Ch1: Skin Flashcards
(276 cards)
1
Q
Pathogens usually enter the lower layers of epidermis and dermis after what?
A
Damage
2
Q
Pathogens can infect the follicle how?
A
Descending from surface of skin
3
Q
Pathogens can also infect subcutaneous and dermis how?
A
Leaving the blood
4
Q
Function of the skin is to do what? (6)
A
- Protect from environment
- Sensation
- Shape
- Temp regulation
- Blood pressure
- Synthesize Vitamin D
5
Q
Normal skin flora inhabit what areas predominately?
A
Moist: groin, armpits
6
Q
What are the most common genera of skin flora? 2
A
- Staph epidermidis (100% of pop)
2. Staph aureus (20% of pop)
7
Q
Host defenses of the skin include?
A
- Stratum corneum: Sloughed cells carry microbes away
- Low moisture = fewer microbes
- Salty sweat = discourage growth
- Sebum = decreases pH –> discourage growth
- Hair follicles = Produce lysozyme
- Lower temperature = discourage growth
- Langerhans cells = APC’s of skin
- Innate immunity
8
Q
What are the two steps for inflammation of the skin? (2)
A
- Recognition
2. Recruitment
9
Q
What happens in recognition?
A
Bacterial components such as peptidoglycan, LPS, and other PAMP’s are recognize by Toll-like receptors that cause release of inflmmatory cytokines
10
Q
What happens in recruitment?
A
Effector cells are recruited to the site of infection by cytokines
11
Q
What is the effect of cytokines on blood capillaries?
A
Dilates them –>
- WBC’s recruited
- Leakage of plasma –> Redness
12
Q
Why does an inflammation cause pain in the skin?
A
Due to high density of nerve endings in the skin, swelling causes pain
13
Q
What is pus formed from? (2)
A
- Neutrophils
2. Lysis of foreign things
14
Q
Viscosity of pus is due to what?
A
DNA
15
Q
What does TLR-4 recognize?
A
LPS from gram-negative bacteria
16
Q
Infections of the skin are of what 3 categories?
A
Breach in skin
Hematogenous infection
Toxin-mediated damage
17
Q
What is a macule?
A
Circumscribed change in skin color that is NOT raised
18
Q
What is a papule?
Does it have liquid?
A
Solid elevated lesion with raised edges
Yes and No.
19
Q
What is a pustule?
A
Circumscribed raised cavity containing pus
20
Q
What is a abscess/boil?
A
Localized inflammation with pus
21
Q
What is a furuncle?
A
Acute, deep-seated red hot nodule or abscess
22
Q
What is a carbuncle?
Where are they normally found?
A
Deeper-seated composed of interconnecting abscesses/boils in subcutaneous fat
Neck and upper back where skin is elastic
23
Q
What two lesions of the skin have pus?
What is pus due to?
A
Pustule and Abscess/boil
Neutrophils
24
Q
What is staphylococci’s shape?
A
Spheres in clusters (Grape-like)
25
What is the test for staphylococcus?
Coagulase test
26
Staph aureus secretes what enzyme?
Coagulase
27
What does coagulase do?
Converts fibrinogen to fibrin
28
How does the coagulase test work?
Bacteria sample is suspeneded in tube with rabbit plasma, if the bacteria has coagulase produced, a clot will form due to fibrin formation
29
What does the aureus mean in staph aureus?
Gold, which i the color of colonies
30
Is staph aureus gram positive or negative?
Positive
31
Size of staph aureus?
1.0 um in diameter
32
What is the habitat of staph aureus?
1. Human skin
2. Anterior nares
3. Conjunctivitis
4. hands and fingers
5. Arms and groin
33
What percentage of human population is colonized with staph aureus?
25-35%
34
Transmission of staph aureus is through what?
1. Direct contact
2. Fomites
3. Endogenous
35
What are fomites?
Objects that can transmit an organism
36
What does endogenous mean?
