Central line-associated bloodstream infection: Clinical sciences

Central line-associated bloodstream infection, or CLABSI for short, is a primary bloodstream infection that develops at least 48 hours after central line placement when no other source of infection is identified. CLABSI also refers to a primary blood infection that occurs on the day of central line removal or the day after. Now, the most common causes of CLABSI include bacteria, such as coagulase-negative staphylococci, Staphylococcus aureus, and enterococci. Less commonly, CLABSI can be caused by fungi, such as Candida. These pathogens can colonize the central line and use its extraluminal or intraluminal surface to reach the bloodstream.

Extraluminal migration is usually specific for organisms that represent a part of normal skin microflora, while intraluminal migration is associated with contamination of the central line, typically from the hands of health care providers. CLABSI can be defined as complicated when the patient has CLABSI with septic shock, septic thrombophlebitis, or metastatic infection; while uncomplicated is CLABSI without these associated complications.

Now, if you suspect CLABSI, you should first perform an ABCDE assessment to determine if your patient is unstable or stable. If the patient is unstable, stabilize the airway, breathing, and circulation. This means that you might need to intubate the patient. Next, obtain IV access, and, if your patient is hypotensive, start IV fluids for volume resuscitation.

Once you are done with the acute management, obtain a focused history and physical examination, and order labs, including CBC and lactate. History typically reveals a central line that’s been in place for more than 2 days, and symptoms such as fever, chills, and fatigue. But, keep in mind that CLABSI can also occur once the central line is removed. In this case, the patient might report symptoms on the day of, or the day after, the catheter removal. Physical exam findings might reveal hypotension and altered mental status, including confusion or lethargy. Additionally, at the central line insertion site, you might detect local erythema, tenderness, and purulence. Finally, lab results typically include elevated WBCs and lactate.

Now that you’ve obtained the history, physical, and lab findings, you should assess for other sources of infection. If there’s another source of infection that can explain current signs and symptoms, such as urinary tract infection or surgical site infection, you should suspect a secondary bloodstream infection. However, if you find no other source of infection, you should suspect complicated CLABSI, defined as CLABSI with septic shock, septic thrombophlebitis, or metastatic infection.

Once you suspect complicated CLABSI, draw two or more blood samples for culture. Do this on two separate occasions to avoid possible false positive results due to contamination. In other words, draw samples from different sites, or at different times. For example, you can draw samples from two different peripheral sites, or you can draw one sample from a peripheral site and one from the lumen of the central line. Avoid drawing blood samples from the lumen only, since cultures drawn through the central line have a higher rate of contamination. Finally, once you have drawn blood cultures and are waiting for results, start empiric antibiotics and remove the central line.

Alright, now, let’s take a look at how to assess blood culture results. If both cultures come back negative, you should consider an alternative diagnosis. On the flip side, you can diagnose complicated CLABSI if at least one blood culture comes back positive for bacteria that are true pathogens, meaning for bacteria that are not a part of human microflora. Additionally, you can diagnose complicated CLABSI if two blood cultures come back positive for bacteria that are commensal organisms, meaning bacteria that represent a part of normal microflora.

Now that you’ve diagnosed complicated CLABSI, switch to tailored antibiotics based on culture results. The antibiotic therapy should last 4 to 6 weeks, unless there's underlying osteomyelitis, which requires an additional 2 weeks of treatment. Finally, keep in mind that your culture results might come back positive for fungi, so in that case, switch from empiric antibiotics to antifungals!