Most common catheter-related bloodstream infection is
**Core Concept**
Central line-associated bloodstream infections (CLABSIs) are a significant concern in critically ill patients, particularly those requiring long-term catheter placement for vascular access. These infections are often caused by microbial colonization of the catheter's luminal surface.
**Why the Correct Answer is Right**
The most common causative organism of CLABSI is Staphylococcus epidermidis, a coagulase-negative staphylococcus that is part of the normal skin flora. This organism produces a biofilm on the catheter's surface, which protects it from antimicrobial agents and host immune defenses. The biofilm is composed of polysaccharide intercellular adhesin (PIA), which enables S. epidermidis to adhere to the catheter material and resist removal. The biofilm also facilitates the transmission of antimicrobial resistance genes among bacterial cells.
**Why Each Wrong Option is Incorrect**
* **Option A:** While Staphylococcus aureus is a common cause of CLABSI, it is not the most common causative organism. S. aureus is more frequently associated with skin and soft tissue infections.
* **Option B:** Escherichia coli is a common cause of urinary tract infections, but it is not the most common cause of CLABSI.
* **Option D:** Pseudomonas aeruginosa is a common cause of ventilator-associated pneumonia, but it is not the most common cause of CLABSI.
**Clinical Pearl / High-Yield Fact**
To reduce the risk of CLABSI, it is essential to maintain aseptic technique during catheter placement and to perform regular catheter site care, including dressing changes and site assessments. Additionally, the use of antimicrobial catheters or prophylactic antibiotics may be considered in high-risk patients.
**Correct Answer:** C. Staphylococcus epidermidis.