Part of normal flora, but can accumulate or go somewhere they shouldn't
37
What is a virulence factor?
Something that can promote disease
38
What are the two cell-associated virulence factors of staph aureus? (2)
1. Polysaccharide capsule
| 2. Protein A
39
Function of polysaccharide capsule?
Surrounds the bacteria and acts as an anti-phagocytic
40
Function of protein A?
binds the FC portion of IgG antibodies (including those directed towards itself) which inhibits antibody-mediated phagocytosis
41
Where is Protein A exactly?
On cell wall and linked to PTG
42
What are the two secreted virulence factors of staph aureus?
Exfoliatin
| Superantigens
43
What is exfoliatin?
Protease that degrades desmosomes of tight junctions between cells in epidermis
44
What does exfoliatin cause? (2)
1. Scalded skin syndrome
| 2. Bullous impetigo
45
Genes encoding S. aureus superantigens are located where?
| What type of transfer does this allow for?
In mobile genetic elements such as bacteriophage and pathogenicity islands
Horizontal transfer
46
Do all staph aureus species have the same superantigens?
No, different isolates have different compositions
47
Superantigens bind to what? 2
Simultaneously to the MHC class II molecule on surface of APC's and the T-cell receptor
48
Result of superantigens binding to APC and T cell?
Non-specific stimulation of T cells (2-20%) resulting in excessive cytokine release leading to to fever, hypotension, rash and a variety of other clinical manifestations
49
What is the most common and important superantigens?
What does it cause?
Symptoms? (3)
Toxic Shock Toxin-1 (TST-1)
Toxic Shock Syndrome
Fever, Hypotension, Shock
50
What are the two categories of staph infections?
Bacterial
| Toxigenic
51
What does bacteria disease of staph do?
The bacteria invades and evokes clinical manifestations
52
What does toxigenic disease of staph mean?
Clinical manifestations are due to staph toxin only
53
Skin diseases of staph?
1. Abscess
2. Impetigo
3. Folliculitis
4. Style
5. Carbuncles
6. Furuncles
54
What is impetigo?
Infection of epidermis leading to bullous impetigo
55
What is foliculitis?
Infection of hair follicle
56
What is a stye?
Folliculitis in eye
57
What are the three main bacterial versions of staph infection?
1. Skin diseases
2. Wound Infection
3. Bacteremia
58
What can cause bacteremia? (4)
1. Ruptured abscess
2. Injury
3. Needle
4. Surgery
59
What can staph cause once in the blood? 4
Osteomyelitis
Arthritis
Pneumonia
Endocarditis
60
Three forms of toxigenic disease from staph aureus?
1. Scalded skin syndrome
2. Bullouis impetigo
3. Toxic shock syndrome
61
Scalded skin syndrome is due to what?
Exfoliatin toxin
62
What does the exfoliatin toxin do uppon reaching the blood?
Spreads out and degrades desmosomes of epidermis --> Top layer of epidermis to be released
63
Complications of SSS? 2
1. Fluid loss
| 2. Secondary infections of skin
64
How does scalded skin syndrome appear?
| What population gets it?
Burn or blister
Neonates and children
65
How do you diagnose SSS? 2
1. Patient history
| 2. Biopsy
66
What is bullous impetigo?
| What causes it?
Localized SSS
| Exfoliatin toxin
67
Toxic shock syndrome is caused by what?
Superantigens that nonspecifically stimulate cytokine production.
68
Most potent superantigen of s. aureus?
| What can it cross that other superantigens can't?
TST-1
| Cross mucal membrane
69
TSS is based on what 4 features?
1. Fever greater than 102
2. Hypotension less than 90 mmHg
3. Rash
4. Abnormalities in 3 organ systems
70
Two types of TSS?
Menstrual
| Non-menstrual
71
Describe menstrual TSS.
