Examkin

Question

Difficulty: MediumInfectious Diseases

A 42-year-old woman is evaluated in the hospital on the fourth day of admission for acute severe pancreatitis. She has been receiving intravenous fluids via a right internal jugular central venous catheter placed on admission. Yesterday, her temperature briefly spiked to 38.3°C (100.9°F). One set of peripheral blood cultures and one set from the central venous catheter were obtained at that time. Today, she reports that her abdominal pain is improving. Her temperature is 37.1°C (98.8°F), blood pressure is 118/76 mm Hg, pulse is 82/min, and respirations are 14/min. Physical examination shows a clean central catheter insertion site with no surrounding erythema or induration. Laboratory studies show a leukocyte count of 9,200/mm³. The aerobic bottle of the peripheral blood culture set is growing coagulase-negative staphylococci after 24 hours of incubation. The anaerobic peripheral bottle and both bottles from the central catheter show no growth. Which of the following is the most appropriate next step in management?

  1. Observation without antimicrobial therapyAnswer
  2. B
    Initiate intravenous vancomycin therapy
  3. C
    Initiate intravenous cefazolin therapy
  4. D
    Remove the central venous catheter and culture the tip
  5. E
    Perform transesophageal echocardiography

Answer

Observation without antimicrobial therapy
Observation without antimicrobial therapy is the correct management because the culture result most likely represents contamination. Coagulase-negative staphylococci (CoNS) are common commensals of the human skin. While they can cause true device-associated infections (such as central line-associated bloodstream infections), true bacteremia typically presents with positive growth in multiple culture bottles drawn from different sites. In this patient, only one of the four bottles grew CoNS, and the patient is clinically stable with a clean catheter site. Therefore, this finding represents a contaminated blood draw, and no antibiotics or line removal is indicated.

Step-by-Step Solution

1
Assess the patient's clinical stability and potential sources of infection.
The patient is hemodynamically stable, afebrile, and clinically improving from her pancreatitis. The central catheter site appears uninfected.
Determines the urgency of intervention and identifies localized signs of true infection.
2
Interpret the blood culture results in the context of the clinical picture.
Only one out of four total bottles (one peripheral aerobic) is positive for coagulase-negative staphylococci (CoNS).
CoNS are ubiquitous skin flora. Determining if they represent true bacteremia requires multiple positive bottles drawn from separate venipunctures.
3
Determine the appropriate management step.
Observation without antimicrobial therapy is indicated.
A single positive bottle for CoNS in the absence of prosthetic hardware or severe clinical deterioration strongly points to sample contamination during phlebotomy, requiring no treatment.

Key Concept

Interpretation of blood culture contamination versus true bacteremia, emphasizing antibiotic stewardship by avoiding treatment for single-bottle positive coagulase-negative staphylococci.
Rate this question

Topics

Infectious Diseases

More questions from this topic