Chapter 51: Catheter-Related Bloodstream Infections: Management and Prevention

Epidemiology and Microbiology

Definitions²

• Catheter colonization: Significant growth of a microorganism in a quantitative or semiquantitative culture of the catheter tip, subcutaneous catheter segment, or catheter hub

• Exit-site infection: Erythema, induration, and/or tenderness within 2 cm of the catheter exit site; may be associated with other signs and symptoms of infection, such as fever or pus emerging from the exit site with or without concomitant bloodstream infections

• Tunnel infection: Tenderness, erythema, and/or induration within 12 cm from the catheter exit site along the subcutaneous tract of a tunneled catheter (eg, Hickman or Broviac) with or without concomitant bloodstream infections

• Pocket infection: Infected fluid in the subcutaneous pocket of a totally implanted intravascular device; often associated with tenderness, erythema, and/or induration over the pocket; spontaneous rupture and drainage, or necrosis of the overlying skin, with or without concomitant bloodstream infection, may also occur

• Catheter-related bloodstream infection: Bacteremia or fungemia in a patient who has an intravascular device and 1 positive result from culture of blood samples from the peripheral vein, clinical manifestations of infection (eg, fever, chills, and/or hypotension), and no apparent source for bloodstream infection (except for the catheter). One of the following should be present: a positive result of semiquantitative (>15 CFU per catheter segment) or quantitative (>10² CFU per catheter segment) catheter culture, whereby the same organism (species and antibiogram) is isolated from a catheter segment and a peripheral blood sample; simultaneous quantitative cultures of blood samples with a ratio of >5:1 (central venous catheter [CVC] versus peripheral catheter); differential time to positivity (ie, a positive result of culture from a CVC is obtained at least 2 hours earlier than a positive result from a culture from peripheral blood)

Diagnosis

1. Blood cultures

   • Clinical findings for establishing the diagnosis of catheter-related infection are unreliable because of poor sensitivity and specificity

   • When catheter infection is suspected, 2 sets of blood cultures should be sent with at least 1 drawn percutaneously²

   • Paired quantitative or qualitative blood cultures with continuously monitored differential time to positivity are recommended when long-term catheters cannot be removed^3,4,5

2. Catheter cultures

   • Culture catheters only when catheter-related bloodstream infection is suspected²

   • Quantitative or semiquantitative cultures are recommended²

   • When culturing a catheter segment, catheter tip should be cultured rather than the subcutaneous segment⁶

   • For suspected pulmonary artery catheter infection, the introducer tip should be cultured²

Management

Nontunneled central venous catheters (CVCs) (see Figures 48-1 and 48-2)²

• CVCs in patients with fever and mild to moderate symptoms do not need to be routinely removed

• CVCs should be removed and cultured if the patient has a tunnel infection (erythema or purulence overlying the catheter exit site) or clinical signs of sepsis

• If blood culture results are positive or if the CVC is exchanged over the guidewire and has significant colonization according to results of quantitative or semiquantitative cultures, the catheter should be removed and placed into a new site

• In some patients without evidence of persistent bloodstream infection, or if the infecting organism is a coagulase-negative staphylococci and if there is no suspicion of local or metastatic complications, the CVC may be retained

• A transesophageal echocardiogram (TEE) should be obtained to rule out vegetations (endocarditis) in patients with a catheter-related S. aureus bloodstream infection if less than 4 weeks of therapy is being considered

• If a TEE is not available and the results of transthoracic echocardiography are negative, the duration of therapy for S. aureus bacteremia should be 4–6 weeks

• After removal of a colonized catheter associated with bloodstream infection, if there is persistent bacteremia or fungemia or a lack of clinical improvement, aggressive evaluation for septic thrombosis, infective endocarditis, and other metastatic infections should commence

• Febrile patients with valvular heart disease or patients with neutropenia whose catheter tip culture reveals significant growth of S. aureus or Candida species on semiquantitative or quantitative culture with no bloodstream infection should be followed up closely for development of infection, and samples of blood for culture should be obtained accordingly

• After a catheter is removed from a patient with a catheter-related bloodstream infection, nontunneled catheters may be reinserted after appropriate systemic antimicrobial therapy is begun

