OVERVIEW
Catheter-associated bloodstream infections (CRBSI) are infections in patients with intravascular catheters or within 48 hours of catheter removal who develop bacteremia or fungemia with manifestations of infection such as fever (>38°C), chills, or hypotension, and who do not have a definitive source of infection other than vascular catheter infection. Laboratory microbiology shows positive peripheral venous blood cultures for bacteria or fungi; or cultures from catheter segments and peripheral blood for pathogenic bacteria of the same species with the same drug sensitivity results.
Questions you may be concerned about
What is the most common pathogenesis of catheter-associated bloodstream infections?
The most common pathogenesis of catheter-associated bloodstream infections includes lax asepsis or improper handling, such as incomplete skin disinfection.
Operator-related factors include incomplete disinfection of the patient’s skin, excessive contact between unsterilized hands and the catheter or catheter skin, which creates an environment conducive to the growth and development of pathogenic bacteria.
Equipment-related factors, including different catheter materials, can lead to catheter-associated bloodstream infections. Infusion connectors are a major source of infection because they are easily contaminated with bacteria. If the puncture site is covered with sterile gauze or transparent dressing for a long period of time, it is also easy to cause local temperature and humidity changes, which are favorable to microbial reproduction and further increase the risk of infection.
Drug-related factors, such as plasma, human serum, nutrient solution, etc. are good culture media for bacteria, and if bacteria-carrying drugs are brought into the catheter, the bacteria will stay inside the catheter to grow and multiply, causing infection.
Patient-related factors include secondary thrombosis. When externally infected bacteria enter the circulation and come into contact with the inside of the catheter, thrombosis often occurs around the catheter, which creates conditions for pathogenic bacteria to grow. The risk of infection is also increased by the patient’s low immunity, low metabolic level, reduced functioning of physiologic systems, and the combination of multiple diseases.
Causes
1. Operator-related factors
Commonly, there are lax aseptic operation or improper operation, such as incomplete skin disinfection, frequent contact between unsterilized hand and catheter or catheter skin, improper operation causes fibrin in blood to form fibrin sheath on the inner surface of catheter, etc., which provides a favorable environment for the growth of pathogenic bacteria.
2. Equipment factors
Different catheter materials are one of the potential factors leading to the occurrence of catheter-associated bloodstream infections; infusion connectors are the main site of bacterial contamination, which is the main source of CRBSI; the prolonged use of sterile gauze or transparent dressings to cover the puncture site is likely to cause the local warmth and humidity, which is conducive to the propagation of microorganisms and increases the risk of infection.
3. Drug factors
Fat emulsion, blood plasma, human serum protein, total parenteral nutrition solution, etc. are good culture media for bacteria. If bacteria-carrying drugs are imported through the catheter, the bacteria will stay inside the catheter and grow and multiply, causing infection.
4. Patient-related factors
Secondary thrombosis is one of the risk factors for CRBSI. After the bacteria from the source of infection in the distant site enter the blood circulation and contact with the inner segment of the catheter, the bacteria adhere and colonize on the catheter, often inducing thrombus to occur in the periphery of the catheter, which creates conditions for the growth of pathogenic bacteria. In addition, the patient’s own low immunity, low metabolic capacity, physiological function decline, combined with a variety of chronic diseases, long hospitalization time, etc. also increase the risk of infection.
Symptoms
Fever, chills, redness, swelling, hardness or pus oozing from the catheterization site are common and non-specific. Almost all catheter infections present with fever, and in about 1/3 of patients the only manifestation is fever. Often sudden onset of high fever combined with toxic symptoms suggests possible CRBSI.
Examination
Routine blood tests indicate elevated white blood cell count, accelerated sedimentation, elevated calcitonin levels, and elevated C-reactive protein; simultaneous cultures of the venous catheter and peripheral blood result in the same bacteria.
Diagnosis
1. Prolonged indwelling catheterization.
2. Sudden high fever combined with toxic symptoms.
3. Simultaneous culture of intravenous catheter and peripheral blood, the result is the same kind of bacteria.
4. The skin at the site of catheterization may be red, swollen, hard or oozing pus.
5. Severe catheter-related infections that subside after catheter removal and appropriate antibiotic therapy.
Differential Diagnosis
Fever is a symptom of most infections and should be differentiated from other causes of infection, mainly by history and ancillary tests such as blood cultures.
Treatment
1. Remove the catheter, sterilize the skin at the catheter, and change the dressing frequently.
2. Antibiotic treatment: use broad-spectrum antibiotics before the results of bacterial culture are obtained; after the pathogen of infection is clearly identified, use drugs for the pathogen.
3. Supportive therapy, nutritional therapy, etc.
Prevention
1. Strictly ensure hand hygiene and cleanliness, choose the most ideal position for tube placement, disinfect skin, disinfect infusion joints, and evaluate the necessity of indwelling catheters on a daily basis.
2. For the old and weak, especially patients with diabetes, malignant disease and other immunity, should strengthen the treatment of basic diseases, pay attention to the protection and enhancement of the body’s immunity.
3. Closely observe the local skin of tube placement for redness, swelling, tenderness, secretion, etc., and monitor the patient’s body temperature.
4. When CRBSI is suspected, infusion should be stopped immediately, peripheral venous needle should be removed, and the necessity of central venous line removal should be evaluated.
5. Sterile gauze should be changed every 48 hours, transparent dressings and infusion heads should be changed every 7 days, and dressings should be changed promptly if they are wet or loose.
6. To minimize systemic toxicity, aspirate rather than flush at the end of antimicrobial administration.
7. Evaluate the necessity of intravascular catheters several times a day and withdraw non-essential catheters.