From the Guidelines
Gram-negative rod bacteremia commonly originates from infections in the urinary tract, gastrointestinal tract, respiratory system, and skin/soft tissue, with the urinary tract being the most frequent source, as noted in studies such as 1 and 1. The urinary tract is the most frequent source, with Escherichia coli being the predominant pathogen, especially in cases of pyelonephritis or complicated urinary tract infections.
- Gastrointestinal sources include intra-abdominal abscesses, cholangitis, and peritonitis, often involving Enterobacteriaceae like Klebsiella and Enterobacter species, as discussed in 1 and 1.
- Respiratory sources such as pneumonia can lead to bacteremia with Pseudomonas aeruginosa or Klebsiella pneumoniae.
- Skin and soft tissue infections, particularly in immunocompromised patients or those with vascular access devices, may involve Pseudomonas, Acinetobacter, or Enterobacteriaceae. Healthcare-associated infections, including those from central venous catheters, surgical site infections, and ventilator-associated pneumonia, are significant contributors to gram-negative bacteremia, as highlighted in 1 and 1. Immunocompromised patients are particularly susceptible to these infections due to their impaired host defenses. The pathophysiology involves bacterial invasion through compromised barriers, followed by entry into the bloodstream, where these organisms release endotoxins that can trigger systemic inflammatory response syndrome and potentially progress to septic shock, as explained in 1 and 1.
From the Research
Common Sources of Gram-Negative Rod Bacteremia
The common sources of Gram-negative rod bacteremia include:
- Pneumonia 2
- Catheter-related infections 2
- Urinary tract infections 2
- Instrumentation of the urinary, respiratory, or gastrointestinal tracts in hospitalized patients 3
- Decubitus ulcers in debilitated, bedridden patients 3
- Osteomyelitis in patients who have undergone previous surgical procedures 3
- Gastrointestinal tract colonization by klebsiellae and Pseudomonas aeruginosa 4
Causative Organisms
The most commonly isolated Gram-negative rod bacteria include: