Central Line-Associated Bloodstream Infection in Children
The classic presentation of CLABSI is the development of fever and chills immediately after accessing a catheter that has been locked for some time. However, the range of clinical presentations is broad, and the catheter may not always be immediately considered as the source of fever. Most episodes are not associated with any visible abnormality at the site of the catheter.
Unless an alternative source is identified, all bloodstream infections in patients with a CVC are classified as CLABSI. This surveillance definition may overestimate the true number of infections that are attributable to the CVC. Therefore, when there is evidence to confirm that the colonized device is the true source of infection, the more specific diagnosis of catheter-related bloodstream infection (CRBSI) is used (Fig. 1). Confirmatory tests include culture of the catheter tip, quantitative blood cultures or differential time to positivity (DTP) of blood cultures drawn from different sites. Data from pediatric oncology patients suggest that up to one third of CLABSI episodes are related to infections at other sites and are therefore not CRBSI. Definitive diagnosis of CRBSI can be important to identify those patients who might benefit from catheter removal or adjunctive therapy. CVC tip culture can identify CRBSI, but precludes salvage of the catheter.
(Enlarge Image)
Figure 1.
Categories of bloodstream infections.10 BSI indicates bloodstream infection.
The most readily available technique to confirm CRBSI without catheter removal is the calculation of DTP between blood cultures drawn from the catheter and from a peripheral vein or separate lumen. In cases of true CRBSI, blood obtained through a colonized lumen will usually indicate growth before uncolonized lumens or peripheral blood because of high intraluminal microorganism burden. To apply, identical volumes of blood must be collected for culture simultaneously from each site, and a continuously monitored blood culture system is needed. In pediatric oncology patients who had simultaneous peripheral and central cultures, a DTP of ≥150 minutes had a specificity of 100% and sensitivity of 89% for CRBSI. For cultures from both lumens of a double-lumen catheter, a DTP of ≥180 minutes had a specificity of 94% and sensitivity of 61%. These data suggest that DTP can be confidently used to diagnose CRBSI, but that the negative predictive value is poor, especially when comparing 2 lumens of a double-lumen catheter.
To maximize the sensitivity and specificity of diagnosis in cases of suspected CRBSI, blood cultures should be collected from the catheter and from the peripheral blood before initiation of antibiotics. Blood should generally be collected from all lumens of a multilumen catheter (although there is an absence of data to support this consensus recommendation), as some can be uncolonized. Similarly, in patients with a single-lumen catheter, at least 2 sets of blood cultures should be collected through the CVC if a peripheral culture is not taken. Normal skin flora are the most common causes of CLABSI and are also frequent blood culture contaminants. Therefore, definitive diagnosis of bloodstream infection with a common skin contaminant requires multiple positive cultures to exclude the possibility of contamination during collection or inoculation. If multiple blood cultures have not been collected before antibiotics, a presumptive diagnosis of CLABSI has to be made, leading to unnecessary treatment in cases where the positive culture has resulted from contamination.
Peripheral blood should be collected in all cases of suspected CLABSI before antibiotics are started, but pediatricians often avoid this. There are a number of important situations in which peripheral blood culture aids management. One example is a patient with severe sepsis in whom catheter removal might limit venous access and compromise treatment. Another is attempted catheter salvage complicated by persistent bacteremia during appropriate antibiotic therapy in which evidence that the catheter is not the primary focus could lead to earlier identification of an intravascular focus such as endocarditis. Lastly, definitive diagnosis of CRBSI can support a decision to remove and replace a catheter in cases of S. aureus or candida infection. All these situations can be difficult to predict at initial presentation.
After diagnosis of CLABSI, blood cultures should be collected daily until cultures from all lumens are negative. Further peripheral cultures may not be necessary if blood can be collected from all lumens of the catheter and the patient is clinically stable.
Complicated catheter-associated infections include tunnel or port pocket infection, endovascular infections such as endocarditis or suppurative thrombophlebitis and metastatic infections such as osteomyelitis and liver, spleen or brain abscess. Catheter-related skin and soft tissue infection can be identified by localized erythema, tenderness, fluctuance or swelling. An intravascular focus may be identified when there is persistent bacteremia or fungemia after CVC removal, despite appropriate antimicrobial therapy. Clinical signs, such as new murmur, peripheral stigmata and cardiac failure or localized tenderness and swelling of a limb, are often absent in infective endocarditis and suppurative thrombophlebitis, respectively.
