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Catheter related blood stream infection (CRBSI)

What is CRBSI?

CRBSI is defined bacteremia or fungemia in a patient who has an intravascular device and more than 1 positive blood culture result obtained from the peripheral vein, clinical manifestations of infection (e.g., fever, chills, and/ or hypotension), and no apparent source for bloodstream infection (with the exception of the catheter). One of the following should be present:

  • A positive result of semi quantitative (>15 colony forming unit- cfu per catheter segment) or quantitative (> 102 cfu per catheter segment) catheter culture, whereby the same organism (species) is isolated from a catheter segment and a peripheral blood culture;
  • Simultaneous quantitative cultures of blood with a ratio of >3:1 cfu/mL of blood (catheter vs. peripheral blood);
  • Differential time to positivity (growth in a culture of blood obtained through a catheter hub is detected by an automated blood culture system at least 2 h earlier than a culture of simultaneously drawn peripheral blood of equal volume).

NB- A positive culture result for a blood sample drawn through a catheter requires clinical interpretation, but a negative result excludes CRBSI

What organisms commonly cause CRBSI?

Coagulase negative staphylococci, S. aureus, aerobic gram negative bacilli and Candida albicans.
Coagulase-negative staphylococci are the most common cause of catheter-related infection. However, if a catheterized patient has a single positive blood culture that grows coagulase negative Staphylococcus species, then additional cultures of blood samples obtained through the suspected catheter and from a peripheral vein should be performed before the initiation of antimicrobial therapy and/or catheter removal to be certain that the patient has true bloodstream infection and that the catheter is the likely source.

What empirical antibiotics should be used when CRBSI is suspecte?

  • Vancomycin is usually recommended because of its activity against coagulase negative staphylococci and S. aureus (including MRSA)
  • Additional empirical coverage for gram negative bacilli and Pseudomonas (ceftazidime etc) is recommended for neutropenic, severely ill or immunocompromised pts
  • Empirical therapy (echinocandin or fluconazole) for candida species should be used for septic patients with any of the following risk factors: total parenteral nutrition, prolonged use of broad-spectrum antibiotics, hematologic malignancy, receipt of bone marrow or solid-organ transplant, femoral catheterization, or colonization due to Candida species at multiple sites.

When would you remove the catheter in CRBSI?

CVCs in patients with mild to moderate CRBSI should not be routinely removed. Always remove the catheter if

  • CVCs in patients with mild to moderate CRBSI should not be routinely removed. Always remove the catheter if
  • Clinical signs of sepsis with organ dysfunction
  • Erythema or purulence overlying the catheter exit site. In tunnelled catheters, pocket infections or port abscess require removal of catheter.
  • For complicated infections like septic thrombosis, endocarditis, osteomyelitis
  • Persistent bacteremia (i.e. positive cultures from the catheter 72 h after the initiation of appropriate therapy) despite appropriate antibiotics
  • Infections due to S. aureus, P. aeruginosa, fungi, or mycobacteria
  • CRBSI due to less virulent microbes that are difficult to eradicate (e.g., Bacillus species, Micrococcus species, or Propionibacteria), catheters should generally be removed after blood culture contamination is ruled out on the basis of multiple positive culture results, with at least 1 blood culture sample drawn from a peripheral vein

Remember

  • Have a low threshold for removal of non tunneled CVCs
  • Antibiotic lock therapy should be used for 2 weeks when the catheter is not removed with CRBSI

What is antibiotic lock therapy?

  • This is filling the catheter lumen with antibiotic solution and leaving them there for hours or days.
  • Antibiotic solutions in strength of 1-5mg/ml are mixed with 50-100 U of heparin or normal saline in sufficient volume to fill the catheter lumen (usually 2-5 ml) and are installed or locked into the catheter lumen during periods when the catheter is not being used (e.g. 12 hr period at night). The volume of installed antibiotic is removed before infusion of IV medication or solution.
  • Cefazolin (5mg/ml with 2500-5000IU/ml of heparin) is the preferred agent for treatment of methicillin-susceptible staphylococci, and vancomycin (2.5-5mg/ml with 2500-5000IU/ml of heparin) is the preferred agent for treatment of MRSA. Ceftazidime (0.5mg/ml with 100 U of heparin) gentamicin (1mg/ml with 2500IU/ml of heparin), or ciprofloxacin (0.2mg/ml with 5000IU/ml of heparin) can be used for treatment of gram-negative microorganisms. Ampicillin (10mg/ml with 5000IU/ml of heparin) is the preferred agent for infections due to ampicillin-sensitive Enterococcus species, and vancomycin is the preferred agent for treatment of ampicillin-resistant enterococci other than vancomycin-resistant enterococci. The use of an ethanol (70%) lock can be considered for the treatment of a mixed gram-positive and gram-negative infection.
  • If antibiotic lock therapy cannot be used in this situation, systemic antibiotics should be administered through the colonized catheter

When can CVCs be re inserted after old catheter has been removed?

  • Non-tunneled catheters may be reinserted after appropriate systemic antimicrobial therapy is begun
  • Reinsertion of tunneled devices should be postponed until after appropriate systemic antimicrobial therapy is begun and after repeat cultures of blood samples yield negative results.

