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Staph & Strep Flashcards

1
Q

Staph organism, growth characteristics

A

Gram positive cocci in clusters

Catalase +, salt tolerant up to 9%NaCl

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2
Q

Staph differentiation

(?)

A

Hemolysis (S. aureus)

Coagulase + S.aureus) - associated with virulence

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3
Q

Coagulase negative staph

A

CNS = S. epidermidis, S. saprophyticus

*opportunists

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4
Q

S. aureus - some presentations due mainly to ________.

What is the classic S. aureus lesion?

A

growth of bacteria

Furuncle (walled off by coagulase)

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5
Q

Staph localized to hair follicles

A

folliculitis

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6
Q

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

What is the PRIMARY cause of this?

A

complication of acne

Primary cause = Propionibacterium acnes

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7
Q

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

Symptoms mainly due to….

A

Staph aureus causes non-bullous impetigo

*Due to immune response

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8
Q

Deep incisional staph infections often present as

A

cellulitis

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

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9
Q

Frequent complication of staph bacteremia

How do you detect?

How do you treat?

A

Endocarditis

Echocardiography to detect

Gentamycin to treat

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10
Q

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

A

Exotoxin release

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11
Q

Bullous exfoliation a.k.a. _________

What are the symptoms/presentation? Who is affected?

A

Staph Scalded Skin Syndrome (SSSS)

  • Intraepidermal splitting of top layers
  • Mostly in children (better prognosis than adults, who have bacteremia)
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12
Q

Bullous impetigo symptoms and who it affects

A

Fluid filled blisters within epidermis (Exfoliative toxin causes)

Almost always in kids under 2 years old

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13
Q

Toxic shock syndrome presentation

A
  • abrupt fever
  • rash with desquamation
  • hypotension
  • multisystem involvement
  • DIC
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14
Q

Toxic shock syndrome underlying pathology

A

caused by immune reaction to TSST

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15
Q

Food poisioning Sx from Staph

What particular type of cell is involved?

A

nausea, vomit, diarrhea, NO FEVER

QUICK (4-24 hours)

Treg cells involved in limiting inflammatory response?

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16
Q

Staph epidermidis associated with…

A

implanted devices (biofilm formation)

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17
Q

___ can also cause surgical implant infections, but…

A

Staph aureus

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

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18
Q

Staph epidermidis is native flora in ___% of patients

A

100%

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19
Q

Staph saprophyticus is associated with ____ because of ________.

Most UTIs are caused by…

A

UTI because of specific adhesin for UT epithelium

UPEC E. coli

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20
Q

Menstrual TSS associated with…

A

use of retained tampons

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21
Q

Staph is difficult to treat beacuse of…

A

rapid MDR

ex. MRSA (mecA on SCC cassette)

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22
Q

Staph virulence factors (antigens)

A
  • Peptidoglycan (inflammatory PAMP)
  • Teichoic acids (check patients for alpha-TA antibodies!)
  • Protein A (binds Fc)
  • Iron-Binding Proteins
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23
Q

Other Staph virulence factors (7)

A
  • 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)
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24
Q

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

A

Panton-Valentine Leukocidin

Forms pores, causes leukopenia

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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)

Bacteriology Lectures (14 decks)

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