Techniques, Materials, and Devices Experimental Study of Hub Contamination: Effect of a New Connection Device: The I System YOSHIFUMI INOUE, MD*; RIICHIRO NEZU, MD*; HIKARU MATSUDA, MD*; MAKOTO FUJII, MD†; SUMIO NAKAI, MD†; MASAFUMI WASA, MD†; YOJI TAKAGI, MD†; AND AKIRA OKADA, MD† From the *First
Department of Surgery and
the
†Department of Pediatric Surgery,
ABSTRACT. Experimental studies of hub contamination of intravenous catheters were done comparing the standard connection method (Luer-Lock connector) with a newly invented connection method (I system). Immersion of the connection
Osaka
University Medical School, Osaka, Japan
bacterial contamination was seen with the Luer-Lock connector, but no bacterial contamination occurred with the I system. These experiments suggest that the use of Luer-Lock connectors is associated with a high risk of bacterial contamination during tubing change, but the I system can prevent contamination during tubing change, which cannot be avoided with Luer-Lock connector. (Journal of Enteral and Parenteral Nutrition 16: 178-180, 1992)
sites into a bacteria-containing solution showed no bacterial contamination of the medium in any tubing. The second experiment investigated whether bacterial contamination would occur during a tubing change procedure. A high incidence of
as an
withstand needle without
sepsis (CRS). Bacteria reach the blood by migrating along the catheter subcutaneous tract.l°2 Another possi-
Experimental Design
The catheter exit site commonly has been considered entry site for bacteria causing catheter-related
can
ble source of CRS is bacterial contamination of the catheter hub.3°4 The hub as a source of infection has been supported by reports of outbreaks of Staphylococcus epidermadis infections whenever there are frequent breaks in aseptic technique handling central venous catheters and infusion lines or solution leaks at the catheter hub.55
more
than 100 insertions of
a
22-gauge
leaking.
microorganism used in all tests was Serratia ATCC no. 14756 (Institute for Fermentation, Osaka, Japan). This is one of the standard microorganisms used to examine the bacterial permeability of these kinds of instruments because it is a small (0.5 x 0.5 to 1 ~m), free-living rod, and is motile with flagella. Moreover, the use of three-way stopcocks, a good source After 1 week of culture, the culture solution was diluted for entry of bacteria, is known to increase the risk of X with II The
marcescens,
liquid thioglycollate medium to 1.0 106 colonyforming units (CFU)/mL, referring to the experiment of Gibilisco et al.’ Bacterial contamination was compared
CRS.66
This study compares the incidence of solution contamination via the catheter hub when a Luer-Lock connector system is used against that using a newly designed connector system based on a completely closed access.
between the I system and the conventional Luer-Lock connector devices. Two 40-cm extension tubings (Nissho, Japan) were connected with an I system or Luer-Lock connector. The tubings were aseptically filled with liquid thioglycollate medium II, and the following experiments
MATERIALS AND METHODS
performed. Experiment 1: Bacterial permeability. The connection
were
Structure and Use of the New Device The
newly designed system consists of two pieces: a a latex-end injection plug with a male screw (I
cap with
plug) and a needle with a Luer-Lock female screw on the end of an extension tube or infusion line (I set) (Fig. 1). This new system is used as follows: (1) The I plug is applied to the hub at the time of catheter insertion. (2) Before the infusion line is connected, the latex end of the I plug is disinfected. (3) The needle of the I set is inserted into the latex end of the I plug. (4) The I plug and I set are fixed together by securing the Luer-Lock (Fig. 2). The latex of the I plug is 7 mm in thickness and Reprint requests: Dr Akira Okada, Department of Pediatric Surgery, Osaka University Medical School, 1-1-50 Fukushima, Fukushima-ku, Osaka 553, Japan.
site of the I system and Luer-Lock connector was immersed in the bacterial solution containing 1.0 X 106 CFU/mL S marcescens for 10 seconds, 10 minutes, or 8 days. Twenty tubings at each immersion time were examined. After immersion, the medium in the tubings was withdrawn and incubated at 31 ± 1°C for 7 days and bacterial growth was evaluated. Experiment 2: Bacterial contamination associated with a tubing change procedure. A 1-mL syringe and 27 gauge needle was used to deliver 2 to 3 drops of 1.0 X 106 CFU/mL S marcescens on the surface of the I system and Luer-Lock connection site. The approximate volume of a drop from a 27-gauge needle was 4.4 X 10-3 mL. Two to 3 drops were inoculated, so the approximate number of microorganisms inoculated was estimated to be 1.0 X 10’ CFU. After the inoculum dried, the connection site
178 Downloaded from pen.sagepub.com at UNIV OF MICHIGAN on June 15, 2015
179 ‘TABLE 1
Contamination rate
(experiment 2)
FIG. 1. Structure of the I system.
