INTRAVASCULAR CATHETER RELATED BLOOD STREAM INFECTION

"It does not matter how slowly you go,

as long as you do not stop"

                                            - Confucious

Since the introduction of central venous catheterization by Forssman in 1929, this invasive procedure evolved to be very helpful in management of both inpatient and outpatients. Central venous catheters are used for indication as varied as hemodynamic monitoring, vasopressors administration, renal replacement therapy, administration of chemotherapeutic agents and total parenteral nutrition.

But central venous catheters have also evolved to be an important source of healthcare related infection, translating to increased morbidity, mortality and financial burden. Intravenous catheter related blood stream infection is the third leading cause of device related infection, after catheter associated urinary tract infection (CAUTI) and ventilator associated pneumonia (VAP).

Intravascular catheter related blood stream infection is one of the ‘never events’ defined by center for medicare and Medicaid services (CMC), and the resulting financial burden is not reimbursable.

CATHETER RELATED BSI (CRBSI) VS CENTRAL LINE ASSOCIATED BSI (CLABSI): Two terms are used to describe intravascular catheter related BSI, catheter related BSI (CRBSI) and central line associated BSI (CLABSI).

But the two are not the same, as they are used for differing purposes, therefore defined differently.

CRBSI is a clinical definition, used for diagnosing and treating patients. It requires specific laboratory workup, to identify the catheter as the source of the BSI.

It demands catheter removal (for catheter tip culture) or quantitative blood culture with specific microbiologic method (differential time to positivity).   

However, for surveillance purpose, definition of intravascular catheter related BSI, as defined in CRBSI, is not practical.

Therefore simpler definition (CLABSI) is used by CDC’s NHSN for surveillance of CRBSI.

In other words CLABSI is used as surrogate for CRBSI, for surveillance of intravascular catheter related BSI.

CLABSI is defined as a primary blood stream infection in a patient, who had a central line, within 48 hour period before the development of BSI and is not related to infection at another site.

CLABSI does not require specific laboratory workup (culture of catheter tip or specific microbiologic method).

Though CLABSI definition is simpler to use, it may overestimate the true incidence of CRBSI. Also it is subject to interobserver variability and lack of standardization.

CATHETER RELATED BLOOD STREAM INFECTION (CRBSI): Defined as blood stream infection in a patient with intravascular catheter, with clinical manifestation of infection (fever, chills and/or hypotension) with no apparent source of infection except the catheter; and at least one positive blood culture obtained from a peripheral vein; and documentation of catheter colonization with the same organism, as peripheral blood culture.

Catheter colonization can be documented by:

1.       If catheter is removed, positive culture of 5 cm of catheter tip, by plate roll over (>15 CFU/catheter segment) or positive culture from luminal flushing or sonication, by broth culture (>100 CFU).

2.       If catheter is not removed, positive blood culture of blood sample drawn from catheter lumen, with colony count three times greater than that from peripheral vein.

3.       If catheter is not removed, microbial growth detected in blood sample drawn from catheter lumen, precedes by 2 hours, to the growth detected in blood sample drawn from peripheral vein. This is known as differential time to positivity (DTP).

4.       If blood could not be drawn from peripheral vein, then positive blood culture of blood sample drawn from two catheter lumens, with colony count in one sample is three times greater than the second.

For pulmonary artery catheter, introducer tip should be cultured.

MANAGEMENT OF CRBSI: Three factor should considered, in the management of CRBSI:

1. Severity of infection,
2. Type of catheter, whether short term or long term catheter,
3. Type of organism growing.

Before starting antimicrobial, paired blood culture should be sent from catheter lumen and peripheral vein.

SEVERITY OF INFECTION AND TYPE OF CATHETER:

Short term catheter should be removed in severe sepsis, local complication (exit site infection, suppurative thrombophlebitis), metastatic complications (endocarditis, osteomyelitis), infection due to staph. aureus, gram negative bacilli, enterococcus, candida and mycobacteria.