S. aureus that normally colonizes the vagina grows to greater numbers during menstruation --> Produced superantigen (mainly TST-1) --> Crosses mucosa --> Enters blood --> Causes symptoms of TSS
72
Increased growth of s. aureus during menstruation is due to what? (3)
1. Increase supply of nutrients in vagina
2. Increase in pH of vagina
3. Drying of vaginal mucosa by highly absorbent tampons leading to tears in epithelium
73
TST-1 production in menstrual TSS is enhanced by what?
Presence of synthetic fibers used in tampons
74
What is non-menstrual TSS? 2
1. When superantigens produced by S. aureus colonizaiton of skin/wounds enters the bloodstream to cause systemic effects
2. S. aureus is present in bloodstream and produces superantigens.
75
Non-menstrual TSS is associated with what? 4
1. Post-operative
2. Post partum
3. Barrier contraceptives
4. Cutaneous infections
76
What are the two tests to run when diagnosing potential staph aureus?
1. Gram-stain = Positive
| 2. Coag test = Positive
77
S. aureus grows well on what medium?
Blood-agar
78
Mannitol salt agar is useful for what reasons in testing for staph aureus
1. Selective: Selects ability of staph to grow in high salt environment
2. Differential: S. aureus can ferment mannitol causing pH indicator to turn yellow
79
Why is culturing so important with staph aureus?
Have to determine degree the strain has resistance to different antibiotics
80
Treatment of skin lesions of staph aureus includes what?
Incision and drainage with or without mupirocin or additional antibiotics
81
What does antibiotic use against s. aureus depend on?
1. Speed lesion is progressing
2. Systemic symptoms
3. extremes of age
82
What percentage of staph aureus is resistant to penicillin?
| Why?
90%
Produce a penicillinase which degrades penicillin
83
MRSA is an isolate that is resistant to what?
All penicillinase-resistant Beta-lactam antibiotics: Methicillin, oxacillin, floxacillin
84
Resistance to methicillin-like antibiotics is associated with what?
What is this?
mecA gene
| Mobile DNA element that encodes a penicillin binding protein that is NOT activated by methicillin like antibiotics
85
Due to the significance of MRSA how do we designate s. aureus?
```
MRSA = Resistant
MSSA = Sensitive
```
86
Is hospital acquired MRSA different from community acquired?
Why?
Yes
They are different genetically, and HA-MRSA is more resistant to antibiotics
87
Which of the two, HA-MRSA and CA-MRSA is a recently emerged infectious agent?
CA-MRSA
88
CA-MRSA have what gene?
mecA
89
CA-MRSA can have what effects in addition to normal s. aureus? (3)
1. Necrotizing fasciitis
2. Purpura fulminans
3. Necrotizing pneumonia
90
Treatment of CA-MRSA is most effective when?
If the antibiotic sensitivity of the organism is determined.
91
In severe cases in which MRSA is suspected, what antibiotics are used? 3
Vancomycin
Linezolid
Daptomycin
92
CA-MRSA requires what to be accurately treated?
Multiple sampling for > 90% sensitivity
93
Treatment of CA-MRSA depends on what? 2
1. Severity of disease
| 2. Local susceptibility data
94
What is VISA?
Vancomycin-intermediate resistant staph aureus
95
VISA produces what anatomically?
Thicker cell wall of PTG that decreases vancomycin's ability to weaken cell wall
96
What is VRSA?
Vancomycin-resistant staph aureus
97
VRSA has what genetic advantage?
What does this do?
Where did it get it from?
vanA gene
Modifies structure of PTG making it not susceptible to vancomycin
Vancomycin-resistant enterococci
98
VanA VRSA have what protein change?
D-ala D-lac in PTG crosslinking instead of D-ala, D-ala
99
What vaccine exists for staph aureus?
None
100
What does the word streptococci mean?
```
Streptus = Pliant
Cocci = Berry
```
101
How does strep stain in a gram stain?
