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Flashcards in Skin- Bacteria Deck (92):
1

What gram stain is Staph Aureus

+

2

Is Staph Aureus thick or thin walled

Thick

3

Where are the granulocytes for Staph Aureus found

Intracellularly

4

What hemolytic is Staph Aureus

Beta

5

What kind of agar does Staph Aureus grow on

Blood agar

6

Is Staph Aureus aerobic or anerobic

Aerobic

7

What color colonies does Staph Aureus grow

White, becomes yellow with age

8

What catalase and coagulase is S. Aureus

Positive

9

Is Staph Aureus found normally on the body

Yes found in anterior nares for 30% of population

10

What is the mechanism of escape for Staph Aureus

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

11

What are other biologically active substances in Staph Aureus

Hemolysins
Hyaluronidase
Nuclease
Lipase
Protease

12

What is the toxin found in S. Aureus

Alpha toxin (Cytotoxin)

13

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

Causes necrosis/ Death
Membranes leak
Causes RBCs to lyse

14

What kind of toxin is Panton- Valentine Leukocidin

Cytotoxin

15

What is the action of Panton Valentine Leukocidin

Lyses neutrophils, damages host cells

16

What diseases are associated with Panton Valentine Leukocidin

Pneumonia
Skin Infections
MRSA

17

What is the virulence of S. Aureus

10^5- 10^6 to start infection
10^ 2 if a suture is present

18

How does Staph cellulitis act?

Alternates btwn walling off and rapid extension of infection

19

What is a furuncle what infection causes it

Boil in hair follicle
Can give rise to stye
Staph

20

Where are carbuncles mostly found?

Back of the neck, formed from furuncle

21

What causes Chronic furunculosis

Delayed hypersensitivity to staphylococcal
Responsible for inflammation and necrosis

22

What disease is chronic staph associated with

Chronic granulomatous Dx
Diabetes

23

Impetigo is a bacterial infection composed of what

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

24

What is bullous impetigo

Caused by S. Aureus, causes skin to exfoliate.
Blisters contain many staphylococci

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)