Central Line-Associated Bloodstream Infections
David B. Banach
Michael J.Satlin
David P. Calfee
INTRODUCTION
Central line-associated bloodstream infections (CLABSIs) are a major cause of morbidity and mortality among hospitalized patients and are associated with substantial costs to the health care system. A mortality rate of 12.3% and excess costs of $6,461 to $29,156 per infection have been reported.
It has been estimated that 92,000 CLABSIs occurred in US hospitals in 2002.
Although much attention toward CLABSI has focused on intensive care units (ICUs), there is an increasing awareness of these infections in non-ICU settings. In fact, in many US hospitals, the majority of patients with central venous catheters are outside the ICU, and many of these non-ICU areas have rates of CLABSI that are similar to or higher than those seen in ICUs.
PATHOGENESIS AND MICROBIOLOGY
CLABSI is usually a complication of bacterial or fungal colonization of the extraluminal and/or intraluminal surfaces of the catheter. Contamination of the external surface of the catheter can occur during insertion or after insertion due to migration of bacteria present on the skin at the insertion site. Intraluminal colonization is typically the result of contamination of the catheter hub or tubing during use or manipulation of the catheter. More rarely, catheters can become colonized due to hematogenous seeding from a distant site of infection or by administration of contaminated medications or fluids.
The organisms most commonly reported to the U.S. Centers for Disease Control and Prevention (CDC) in 2006 and 2007 as causes of CLABSI included, in descending order of frequency, coagulase-negative staphylococci (34.1%), Enterococcus species (16%), Candida species (11.8%), Staphylococcus aureus (9.9%), and Klebsiella pneumoniae (4.9%). Other gram-negative organisms make up the remainder of the ten most common causes of CLABSI.
SURVEILLANCE AND CLINICAL DEFINITIONS
For surveillance and epidemiologic purposes, catheter-associated bloodstream infection is defined as a bloodstream infection in a patient with a central venous catheter in place at the time of or within 48 hours of collection of the blood sample, for which no other source of the bloodstream infection (e.g., pneumonia, surgical site infection) can be identified.
CLINICAL MANIFESTATIONS
Patients with CLABSI often present with nonspecific signs and symptoms, such as fever and leukocytosis. Localized signs and symptoms of infection, such as erythema, tenderness, swelling, or purulent discharge at the catheter exit site or along the catheter tunnel, are seen in only a small minority of patients with CLABSI. Complications of CLABSI can include sepsis, endocarditis, septic thrombophlebitis, and metastatic infection (e.g., osteomyelitis, septic arthritis, epidural abscess).
DIAGNOSIS
The diagnosis of CLABSI should be considered in any patient with a central venous catheter who develops a fever and/or other signs of systemic infection. Similarly, CLABSI should be considered in any patient with a central venous catheter who has a positive blood culture and no other obvious source of the bloodstream infection (e.g., pneumonia, urinary tract infection, surgical site infection).
Inflammation and purulence at the catheter site are frequently absent in patients with CLABSI; however, the catheter exit site and tract should be thoroughly examined for signs of inflammation.
In patients with suspected CLABSI, two sets of blood cultures should be obtained prior to the initiation of antibiotic therapy.
Blood cultures should be drawn from two separate sites.
Whenever possible, at least one set of blood cultures should be obtained by percutaneous venipuncture. Although blood cultures obtained by aspiration of blood through the central venous catheter are highly sensitive for the detection of CLABSI, they are of lower specificity than blood specimens obtained from peripheral veins.
The sensitivity of a blood culture is dependent on the quantity of blood collected. Volumes of 30 to 40 mL provide optimal sensitivity. In clinical practice, however, 10 mL of blood per culture site are typically obtained.
Several additional microbiologic tests can provide additional information that may help to determine if the catheter is the true source of a bloodstream infection and thus diagnose CRBSI.
Quantitative or semiquantitative cultures of the catheter tip: growth of >102 colony-forming units (CFU) per catheter segment of the same organism isolated from blood culture(s) by the quantitative method or >15 CFU by the semiquantitative method suggests that the catheter was the source of the bloodstream infection.
Paired quantitative blood cultures obtained from the catheter and from a peripheral vein: a microbial colony count from the catheter-aspirated blood specimen that is more than threefold greater than the colony count from a peripheral blood specimen is suggestive of CRBSI.
Differential time to positivity of paired blood cultures obtained from the catheter and from a peripheral vein: with the use of continuously monitored blood culture systems, detection of microbial growth from the blood specimen drawn through the catheter more than two hours before growth is detected in a simultaneously drawn peripheral blood sample is suggestive of CRBSI. Of the three mentioned methods, this is most likely to be readily available to most clinicians since most clinical microbiology laboratories use continuously monitored blood culture systems.
TREATMENT
Guidelines published in 2009 by the Infectious Diseases Society of America (IDSA) provide evidence-based recommendations and a detailed review of the diagnosis and treatment of vascular catheter-related infections.
The decision to initiate empiric antibiotic therapy and the selection of an empiric regimen are based on several factors, including severity of illness, underlying medical conditions, the suspected pathogens, and local antibiotic susceptibility patterns. Until culture results become available, it is reasonable to initiate empiric therapy with a broad-spectrum antibiotic regimen that provides coverage for the most likely bacterial pathogens. Antifungal agents are not typically included in an empiric regimen unless the patient has identified risk factors for candidemia. Empiric antibiotic therapy should be adjusted based on organism identification and susceptibility testing results, once available.Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
