Laboratorio

Question 1

%positive blood cultures

Answer 1

85% of all IE

Question 2

Number of sets of cultures

Answer 2

three, including at least one aerobic and one anaerobic. Each containing 10mL

Question 3

In IE, bacteraemia is almost constant, which has two impli- cations

Answer 3

• there is no rationale for delaying blood sampling to coincide with peaks of fever
• virtually all cultures are positive, a single positive blood culture shoud be regarded cautiously

Question 4

Although IE caused by anaerobes is uncommon, cultures should be incubated in both aerobic and anaerobic atmospheres to detect organisms such as

Answer 4

Bacteroides or Clostridium species

Question 5

Blood-culture negative IE (BCNIE) occurs in

Answer 5

2. 5–31% of all cases of IE
   - most commonly as a consequence of prior antibiotic administration
   - Fastidious organisms

Question 6

The polymerase chain reaction (PCR) allows rapid and reliable detection of fastidious and non-culturable agents in patients with IE in (*) samples

Answer 6

The technique has been validated using valve tissue from
patients undergoing surgery for IE. Lack of reliable application to whole blood samples, risk of contamination, false negatives due to the presence of PCR inhibitors in clinical samples, inability to provide information concerning bacterial sensitivity to antimicrobial agents, and persist- ent positivity despite clinical remission