transmitted via (blank)
airborne droplets
123
strep skin infections can be controlled by good (blank)
hygeine
124
What percent of the population can be asymptomatic carriers of strep infections?
5-20%
125
what is the reservoir for transmission of strep?
asymptomatic carriers
126
Decades-long immunity to strep is given via the (blank) protein
M protein
127
What is the firstline drug for strep?
Penicillin
128
T/F: all strains of strep are sensitive to PCN
true
129
Why is it essential that a strep infection be treated QUICKLY and COMPLETELY?
reduces the Ab response and limits the chance of progression in the future to RF or AGN
130
If you have a mixed infection of strep and staph aureus, what abx is your choice?
vancomycin or oxacillin
131
What is the abx for necrotizing fasciitis?
High dose PCN with clindamycin
132
What must you do besides give abx to control necrotizing fasciitis?
drainage and surgical treatment
133
If someone has a PCN allergy and has necrotizing fasciitis, the fuck are you supposed to give them??
clindamycin or a narrow specture cephalosporin, or maybe even a macrolide
134
T/F: MRSA without any other simultaneous infections is a common cause of necrotizing fasciitis
false1!
135
Staph aureus is coagulase (neg/pos)
NEGATIVE
136
staph aureus presents in (blank) like clusters
grape like
137
Staph is coagulase negative and catalase (blank)
POSITIVE
138
What color pigment may staph aureus have?
GOLD; AUreus, hellooooo
139
t/F: staph aureus may be non-hemolytic
true, also may be beta
140
T/F: staph aureus is sensitive to physical and chemical agents
false; resistant
141
Staph aureus carries multiple (blank or blank) that give it PCNase activity along with toxin production
plasmids and bacteriophages
142
What percent of the staph genome is a conserved core genome?
80%
143
20% of the staph genome is made of mobile genetic elements including bacteriophages, plasmids, transposons, and (blanks), which act like transposons
staph chromosomal cassettes
144
What are the two huge important functions of the staph mobile genetic elements?
virulence factors and antibiotic resistance
145
Regulation of the staph mobile genetic elements is (blank)-like, and is exemplified by the accessory gene regulator agr that allows for quorum sensing
operon-like
146
staph aureus accounts for 80% of bullous and pustular forms of (blank)
impetigo; S. pyogenes alone or in conjunction with S aureus for the remainder
147
Abscesses, folliculitis, furuncles, and carbuncles are caused by (s. aureus/ s. pyogenes0
aureus
148
T/F: staph aureus can cause osteomyelitis
true
149
T/F: staph aureus can cause pneumonia and septic arthritis
true
150
staphylococcal (blank) follows broad spectrum abx use
enterocolitis
151
Staph (blanks) cause food poisoning, scalded skin syndrome, bullous impetigo, and TSS
toxins
152
Staph aureus is (weakly/strongly) virulent
weakly!! the minimal dose to get an infection is LARGE
153
Unlike strep, Skin lesions with staph areus cause (blank), irreversible tissue damage and scarring
PUS FORMATION AKA SUPPURATION
154
75% of clinical cases of staph have a type 5 or 8 antiphagocytic (blank)
capsule
155
What two components of the capsule in staph contribute to the inflammation?
PDG layer and lipoteichoic acid
156
Protein A in the staph capsule has a high affinity for the Ig(blank) Fc fragment
IgG
157
Coagulase in staph converts (blank to blank) and helps localize lesions and is a marker for other species
fibrinogen to fibronectin
158
Catalase in staph facilitates (blank)
intracellular survival
159
T/F: staph carries PCNase
true
160
What are the cytotoxins that staph aureus codes for?
alpha, beta, delta, and gamma along with PV leukocidin
161
staph cytotoxins are toxic via mechanisms for what three cell types?
erythrocytes, leukocytes, and platelets
162
what two toxins lead to scalded skin syndrome?
exfoliating toxin a and b
163
Pyrogenic exotoxins of s aureus are coded by (blanks) for the enterotoxins or (blanks) for TSST
plasmids for enterotoxins
| bacteriophage for TSST
164
T/F: Superags are pyrogenic exotoxins
true
165
T/F: superags have toxic effects that are different than the superag effects
true
166
SEA, SEB, SEC, SED, and SEE are what class of staph toxins?
enterotoxins
167
what are the five classes of staph toxins?