Gram positive
102
Two special shape characteristics of strep?
1. Spherical
| 2. Cell division occurs in one plane --> Chain
103
How does strep react in a catalase test?
Catalase = Negative
104
Is strep an anaerobe or aerobe?
| Do they tolerate O2?
Anaerobe
| Yes
105
Two ways to classify strep?
Hemolysis
| Lancefield
106
Describe the hemolysis classification of strep
Beta strep: Complete cleaning around colony
Alpha: Partial clearing (green)
Gamma: No hemolysis
107
What is hemolysis of strep performed on?
Agar plates with blood
108
What is lancefield classificaiton based on?
Presence of different carbohydrates in the cell walls of different strep species
109
How many species are in Group A and Group B strep?
Essentially one each
110
What is the Group A strep?
Streptococcus pyogenes
111
What is group A streps
Hemolysis classification?
Gram stain?
Appearance similar to?
Beta hemolytic
Gram positive
Similar to other beta-hemolytic
112
Habitat of s. pyogenes?
| Specifically? (4)
Human mucosal surfaces
Nasopharynx
Skin
Vagina,
Perianal
113
What other organisms can s. pyogenes inhabit?
Only humans
114
Transmission of s. pyogenes is how? 2
Droplets
| Direct contact
115
Cell associated Virulence factors of S. pyogenes? 2
1. Polysaccharide capsule
| 2. M protein
116
The polysaccharide capsule is comprised of what in s. pyogenes?
Is it antigenic?
Is it similar to hyaluronic acid in our bodies?
Function?
Hyaluronic acid
Not antigenic
Identical to hyaluronic acid in our bodies
Inhibits phagocytosis
117
What is it called when s. pyogenes avoids detection by using the same hyaluronic acid as in humans?
Molecular mimicry
118
The M protein of s. pyogenes is where?
Embedded in cell wall
119
How many serotypes of M protein exist?
| Does an antibody against one serotype protect against other serotypes?
Over 100
No
120
What is the M protein's 100 serotypes an example of?
Antigenic variation
121
The M protein has what function? 2
1. Inhibits phagocytosis
| 2. Allows GAS to adhere to human epithelial cells
122
What is the most important virulence factor of GAS?
M protein
123
What are the five secreted virulence factors of GAS?
1. Streptolysin O
2. DNAse's
3. Protease
4. Streptokinase
5. Superantigens
124
What does streptolysin O do?
It is a pore-forming toxin that lyses eukaryotic cells
125
How is streptolysin O seen diagnostically?
It is responsible for Beta-hemolysis
126
What form is streptolysin O in?
Monomer
127
An elevated antibody titer to streptolysin O (ASO test) indicates what?
1. Recent strep pyogenes pharyngeal infection, but not skin infection.
2. Rheumatic fever
128
How many types of DNAses does s. pyogenes release?
Four (A, B, C, D)
129
DNAses are secreted into human host to do what?
Degrade nucleic acids present in Neutrophil Extracellular Traps, a part of innate immunity
130
An elevated antibody titer to DNAse B suggests what? (2)
1. S. pyogenes skin infection recently
| 2. Post-streptococcal glomerulonephritis
131
What does protease do? (2)
| What is it also known as?
1. Degrades human proteins
2. Promotes tissue invasion
Aggressin
132
Streptokinase has what function?
Activates plasminogen to plasmin
133
Plasmin can activate what? 3
1. MMP's
2. Collagenases
3. Proteins involved in tissue repair
134
Human plasmin can also bind to the surface of bacterium to do what? (2)
1. Degrade tissue
| 2. Promote dissemination
135
What are the superantigens in strep pyogenes called?
Streptococcal pyrogenic exotoxins
136
SPE's are encoded by what?
Bacteriophage
137
Streptococcal superantigens function how?
Same as superantigens in staph
138
What is impetigo?
Infection of epidermis caused by S. pyogenes, S. aureus, or both
139
What is erysipelas?