CH, chlorhexidine gluconate; PI, povidone iodide. * p < .01 us I system, x2 analysis.
Experiment 2 Bacterial growth in the medium of the tubing in the Luer-Lock connector group was observed in 9 of the 20 (45%) disinfected with CH, and in 12 of the 20 (60%) with PI (21 in 40 overall) (Table 1). In the I system group, no bacterial growth was observed in any tubings disinfected with either CH or PI (0 in 40 overall). The difference in contamination between the Luer-Lock connector and the I system was highly significant ( p < .01
by X2 analysis). FIG. 2. Method for
using the I system. DISCUSSION
FIG. 3. Experimental design: Experiment 2.
disinfected as follows (Fig. 3). For the Luer-Lock connector, the surface of the connection was swabbed for 1 minute with chlorhexidine gluconate (CH) or povidone iodide (PI), and the tubings were disconnected. The hub was disinfected again with CH or PI for 1 minute and a new tubing was connected. For the I system, the I set was disconnected without disinfection. The latex end of the I plug was swabbed with CH or PI for 1 minute and a new I set tubing was connected. The newly attached tubings were filled with sterile liquid thioglycollate medium II. The medium in the tubing was incubated in the same manner as in experiment 1. Forty experiments were performed with each connector : Luer-Lock, 20 with CH, 20 with PI; I system, 20 with CH, 20 with PI.
was
RESULTS
Experiment
1
No bacterial growth of the medium was observed in tubings with either type of connector after immersion for 10 seconds, 10 minutes, or 8 days.
any
The hub hypothesis’ of CRS is in part based on the observation that there is often a lack of correlation between the patient’s skin flora and the bacteria found on an infected catheter. In addition, catheter tunneling to establish a protective subcutaneous tract does not dramatically reduce the incidence of CRS. In a study by Von Meyenfeldt et al,9 the CRS incidence was 6.6% in the direct insertion group and 6.3% in the subcutaneous tunneled group. Holm and Wretlind’° reported that the incidence of CRS was reduced by prophylactic flambage of the connection site and recommended daily sterilization with heat treatment. Stotter et all’ reported that a new connection shield containing PI-impregnated foam reduced the incidence of CRS from 39% to 8%. They concluded that aseptic care of the catheter junction was vital to the avoidance of CRS. Finally, the importance of the hub as a portal of entry is supported by the experience with double- and triple-lumen catheters. Pemberton et all’ compared the incidence of CRS between single-lumen catheters (SLC) and triple-lumen catheters (TLC). The TLC had an increased CRS incidence (19%) compared with the SLC (3%), and there was no difference in infected catheter exit sites (5% for TLC and 3% for SLC). Powell et a113 compared the risk of infection accompanying the use of bilateral subclavian single lumen catheters and one double-lumen catheter. Total catheter-related infections were identical in both catheters. They proposed that because the number of hubs was the same in both groups, the lack of difference in the incidence of CRS was reasonable. The results of experiment 1 suggest that bacteria cannot break through a connection site of either the LuerLock or I system type. Experiment 2, however, shows a high probability of bacterial contamination with the Luer-Lock connection method during manipulation, which was prevented with the new I system. We believe this improved result was due to the maintenance of a
Downloaded from pen.sagepub.com at UNIV OF MICHIGAN on June 15, 2015
180
closed system when tubings is unique to the I system.
were
changed,
a
feature that 4. 5.
CONCLUSION 6.
