Report

Center for Biofilm Engineering An in vitro Comparison of Intraluminal Biofilm Bacteria Transfer of Three Peripheral Intravenous Valved Blood Control Catheters RYDER SCIENCE, Inc. …..medical biofilm research Ryder M1, deLancey Pulcini E2, Parker A2, and James G2 (1) Ryder Science, Escondido, CA, (2) Center for Biofilm Engineering, Montana State University-Bozeman INTRODUCTION Blood exposure that might place healthcare personnel at risk for HBV, HCV, or HIV infection is defined as a percutaneous injury (e.g. a needlestick or cut with a sharp object) or contact of mucous membrane or non-intact skin (e.g. exposed skin that is chapped, abraded, or afflicted with dermatitis) with blood, tissue, or other body fluids that are potentially infectious (MMWR, June 29, 2001/50(RR11);1-42). The insertion of peripheral intravenous catheters (PIVC) is the most common invasive procedure performed in hospitals. Preventing bloodborne pathogen exposure to healthcare workers during intravenous catheter insertion has been an ongoing challenge. The new generation of PIVCs utilizes additional internal components within the catheter hub to reduce blood exposure during insertion. These components increase the internal surface area that is thought to increase the potential for biofilm formation and subsequent transfer of bacteria into the bloodstream. This raises concern for an increased risk for bloodstream infection. METHODS At Time 96 hours, one of each catheter type was destructively sampled (including all internal components; the hub, spike, septum, etc.). Each part was vortexed, sonicated and vortexed again to detach and disaggregate the biofilm to form a bacterial suspension for viable plate counts (CFU/ml). One of each assembly type was formalin fixed for scanning electron microscopy (SEM), disassembled and imaged. Statistical analyses were performed in Minitab v.16 by fitting ANOVA models to the log densities (LDs) for each of the Flush 1, Flush 2, or Sonicant data. The ANOVA included experiment as a random effect; and time, "hub type", and the two-way interaction as fixed effects. Since the interaction between time and "hub type" was not significant, the main effects due to time and hub were directly interpreted. A weighted ANOVA model was fit to the Flush 2 data to account for heteroscedastic variance of the LDs. Tukeys multiple comparison method was used for all pairwise comparisons. Statistical significance was determined with respect to a significance level of 5% (95% confidence). PURPOSE The purpose of the this study was to compare the bacterial transfer rate and intraluminal biofilm formation between three valved blood control PIVCs in a clinically simulated in vitro model. METHODS Three PIVCs were tested: Smiths Medical ViaValve® Safety I.V. Catheter, BD Insyte™ Autoguard™ BC Shielded I.V. Catheter and the B. Braun Introcan® Safety 3 Catheter. Six experiments were run with three time points measured within each run: 0, 72 and 96 hours. Catheters were preconditioned with Bovine Serum Albumin (BSA) using a pressurized serum bottle to mimic venous insertion of the catheters. RESULTS (cont.) RESULTS ViaValve® Safety I.V. Catheter A luer fitting inserted .208” (halfway between ISO min & max) B in back of seal BD Insyte™ Autoguard™ BC Shielded I.V. Catheter A in & around plunger B In over six experimental runs, the bacterial log densities in Flush 1 and Flush 2 were compared among three catheters types: the ViaValve®, Autoguard™ BC, and Introcan® Safety 3. In 4/2012, three experiments were performed with the Autoguard™ BC and ViaValve®. Three other experiments with the Introcan® Safety 3 and ViaValve® were run in 10/2012. In each experiment, the bacterial log densities in Flush 1 and Flush 2 measured at three different time points: 0, 72 and 96 hours. in seal in tube (entire length not shown) in eyelet in hub B. Braun Introcan® Safety 3 Catheter A There were statistically significantly smaller bacterial mean log densities in Flush 1 and Flush 2 for ViaValve® compared to either the Autoguard™ BC (p-value = 0.003 and 0.001 respectively) or Introcan® Safety 3 catheters (p-value = 0.014 and 0.010 respectively). There were no differences in the bacterial mean log densities between the Autoguard™ BC or the Introcan® Safety 3 in either Flush 1 or Flush 2 (p-value = 0.17 and 0.55 respectively). In and around in tube (entire plunger length not shown) B Figure 1. Preconditioning of catheters with albumin prior to inoculation with Staphylococcus aureus. in actuator in tube (entire length not shown) For ViaValve®, the rate of decrease of the bacterial