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Skin- Bacteria Flashcards

(92 cards)

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1
Q

What gram stain is Staph Aureus

A

+

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2
Q

Is Staph Aureus thick or thin walled

A

Thick

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3
Q

Where are the granulocytes for Staph Aureus found

A

Intracellularly

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4
Q

What hemolytic is Staph Aureus

A

Beta

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5
Q

What kind of agar does Staph Aureus grow on

A

Blood agar

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6
Q

Is Staph Aureus aerobic or anerobic

A

Aerobic

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7
Q

What color colonies does Staph Aureus grow

A

White, becomes yellow with age

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8
Q

What catalase and coagulase is S. Aureus

A

Positive

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9
Q

Is Staph Aureus found normally on the body

A

Yes found in anterior nares for 30% of population

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10
Q

What is the mechanism of escape for Staph Aureus

A

Staph in general is coated with fibrin, makes it resistant to phagocytosis

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11
Q

What are other biologically active substances in Staph Aureus

A 
Hemolysins 
Hyaluronidase 
Nuclease
Lipase
Protease
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12
Q

What is the toxin found in S. Aureus

A

Alpha toxin (Cytotoxin)

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13
Q

What is the action of the toxin found in S. Aureus

A

Causes necrosis/ Death
Membranes leak
Causes RBCs to lyse

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14
Q

What kind of toxin is Panton- Valentine Leukocidin

A

Cytotoxin

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15
Q

What is the action of Panton Valentine Leukocidin

A

Lyses neutrophils, damages host cells

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16
Q

What diseases are associated with Panton Valentine Leukocidin

A

Pneumonia
Skin Infections
MRSA

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17
Q

What is the virulence of S. Aureus

A

10^5- 10^6 to start infection

10^ 2 if a suture is present

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18
Q

How does Staph cellulitis act?

A

Alternates btwn walling off and rapid extension of infection

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19
Q

What is a furuncle what infection causes it

A

Boil in hair follicle
Can give rise to stye
Staph

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20
Q

Where are carbuncles mostly found?

A

Back of the neck, formed from furuncle

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21
Q

What causes Chronic furunculosis

A

Delayed hypersensitivity to staphylococcal

Responsible for inflammation and necrosis

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22
Q

What disease is chronic staph associated with

A

Chronic granulomatous Dx

Diabetes

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23
Q

Impetigo is a bacterial infection composed of what

A

S. Aureus, 30% of the time found with streptococci

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24
Q

What is bullous impetigo

A

Caused by S. Aureus, causes skin to exfoliate.

