The Longer the Scrub, the Cleaner the Hub

In order to prevent contamination of central venous catheters (CVCs) in patients undergoing hematopoietic stem cell transplants (HSCT), nurses put a lot of time and focus into disinfecting the needleless connectors (NC) or “scrubbing the hub.”

CVCs increase the risk of central line associated bloodstream infections, which are associated with increased morbidity, mortality, and health care costs.

In a poster presented at the 2019 Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR, investigators sought to evaluate the impact of the length of mechanical friction on NC disinfection.

To start, the team divided 60 sterile NCs into groups of 10 and then contaminated them for 30 minutes with a McFarland solution comprising Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. Afterwards, investigators flushed the NCs with 1 mm of sterile saline into a sterile tube and 10 μL loops were used to inoculate blood agar plates.

“The first group was negative controls which were flushed after being removed from the package, the second group was positive controls with no scrubbing done prior to the flush,” the investigators wrote in the abstract. “For the remaining 4 groups, 2% chlorhexidine gluconate plus 70% alcohol pads were used to scrub the NC per routine practice for 15 seconds, 30 seconds, 45 seconds, and 60 seconds. All the groups had the same drying time of 30 seconds. After 24 hours of incubation at 38 degrees Celsius positive cultures were identified and number of colonies on each plate were recorded. Ten nurses participated in the study scrubbing the hubs.”

The primary outcome was to determine whether longer scrubbing time leads to less bacterial growth. And indeed, investigators observed an inverse relationship between scrubbing time and bacteria colony growth.

All of the negative controls were negative; 7 out of 10 positive controls were positive with a mean of 127 CFU/ml. In the 3^rd group, 8 out of 10 were positive with a mean of 171 CFU/ml; in the 4^th group, 6 out of 10 were positive with a mean of 122 CFU/ml; in the 5^th group, 4 out of 10 were positive with a mean of 55 CFU/ml; and in the 6^th group, 3 out of 10 were positive with a total of 15 CFU/ml.

“Longer scrubbing time appears to decrease line contamination which can be translated into clinical practice,” the investigators concluded.

The poster, “Scrubbing the Hub, How Long Is Enough?”, was presented Saturday, February 23, 2019, at the Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR in Houston, Texas.