mean LD over time was small but not statistically significant in either Flush 1 (0.11/day) or Flush 2 (-0.03/day). For the Autoguard™ BC, there was a statistically significant rate of decrease over time in the Flush 1 (-0.21/day) but not Flush 2 (-0.05/day). For the Introcan® Safety 3, a statistically significant increase was found in both Flush 1 (0.71/day) and Flush 2 (0.91/day). The rates of change in bacterial mean LD over time amongst the three catheters were not significantly different in either Flush 1 (p-value ≥ 0.121) or Flush 2 (p-value ≥ 0.063). in eyelet in hub Figure 4. A. Cross-sectional schematic of the catheter hub accessed with syringe. B. Internal volume and surface area in contact with blood (in red). Blood locations used to calculate surface area and volume in Table 3. After preconditioning, a needleless connector (SmartSite®) was attached to each catheter, inoculated by flushing with 0.5 ml of a 104 colony forming units per ml (CFU/ml) of Staphylococcus aureus, and incubated at room temperature for 2 hours. Comparison for Surface Area (in2) and Biofilm Count (CFU) 4.90 Internal Surface Area (in²) 5.0 Log Sum CFU 4.02 4.5 3.84 4.0 3.5 Table 1. Yellow indicates that the mean LD of bacteria in Flush 1 through the ViaValve® catheter was statistically significantly smaller than either the mean LD for the Autoguard™ BC (p-value = 0.0030) or the mean LD for the Introcan® Safety 3 (p-value = 0.014). Count 3.0 2.5 2.0 0.96 1.5 0.73 1.0 0.34 0.5 Green indicates that the mean LD for Autoguard™ BC was not statistically significantly different than the mean LD for the Introcan® Safety 3 (p-value = 0.17). 0.0 ViaValve® Autoguard™ BC Product Introcan® Safety 3 Figure 5. Comparison of surface area (in2) and biofilm count (CFU) Figure 2. Incubation of inoculated catheters The existing needleless connectors were then replaced with new sterile connectors and unattached (planktonic) bacteria were rinsed from the fluid path using sterile Phosphate Buffered Saline (PBS). The catheters were then either sampled or subjected to simulated clinical use by flushing 17 times daily with 0.5 ml sterile nutrient and 1 flush at the end of the day with normal saline for 72 and 96 hours. The catheters were sampled with a two-step procedure. First, each catheter was flushed to recover planktonic bacteria and plated to determine CFU/ml (Flush 1). The connector surface was disinfected, sonicated in PBS to remove firmly attached (biofilm) sessile bacteria, and flushed a second time and plated (Flush 2). Table 2. Yellow indicates that the mean LD of bacteria in Flush 2 through the ViaValve® catheter was statistically significantly smaller than either the mean LD for the Autoguard™ BC (p-value < 0.0005) or the mean LD for the Introcan® Safety 3 (p-value = 0.010). Green indicates that the mean LD for the Autoguard™ BC was not statistically significantly different than the mean for the Introcan® Safety 3 (difference in means was 0.605 , p-value = 0.553). Internal Volume and Surface Area in Contact with Blood ViaValve® Autoguard™BC % difference Internal volume (in3) 0.0038 0.0082 116% (2.2 x more volume) Internal surface area (in2) 0.34 0.73 114% (2.1 x more SA) ViaValve® Introcan® 3 Internal volume (in3) 0.0038 Internal surface area (in2) 0.34 Figure 3. Flushing catheters for clinical simulated use and for planktonic and biofilm bacteria counts % difference 0.017 347% (4.5 x more volume) 0.96 182% (2.8 x more SA) Table 3. Comparison of the internal volume and surface area of the Autoguard™ BC and the Introcan Safety® 3 catheter hubs to ViaValve® Figure 6. Scanning electron microscope image of a component of a blood valve within the flow path. The large aggregates of spherical objects Indicate biofilm formation by Staphylococcus aureus. RESULTS (cont.) • There were statistically significantly smaller bacterial mean log densities in Flush 1 and Flush 2 for ViaValve® compared to either the Autoguard™ BC (p-value = 0.003 and 0.001 respectively) or Introcan® Safety 3 catheters (p-value = 0.014 and 0.010 respectively). • There were no differences in the bacterial mean log densities between the Autoguard™ BC or the Introcan® Safety 3 in either Flush 1 or Flush 2 (p-value = 0.17 and 0.55 respectively). • ViaValve® Safety I.V. Catheters had fewer bacteria on internal surfaces as well as a smaller internal surface area and less complex fluid path. • ViaValve® Safety I.V. Catheters had a statistically significant lower bacterial transfer rate as well as the lowest surface area and biofilm bacteria CFU counts which may minimize the risk of bloodstream infection.