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Flashcards in Staph & Strep Deck (93):
1

Staph organism, growth characteristics

Gram positive cocci in clusters

Catalase +, salt tolerant up to 9%NaCl

2

Staph differentiation

(?)

Hemolysis (S. aureus)

Coagulase +  S.aureus) - associated with virulence

3

Coagulase negative staph

CNS = S. epidermidis, S. saprophyticus

*opportunists

4

S. aureus - some presentations due mainly to ________.

What is the classic S. aureus lesion?

growth of bacteria

Furuncle (walled off by coagulase)

5

Staph localized to hair follicles

folliculitis

6

S. aureus is a frequent complication of ________ via invasion of sebacious glands.

What is the PRIMARY cause of this?

complication of acne

 

Primary cause = Propionibacterium acnes

7

_______ is the most common cause of _______, which is an infection of the superficial epidermis (most common bacterial skin disease)

 

Symptoms mainly due to....

Staph aureus causes non-bullous impetigo

 

*Due to immune response

8

Deep incisional staph infections often present as 

cellulitis

(20% from staph aureus, 14% from coaulase negative staph)

9

Frequent complication of staph bacteremia

How do you detect?

How do you treat?

Endocarditis

Echocardiography to detect

Gentamycin to treat

10

Some staph presentations are due to bacterial growth, while others are due to _____________

Exotoxin release

11

Bullous exfoliation a.k.a. _________

What are the symptoms/presentation? Who is affected?

Staph Scalded Skin Syndrome (SSSS)

  • Intraepidermal splitting of top layers
  • Mostly in children (better prognosis than adults, who have bacteremia)

12

Bullous impetigo symptoms and who it affects

Fluid filled blisters within epidermis (Exfoliative toxin causes)

Almost always in kids under 2 years old

13

Toxic shock syndrome presentation

  • abrupt fever
  • rash with desquamation
  • hypotension
  • multisystem involvement
  • DIC

14

Toxic shock syndrome underlying pathology

caused by immune reaction to TSST

15

Food poisioning Sx from Staph

 

What particular type of cell is involved?

nausea, vomit, diarrhea, NO FEVER

QUICK (4-24 hours)

Treg cells involved in limiting inflammatory response?

16

Staph epidermidis associated with...

implanted devices (biofilm formation)

 

17

___ can also cause surgical implant infections, but...

Staph aureus

 

but Epidermidis doesn't cause the diseases that S. aureus causes

18

Staph epidermidis is native flora in ___% of patients

100%

19

Staph saprophyticus is associated with ____ because of ________.

 

Most UTIs are caused by...

UTI because of specific adhesin for UT epithelium

 

UPEC E. coli

20

Menstrual TSS associated with...

use of retained tampons

21

Staph is difficult to treat beacuse of...

rapid MDR

 

ex. MRSA (mecA on SCC cassette)

22

Staph virulence factors (antigens)

  • Peptidoglycan (inflammatory PAMP)
  • Teichoic acids (check patients for alpha-TA antibodies!)
  • Protein A (binds Fc)
  • Iron-Binding Proteins

23

Other Staph virulence factors (7)

  • Coagulase - (wall off infctn)
  • Hyaluronidase, Staphylokinase (tissue invasion)
  • Hemolysins (Alpha toxin (RBC) and Beta Toxin (sphingomyelin), leukocidin (WBC)
  • Exfoliative toxin - SSSS, bullous impetigo
  • TSST-1 - (superantigen, induces IL-1/TNF)
  • Enterotoxin (also superantigens...food poisoning)
  • Quorum Sensing (turns on biofilm genes)

24

What is the big virulence factor that is associated with mrsa?

Panton-Valentine Leukocidin

 

Forms pores, causes leukopenia

25

Superantigens are located on ____ and spread via ______

PAI's

transduction

26

Four control measures that have helped deal with MRSA

Better hand hygeine

catheter routes targeted

MRSA-specific detection and decolonization


*Isolation of carriers and Daily chlorhexadine wash

27

Recurrent furuncles from staph treated by...

drainage and tetracycline

 

(uncomplicated one may only need draining)

28

MRSA Tx

Bactrim, clindamycin, doy, linezolid

 

Severe = Vancomycin

29

Staph saprophyticus Tx

quinolones, bactrim, augmentin

30

Staph optomized treatment requires...

susceptibility testing

 

broth dilution, E test, or Kirby Bauer

31

Antibiotic resistance spreads via

R plasmids (conjugation)

32

Strep organism and appearance

Gram positive cocci

  • may be oval
  • in chains or pairs

33

Strep capsule 

 

-growth characteristics/requirements

capsule -- hyaluronic acid (group A) or polysaccharide

 

-fastidious growth, facultative, but prefers 5-10% CO2

34

__% of patients are carriers for beta hemolytic strep

10%

35

Strep classification is based on what four things?

