Chapter 32: Cardiovascular system

Question 1

which are the routs will lead to cardiovascular infections

Answer 1

Intravascular: starting inside thought the introduction of a catheter, Pacer, needles, prosthetic valves. usually bacteria will create a biofilm to evade antibiotics and phagocytosis. usually those microbes are apart of the normal flora

Extravascular: entering though the lymphatic system caused by surgery or trauma. the dissemination happens if the number of microbes overwhelms the immune system. sources are pericarditis, UTI, pneumonia

Question 2

symptoms of a systemic cardiovascular infection

Answer 2

tachypnea, tachycardia, hypotension, abdominal pain/nausea/vomiting, shaking chills and FEVER.

the most dangerous symptom is Hemodynamic instability, septic shock

Question 3

transient bacteremia and intermittent bacteremia definition

Answer 3

transient bacteremia: (30-45min)bacteremia after small procedures like a dental procedure. brushing your teeth can even cause that. it could lead to endocarditis in patients with prosthetic heart valve or previous damage to the endocardium

intermittent bacteremia: waves of bacteremia released periodically from a site of infection. dangerous in the immunocompromised. can result in a continuous bacteremia everywhere. the source of the bacteremia could be resp/genitourinary/GI

Question 4

sepsis and septic shock definition and prevalence

Answer 4

sepsis is the presence of actively dividing bacteria in the blood and their harmful by products, rapidly progressing that can arise from infections throughout the body. the subsequent release of cytokines from the cells causes elevated WBC, tachycardia, tachypnea.. could lead to septic shock in the immunocompromised, old, prevalent in young infant.

most dangerous cases for septic shock are from Gram negative rods, endotoxins such as LPS. hypermetabolic state leads to DIC, then clot-lyse cycle leads to depletion of clotting factors, eventually O2 depletion/acid-base disturbance/electrolyte disturbance causes multi organ failure

Question 5

patients at risk for sepsis

Answer 5

asplenic patient
immunocompromised
infants
patients with chronic illness 
procedures(surgery, endoscopy, catherization)

Question 6

infection of which organs can cause continuous bacteremia

Answer 6

reticuloendothelial system (liver, spleen, bone marrow)
meninges
pleura

Question 7

main organisms that causes endocarditis

Answer 7

mostly bacteria (strep pyogenes)

Question 8

why does endocarditis happen mostly in damaged areas

Answer 8

damage=>turbulence=>damage=>platlelts try to fix by creating a fibrin mesh=>mesh helps bacteria lodge and be protected from the immune system and antibiotics. spetic emboli can break off and travel to the brain (or anywhere, you can see clots on fingernails)

Question 9

subacute bacterial endocarditis(SBE) vs accute bacterial endocarditis (ABE)

Answer 9

SBE: develop gradually, caused by less virulent organism Strep viridans (G positive, oral flora)

ABE: faster development, staphylococcus aureus, leads to murmurs and CHF and permanent valve damage

Question 10

how do microbes colonize catheters

Answer 10

microbes that cause catheter-related infections usually create a slime layer to connect each other and protect themseves from antibiotics they can go directly to the blood afterwards and cause bacteremia. then they can become a permanent source of infection

Question 11

most common microbes in catherter-related infections and how do you diagnose and treat it

Answer 11

skin flora: staph spp, S.aureus, corynebacterium spp., candida
to diagnose, take two cultures one from the catheter and one from the blood and they must match

to treat, remove the catheter (since its a constant source of infection)and give antibiotic

if there was gangrene of the gallbladder/intestine they have to be surgically removed, abcess’ must be drained

Question 12

do you give antibiotic anaphylaxis to patients susceptible to endocarditis before operations/ dental procedures

Answer 12

Yes

Question 13

most common isolates (single organism bacteremia)

Answer 13

gram postive cocci : staphylococcus Spp., S.aureus, enterococcus Spp., streptococcus, streptococcus pneumoniae

Enterobacteriaceae: enterobacter spp., blebsiella spp. proteus spp.

Question 14

common isolate in endocarditis

Answer 14

oral flora: strep viridans

Question 15

can any organism cause endocarditis ?

Answer 15

yes, any organism isolated from the blood should be significant

Question 16

how long till fever develop if there was bacteremia, whats the best time to take a culture if bacteremia is suspected/known ?