Infection of dermis
140
What is cellulitis?
| What typically causes it?
Infection of dermis and/or cutaneous tissue
1. S. pyogenes
2. S. aureus
141
What are some Characteristics of cellulitis?
1. Might be able to culture the bacteria
2. Lymph nodes are swollen
3. Fever, chills, malaise
4. Infection can progress rapidly --> Sepsis
142
Which has a more clear demarcation, erysipelas or cellulitis?
Erysipelas
143
what is necrotizing fasciitis?
Infection of subcutaneous CT and fascia with myonecrosis
144
What can cause necrotizing fasciitis? 4
1. S. pyogenes
2. MRSA
3. Clostridium perfringens
4. Aeromonas hydrophila
145
Where does necrotizing fasciitis typically begin?
Site of trauma
146
Symptoms of necrotizing fasciitis?
Intense pain
147
What antibiotic works well against necrotizing fasciitis?
Penicillin
148
Foot/limb infections in diabetic patients are typically caused by what?
Mixed infections of s. aureus, s. pyogenes, pseudomonas, enterobacteriaceae
149
Diabetic neuropathy is due to what?
Tissue hypoxia
150
What is post infection sequelae?
Disease that occurs after primary infection
151
Can post-infection sequelae occur even if the microbe has been eliminated?
Yes
152
Post-infection sequelae is caused by what?
Misdirected immune response to microbe
153
S. pyogenes infection precedes what three post-infection sequelae?
What type of infection does each follow?
1. Post-streptococcal acute glomerulonephritis (PSAGN): Skin
2. Acute rheumatic fever/heart disease: Pharyngeal
3. Pediatric autoimmune neuropsychiatric disorders: (Pharyngeal)
154
What happens in PSAGN
Antibody-antigen complexes are deposited in glomerula of kidney causing inflammation and damage
155
Laboratory diagnosis of s. pyogenes shows what in
1. Gram stain
2. Blood-agar culture
3. Catalase
4. Lancefield:
1. Gram positive
2. Beta-hemolytic
3. Catalase negative
4. Group A
156
To obtain evidence of a recent s. pyogenes skin infection determine what?
Levels of antibody titer against streptococcal DNAseB
157
What is drug of choice for s. pyogenes?
| What else works? (3)
Penicillin
| Amoxicillin, Erythromycin, Cephalosporins
158
Why is erythromycin used sometimes instead of penicillin?
Avoid allergic responses to penicillin
159
Is there a vaccine for s. pyogenes?
no
160
what are the two most important gram positive spore formers?
Clostridia
| Bacillus
161
What does clostridium perfringens cause?
Gas gangrene
162
4 main features of gas gangrene?
1. Gram positive
2. Bacillus shape
3. Forms endospores
4. Anerobic
163
Habitat of clostridium perfringens? (4)
1. GI tract of animals
2. Soil
3. Water
4. Sewage
164
How does one make sure to be rid of clostridium perfringens on fomites?
Autoclave
165
How is c. perfringens transmitted?
Exogenously or endogenously
166
Two clinical infections of c. perfringens?
Traumatic gas gangrene
| Spontaneous/Nontraumatic gas gangrene
167
Traumatic gas gangrene results from what?
Contamination at site of trauma (cut, gun shot, puncture wound) with spores that germinate to initiate infections.
168
How does trauma facilitate better growth of c. perfringens?
Trauma --> Decreased tissue oxygenation
169
Spontaneous/nontraumatic gas gangrene occurs in patients with what?
Why?
Specifically what?
Vascular diseases
Tissues lack adequate oxygen
Diabetes, colon cancer, atherosclerosis
170
Since c. perfringens is an anaerobe, it ferments, thus producing what?
H2S that stinks and you can see the gas
171
Laboratory diagnosis of c. perfringens? (2)
1. Gram positive rods in fluid from infected area
| 2. Nagler's reaction
172
How does Nagler's reaction work to test for c. perfringens?
