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
a National Science Foundation Engineering Research Center in the MSU College of Engineering
METHODS
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 nonintact 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.
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.
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).
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.
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 the ViaValve™. Three other
experiments with the Introcan® Safety 3 and the
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.
RESULTS
ViaValve™ Safety I.V. Catheter
A
luer fitting inserted .208” (halfway
between ISO min & max)
4.90
Internal Surface Area (in²)
5.0
Log Sum CFU
4.5
4.02
3.84
4.0
3.5
3.0
B
in back of seal
in actuator
in tube (entire
length not shown)
2.5
2.0
1.5
0.96
0.73
There were statistically significantly smaller bacterial
mean log densities in Flush 1 and Flush 2 for the
ViaValve™ compared to either the Autoguard™ BC (pvalue = 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).
For the 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).
Flush 1
Mean Log Repeatability
Catheter
(CFU/ml)
SD
ViaValve™
0.8751
1.69
Autoguard™ BC
1.223
0.4216
Braun Introcan® Safety 3
3.8451
0.86
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.
Figure 1. Preconditioning of catheters with albumin
prior to inoculation with Staphylococcus aureus.
RESULTS
1.0
METHODS
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
Count
INTRODUCTION
Figure 3. Flushing catheters for clinical simulated
use and for planktonic and biofilm bacteria counts
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 and 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).
BD Insyte™ Autoguard™ BC Shielded I.V. Catheter
0.0
A
Figure 5. Comparison of surface area (in2) and biofilm
count (CFU)
in & around
plunger
B
Green indicates that the mean LD for Autoguard™ BC
was not statistically significantly different than the
mean for the Introcan® Safety 3 (p-value = 0.17).
Flush 2
Significant
Groups
A
B
B
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).
in seal
ViaValve™
Autoguard™ BC
Introcan® Safety 3
Product
in tube (entire
length not shown)
in eyelet
in hub
B. Braun Introcan® Safety 3 Catheter
A
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.
Significant
Groups
A
B
B
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).
Mean Log Repeatability
Catheter
(CFU/ml)
SD
ViaValve™
0.9168
2.0065
Autoguard™ BC
2.2979
0.2882
Braun Introcan® Safety 3
4.332
0.776
0.34
0.5
In and around
plunger
B
in tube (entire
length not shown)
 There were statistically significantly smaller
bacterial mean log densities in Flush 1 and
Flush 2 for the ViaValve™ compared to either
the Autoguard™ BC (p-value = 0.003 and 0.001
respectively) or Introcan® Safety 3 catheters (pvalue = 0.014 and 0.010 respectively).
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.
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
CONCLUSIONS
% 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 the ViaValve™
 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 (pvalue = 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.
This project was funded by Smiths Medical Inc.
This information was provided under a Montana State University Testing
Services Agreement and is not intended to endorse or recommend any
product or service.
June 2013