Ch1: Skin Flashcards Preview

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Flashcards in Ch1: Skin Deck (276):
1

Pathogens usually enter the lower layers of epidermis and dermis after what?

Damage

2

Pathogens can infect the follicle how?

Descending from surface of skin

3

Pathogens can also infect subcutaneous and dermis how?

Leaving the blood

4

Function of the skin is to do what? (6)

1. Protect from environment
2. Sensation
3. Shape
4. Temp regulation
5. Blood pressure
6. Synthesize Vitamin D

5

Normal skin flora inhabit what areas predominately?

Moist: groin, armpits

6

What are the most common genera of skin flora? 2

1. Staph epidermidis (100% of pop)
2. Staph aureus (20% of pop)

7

Host defenses of the skin include?

1. Stratum corneum: Sloughed cells carry microbes away
2. Low moisture = fewer microbes
3. Salty sweat = discourage growth
4. Sebum = decreases pH --> discourage growth
5. Hair follicles = Produce lysozyme
6. Lower temperature = discourage growth
7. Langerhans cells = APC's of skin
8. Innate immunity

8

What are the two steps for inflammation of the skin? (2)

1. Recognition
2. Recruitment

9

What happens in recognition?

Bacterial components such as peptidoglycan, LPS, and other PAMP's are recognize by Toll-like receptors that cause release of inflmmatory cytokines

10

What happens in recruitment?

Effector cells are recruited to the site of infection by cytokines

11

What is the effect of cytokines on blood capillaries?

Dilates them -->
1. WBC's recruited
2. Leakage of plasma --> Redness

12

Why does an inflammation cause pain in the skin?

Due to high density of nerve endings in the skin, swelling causes pain

13

What is pus formed from? (2)

1. Neutrophils
2. Lysis of foreign things

14

Viscosity of pus is due to what?

DNA

15

What does TLR-4 recognize?

LPS from gram-negative bacteria

16

Infections of the skin are of what 3 categories?

Breach in skin
Hematogenous infection
Toxin-mediated damage

17

What is a macule?

Circumscribed change in skin color that is NOT raised

18

What is a papule?
Does it have liquid?

Solid elevated lesion with raised edges
Yes and No.

19

What is a pustule?

Circumscribed raised cavity containing pus

20

What is a abscess/boil?

Localized inflammation with pus

21

What is a furuncle?

Acute, deep-seated red hot nodule or abscess

22

What is a carbuncle?
Where are they normally found?

Deeper-seated composed of interconnecting abscesses/boils in subcutaneous fat
Neck and upper back where skin is elastic

23

What two lesions of the skin have pus?
What is pus due to?

Pustule and Abscess/boil

Neutrophils

24

What is staphylococci's shape?

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

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Sporotrichosis enters body how?

Skin breaks and then follows lymphatics

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Systemic mycoses that can manifest in the skin include? (4)

blastomycosis, coccidioidomycosis,
histoplasmosis, and cryptococcosis.

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The systemic mycoses are initiated how?

Inhaled and then disseminate in blood

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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

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Common bacterial causes of reactive arthritis? 5

Campylobacter spp.,
Yersinia spp.,
Salmonella spp.,
Shigella spp.,
Chlamydia trachomatis

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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

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How do you diagnose septic arthritis?

Culture synovial fluid and blood

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Common ways to pick up septic arthritis? 2

Surgery
Hematogeneously

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Common bacterial causes of septic arthritis?

S. aureus
S. pyogenes
S. agalactiae

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Treatment of bacterial arthritis? 2

Antibiotics and Drainage

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Osteomyelitis is what? 3

Bone infection by an adjacent infection (direct), orthopedic surgery, hematogenously

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Symptoms of osteomyelitis? (2)

1. Pain at site
2. Fever

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Diagnosing osteomyelitis? (2)

1. Radiology
2. Culturing

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Osteomyelitis is treated how? 2

1. Surgery
Antibiotics

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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

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Treatment of osteomyelitis?

1. Identify bacteria and resistance through needle aspiration and culture

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Antibiotic therapy lasts how long for osteomyelitis?

4-6 weeks

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Transmission of infective endocarditis?

Hematogenous: Circulating microbes bind to valves

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Guaranteed symptoms of infective endocarditis? (2)

1. Fever
2. Fatigue
3. Heart murmur

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Endocarditis is categorized in what two ways?
What type of bacteria

Acute: Virulent bacteria like Staph Aureus
Chronic: Less virulent: Strep viridans

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Viridans strep describes what group?

Strep that lives in oral cavity normally

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Viridans strep regularly enter bloodstream when? 3

1. Tooth brushing
2. Flossing
3. Dental procedures

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What type of heart do the less virulent strep viridans infect?

Previously damaged

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What is the mortality of infective endocarditis with treatment?
With no treatment?

20-50%
Fatal

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What is the diagnosis criteria for infectious endocarditis?
What is required? (3)

Duke criteria

2 Major
1 major and 3 minor
5 minor

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Major criteria for infectious endocarditis? 2

1. More than one positive blood culture
2. Evidence of myocardial involvement

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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

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What is most important test for diagnosing infective endocarditis?

Blood culture

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Treatment for infective endocarditis? (2)

1. 2-6 weeks of IV antibiotics
2. Surgical replacement