Since c. perfringens secretes a lecithinase, when it is grown on agar plate with lecithin (egg yolk), it will degrade the lecithin and form a zone of opacity.
173
Treatment of c. perfringens? (3)
1. Prompt surgical remova of dead, damaged, infected tissue
2. Amputation if necessary
3. Antibiotics (penicillin)
174
IV drug users can insert drugs how? 3
1. Using contaminated needles
2. Not disinfecting skin
3. Injecting drugs contaminated with microbes
175
Is propionibacterium acnes part of normal flora?
Yes
176
What type of bacteria is propionibacterium acnes?
Anaerobe
177
Habitat of propionibacterium acnes?
Sebaceous glands of skin because there is not much oxygen and sebum provides nutrients
178
End product of propionibacterium acnes eating sebum? (3)
1. Fatty acids
2. Inflammation
3. Pus
179
Transmission of propionibacterium acnes?
Endogenously
180
Inflammatory acne is due to what?
Bacterial infection, and mainly propionibacterium acnes
181
What are the sebum channels called?
Pilosebaceous ducts
182
What must happen to pilosebaceous ducts for propionibacterium acnes to grow well?
Duct has to get clogged so that bacteria are not washed out to surface of skin.
183
Hormonal changes associated with puberty may result in acne why? (2)
1. Increased sebum production
| 2. Increased keratinizaiton
184
Treatment of propionibacterium acnes? (4)
1. Benzoyl Peroxide
2. Tetracycline
3. Erythromycin
4. Retoinoids
185
What does benzoyl peroxide do?
Generates O2 as it breaks down in skin --> Inhibits propionibacterium acnes growth
186
What do retinoids do?
Inhibit sebum production
187
Burns have what two main effects on skin?
1. Damage physical barrier of skin
| 2. Diminish neutrophil function
188
Minimizing colonization of burn involves what?
Topical antimicrobials like silver nitrate
189
Most important pathogens involved in burn wounds? (3)
1. Pseudomonas aeruginosa
2. Staph aureus
3. Strep pyogenes
190
Physical treatment of burn? (2)
1. Surgical debridement to decrease bacterial numbers
| 2. Different forms of silver to inhibit microbes
191
Antibiotic treatment of burns?
Whatever antibiotic is best for the specific agent
192
Pediatric burn patients are more susceptible to what? 2
1. Bacteremia
2. Toxic shock syndrome
S. aureus and x. pyogenes
193
Pseudomonas aeruginosa is seen in what clinical infection setting?
Burns
194
Pseudomonas aeruginosa can cause what? (3)
1. Pyoderma
2. External otitis
3. Hot tub rash/itch
195
What is pyoderma?
Infection of epidermis
196
What is external otitis?
Infection of external auditory canal
197
Pseudomonas aeruginosa is diagnosed how in the lab?
1. Using Woods lamp with UV light to see fluorescein which is produced by Pseudomonas aeruginosa
2. Culture from blood or skin
198
Treatment of vaccine for Pseudomonas aeruginosa?
Treatment: Ceftazidime
Vaccine: none
199
Is Pseudomonas aeruginosa very resistant to antibiotics?
Yes to many common ones
200
Leprosy is called by what?
Mycobacterium leprae
201
Characteristics of Mycobacterium leprae? 5
1. Acid fast positive
2. Aerobe
3. Grows best at 30 degrees Celsius
4. Can not culture on solid media
5. grows on armadillo
202
Habitat of Mycobacterium leprae? (3)
1. humans
2. armadillos
3. monkeys
203
Is Mycobacterium leprae a zoonotic disease?
No, have to get from another human
204
How is Mycobacterium leprae transmitted?
Nasal secretions
205
Mycobacterium leprae has a predilection for what type of cell?
Schwann cells
206
What does Mycobacterium leprae do upon entering body?
