Center for
Biofilm
Engineering
Evaluation of Fluid Path Colonization in Needle-Free Connectors and Biofilm
Formation in Central Venous Catheters
E. deLancey Pulcini1, A.E. Parker1, M. Ryder2, G. James1
(1) Center for Biofilm Engineering Montana State University-Bozeman (2) Ryder Science Inc. Escondido, CA
Poster#275
ASM Biofilms
2012
a National Science Foundation Engineering Research Center in the MSU College of Engineering
METHODS
In the United States, approximately 80,000 catheterrelated bloodstream infections (CRBSI) occur in ICUs
annually1 and approximately 250,000 CRBSIs occur
hospital wide annually2.
The connector septum was inoculated twice a day with 106
CFU Staphylococcus aureus ATCC # 6538. The inoculated
connector was allowed to dry for 30 minutes and then was
attached to a catheter.
Needle-free connectors collected from patients have been
shown to contain bacterial biofilms3. Previous studies
have shown bacterial contamination and bacterial transfer
through needle-free connectors4.
Each connector-catheter set was flushed with 3.0 ml sterile
saline which was collected and plated (First Flush). The
catheter-connector sets were sterile saline (SS) flushed
twice more, locked with sterile Brain Heart Infusion Broth
(BHI) for 1 hour and SS flushed three more times. The last
flush was also collected and plated (Last Flush).
The objective of this study was to determine if there was a
difference, by connector type, in the colonization of the
fluid pathway in inoculated needle-free connectors and in
attached vascular catheters after repeated flushing with no
disinfection.
METHODS
A total of 8 needle-free connectors were evaluated in this
study. Three of each connector type were evaluated in
three replicate runs (n=9) with the MicroClave® (ICU
Medical Inc.) serving as the matched control for every run
(n =27).
MicroClave® (ICU Medical Inc.)
Statistical analysis was performed using mixed effect
ANOVA analysis and Tukey’s tests to determine significant
mean differences of bacteria in the flush, hub, catheter
segment or connector amongst the different needle-free
connectors. A multiple linear regression was used to
determine if any combination of the variables measured in
the study could significantly predict the log density of
bacteria either in the flush.
SmartSite® (CareFusion Corp.)
Microclave
SmartSite
ClearLink
Invision
Maximus
Q-syte
One-Link
Bionector
6.5
6.4
6.3
6.2
6.1
6.0
5.9
0
1
2
3
4
MicroClave
One-Link
ClearLink
Maximus
SmartSite
Q-syte
Bionector
Invision
Least Square Mean
(Log CFU/hub)
1.594
1.694
1.853
2.101
2.095
2.925
2.905
3.14
Significant Groups
A
A B
A B C
A B C D
B C D E
C
E F
D E F
D
F
Day
The least square mean for the destructive sampling of the
catheter hubs was calculated for Days 3 and 4 combined. The
color scheme indicates the significant groups (p< 0.05)
The mean log densities (LD) of the surface inoculations
averaged across all days were statistically equivalent as
long as mean differences as large as 0.37 were assumed
to be negligible. For each day individually, the mean LD of
the surface inoculum (averaged across the two
inoculations for each day) were shown to be statistically
equivalent as long as mean differences as large as 0.53
were assumed to be negligible.
Daily least square mean bacterial densities in the flush
5.5
Connector
Microclave
SmartSite
ClearLink
Invision
Maximus
Q-Syte
One-Link
Bionector
5.0
4.5
3.5
Catheter Segment Days 3 and 4
Least Square Mean
(Log CFU/segment)
Significant Groups
MicroClave
0.845
A
One-Link
1.14
A
B
ClearLink
1.194
A
B
Maximus
1.426
A
B
Invision
1.541
B
SmartSite
1.58
B
Bionector
1.646
B
Q-Syte
1.797
B
The least square mean for the destructive sampling of the
catheter segments was calculated for Days 3 and 4 combined.
The color scheme indicates the significant groups (p< 0.05).
0
1
2
3
4
Invision® (RyMed Technologies Inc.)
Maximus® (MaxPlus) (CareFusion Inc.)
Figure 1. The connector-catheter sets were placed in
conical vials between flushes. The technician is flushing
one of the connector-catheter sets.
