Preventing infections caused by central catheters

Each year, roughly 200,000 blood transfusions are given at MD Anderson Cancer Center. Some patients experience negative reactions to the transfusions that can exacerbate their illness and lead to the waste of precious blood products such as red and white blood cells, plasma and platelets. While medical staff report and investigate these reactions, they may not be aware that a possible culprit is the very central venous catheter (CVC) that delivers the life-saving blood.

A study published in the April 2014 online issue of TRANSFUSION examined all transfusion reactions at MD Anderson from 2007 to 2011 and revealed CVCs may be a relatively unknown cause of some reactions due to hidden microbes living within the portal.

“Transfusions generally are safe today thanks to the rigorous screening of the donors and testing of the products. Yet some recipients experience reactions such as fever, chills, skin hives or other rare, but severe, reactions,” said study senior investigator Xiang-Yang Han, M.D., Ph.D., professor in Laboratory Medicine. “Transfusion reactions usually are attributed to the blood products or the conditions of the recipients. Our study found that some of these reactions could result from use of the CVC itself due to hidden microbes.”

Microbes, which are all around us, are abundant on the skin and in the oral cavity and lower gut. Many adhere to objects such as an indwelling CVC that is required for the long-term delivery of cancer treatment drugs. A low percentage of CVCs may be colonized by microbes leading to bloodstream infection. At an early stage or due to weak pathogens, these colonies may be subclinical or hidden.

CVCs provide ready vascular access for transfusion and approximately three quarters of the transfusions at MD Anderson — close to 150,000 annually — are made through indwelling CVCs. During transfusion, microbes hidden in CVCs are carried into the bloodstream, causing fever, chills and other signs of infection, as well as mimicking transfusion reactions.

Han, a microbiologist, and co-investigator Ben Lichtiger, M.D., Ph.D., clinical professor in Laboratory Medicine, realized this likelihood in 2006 and started recording the use of CVC in the investigation of transfusion reactions. From 2007 to 2011, a total of 999 transfusion reactions occurred in 857 patients.

Kristin Ricci, M.D., a transfusion medicine fellow and lead author, joined Han and Lichtiger to analyze the reactions. The team collected microbiologic data of patients who had blood samples cultured within seven days before and/or after the transfusion reactions, focusing on 606 reactions in patients with both CVC transfusions and cultures performed. Among them, 60 reactions (10 percent) occurred in patients who had at least one significant microorganism cultured from the blood samples.

“This suggests that the patients may have had catheter-related bloodstream infections caused by CVC transfusion,” said Han. “As far as we know, there is not a general awareness of this connection.”

The authors noted in the TRANSFUSION article that, “while it is intuitive and known that a transfusion port may be colonized by microbes, our study linking transfusion reactions with microbes hidden in the port reflects a close teamwork of specialists in transfusion medicine and microbiology. These findings may have implications for both clinical and laboratory teams with regards to transfusions.”

They added that the risk of bloodstream infection should be weighed against the benefit of convenient vascular access via a CVC.

Because the CVC may remain in the patient for up to several months, the team plans to investigate whether the duration of indwelling CVCs and the type of catheter affects the occurrence of such septic ‘transfusion’ reactions.

The study team also included Fernando Martinez, M.D., assistant professor in Laboratory Medicine. Ricci is now at the Cleveland Clinic.