  1. Hemolysis (alpha, beta, or gamma/none)
  2. Lancefield serotyping (specific amino-sugar and teichoic acid cell wall antigens)
  3. Biochemistry (AB resistance, NaCl tolerance, bile esculin)
  4. Colonization patterns (Entero, Lacto, Pneumo-cocci)

36

Strep pyogenes classification

  • Group A
  • Beta hemolytic
  • Bacitracin-sensitive

37

S. pyogenes causes ____ infections. Six examples?

Invasive infections

  1. Human erysipelas (dermis and SubQ)
  2. Puerperal fever (postpartum)
  3. Surgical sepsis 
  4. Scarlet Fever (bacteremia - characteristic rash and strawberry tongue)
  5. Streptococcal toxic shock-like syndrome (TSLT superantigen)
  6. Necrotizing fasciitis (deep fascia cellulitis)

38

Scarlet fever rash appearance

Ddx from which other rash?

Diffuse upper body rash

Ddx from measles rash (top-down)

 

39

Scarlet fever usually starts as...

Pharyngitis

40

Necrotizing fasciitis may be caused by ___ or ____

TSST (staph) or TSLT (strep)

41

Two other invasive infections from s. pyogenes

  1. PNA
  2. Bacteremia

 

*both are serious infections

42

Two local infections from s. pyogenes

Pharyngitis (fever, anterior lymphadenopathy)

Impetigo (non-bullous)

 

43

Two post-infection sequellae (due to ____ )

 

d/t immune mimicry (immune complexes)

Acute Rheumatic Fever - valve damage

Acute glomerulonephritis - blood/protein in urine

44

Animal carriers of s. pyogenes

None. Only humans (10-20% carrier rate)

45

Strep throat spread via ____, common during ____, and usual age of onset.

Spread in nasal droplets and by contact

 

Common in winter

 

Kids 6-13

46

Strep impetigo most common during ____, spread by _____, and age of onset.

  • Common in summer
  • Spread by contact, contiguity, and fomites
  • Preschool kids

47

Strep rheumatic fever occurs how long after disseminated strep infection?

 

Condition is more likely to be brought on by...

1-4 weeks

 

The second infection

48

What are the virulence factors of Strep pyogenes?

  1. M protein
  2. Hyaluronic acid capsule
  3. C substance
  4. C5a peptidase
  5. streptokinase/streptodornase
  6. hyaluronidase
  7. exotoxins
  8. hemolysins

49

Strep M protein is associated with...

thrumatic sequellae

50

Strep's Hyaluronic acid capsule function

mimics host, antiphagocytic

51

What is C substance?

capsular polysaccharide

 

*enhances invasiveness

52

  1. Streptokinase function
  2. Streptodornase function

  1. dissolves fibrin clots
  2. DNAse

53

Strep "spreading factor"

hyaluronidase

54

Strep. pyogenes exotoxins (types, function, and associated with...)

A, B, C

pyrogenic

Associated with scarlet fever, strep TSS

55

S. pyogenes Hemolysins - O2 sensitivity

Streptolysin O = O2 sensitive

Streptolysin S = Not

56

Control measures for S. pyogenes

pasturization of milk

isolate carriers from susceptible patients (not quarantine)

57

Group A strep are sensitive to...

PenG

58

How do you treat ARF/AGN

anti-inflammatory drugs and rest

 

59

Rheumatic fever management?

Long term PenG prophylaxis (prevents recurrence)

60

S. agalactiae classification

(group, hemolysis, cAMP, bacitracin)

  • Group B
  • Beta hemolytic
  • cAMP positive
  • Bacitracin-resistant

61

S. agalactiae typed by...

its polysaccharide capsule

62

Acute S. agalactiae diseases in infants and elderly

  1. Neonatal Sepsis (and PNA 1-7 days post-partum) -- most common cause of neonatal sepsis in US
  2. Neonatal Meningitis (1 week - 3 months)
  3. Respiratory Distress Syndrome "RDS" (bacteremia, soft tissue infections)

63

S. agalactiae spread when?

From infected mom to baby during delivery (chance of vertical transmission is 50%)

64

Group B strep control

Screen before delivery (36 weeks)

65

How to treat if there is a positive GBS screen in pregnant mom?