Diagnosis and Definitions
The classic presentation of CLABSI is the development of fever and chills immediately after accessing a catheter that has been locked for some time. However, the range of clinical presentations is broad, and the catheter may not always be immediately considered as the source of fever. Most episodes are not associated with any visible abnormality at the site of the catheter.
Unless an alternative source is identified, all bloodstream infections in patients with a CVC are classified as CLABSI. This surveillance definition may overestimate the true number of infections that are attributable to the CVC. Therefore, when there is evidence to confirm that the colonized device is the true source of infection, the more specific diagnosis of catheter-related bloodstream infection (CRBSI) is used (Fig. 1). Confirmatory tests include culture of the catheter tip, quantitative blood cultures or differential time to positivity (DTP) of blood cultures drawn from different sites. Data from pediatric oncology patients suggest that up to one third of CLABSI episodes are related to infections at other sites and are therefore not CRBSI. Definitive diagnosis of CRBSI can be important to identify those patients who might benefit from catheter removal or adjunctive therapy. CVC tip culture can identify CRBSI, but precludes salvage of the catheter.
(Enlarge Image)
Figure 1.
Categories of bloodstream infections.10 BSI indicates bloodstream infection.
The most readily available technique to confirm CRBSI without catheter removal is the calculation of DTP between blood cultures drawn from the catheter and from a peripheral vein or separate lumen. In cases of true CRBSI, blood obtained through a colonized lumen will usually indicate growth before uncolonized lumens or peripheral blood because of high intraluminal microorganism burden. To apply, identical volumes of blood must be collected for culture simultaneously from each site, and a continuously monitored blood culture system is needed. In pediatric oncology patients who had simultaneous peripheral and central cultures, a DTP of ≥150 minutes had a specificity of 100% and sensitivity of 89% for CRBSI. For cultures from both lumens of a double-lumen catheter, a DTP of ≥180 minutes had a specificity of 94% and sensitivity of 61%. These data suggest that DTP can be confidently used to diagnose CRBSI, but that the negative predictive value is poor, especially when comparing 2 lumens of a double-lumen catheter.
To maximize the sensitivity and specificity of diagnosis in cases of suspected CRBSI, blood cultures should be collected from the catheter and from the peripheral blood before initiation of antibiotics. Blood should generally be collected from all lumens of a multilumen catheter (although there is an absence of data to support this consensus recommendation), as some can be uncolonized. Similarly, in patients with a single-lumen catheter, at least 2 sets of blood cultures should be collected through the CVC if a peripheral culture is not taken. Normal skin flora are the most common causes of CLABSI and are also frequent blood culture contaminants. Therefore, definitive diagnosis of bloodstream infection with a common skin contaminant requires multiple positive cultures to exclude the possibility of contamination during collection or inoculation. If multiple blood cultures have not been collected before antibiotics, a presumptive diagnosis of CLABSI has to be made, leading to unnecessary treatment in cases where the positive culture has resulted from contamination.
Peripheral blood should be collected in all cases of suspected CLABSI before antibiotics are started, but pediatricians often avoid this. There are a number of important situations in which peripheral blood culture aids management. One example is a patient with severe sepsis in whom catheter removal might limit venous access and compromise treatment. Another is attempted catheter salvage complicated by persistent bacteremia during appropriate antibiotic therapy in which evidence that the catheter is not the primary focus could lead to earlier identification of an intravascular focus such as endocarditis. Lastly, definitive diagnosis of CRBSI can support a decision to remove and replace a catheter in cases of S. aureus or candida infection. All these situations can be difficult to predict at initial presentation.
After diagnosis of CLABSI, blood cultures should be collected daily until cultures from all lumens are negative. Further peripheral cultures may not be necessary if blood can be collected from all lumens of the catheter and the patient is clinically stable.
Diagnosis of Complications Resulting From CLABSI
Complicated catheter-associated infections include tunnel or port pocket infection, endovascular infections such as endocarditis or suppurative thrombophlebitis and metastatic infections such as osteomyelitis and liver, spleen or brain abscess. Catheter-related skin and soft tissue infection can be identified by localized erythema, tenderness, fluctuance or swelling. An intravascular focus may be identified when there is persistent bacteremia or fungemia after CVC removal, despite appropriate antimicrobial therapy. Clinical signs, such as new murmur, peripheral stigmata and cardiac failure or localized tenderness and swelling of a limb, are often absent in infective endocarditis and suppurative thrombophlebitis, respectively.
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