The standard Luer-Lock connection exposes the patient to a significant risk of bacterial contamination during tubing changes that can be avoided with the newly designed I system connection method. To prove the effectiveness of improved hub care with the I system in reducing CRS in patients, prospective randomized patient studies need to be conducted. REFERENCES
8:668—672, 1984 Sitges-Serra A, Linares J: Tunnels do not protect against venouscatheter- related sepsis. Lancet 2:459-460, 1984 Deitel M, Krajden S, Saldnha CF, et al: An outbreak of Staphylococcus epidermidis septicemia. JPEN 7:569-572, 1983 Dryden GE, Brickler J: Stopcock contamination. Anesth Analg 58:141—142, 1979
7. Gibilisco PA, Lopez GA, Appleman MD, et al: In vitro contamination of "Piggyback/Heparin Lock" assemblies: Prevention of contamination with a closed, positive locking device (Click-Lock). JPEN 10:431—434, 1986 8. Sitges-Serra A, Linares J, Garau J: Catheter sepsis: The clue is the hub. Surgery 97:355-357, 1985 9. Von Meyenfeldt M, Stapert J, DeJohn P, et al: TPN catheter sepsis: Lack of effect of subcutaneous tunneling of CVC catheters on sepsis rate. JPEN 5:514-517, 1980 10. Holm I, Wretlind A: Prophylaxis against infection and septicemia in parenteral nutrition via central venous catheter. Acta Chir
Scand 141:173—181, 1975 1.
Snydman DR, Gorbea HF, Pober BR, et al: Predictive value of surveillance skin cultures in total parenteral nutrition related
infection. Lancet 2:1385-1388, 1982 DG, Weise CE, Sarafin HW: A semiquantitative culture method for identifying intravenous-catheter related infection. N Engl J Med 296:1305—1309, 1977 3. Sitges-Serra A, Puig P, Linares J, et al: Hub colonization as the initial step in an outbreak of catheter-related sepsis due to coagulase-negative staphylococci during parenteral nutrition. JPEN 2. Maki
11. Stotter AT, Ward H, Waterfield AH, et al: Junctional care: The key to prevention of catheter sepsis in intravenous feeding. JPEN
11:159—162, 1987 LB, Lyman B, Lander V, et al: Sepsis from triple- vs single-lumen catheters during total parenteral nutrition in surgical or critically ill patients. Arch Surg 121:591-594, 1986 13. Powell C, Fabri PJ, Kudsk KA: Risk of infection accompanying the use of single-lumen vs double-lumen subclavian catheters: A prospective randomized study. JPEN 12:127-129, 1982 12. Pemberton
Downloaded from pen.sagepub.com at UNIV OF MICHIGAN on June 15, 2015
Department of Surgery and
the
†Department of Pediatric Surgery,
ABSTRACT. Experimental studies of hub contamination of intravenous catheters were done comparing the standard connection method (Luer-Lock connector) with a newly invented connection method (I system). Immersion of the connection
Osaka
University Medical School, Osaka, Japan
bacterial contamination was seen with the Luer-Lock connector, but no bacterial contamination occurred with the I system. These experiments suggest that the use of Luer-Lock connectors is associated with a high risk of bacterial contamination during tubing change, but the I system can prevent contamination during tubing change, which cannot be avoided with Luer-Lock connector. (Journal of Enteral and Parenteral Nutrition 16: 178-180, 1992)
sites into a bacteria-containing solution showed no bacterial contamination of the medium in any tubing. The second experiment investigated whether bacterial contamination would occur during a tubing change procedure. A high incidence of
as an
withstand needle without
sepsis (CRS). Bacteria reach the blood by migrating along the catheter subcutaneous tract.l°2 Another possi-
Experimental Design
The catheter exit site commonly has been considered entry site for bacteria causing catheter-related
can
ble source of CRS is bacterial contamination of the catheter hub.3°4 The hub as a source of infection has been supported by reports of outbreaks of Staphylococcus epidermadis infections whenever there are frequent breaks in aseptic technique handling central venous catheters and infusion lines or solution leaks at the catheter hub.55
more
than 100 insertions of
a
22-gauge
leaking.
microorganism used in all tests was Serratia ATCC no. 14756 (Institute for Fermentation, Osaka, Japan). This is one of the standard microorganisms used to examine the bacterial permeability of these kinds of instruments because it is a small (0.5 x 0.5 to 1 ~m), free-living rod, and is motile with flagella. Moreover, the use of three-way stopcocks, a good source After 1 week of culture, the culture solution was diluted for entry of bacteria, is known to increase the risk of X with II The
marcescens,
liquid thioglycollate medium to 1.0 106 colonyforming units (CFU)/mL, referring to the experiment of Gibilisco et al.’ Bacterial contamination was compared
CRS.66
This study compares the incidence of solution contamination via the catheter hub when a Luer-Lock connector system is used against that using a newly designed connector system based on a completely closed access.