Answer 16

45min, the perfect specimen is one taken immediately before the development of a high temperature.
all cultures should be drawn prior to starting antibiotics

Question 17

best timing for a blood sample collection and its amount/delusion

Answer 17

right before a fever, or during acute phase. but the volume of blood collected is way more important than timing, bigger sample yields better sensitivity (ideal 1 part blood and 5 parts broth 10ml per blood culture bottle)

Question 18

best blood to broth ration for a blood culture

Answer 18

the key is largest amount of blood with the smallest volume of broth possible 10ml blood to 50ml broth for adult

Question 19

what do blood culture have as anticoagulant

Answer 19

sodium polyanethanol sufonate SPS, heparin cant be used because it inhibits bacterial growth

Question 20

what are the features of sodium polyanethanol sulfonate?

Answer 20

used for blood cultures
inactivates neutrophil
inactivates certain antibiotics
inhibits cetrain bacteria (peptostreptococcus anarobicus, neisseria gonorrhoeae, neisseria meningitidis, gardnerella vaginalis, streptobacillus moniliformis)

Question 21

what is fastidious organisms supplement FOS

Answer 21

it helps the limited numbers of organisms present in a suboptimal sample grow better.

Question 22

what supplements do you add to help bacterial growth in a culture

Answer 22

FOS
charcoal
resin beads

Question 23

most common organisms found in blood infection

Answer 23

bacteria

Question 24

example of aerobic organism in the blood

Answer 24

pseudomonas aeruginosa

Question 25

examples of patients with anaerobic bacteremia

Answer 25

because of the decline in anaerobic bloodstream infections, hospitals have two aerobic bottles instead of one aerobic and one anaerobic

patients which are suspected to have anaerobic infections are those who had a surgery, hospitalized or in ICU

Question 26

how to process a specimen

Answer 26

two bottles, incubate at 35 C, see changes in color/hemolysis/bubbles/cell growth

if there is no change in 7 days then blind sub (performing a subculture when there is no change or indication of bacteria, we use chocolate agar to see organism like hemophilus spp.)

Question 27

different blood culture methods

Answer 27

Biphasic: solid media on top of broth bottle
signal system: gas produced by organism forces broth into chamber
lysis centrifugation: no broth, soap like agent lyses red and white blood cells and sediment is plated

Question 28

features of automated blood culture systems

Answer 28

continuous monitoring
bottle has to be held only 5 days
checks the culture every 10 min
can detect positive culture in 6-24h
expensive
detects CO2

Question 29

catheter culture method

Answer 29

role the tip of the catheter on a blood agar plate

Question 30

properly reporting a positive culture

Answer 30

reporting that its a gram-postitive cutlrure cocci in pairs helps the physician know that its a strep. pneumonia rather than strep spp.

Question 31

based on what do you select the media for subculture

Answer 31

based on the results
G-positive aerobic: sheep blood and chocolate agar

G-negative rods: MacConkey agar
yeast: fungal media

Question 32

what should u do after the detection of an organism in a culture

Answer 32

rapid start identification(using PNA-FISH peptide nucleic aid fluorescent in situ hybridization) test and susceptibility testing for all the isolated specimens (usually more than one blood sample is isolated)

Question 33

extravascular infections are the result of microorganism originating within the cardiovascular system

true or false

Answer 33

Flase

Question 34

the most dangerous symptoms of cardiovascular infection is:

chills
abdominal pain
vomitting
hemodynamic instability

Answer 34

hemodynamic instability

Question 35

a healthy 21 yo visit the dentist for his annual examination and routine leaning. the most likely type of bacteremia that he will get is

transient bacteremia
intermittent bacteremia
continuous bacteremia
septic shock

Answer 35

transient bacteremia

Question 36

streptocuccus viridans group, the most common cause of subacute bacterial endocarditis, originates as a part of the normal …… flora

skin
GI
oral
Genital

Answer 36

oral

Question 37

bacteremia can be caused by a variety of organisms. which of the follwoing tends to be the most frquently isolated

G-positive cocci
G-negative rods
G-positive rods
G-negative cocci

Answer 37

G-positive cocci

Question 38

the principle of operation of BacT/Alert blood culture system is

• monitoring florescence production that is proportional to the amount of CO2 in the bottle
• Co2 production that changes the color of the colorimetric sensor of the bottle
• monitoring headspace pressure changes because of gas production by bacteria
• lyses of both the red and the white blood cells

Answer 38

Co2 production that changes the color of the colorimetric sensor of the bottle

Question 39

when brucellosis is suspected, blood cultures should be kept incubated and examined for

4days
2weeks
1month
untill it runs positive

Answer 39

1 month

Question 40

study special cases

Answer 40

u didnt study them yet ya nig nog