Invades schwann cells, tissue macrophages, and endothelial cells --> Granuloma formation
207
What special distinction does Mycobacterium leprae have?
Only bacteirum known to damage the peripheral nervous system
208
Two states of leprosy?
Tuberculoid
| Lepromatous
209
Symptoms of tuberculoid leprosy?
Regions of skin lose sensation due to nerve damage from immune response --> injury and secondary skin infection
210
What limits the infection in tuberculoid leprosy?
What gets activated?
How much bacteria is in skin and nose?
Cell mediated immunity
Macrophages
Very little, due to CMI response
211
What does the tubercle mean in tuberculoid leprosy?
Granuloma containing M. tuberculosis has formed which indicates an effective immune response
212
Is the person very infectious in tuberculoid leprosy?
No.
213
Lepromatous leprosy refers to a disease state of what?
When CMI response is ineffective.
214
Are you safe if lepromatous leprosy skin test comes back negative?
No
215
Bacteria in lepromatous leprosy grow where?
Skin and peripheral nerves --> Not contained by immune system
216
which form of leprosy is most contagious?
Lepromatous
217
Diagnosis of Mycobacterium leprae? (2)
1. Acid fast test on nose, lesion, and earlobe biopsies
| 2. Lepromin test
218
What is lepromin test?
Extract of Mycobacterium leprae
219
Antibiotics for Mycobacterium leprae? 3
Dapsone (folic acid synthesis)
Rifampin
Clofazimine
220
Mycobacterium marinum is endemic where?
Wetlands
221
How is mycobacterium marinum commonly called?
Fish tank or swiming pool granuloma
222
Initially where does M. marinum infect?
Visibly looks how to start?
Progresses to what?
Skin at sites of minor trauma
After 2-8 weeks looks like papule
Becomes suppurative ulcer
223
Mycobacterium ulcerans is endemic where?
Infections occur where?
Sign of disease?
Africa and australia
Sites of trauma
Painless ulcerative lesions
224
Mycobacterium tuberculosis colonizes skin how? (2)
1. Usually hematogenous dissemination
| 2. Direct inoculation can occur
225
How does m. tuberculosis look clinically?
Papule --> Painless ulcer
226
Superficial mycoses include what?
Pityriasis versicolor or tinea versicolor
227
What causes pityriasis versicolor/tinea versicolor?
Malassezia furfur
228
Is malassezia furfur a normal flora of skin?
How does its lesion appear?
Why?
Is it contagious?
Yes
Well-demarcated with scaling patches of different color
Melanin synthesis disrupted
No
229
KOH wet mount of a malassezia furfur appears how?
Spaghetti and meatball yeast forms
230
Dermatophyte infections involve organisms that do what?
Eat keratin
231
Dermatophyte infections are spread by what?
Spores
232
What are the three dermatopyte species?
1. Trichophyton
2. Microsporum
3. Epidermophyton
233
Dermatophytes invade what structures? 3
1. Skin
2. hair
3. nails
234
How can dermatophytes be clinically diagnosed? (2)
1. Fluoresce under UV light
| 2. Grow on sabouraud's agar
235
Symptom of dermatophytes?
Itching
236
Dermatophyte infections are treated how?
| Do they disseminate?
Topically
| No
237
Tinea means what?
| What causes it?
Ringworm
| Fungi
238
What is tinea capitis?
Ringworm of scalp and hair
239
Is tinea capitis infectious?
| What is important for transmission?
Yes very
Fomites
240
Most common causes of tinea capitis?
Trichophytan
| Microsporum (most likely)
241
What is tinea cruris?
| What is common cause? 2
Jock itch
Tricophyton
Epidermophyton
242
What is tinia pedis?
| What is common cause?
Athletes foot
| Tricophyton
243
Candida species cause what two skin manifestations?
1. Thrush
| 2. Diaper rash
244
Candida albicans require what for growth?