between the I system and the conventional Luer-Lock connector devices. Two 40-cm extension tubings (Nissho, Japan) were connected with an I system or Luer-Lock connector. The tubings were aseptically filled with liquid thioglycollate medium II, and the following experiments
MATERIALS AND METHODS
performed. Experiment 1: Bacterial permeability. The connection
were
Structure and Use of the New Device The
newly designed system consists of two pieces: a a latex-end injection plug with a male screw (I
cap with
plug) and a needle with a Luer-Lock female screw on the end of an extension tube or infusion line (I set) (Fig. 1). This new system is used as follows: (1) The I plug is applied to the hub at the time of catheter insertion. (2) Before the infusion line is connected, the latex end of the I plug is disinfected. (3) The needle of the I set is inserted into the latex end of the I plug. (4) The I plug and I set are fixed together by securing the Luer-Lock (Fig. 2). The latex of the I plug is 7 mm in thickness and Reprint requests: Dr Akira Okada, Department of Pediatric Surgery, Osaka University Medical School, 1-1-50 Fukushima, Fukushima-ku, Osaka 553, Japan.
site of the I system and Luer-Lock connector was immersed in the bacterial solution containing 1.0 X 106 CFU/mL S marcescens for 10 seconds, 10 minutes, or 8 days. Twenty tubings at each immersion time were examined. After immersion, the medium in the tubings was withdrawn and incubated at 31 ± 1°C for 7 days and bacterial growth was evaluated. Experiment 2: Bacterial contamination associated with a tubing change procedure. A 1-mL syringe and 27 gauge needle was used to deliver 2 to 3 drops of 1.0 X 106 CFU/mL S marcescens on the surface of the I system and Luer-Lock connection site. The approximate volume of a drop from a 27-gauge needle was 4.4 X 10-3 mL. Two to 3 drops were inoculated, so the approximate number of microorganisms inoculated was estimated to be 1.0 X 10’ CFU. After the inoculum dried, the connection site
178 Downloaded from pen.sagepub.com at UNIV OF MICHIGAN on June 15, 2015
179 ‘TABLE 1
Contamination rate
(experiment 2)
FIG. 1. Structure of the I system.
CH, chlorhexidine gluconate; PI, povidone iodide. * p < .01 us I system, x2 analysis.
Experiment 2 Bacterial growth in the medium of the tubing in the Luer-Lock connector group was observed in 9 of the 20 (45%) disinfected with CH, and in 12 of the 20 (60%) with PI (21 in 40 overall) (Table 1). In the I system group, no bacterial growth was observed in any tubings disinfected with either CH or PI (0 in 40 overall). The difference in contamination between the Luer-Lock connector and the I system was highly significant ( p < .01
by X2 analysis). FIG. 2. Method for
using the I system. DISCUSSION
FIG. 3. Experimental design: Experiment 2.
disinfected as follows (Fig. 3). For the Luer-Lock connector, the surface of the connection was swabbed for 1 minute with chlorhexidine gluconate (CH) or povidone iodide (PI), and the tubings were disconnected. The hub was disinfected again with CH or PI for 1 minute and a new tubing was connected. For the I system, the I set was disconnected without disinfection. The latex end of the I plug was swabbed with CH or PI for 1 minute and a new I set tubing was connected. The newly attached tubings were filled with sterile liquid thioglycollate medium II. The medium in the tubing was incubated in the same manner as in experiment 1. Forty experiments were performed with each connector : Luer-Lock, 20 with CH, 20 with PI; I system, 20 with CH, 20 with PI.
was
RESULTS
Experiment
1
No bacterial growth of the medium was observed in tubings with either type of connector after immersion for 10 seconds, 10 minutes, or 8 days.