Do we ever use these prophylactically?

Intrapartum Ceph3 or Ampicillin + Streptomycin 

 

Yes. Give prophylactically if baby is premature or if there was no GBS screening done

66

Enterococci and S. bovis are ___ strep

Group D

67

GDS hemolysis

Growth characteristics in NaCl and Bile esculin

non hemolytic, but sometimes alpha

Growth in 6.5% NaCl, bile-esculin growth

68

GDS members

E. faecalis

E. faecium

Strep bovis

69

GDS is a common ____ infection, which causes what conditions?

nosocomial infeciton

Bacteremia, endocarditis, UTI

70

  • GDS transmitted mostly via...
  • What is the portal of entry?

  • hospital workers' hands
  • Enter GI tract and bacteremia from colon lesions

71

Big problem with Group D strep

 

MDR

72

Intrinsic resistance of enterococci to ______

...but OK for ____

 

GDS resistant to ____ because it can steal ____ from host

resistant to B-lactams

OK for S. bovis

 

SxT resistant because it can use host's folate

73

Antibiotic Tx for GDS

Preferred Tx for S. bovis?

Tx for Enterococcus? Problems?

  1. GDS = High-dose Penicillin + aminoglycoside
  2. Bovis = Penicillin or ceftriaxone 
  3. Enterococcus = Vancomycin (but vanR is a problem)

74

80% of infective endocarditis are caused by...

Staph or strep infections

75

Indications for antibiotic prophylaxis against endocarditis has been restricted to...

invasive dental procedures in patients with:

  • a prosthetic valve
  • history of endocarditis
  • unrepaired cyanotic congenital heart disease

76

Viridans strep hemolysis, and growth resistances

alpha hemolytic

optochin resistant

ox-bile resistant

77

most common viridans strep infection?

 

Sx?

sub-acute bacterial endocarditis 

(especially after tooth extraction or dental surgery)

 

Sx = heart murmur, weakness, embolism, anemia

78

VIrians strep is normal flora of 

URT

79

Viridans strep prophylaxis and Tx

prophylactic AB before and after oral surgery

Long term Penicillin or Vancomycin

80

Better Strep viridans outcome with...

surgical management of endocarditis

81

Pneumococci hemolysis and growth characteristics

alpha hemolytic

optochin sensitive

ox bile sensitive

82

Pneumococci appearance and structure (capsule)

diplococci with large polysaccharide capsule

83

Bad types of pneumococcus

  • 3
  • 19A 
  • 23F

84

Test for pneumococci

Quellung reaction

 

  1. polyvalent antiserum against capsule
  2. added to sputum
  3. if pneumococcus is present the capsule swells
  4. visualize with negative stain

85

S. pneumoniae presentation

  • sudden onset lobar PNA 
  • Fever, chills, pain, mental status change
  • HIGH leukocytes

86

Patterns of PNA

  1. Lobar = (consolidation of one/more lobe, bronchi often OPEN -- bronchogram Xray)
  2. BronchoPNA = peribronchial thickening, alveolar consolidation
  3. Interstitial = inflammation/edema of interstitial tissue of the lung, fibrosis

87

Four routes of acquisition of pneumococcus

Community

Hospital

Ventilator-associated

Aspiration

88

Causes of Aytpical bacterial PNA

  1.   Mycoplasma pneumoniae
  2.   Chlamydia pneumoniae + psittaci
  3.   Legionella pneumophila
  4.   Coxiella burnetti
  5.   Bordetella pertussis

89

60% of bacterial Community-acquired PNA is caused by _____

pneumococcal disease

90

pneumococcus is the number 2 cause of _____

and the number one cause of _____

#2 cause of Otitis Media

#1 cause of meningitis for middle-aged adults

91

Risk factors for pneumococcus infection

mucus accumulation

alcohol/drug use

general debility

92

Pneumococcus pathogenesis based on... (3)

colonization of tissues

polysaccharide capsule

debilitated host

 

**IgA protease is of limited virulence

93

Pneumococcal vax

23 valent capsule vaccine

PPSV23

for ADULTS (especially at-risk)