What is the recommended duration of therapy for CRBSI?

  • Uncomplicated bacteremia- 10-14 days other than for coagulase negative staphylococci (5-7 days if catheter is removed, 10-14 days if catheter is retained). Coagulase negative staphylococcal infection may resolve with removal of the catheter and no antibiotic therapy, yet many experts believe that such infections should be treated.
  • Complicated infections- 4-6 week’s antibiotic therapy should be considered if there is persistent bacteremia or fungemia after catheter removal or if there is evidence of endocarditis, or septic thrombosis, and 6-8 weeks of therapy should be considered for the treatment of osteomyelitis. (suspect these complications if there is persistent bacteremia or fungemia, or a lack of clinical response)
  • Duration of antifungal treatment for candidemia should be for 14 days after the last positive blood culture result and when signs and symptoms of infection have resolved. Amphotericin (0.5 mg/kg/day) or fluconazole (400mg/day) can be used.

Discuss S. aureus CRBSI?

  • Highest mortality  amongst CRBSI
  • Patients with S. aureus CRBSI should have the infected catheter removed, and they should receive 4–6 weeks of antimicrobial therapy. Patients can be considered for a shorter duration of antimicrobial therapy (i.e., a minimum of 2 weeks) if the patient is not diabetic; if the patient is not immunosuppressed; if the infected catheter is removed; if the patient has no prosthetic intravascular device (e.g., pacemaker or recently placed vascular graft); if there is no evidence of endocarditis or suppurative thrombophlebitis on TOE and ultrasound, respectively; if fever and bacteremia resolve within 72 h after initiation of appropriate antimicrobial therapy; and if there is no evidence of metastatic infection on physical examination and sign- or symptom-directed diagnostic tests
  • TOE should be done because of high rates of complicating endocarditis; if TEE is not available and results of transthoracic echocardiography are negative, the duration of therapy should be decided clinically for each patient. TOE should be performed at least 5–7 days after onset of bacteremia to minimize the possibility of false-negative results
  • For MRSA- vancomycin is the drug of choice. However it should not be used with b-lactam susceptible S. aureus because vancomycin has higher failure rates that do either oxacillin or nafcillin, and it results in slower clearance of bacteremia among patients with S. aureus endocarditis.

What is the treatment of septic thrombosis?

  • Always remove the catheter
  • Incision and drainage and excision of the infected peripheral vein and any involved tributaries should be done. Surgical exploration is needed when infection extends beyond the vein into surrounding tissue.
  • Surgical excision and repair is needed in cases of peripheral arterial involvement with pseudoaneurysm formation
  • Heparin is needed in the treatment of septic thrombosis of the great central veins and arteries but not peripheral veins
  • Appropriate antibiotics for 4-6 weeks
  • Thrombolysis is not recommended.

What is the evidence based interventions which effectively reduce the risk of catheter related bloodstream infections?

  • Tunneled catheters by decreasing the extent of extraluminal contamination.
  • Antimicrobial coated short term CVCs are effective in reducing CRBSI
  • A single lumen CVC is to be preferred. If a multi lumen catheter is used, it is recommended to identify and designate one port exclusively for PN.
  • US placement of catheters may indirectly reduce the risk of contamination and infection
  • The catheter exit site of a non-tunneled central venous access should be covered preferably with a sterile, transparent, semi-permeable polyurethane dressing, which should be routinely changed every 7 days or sooner if they are no longer intact or moisture collects under the dressing. If a patient has profuse perspiration or if the insertion site is bleeding or oozing, a sterile gauze dressing is preferable to a transparent, semi-permeable dressing.
  • Chlorhexidine impregnated dressing are effective in reducing the extraluminal contamination of the catheter exit site with non-tunneled CVCs at high risk infection. Stitches should not be use routinely to stabilise CVCs as they may be associated with a high risk of contamination of the exit site. Use manufactured catheter stabilization devices.
  • The most appropriate skin antiseptic for prevention of catheter related blood stream infection is chlorhexidine as 2% solution in 70% isopropyl alcohol, and it should be preferred for both skin preparation and cleaning of the catheter exit site. Alcoholic povidone-iodine solution should be used in patients with a history of chlorhexidine sensitivity
  • Stopcocks, catheter hubs and sampling ports of needle-free connectors are an important route of intraluminal contamination and subsequent CRBSI, and they should always be disinfected before access, preferably using 2% chlorhexidine gluconate in 70% isopropyl alcohol.
  • The intravenous catheter administration set should be changed every 24 hrs (when using lipid PN) or every 72 hrs (if lipids are not infused)
  • Low-dose systemic anticoagulation or catheter flushing with heparin do not reduce the risk of catheter contamination, and are not recommended for prevention of CRBSI
  • Proper education and specific training of the staff is universally recommended as one of the most evidence based strategy for reducing the risk of catheter related infections
  • Adequate policy of hand washing

Ref

  1. ESPEN (2006) guidelines
  2. Guidelines for the Management of Intravascular Catheter–Related Infections. Clinical Infectious Diseases 2009; 49:1-45


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