any
The hub hypothesis’ of CRS is in part based on the observation that there is often a lack of correlation between the patient’s skin flora and the bacteria found on an infected catheter. In addition, catheter tunneling to establish a protective subcutaneous tract does not dramatically reduce the incidence of CRS. In a study by Von Meyenfeldt et al,9 the CRS incidence was 6.6% in the direct insertion group and 6.3% in the subcutaneous tunneled group. Holm and Wretlind’° reported that the incidence of CRS was reduced by prophylactic flambage of the connection site and recommended daily sterilization with heat treatment. Stotter et all’ reported that a new connection shield containing PI-impregnated foam reduced the incidence of CRS from 39% to 8%. They concluded that aseptic care of the catheter junction was vital to the avoidance of CRS. Finally, the importance of the hub as a portal of entry is supported by the experience with double- and triple-lumen catheters. Pemberton et all’ compared the incidence of CRS between single-lumen catheters (SLC) and triple-lumen catheters (TLC). The TLC had an increased CRS incidence (19%) compared with the SLC (3%), and there was no difference in infected catheter exit sites (5% for TLC and 3% for SLC). Powell et a113 compared the risk of infection accompanying the use of bilateral subclavian single lumen catheters and one double-lumen catheter. Total catheter-related infections were identical in both catheters. They proposed that because the number of hubs was the same in both groups, the lack of difference in the incidence of CRS was reasonable. The results of experiment 1 suggest that bacteria cannot break through a connection site of either the LuerLock or I system type. Experiment 2, however, shows a high probability of bacterial contamination with the Luer-Lock connection method during manipulation, which was prevented with the new I system. We believe this improved result was due to the maintenance of a
Downloaded from pen.sagepub.com at UNIV OF MICHIGAN on June 15, 2015
180
closed system when tubings is unique to the I system.
were
changed,
a
feature that 4. 5.
CONCLUSION 6.
The standard Luer-Lock connection exposes the patient to a significant risk of bacterial contamination during tubing changes that can be avoided with the newly designed I system connection method. To prove the effectiveness of improved hub care with the I system in reducing CRS in patients, prospective randomized patient studies need to be conducted. REFERENCES
8:668—672, 1984 Sitges-Serra A, Linares J: Tunnels do not protect against venouscatheter- related sepsis. Lancet 2:459-460, 1984 Deitel M, Krajden S, Saldnha CF, et al: An outbreak of Staphylococcus epidermidis septicemia. JPEN 7:569-572, 1983 Dryden GE, Brickler J: Stopcock contamination. Anesth Analg 58:141—142, 1979
7. Gibilisco PA, Lopez GA, Appleman MD, et al: In vitro contamination of "Piggyback/Heparin Lock" assemblies: Prevention of contamination with a closed, positive locking device (Click-Lock). JPEN 10:431—434, 1986 8. Sitges-Serra A, Linares J, Garau J: Catheter sepsis: The clue is the hub. Surgery 97:355-357, 1985 9. Von Meyenfeldt M, Stapert J, DeJohn P, et al: TPN catheter sepsis: Lack of effect of subcutaneous tunneling of CVC catheters on sepsis rate. JPEN 5:514-517, 1980 10. Holm I, Wretlind A: Prophylaxis against infection and septicemia in parenteral nutrition via central venous catheter. Acta Chir
Scand 141:173—181, 1975 1.
Snydman DR, Gorbea HF, Pober BR, et al: Predictive value of surveillance skin cultures in total parenteral nutrition related
infection. Lancet 2:1385-1388, 1982 DG, Weise CE, Sarafin HW: A semiquantitative culture method for identifying intravenous-catheter related infection. N Engl J Med 296:1305—1309, 1977 3. Sitges-Serra A, Puig P, Linares J, et al: Hub colonization as the initial step in an outbreak of catheter-related sepsis due to coagulase-negative staphylococci during parenteral nutrition. JPEN 2. Maki
11. Stotter AT, Ward H, Waterfield AH, et al: Junctional care: The key to prevention of catheter sepsis in intravenous feeding. JPEN
11:159—162, 1987 LB, Lyman B, Lander V, et al: Sepsis from triple- vs single-lumen catheters during total parenteral nutrition in surgical or critically ill patients. Arch Surg 121:591-594, 1986 13. Powell C, Fabri PJ, Kudsk KA: Risk of infection accompanying the use of single-lumen vs double-lumen subclavian catheters: A prospective randomized study. JPEN 12:127-129, 1982 12. Pemberton
Downloaded from pen.sagepub.com at UNIV OF MICHIGAN on June 15, 2015
