Introduction:
Intravascular catheters pose a severe threat to blood infections in hospitalized patients. These catheters are frequently used in intensive care units (ICU), and physicians should be prepared to handle the infections caused by them. In the U.S., around 150 million catheters are purchased by hospitals and clinics every year. Catheter-related infections cause expensive complications for hospital care as they frequently occur in the ICU (intensive care unit) settings.
What Is the Pathogenesis of Microorganisms on Catheter Surfaces?
The pathogenesis of microorganisms on catheter surfaces is of two forms:
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The Sessile Form: In this form, the organisms are embedded in a biofilm.
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The Planktonic Free-Floating Form: In this form, organisms disseminate over the catheter surface.
The transmission and electron microscopic studies revealed that all the vascular catheters, even in which the cultures are negative, are colonized by microorganisms. This risk of infection can be reduced by tunneling the catheter below the skin and extending the distance between the catheter–skin interface and the catheter–vessel interface or by implanting the catheter completely. Contamination of the catheter by bacteria or fungi can also lead to intraluminal infection of the catheter and spread of that infection to the main bloodstream.
What Is the Epidemiology of Intravascular Catheter-Related Infection?
In the United States, around 2,50,000 cases of this infection occur every year, out of which 80,000 cases were reported in the ICUs. The chances of infection increase with the increase in the duration of stay in the hospital. It was further determined that the infection also depends upon the type of catheter used. The incidence of infection with a long-term central venous catheter is high as they are used for a longer duration and removed only when there is an infection.
What Are the Risk Factors Involved in Intravascular Catheter-Related Infection?
The risk factors in intravascular catheter-related infection include:
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Patient Factor: The bloodstream infection depends on the severity of the illness, compromised integrity of the skin, and presence of another distant infection.
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Type of Catheter: The type of catheter influences the risk of bloodstream infection, as the chances of infection increase with the increase in lumen number of the catheter type. Catheters with antiseptic or antimicrobial coating can reduce the risk of such infections. The risk of bloodstream infection also varies by the anatomic site of insertion. It has been shown that the risk is most significant for groin insertion, intermediate for neck insertion, and lowest for chest or upper extremity insertion.
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Operator-Related Factor: The risk of infection also depends on the placement and maintenance of the catheter by the operator.
What Are the Organisms Involved in the Infection?
The microorganisms that cause intravascular catheter-related infection include:
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Staphylococci (both Staphylococcus aureus and the coagulase-negative Staphylococci).
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Enterococci.
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Aerobic gram-negative Bacilli.
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Yeast.
Certain pathogens represent specific host, treatment, and catheter characteristics like S. aureus infections are associated with infections of hemodialysis catheters. Gram-negative Bacilli have been associated with infections in patients with cancer. Gram-negative Bacilli and some yeast species can cause infections with catheters placed in femoral veins. Candida is usually associated with infections related to the administration of parenteral nutrition.
How Is the Intravascular Catheter-Related Infection Diagnosed?
The infection is diagnosed in patients who develop systemic inflammatory response syndrome and show the following symptoms:
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Temperature less than 36°C or greater than 38°C.
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Heart rate is more than 90/minute.
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Respiratory rate higher 20/minute.
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Peripheral white blood cells (neutrophils) count less than 4000/µL or more than 12000/µL.
A diagnosis of intravascular catheter-related Infection is achieved by any of the following three criteria:aci
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The same organism recovered from percutaneous blood culture and from quantitative (greater than 15 colony-forming units) culture of the catheter tip.
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The same organism recovered from a percutaneous and a catheter lumen blood culture, with growth detected two hours sooner (two hours less incubation).
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The same organism recovered from a quantitative percutaneous and a catheter lumen blood culture, with a three-fold greater colony count in the latter.
Catheter-related infection can be suspected in a patient with an intravascular catheter who develops the clinical criteria of systemic inflammatory response syndrome. In patients with short-term central venous catheters without severe sepsis or shock, the catheter should be exchanged with a guide wire for a new catheter. A culture of the tip of the removed catheter should be done without sacrificing the site of insertion.
In order to reduce the incidence of blood culture contamination, the skin and the hub of the catheter should be cleansed with alcohol, tincture of iodine or alcohol chlorhexidine, and allowed to dry before specimen collection.
How to Manage Intravascular Catheter-Related Infection?
The following antimicrobials are recommended for empiric treatment of intravascular catheter-related Infection:
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Vancomycin can be used where the prevalence of Methicillin resistance Staphylococci aureus infection is seen. Otherwise, first-generation Cephalosporin such as Cefazolin or antistaphylococcal Penicillin such as Nafcillin can be used.
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Vancomycin can be replaced with Daptomycin, where the prevalence of Methicillin-resistant S. aureus is increased.
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Antibiotics active against gram-negative Bacilli can be used in case of increased severity of illness or femoral catheterization.
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Antibiotics active against Pseudomonas aeruginosa can be used in the case of neutropenia, severe illness, or known colonization.
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Antimicrobials are active against Candida, such as Echinocandin, in the case of femoral catheterization, prolonged administration of broad-spectrum antibiotics, hematologic malignancy, or stem cell therapy.
For successful management of this infection, early diagnosis, cost-effective prevention, effective treatment, and a thorough understanding of the pathogenesis are essential.
Conclusion:
Intravascular catheters are required for the care of a number of hospitalized patients. However, they can give rise to a bloodstream infection. Intravascular catheters are necessary for complicated medical and surgical interventions such as bone marrow and organ transplantations, hemodialysis, cancer therapies, and abdominal, cardiothoracic, and trauma surgery. The reported frequency of bloodstream infections is associated with various types of intravascular catheters. The pathogenesis of catheter-related bloodstream infections has led to the development of management and prevention strategies in order to avoid this infection. These infections can be prevented by selecting the optimal type of catheter, proper insertion and maintenance of the catheters, and further removing the catheters when they are no longer needed.