1. cytotoxins
2. exfoliating toxins
3. pyrogenic toxins
4. enterotoxins
5. toxic shock syndrome toxin
168
T/F: staph is resistant to extended boiling and gastric acids
true
169
what is the incubation time for staph food poisoing?
1-6 hours
170
staph food poisoning targets *(blank) of the smooth muscle of the intestine
sensory nerve endings
171
How long is it until staph food poisoning passes?
24 hours
172
Exfoliative skin disease is aka
scalded skin syndrome
173
Bullous impetigo is the local form of:
scalded skin syndrome
174
The toxin in scalded skin syndrome is a (blank) protease
serine
175
the toxin in scalded skin syndrome cleaves the (blank) junction to form fragile, thin-roofed vesicopustules
derm-epiderm
176
scalded skin syndrome is usually seen in (kids/elderly)
kids
177
desqumation is a complication seen in:
scalded skin syndrome
178
toxic shock syndrome gives you an increased susceptibility to (blank)
endogenous exotoxin
179
T/F: toxic shock syundrome has a direct effect on vascular endothelial cells
true
180
When is TSST-1 stimulated in staph infections?
poor growth conditions; one hell of a "fuck you"
181
T/F: blood cultures are usually negative in TSS
true, super wierd
182
Superags will bind the MHC (blank) to the tCR
MHC II
183
T/F: TSST-1 froms staph and SpeA from strep elicit the same systemic symptoms and cytokine release
true!!!!
184
Direct examination of what two fluids will show you staph?
pus and CSF
185
what type of special media is needed to isolate staph?
mannitol salt agar
186
Coagulase (pos/neg) distinguishes s aureus from other staph strains
coag pos
187
T/F: Staph aureus ferments mannitol
true, that's why you use mannitol salt agar
188
What special media do you need to culture MRSA and what two abx do you use for sensitivity testing?
chromogenic media with disks of oxacillin or cefotoxin
189
Dx of MRSA via PCR is looking for the (blank) gene
mecA
190
T/F: Abx sensitivity testing is essential for the Dx of staph
true
191
When do you do subspecies typing of staph?
for epidemic strains
192
Antibiograms, biotyping, phage typing, and nucleic acid analysis are used to determine the (blank) for epidemic strains
subtype
193
What is the primary reservoir of staph aureus and where does it reside in the reservoir?
MAN, normal flora of lower large bowel, skin, anterior nares
194
T/F: staph aureus infection can be transmitted via aerosol
true
195
T/F: staph aureus infections can be endogenous
true
196
what is the carrier rate of staph in the normal pop?
30%
197
What is used for decontamination of nasal carriers of staph?
mupirocin
198
T/f: there is no immunity made against staph, allowing for multiple reinfections
true
199
What must the PCN based drugs have to be effective against MRSA?
must be PCNase resistant
200
What are the most commonly used abx against MRSA?
```
Penicillinase-resistant penicillins, e.g., oxacillin
Clindamycin
TMP-SMX
Doxycycline
Linezolid
Vancomycin
Daptomycin
```
201
T/F: PCNase producing staph is uncommon except in the hospital setting
false; very common
202
What type of staph has a thicker, more disorganized cell wall with free ala-ala groups as decoys for vancomycin?
VISA
203
the vanA gene operon encodes for ala-lactate production in what strain of staph?
VRSA
204
T/F: VRSA is still rather rare
true
205
what is the cassette that codes for MRSA abx resistance?
SCCmec
206
SCCmec codes for a (pos/neg) repressor operon and mecA which codes for (blank)
negative repressor operon and mecA which codes for PBP 2a which has low affinity for b-lactam abx
207
What are the risk factors associated with HCA-MRSA?
surgery, indwelling catheters
208
HCA-MRSA is (multi/Pauci) resistant
multi
209
T/F: community acquired MRSA has no risk factors
true
210
What is the most common cause of soft tissue infection in the community?
MRSA
211
CA-MRSA carries (blank) leukocidin
PV leukocidin
212
CA-MRSA is (blank) resistant
Pauci resistant
213
How do you decolonize MRSA colonzied patients?
1 week of body washing with chlorhexidine and use of nasal mupirocin