Moisture
245
Subcutaneous mycoses is caused the most by what in the US?
Sporotrichosis
246
Sporotrichosis is a noedular condition caused by what?
Sporothrix schenckii
247
Sporothrix schenckii is seen where? (3)
1. Soil
2. Thorned plants (gardeners)
3. Sphagum moss
248
Sporotrichosis enters body how?
Skin breaks and then follows lymphatics
249
Systemic mycoses that can manifest in the skin include? (4)
blastomycosis, coccidioidomycosis,
| histoplasmosis, and cryptococcosis.
250
The systemic mycoses are initiated how?
Inhaled and then disseminate in blood
251
Reactive arthritis is also known as what?
What happens in this disease?
Additional symptoms? (2)
Reiters' syndrome
Microbe --> Autoimmune response --> Inflamed joints
Conjunctivitis and urethritis
252
Common bacterial causes of reactive arthritis? 5
```
Campylobacter spp.,
Yersinia spp.,
Salmonella spp.,
Shigella spp.,
Chlamydia trachomatis
```
253
Septic arthritis is caused how?
| Symptoms? (3)
Circulating bacteria in the blood localizes in a joint or bacteria gains access to join through skin.
Fever, pain, swelling
254
How do you diagnose septic arthritis?
Culture synovial fluid and blood
255
Common ways to pick up septic arthritis? 2
Surgery
| Hematogeneously
256
Common bacterial causes of septic arthritis?
S. aureus
S. pyogenes
S. agalactiae
257
Treatment of bacterial arthritis? 2
Antibiotics and Drainage
258
Osteomyelitis is what? 3
Bone infection by an adjacent infection (direct), orthopedic surgery, hematogenously
259
Symptoms of osteomyelitis? (2)
1. Pain at site
| 2. Fever
260
Diagnosing osteomyelitis? (2)
1. Radiology
| 2. Culturing
261
Osteomyelitis is treated how? 2
1. Surgery
| Antibiotics
262
Common bacterial causes of osteomyelitis?
Which type is common in newborns?
Which type is common in sickle cell?
S. aureus: newborns
Coag negative staph
Strep
Salmonella: Sickle Cell
263
Treatment of osteomyelitis?
1. Identify bacteria and resistance through needle aspiration and culture
264
Antibiotic therapy lasts how long for osteomyelitis?
4-6 weeks
265
Transmission of infective endocarditis?
Hematogenous: Circulating microbes bind to valves
266
Guaranteed symptoms of infective endocarditis? (2)
1. Fever
2. Fatigue
3. Heart murmur
267
Endocarditis is categorized in what two ways?
| What type of bacteria
Acute: Virulent bacteria like Staph Aureus
Chronic: Less virulent: Strep viridans
268
Viridans strep describes what group?
Strep that lives in oral cavity normally
269
Viridans strep regularly enter bloodstream when? 3
1. Tooth brushing
2. Flossing
3. Dental procedures
270
What type of heart do the less virulent strep viridans infect?
Previously damaged
271
What is the mortality of infective endocarditis with treatment?
With no treatment?
20-50%
| Fatal
272
What is the diagnosis criteria for infectious endocarditis?
| What is required? (3)
Duke criteria
2 Major
1 major and 3 minor
5 minor
273
Major criteria for infectious endocarditis? 2
1. More than one positive blood culture
| 2. Evidence of myocardial involvement
274
Minor criteria for infectious endocarditis? (6)
1. Predisposition (Rheumatic fever, IV drug use)
2. Fever
3. Vascular problems (Emboli, bleeding)
4. Immunological problem (glomerulonephritis)
5. One positive blood culture
6. Echocardiographs consistent with endocarditis
275
What is most important test for diagnosing infective endocarditis?
Blood culture
276
Treatment for infective endocarditis? (2)
1. 2-6 weeks of IV antibiotics
| 2. Surgical replacement
