Protocol for Detection of Biofilms on Needleless Connectors Attached to Central Venous Catheters

Abstract

Central venous catheter needleless connectors (NCs) have been shown to develop microbial contamination.A protocol was developed for the collection, processing, and examination of NCs to detect and measure biofilms on these devices. Sixty-three percent of 24 NCs collected from a bone marrow transplant center contained biofilms comprised primarily of coagulase-negative staphylococci.Intravenous (i.v.) access lines (6, 7) and needleless connectors (NCs) (3, 4) have been demonstrated to be a risk factor for blood stream infection (BSI). Patients who require long-term i.v. access, such as bone marrow transplant patients, are at even greater risk for BSI. To deliver i.v. fluids (e.g., medication, blood products, or nutrients), tubing must be connected to i.v. catheters that enter the patient's bloodstream. Until recently, such connections have been made using beveled, hollow-bore needles that pierce an elastic membrane on a catheter end cap. Because of the potential for needle-stick injuries and health care worker exposure to bloodborne pathogens, many institutions have recently adopted the use of NCs. Though safer for health care workers, the potential for NCs to increase BSI risk to patients has been documented in outbreaks of nosocomial BSI (3,4). In October 1998, the Centers for Disease Control and Prevention (CDC) was asked to investigate a BSI outbreak at a bone marrow transplant center in which NCs were involved. As part of this investigation, CDC assessed the ability of NCs to harbor biofilms that could act as a reservoir for BSI pathogens. It is well established that biofilms may develop on intravascular devices, including central venous catheters (CVCs) (1,2,8). Though contamination of NCs by various organisms has been observed (3, 4), the occurrence of biofilms on these devices has, to our knowledge, not been documented. The objectives of this study were (i) to develop a standardized protocol that could be used to collect, ship, and process NCs for biofilm contamination and (ii) to determine whether biofilms could develop on these devices and what organisms were the primary colonizers. Hickman NCs were collected from patients with long-term CVCs in a single bone marrow transplant center in which an outbreak of BSIs had occurred.Collection and shipment of NCs. Female-female luer couplings (no. 06359-42; Cole Parmer, Niles, Ill.) were autoclaved and then used to connect two 5-ml syringes. One of the syringes contained 5-ml of phosphate-buffered saline (PBS; pH 7.2; Life Technologies, Grand Island, N.Y.). Syringe pairs were placed into zip-lock bags and shipped on ice packs to the bone marrow transplant center for the collection of NCs. By using an aseptic technique, the NCs were removed from the patient's CVC and placed into an unused sterile Petri dish and transported to the laboratory. After the two syringes were separated, the luer coupling remained on one syringe. The smaller end of the NC was then wiped with a sterile alcohol pledget and connected to the syringe without the luer coupling. The other end o...

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