04-23 Bacteremia & Endocarditis Flashcards Preview

AA - SBM I.D. > 04-23 Bacteremia & Endocarditis > Flashcards

Flashcards in 04-23 Bacteremia & Endocarditis Deck (35):
1

Intermittent vs. Continuous Bacteremia

—intermittent is due to infx and obstruction (e.g. pylo, cholecystitis), undrained abscesses
—Continuous is due to an endovascular source (e.g. infectious endocarditis, infected grafts/shunts, infected arterial aneurysm

2

Sort these pathogens into normal flora (often contaminant) vs. likely pathogen.
—Coag-neg staph
—Anaerobes
—Propionibacterium acnes
—Bacillus spp
—Strep viridans
—Strep pyogenes
—Strep pneumoniae
—Gram neg bacilli
—Staph aureus

nl flora —Coag-neg staph (unless FB)
pathogen—Anaerobes
nl flora —Propionibacterium acnes
nl flora —Bacillus spp
nl flora —Strep viridans
pathogen—Strep pyogenes (GROUP A)
pathogen—Strep pneumoniae
pathogen—Gram neg bacilli
pathogen—Staph aureus

Contaminants usually:
—grown on just on one of the two or three cultures you drew.
—present without left-shift
—have no 1° infx or predisposing

3

infective vs. marantic endocarditis

infective is infection of valves or mural endocardium

marantic has sterile vegetations due to malig or CT dz

4

Acute vs. Subacute endocarditis

Acute: rapid progression, presents w/in 1 wk of sx onset
—abrupt onset (pt remembers start)
—due to INVASIVE pathogen (S. aureus, β-hemolytic strep, Pneumococcus)
—occurs on normal or abnl valves
—heart murmur ∆ing rapidly → CHF
—systemic sx: rigors & high fever
—More cutaneous and visceral emboli

Subacute: SBE sx may start weeks to months before presentation
—due to low-grade pathogens (Viridans strep, coag-neg staph)
—occurs on ABNORMAL valves

5

Pathogenesis

1. jet lesion (turbulent flow) or trauma (catheters, particles from IVDU) or chronic inflammation →
2. local thrombosis →
a. acts as nidus for infection
b. fibrin-plts blocks PMNs from bacteria

6

Predisposing factors to endocarditis in native valves besides IVDU, MVP, degen valve, rheumatic heart dz etc.

—poor dental hygiene
—dialysis
—prev. endocarditis

7

Viridans strep
—species
—sp. esp common in elderly?

Viridans streptococci are part of nl oral and colonic flora
—S. sanguis, S. bovis, S. mutans, S. mitis
—S. bovis common in elderly w/ chronic lesions, cancer

8

Microbe causing IE in older men?

enterococci in men with BPH or other persistent bladder outlet obstruction
—also generally common in nosocomial

9

Polymicrobial IE common in?

IVDU (putting needle in mouth, wiping it on something)

10

Top Causes of IE?

S. aureus now = Viridans Strep spp.
—Staph esp in IVDU and nosocomial

11

Group of non-classic organisms that can also causes IE

HACEK
—Haemophilus
—Actinobacillus
—Cardiobacterium hominis
—Eikenella
—Kingella

12

Other non-classic IE organisms

Bartonella spp. (cat-scrath, trench fever)
Q fever (Coxiella burnetii)
Nutritionally-variant strep
Chlamydia spp.
Legionella spp.
Brucella spp.
Fungi

13

Most common non-culture finding in SBE?
—Others?

Fever (95%)

Others:
anorexia, wt loss, malaise, night sweats
myalgias
murmur
emoblic stigmata (petcchiae on skin, conjuctivae)
splenomegaly

14

Osler's nodes

tender subQ nodules often in pulp of digits or thenar eminence; due to immune complex

15

Splinter hemorrhages

linear, red at first then brown, lesions under the nails due to emboli

16

Janeway lesions

nontender erythematous, hemorrhagic, or pustular lesions, often on palms or soles

17

Embolus sites

Stroke
Amaurosis fugax
Acute abd pain, ileus, GI bleed
MI
Spleen
Kidney (micro hematuria, renal insuff)

18

IE in IVDUs
—Usual organisms
—Which valve?
—Presentation

Organisms
—S. aureus, Gm-negs (esp Pseudomonas), polymicrobial, Candida albicans
—Tricuspid valve often
–Present w/ high fever, cough, chills, malaise, pleuritic CP (septic pulmonary emboli = hallmark of R-sided IE)

19

True or false: mechanical valves have a higher rate of IE than bioprosthetic valves?

False, the two types have comparable rates of IE

20

Incidence of IE in prosthetic valve pts?
—Time correlation w/ source of infx?

1-3% w/in 1 year s/p inplant
—if w/in 2 mos, infx likely nosocomial
—if >12 mos s/p = "community acquired"

21

Duke Criteria for Dx of IE

MAJOR CRITERIA
—Typical orgs or 2 sep BCs or persistently (+) BCs
—Endocardial involve (regurg, echo proof)

MINOR CRITERIA
—Predispos (IVDU, prev IE, valvulopathy)
—Fever >38°C
—Vascular phenomena
—Immun phenom (RF, GN, Osler's nodes, Roth spots)
—Micro findings that don't meet MAJ CRIT

[Definitive if 2 MAR or 1 MAJ + 1 MINOR or 3 MINOR]

22

Roth spots

retinal hemorrhages with white or pale centers composed of coagulated fibrin

23

What IE Complications do you need to worry about?

—CHF
—heart block (if in septum)
—purulent pericarditis
—myocard abscess
—stroke or brain abscess
—mycotic aneurysm rupture (Dx w/ CT or MRI)
—splenic, renal and/or hepatic emboli/abscesses
—iliac/mesenteric ischemia

24

mycotic aneurysm

"an aneurysm arising from bacterial infection of the arterial wall. It can be a common complication of the hematogenous spread of bacterial infection" [wiki]
—classic mushroom shape (thus "mycotic")

25

Don't forget to get cultures BEFORE starting abx, okay?

ok

26

Length of abx course?

at least 4 wks for native valve IE
at least 6 wks for prosthetic valve IE

27

HACEK tx?

ceftriaxone

28

MSSA tx?

Nafcillin

29

MRSA tx?

vanco

30

Viridans strep tx w/ MIC ≤ 0.1ug/mL?

Pen G or ceftriaxone

31

Strep w/ MIC 0.1-0.5ug/mL

Pen + gent

32

enterococci or fastidious/resistant strep?

Pen + gent

33

Tx for biofilm forming bacteria?

rifampin

34

Indications for surg?

—persistent bacteremia even w/ abx
—Perivalvular dz
—Heart block
—CHF
—recurrent major emboli
—Vegetations >1cm
—If infected with: Pseudomonas, fungi, highly resistant eneterococci (cause >50% of mortality from IE)

35

Indications for abx prophylaxis?

Most cases of IE are NOT related to specific events/procedures.
—Remember, prophylaxis effectiveness is largely UNPROVEN and it does carry RISK (anaphylaxis, C. diff)

INDICATIONS
—Pts who are at high risk who are undergoing procedures likely to cause significant bacteremia