Blisters contain many staphylococci

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25
Where do the majority of wound infections come from
S. Aureus. Patients own strain Hospital acquired
26
When do you find Staphylococcal pneumonia
Secondary to another lung injury: influenza, aspiration
27
What causes scalded skin syndrome
S. Aureus
28
How does Scalded skin present
Toxin absorbed into blood causing erythema and intraepidermal desquamation
29
What causes Exfoliatins?
S. Aureus
30
How does exfoliatins present?
Intercellular splitting of epidermis Split between Statum Spinosum and stratum granulosum Disruption of intercellular junctions
31
What infection causes toxic shock
S. Aureus
32
What are some signs of toxic shock
Rash | Strawberry tongue
33
How is rash from toxic shock differ from scalded skin syndrome
Rash develops then desquamation at deeper levels than scalded skin syndrome
34
Pyrogenic exotoxin
Toxic shock syndrome toxin 1 Stimulates cytokines Direct toxic effect on endothelial cells
35
Pathogenicity of Pyrogenic exotoxin
Similar to exotoxin of Group A strep | Stimulates enhanced T lymphocytes
36
Treatment for S. Aureus
Methicillin | Many strains resistant: MRSA
37
What is the difference between hospital and community acquired MRSA
Community acquired is susceptible to clindamycin, also carries PVL toxin Typically an uncomplicated skin infection. needs incision and drainage
38
Where is coagulase negative staphlococci usually found?
Skin, anterior nose
39
What do coagulase neg staphlococci have for virulence factors
Lacks major virulence factors | Not beta hemolytic
40
What are the characteristics of S. Iugdunesis
Coagulase negative Cuases infections similar to S. Aureus Forms abcesses
41
What is the virulence factor for S. Epidermidis
Produces extracell polysaccharide slime/biofilm | Protects it from phagocytosis, antibiotics
42
What is the clinical significance of coagulase neg staph
Normal flora | Need to collect deep invasive samples
43
When is coagulase neg staph detection significant
If intracellular gram + cocci are seen in gram stain
44
Where is coagulase neg staph usually found
On implants
45
Characteristics of streptococci
Normal flora Found in mouth GI Gram + cocci/ chains
46
Characteristics of pyogenic streptococci
Beta hemolytic | Causes purulent infections
47
What kind of toxin is released by Group A toxin
Pyrogenic exotoxin (SPE)
48
What are the effects of SPE (pyrogenic exotoxin )
Stimulates cytokine release | Red rash on skin- scarlet fever
49
Pharyngitis is found in which strep
Group A
50
How does Group A strep phryngitis spread
Direct contact or aerosols
51
Scarlet fever has what characteristics
Strawberry tongue Sandpaper rash Deep red color cheeks Punctate hemorrhages on palates
52
What is a complication for post strep
``` Acute Rheumatic fever Acute glomerulonephritis (antigen/antibody complex in kidneys) ```
53
Characteristics of Impetigo
Group A strep infection of skin | Glomerulonephritis is a complication
54
Difference between cellulitits and erysipelas
Cellulitis- deep dermis rash with fever (s. Aureus) Erysipelas- upper dermis (Group A >C,G) Both are beta hemolytic
55
Erysipelas presentation
Group A strep infection of upper dermis | Typically on face
56
Necrotizing fascitis is typically seen where
Beta hemolytic group A Streptococcus
57
Vascular compromise can be seen in what
Strep A TSS
58
How to diagnose Beta Streptococcus infections
Gram Stain Blood cultures Wound cultures
59
Human bites related to which infections
Group A strep infections
60
Which strep is known for deep tissue abscesses
S. Milleri
61
What causes dental caries
S. Mutans (viridan species)
62
Nutitionally deficient streptococci
Abiotrophia
63
What is needed to grow abiotrophia?
Vitamin or nutrients from other bacteria/ human cells Causes bacterial endocarditis Need to add feeder colony
64
what kind of hemolytic strep is enteroccus
non-hemolytic strep
65
Which corynebacterium is related to skin infections
Corynebacterium ulcerans
66
Which corynebacterium is related to nosocomial blood and wound infections
Corynebacterium jeikeium
67
Characteristics of Erysipelothrix Rhusiopathiae
Gram +, found in animals meat and seafood
68
Characteristics of Erysipeloid
Slow spreading skin infection Found in fishermen, butchers, vets Tx penicillin
69
Characteristics of anaerobic infections
Mixed gram + and -
70
Where are anaerobes normally found on human body
Stool of colon Mouth Vagina Sebaceuous gland
71
When do anaerobes attack
After tissue trauma/injury
72
How to collect anaerobes in culture
Abscess aspirate Surgically removed tissue Blood
73
Characteristics of clostridium perfringens
``` Gram + Spore forming rods Fast growing anaerobic fermenter (generates H2 and CO2) Encapsulated/ non motile Found in colon and soil ```
74
What are the culture characteristics of Clostridium perfringens
Double zone hemolysis (blood agar) | Litmus milk stormy fermentation
75
What are the toxins associated with clostridium perfringens
Alpha: Main pathogenic factor- causes necrosis Theta: Toxic for heart muscle/ capillaries (similar to streptolysin O in beta strep) Enterotoxin: food poisoning
76
Clinical presentation of C. Perfringens
``` Gas necrosis ( crepitation ) Destruction of collagenase DNAse Hyaluronidase Protease ```
77
Where does C. Perfringens occur?
Traumatic wounds
78
What kind of diagnosis is gas gangrene
clinical diagnosis
79
How is anaerobic cellulitis different from other forms of cellulitis
Less pain and swelling
80
What would be seen with a dog bite
Anaerobic cellulitis | Mixed anaerobic flora
81
Pathogenic non-sporeforming gram + anaerbic rods
Actinomyces | Propionibacterium
82
Less pathogenic non-sporeforming gram + anaerobic rods
Mobiluncus (vaginitis) Lactobacillus Eubacterium Rothia
83
Characteristics of actinomyces
Long Gram + rods Branching no spores/ not acid fast Sulphur granules
84
Most common actinomycetes
A. Israelii | Mouth infection 4-10 days to grow
85
Where does actinimyses usually colonize
Mouth, Pneumonia, neck/head
86
Characteristics of Propionibacterium
Anaerobe Gram +, non-sporeforming rods Part of normal skin flora
87
What is the most common gram neg rod causing anaerobic infections
Bacteroides Fragilis
88
Louse borne typhus fever is from what
Rickettsia Prowazekii
89
Characteristics of typhus fever
Rash 10 days after illness | Comprises circulation
90
Lab diagnosis for Rickettsia
Culture difficult PCR best Immuno assays for antibody
91
Classic lyme disease
Tick bite-> spirochete Erythema chromicum migrans Constitutional sx for months Meningeal irritation
92
Diagnosis of burgdorferi
EIA antibody/ western | Enzyme immuno assay

Micro (14 decks)

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