One-Link® (Baxter Inc.)
Bionector® (Vygon Inc.)
Figure 2. For surface inoculation controls, the connector
was swabbed in order to determine the concentration of
bacteria on the connector septum.
The least square mean for all flushes for all days was
calculated. The color scheme indicates the significant
groups (p< 0.05).
The mean LD of bacteria in the hub for the MicroClave
connector was significantly smaller than the SmartSite, Invision,
Q-Syte and Bionector connectors.
The mean LD of bacteria in the catheter segment for the
MicroClave was significantly smaller that the SmartSite, Invision,
Q-Syte and Bionector connectors.
The mean LD of bacteria in the MicroClave connector was
significantly smaller than the SmartSite, Invision, and Bionector
connectors.
The daily mean LD of bacteria attached in the hub and in the
connector were better predictors of the daily mean LD of
bacteria recovered from the flush than the mean LD of bacteria
in the catheter segment.
Catheter Tubing
2. Maki DG, Kluger DM, Crnich CJ. The risk of
bloodstream infection in adults with different intravascular
devices: a systematic review of 200 published prospective
studies. Mayo Clin Proc 2006. 81:1159–1171
Mean Flush for all Days and all Flushes
Q-Syte (BD and Co.)
The MicroClave connector had the significantly smallest mean
log density (LD) of bacteria in the flush compared to any of the
other connector types (p<0.0005).
1. Mermel LA. Prevention of intravascular catheter-related
infections. (Erratum: Ann Intern Med 133:395, 2000). Ann
Intern Med 2000. 132:391–402.
The Q-Syte had the significantly largest mean LD of
bacteria in the flush compared to any of the other
connector types. (p <0.0005).
Least Square Mean
(Log CFU/flush)
Significant Groups
Microclave
3.128
A
Bionector
3.637
B
One-Link
3.907
B C
ClearLink
4.176
C D
SmartSite
4.176
C D
Invision
4.368
D E
Maximus
4.573
E
Q-Syte
5.276
F
The least square mean for the destructive sampling of the
connectors was calculated for Days 3 and 4 combined.
The color scheme indicates the significant groups
(p< 0.05).
REFERENCES
Day
The mean log density (LD) in the daily flush for the
MicroClave connector was significantly smaller compared
to any of the other connector types tested (p<0.0005).
Connector Days 3 and 4
Least Square Mean
(CFU/connector)
Significant Groups
MicroClave
2.544
A
One-Link
2.592
A
B
ClearLink
3.005
A
B
C
SmartSite
3.274
B
C
Maximus
3.902
A
C
Q-Syte
3.936
A
C
Bionector
3.481
C
Invision
3.79
C
CONCLUSIONS
4.0
3.0
ClearLink® (Baxter Inc.)
RESULTS
Hub Days 3 and 4
6.6
The connector-catheter sets were inoculated a second
time each day after the 6th sterile saline flush followed by a
second round of flushing, plating and locks for a total of 18
connector accesses daily, considered to be a routine
number of accesses in an intensive care unit.
The entire procedure, inoculation and flushing, was
repeated each day for 5 days. On Days 4 and 5, two
connector-catheter sets for each connector type were
destructively sampled for bacterial counts and microscopy.
RESULTS
Surface Inoculation
mean log(CFU/flush)
Needle-free connectors were developed for use with
vascular catheters to prevent needle stick injuries to health
care workers. The use of needle-free connectors has been
implicated in catheter related bloodstream infections.
RESULTS
Mean log(CFU/connector)
INTRODUCTION
Catheter Hub
Figure 3. Image of a triple lumen catheter. For this project,
single lumen catheters were used.
3. Donlan RM, Murga R, Bell M, Toscano CM, Carr JH,
Novicki TJ, Zuckerman C, Corey LC, Miller JM. Protocol
for detection of biofilms on needleless connectors
attached to central venous catheters. J Clin Microbiol.
2001. 39:750-3.
4. Ryder M, Fisher S, Hamilton G, Hamilton M, James G.
Bacterial transfer through needlefree connectors:
comparison of nine different devices. Presented at the
Society for Healthcare Epidemiology of America Annual
Scientific Meeting, April 2007
ACKNOWLEDGEMENTS
This research was funded by ICU Medical.