Long term catheter should be removed in severe sepsis, infection due to staph. aureus, pseudomonas, candida, mycobacteria, local complication (exit site, tunnel or port infection, suppurative thrombophlebitis) or metastatic complications (endocarditis, osteomyelitis).

For difficult to eradicate and less virulent organisms, bacillus, micrococcus and propionobacterium, both short term and long term catheter should be removed, but before removal of catheter, contamination should be ruled out by multiple cultures.

CATHETER EXCHANGE OVER GUIDEWIRE:

In patients with short term catheter, who have high risk of mechanical complication with new catheter insertion, catheter exchange over guidewire may be done. However, tip of the removed catheter should be cultured, and if it is positive, new catheter should be inserted at another site.

In patients with long term catheter, with limited vascular access or increased risk of bleeding, catheter exchange over guidewire may be done, if there is no local complication like exit site infection or tunnel infection. 

Antimicrobial impregnated catheter should be preferred for exchange over guidewire.

CATHETER SALVAGE:

Short term catheter should not be removed in hemodynamically stable patients, who don’t have prosthetic valve or pacemaker or recently placed vascular graft. However if CRBSI is documented, it should be removed.

Long term catheter should be salvaged in patient with, limited vascular access and who require it for survival. It should be done in uncomplicated CRBSI (no local or distant complication), and infection not due to staph. aureus, pseudomonas, candida, bacillus, micrococcus, propionobacterium and mycobacteria.

If catheter salvage is attempted, repeat culture should be done 72 hours after starting empirical antimicrobial. If culture is still positive, despite susceptibility to empirical antimicrobial, catheter should be removed.

If catheter salvage is attempted, antibiotic lock should be used along with systemic antimicrobial. If this cannot be done, systemic antibiotic should be administered through the colonized catheter.

TYPE OF ORGANISM AND ANTIMICROBIAL THERAPY:

While counting duration of antimicrobial therapy, day one should be considered the day on which first negative blood culture is obtained.

Vancomycin should be started empirically. Linezolid should not be use empirically.

Beta lactam/ beta lactamase inhibitor (BL/BLI), fourth generation cephalosporin or carbapenem should be added empirically to cover GNB.

Empirical combination antimicrobial to cover MDR GNB including pseudomonas, should be added in patients with neutropenia, severely ill patients and history of colonization with such organisms, till culture results are available.

Empirical antifungal should be added to cover candida CRBSI in patients with femoral catheter, prolong use of broad spectrum antibiotics, total parenteral nutrition, hematological malignancy, bone marrow or solid organ transplant recipient and history of multiple site candida colonization.

Echinocandin should be used empirically as antifungal agent.

Fluconazole may be used in patients with no azole exposure in last three months, in healthcare settings with very low risk of Candida krusei or Candida glabrata infection.

If patient is growing coagulase negative staphylococcus in single blood culture, contamination should be ruled out before stating antibiotic or catheter removal. Paired blood culture should be sent from catheter lumen and peripheral vein to rule out contamination.

DURATION OF ANTIMICROBIAL:

Antimicrobial therapy should be administered for four to six weeks in patients with persistent bacteremia (positive blood culture 72 hours after catheter removal), complicated BSI (suppurative thrombophlebitis, endocarditis). For complicated BSI with osteomyelitis, therapy should be given for six to eight weeks. 

TRANSESOPHAGEAL ECHOCARDIOGRAPHY (TEE):

In staph. aureus and entercoccal CRBSI, infective endocarditis should be ruled out in following scenarios. Clinical evidence of infective endocarditis, persistent bacteremia (positive blood culture 72 hours after appropriate antibiotic therapy or catheter removal), radiographic evidence of septic pulmonary emboli or presence of prosthetic valve, pacemaker or other endovascular foreign body.

References:

Guidelines for the prevention of intravascular catheter related infections. CDC NHSN 2011.

CPG for the diagnosis and management of intravascular catheter related infection: 2009 update by IDSA.