T3-L8: Pathogen-Antibiotic Matching 3

Question 1

What is the most likely diagnosis for the following case:

Scenario 1.
QF 46 year old male with acute lymphoblastic leukaemia
p/c fever >38oC and chills 7 days after chemotherapy

History of presenting complaint: no localising symptoms, fevers seems worse after use of Hickman line (a cuffed/tunneled central venous catheter).

PMH: nil else Allergies: none known

Examination: no localising signs, T38.4oC, pulse 85, BP 130/75, respiratory rate 16, alert, Hickman exit site healthy.

Answer 1

Intravascular catheter-associated bloodstream infection (CRBSI)

Question 2

What is the best test used to confirm Intravascular catheter-associated bloodstream infection (CRBSI)?

Answer 2

Paired through-catheter and peripheral blood cultures.

Question 3

What is the best test used to confirm endocarditis?

Answer 3

3 sets of blood cultures taken at different times

Question 4

What is differential time to positivity?

Answer 4

The difference in the time to positivity (TTP) between blood cultures drawn simultaneously from the CVC (central venous line) and a peripheral vein. The greater the number of organisms in the blood, the quicker the duration in time to positivity. The DTP of 2 hours could support intravascular infection.

Question 5

Which organisms are most likely to cause intravascular catheter-associated bloodstream infection (CRBSI)?

Answer 5

Pathogens found on the skin such as coagulase negative staphylococcus. This is followed by enterococcus species and candida.

Step pyogenes can cause invasive infection, pneumonia, endocarditis, it is not a common cause of intravascular catheter related infection.