Tunneled CVCs and intravascular devices (see Figure 48-3)

• Clinical assessment is recommended to determine whether the CVC or the ID is the source of infection or bloodstream infection

• For complicated infections, the CVC or the ID should be removed

• For salvage of the CVC or the ID in patients with uncomplicated infections, antibiotic lock therapy should be used for 2 weeks with standard systemic therapy for treatment of catheter-related bacteremia caused by S. aureus, coagulase-negative staphylococci, and Gram-negative bacilli for suspected intraluminal infection in the absence of tunnel or pocket infection

• Tunneled catheter pocket infections or port abscess require removal of a catheter and usually 7–10 days of appropriate antibiotic therapy

• Reinsertion of tunneled intravascular devices should be postponed until after appropriate systemic antimicrobial therapy is begun, based on susceptibilities of the bloodstream isolate and after repeated cultures of blood samples yield negative results

Prevention

1. Site of catheter insertion⁷

   • Subclavian site has lowest rate of infectious complications

   • Catheters inserted into an internal jugular vein have been associated with higher risk of infection than that of those inserted into a subclavian or femoral veins^8,9

   • Femoral catheters are at high risk for thromboembolic disease

2. Skin antisepsis

   • Chlorhexidine (>0.5%) should be used in adult and adolescent patients, unless there is a contraindication to its use

3. Catheter-site dressing regimens

   • Transparent, semipermeable polyurethane dressings are reliable, secure, and convenient

   • Chlorhexidine-impregnated sponge dressings can reduce the risk of bacteremia with CVCs in place >4 days. This small disk can be placed over the insertion site and left in place for up to 7 days

   • Mupirocin ointment applied at the insertion sites of CVCs prevents catheter-related bloodstream infections, but it has also been associated with mupirocin resistance and selection for fungal organisms. This ointment may adversely affect the integrity of polyurethane catheters and is therefore not recommended

   • Mupirocin ointment has been used intranasally to decrease nasal carriage of S. aureus and reduce the risk of catheter-related bloodstream infections. However, this practice is not recommended because of the development of resistance

4. Antimicrobial/antiseptic impregnated catheters

   • Certain antimicrobial or antiseptic-impregnated or antiseptic-coated catheters have been shown to decrease the risk of catheter-related bloodstream infection¹⁰

   • Catheters coated with chlorhexidine/silver sulfadiazine on the external luminal surface only reduced the risk of bacteremia compared with standard noncoated catheters.^11,12 Selection of resistance to chlorhexidine/silver sulfadiazine is a concern; however, this has not yet been demonstrated. These catheters may be cost-effective in the ICU and in burn patients, neutropenic patients, and patients who have had catheters placed under emergency conditions

   • Catheters impregnated on the internal and external surfaces with minocycline/rifampin are associated with lower rates of bacteremia when compared with chlorhexidine/silver sulfadiazine-impregnated catheters.¹³ No minocycline/rifampin-resistant organisms were reported, although this is a theoretical risk

   • A second-generation catheter is now available with a chlorhexidine coating on both the internal and external luminal surfaces

   • The decision to use chlorhexidine/silver sulfadiazine- or minocycline/rifampin-impregnated catheters should be based on the need to enhance prevention of catheter-related bloodstream infections and balanced against the concern for possible emergence of resistant pathogens and the cost of implementing this strategy

5. Antibiotic lock prophylaxis

   • Antibiotic lock prophylaxis can be useful in neutropenic patients with long-term catheters using a solution containing heparin plus 25 mcg/mL of vancomycin

   • This practice can increase the risk of VRE.¹⁴ Antibiotic lock prophylaxis is not recommended routinely, although in patients with difficult access who have had multiple episodes of bacteremia, it is not an unreasonable strategy

6. Replacement of catheters

   • There are no studies that show an advantage of routine catheter replacement at scheduled time intervals as a method to reduce catheter-related bloodstream infections^15,16,17

   • Replacement of temporary catheters over a guidewire in the setting of bacteremia is not an acceptable replacement strategy, because the source of infection is usually colonization of the skin tract from the insertion site to the vein^18,19

7. Chlorhexidine baths:

   • Chlorhexidine baths daily have been shown to reduce the risk of hospital acquired infection, including catheter-related infections