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Chlorhexidine coating of urinary catheters and effects on biofilm formation
A D VA N C E S
PAG E 5
CHLORHEXIDINE COATING OF URINARY CATHETERS AND EFFECTS ON BIOFILM FORMATION Background Urinary tract infection (UTI) will eventually occur in 14% of all dogs during their lifetime. UTIs occur more commonly in females compared with males, because the urethra in females is relatively short and wide. Most UTIs result from ascending infection of bacteria originating from the perineal area and the gastrointestinal tract. The defense mechanisms against UTI include anatomic barriers such as urethral length, high pressure zones, normal urethral peristaltics, and unidirectional valves, as well as mucosal properties such as the presence of glycosaminoglycan and local antibodies. Urine properties (e.g., volume flow and osmolarity) and its complete elimination also are important factors in preventing and eliminating UTI. Urinary catheter placement eliminates many of the defense mechanisms, allowing introduction of bacteria into the urinary tract during the procedure. The risk is amplified if strict aseptic technique is not maintained. Half of catheterized dogs develop UTI. The incidence of catheterassociated UTI increases with age and the duration of time for which the urinary
PAG E 6
A D VA N C E S
catheter is kept in place. Each additional day is estimated to increase the incidence of UTI by 27%. UTI is the most common nosocomial infection in humans, accounting for 40% of all nosocomial infections. This is probably true also of dogs. Previous use of antibiotics, female sex, duration of hospitalization, and reason for hospitalization are all risk factors for hospital-acquired UTI in human patients. UTIs may have severe clinical consequences, because the infection may not be limited to the urinary bladder, and may ascend to the kidneys and predispose to pyelonephritis and urosepsis. This risk is further increased because many patients requiring catheterization also have other predisposing factors (e.g., recumbency), and therefore are at a greater risk for severe clinical consequences of catheterassociated UTI. Methods used to prevent urinary catheter-associated UTI in dogs have been unsuccessful. The use of systemic antibiotics does not prevent catheter-associated UTI and may even predispose to the emergence of resistant bacteria. One speculated reason for the failure of systemic antibiotic administration in preventing urinary catheter-associated UTI is biofilm formation. Bacteria within the biofilm are more protected from antibiotics. The prevention of catheter-associated UTI also is hindered by the number and types of organisms present on the urinary catheter. Because of the low efficacy of antibiotics in preventing catheter-associated UTI, antimicrobial-impregnated urinary catheters have been considered as a preventative therapy for catheter-associated UTI and biofilm formation. Antiseptic and antimicrobial agents such as silver and nitrofurazone previously have been assessed as urinary catheter-coating materials but were associated with variable success. Chlorhexidine is widely used as an antiseptic agent in veterinary medicine. It has low toxicity to mammals and a broad antimicrobial spectrum. Chlorhexidine might be an effective coating material to prevent catheter-associated UTI. The development of sustained-release varnish (SRV) of chlorhexidine for use on urinary catheters had been reported recently.
Objectives To assess the efficacy of urinary catheters coated with SRV of chlorhexidine in
decreasing catheter-associated biofilm formation in dogs.
Procedure Thirteen dogs were catheterized with urinary catheters coated with SRV of chlorhexidine (study group), and 13 dogs were catheterized with an untreated urinary catheter (control group). Presence and intensity of biofilm formation on the urinary catheters were assessed and compared between the groups by evaluating colonyfoaming units (CFU) of biofilm bacteria, and semiquantitatively using confocal laser scanning microscopy and electron microscopy.
Results None of the dogs experienced adverse effects associated with the presence of the urinary catheters. Median CFU count of biofilm bacteria at all portions of the urinary catheter was significantly lower in the study group compared with the control group. The degree of biofilm formation on the urinary catheters as evaluated by confocal laser scanning microscopy and electron microscopy was significantly lower in the study group compared with the control group. Electron microscopy examination identified crystals on some of the urinary catheters. The proportion of catheters on which crystals were observed was significantly lower on the distal part of the urinary catheters in the study group compared to the control group (16.7% versus 66.7%, respectively).
Author Conclusion Chlorhexidine SRV urinary catheters effectively decrease urinary catheterassociated biofilm formation in dogs.
Inclusions Three figures, 2 tables, 32 references.
Editor Annotation This study evaluated the use of urinary catheters coated with SRV of chlorhexidine in mitigating biofilm formation on urinary catheters in dogs. UTIs are a common disorder in dogs. Bacteria within biofilm are more protected from antibiotics. Results revealed that there was a significant decrease in biofilm bacteria on all proportions of the urinary catheters in the study group versus the control group. With electron microscopy, crystals were identified on some urinary catheters which were
significantly lower on the distal part of the urinary catheter in the study group compared to the control group. Bacterial colonization on the crystalline layer can render the coated catheters less effective, since bacteria adhere to the crystals rather than the antimicrobial-coated catheter. The conclusion was that the SRV-chlorhexidine coated catheters did decrease urinarycatheter-associated biofilm formation in dogs. If commercially available, the use of SRV of chlorhexidine on urinary catheters could significantly reduce the risk of catheter-induced UTIs in dogs. (MM) Segev G, Bankirer T, Steinberg D, et al. Evaluation of urinary catheters coated with sustainedrelease varnish of chlorhexidine in mitigating biofilm formation on urinary catheters in dogs. J Vet Intern Med 2013;27:39-46.
PAG E 5
CHLORHEXIDINE COATING OF URINARY CATHETERS AND EFFECTS ON BIOFILM FORMATION Background Urinary tract infection (UTI) will eventually occur in 14% of all dogs during their lifetime. UTIs occur more commonly in females compared with males, because the urethra in females is relatively short and wide. Most UTIs result from ascending infection of bacteria originating from the perineal area and the gastrointestinal tract. The defense mechanisms against UTI include anatomic barriers such as urethral length, high pressure zones, normal urethral peristaltics, and unidirectional valves, as well as mucosal properties such as the presence of glycosaminoglycan and local antibodies. Urine properties (e.g., volume flow and osmolarity) and its complete elimination also are important factors in preventing and eliminating UTI. Urinary catheter placement eliminates many of the defense mechanisms, allowing introduction of bacteria into the urinary tract during the procedure. The risk is amplified if strict aseptic technique is not maintained. Half of catheterized dogs develop UTI. The incidence of catheterassociated UTI increases with age and the duration of time for which the urinary
PAG E 6
A D VA N C E S
catheter is kept in place. Each additional day is estimated to increase the incidence of UTI by 27%. UTI is the most common nosocomial infection in humans, accounting for 40% of all nosocomial infections. This is probably true also of dogs. Previous use of antibiotics, female sex, duration of hospitalization, and reason for hospitalization are all risk factors for hospital-acquired UTI in human patients. UTIs may have severe clinical consequences, because the infection may not be limited to the urinary bladder, and may ascend to the kidneys and predispose to pyelonephritis and urosepsis. This risk is further increased because many patients requiring catheterization also have other predisposing factors (e.g., recumbency), and therefore are at a greater risk for severe clinical consequences of catheterassociated UTI. Methods used to prevent urinary catheter-associated UTI in dogs have been unsuccessful. The use of systemic antibiotics does not prevent catheter-associated UTI and may even predispose to the emergence of resistant bacteria. One speculated reason for the failure of systemic antibiotic administration in preventing urinary catheter-associated UTI is biofilm formation. Bacteria within the biofilm are more protected from antibiotics. The prevention of catheter-associated UTI also is hindered by the number and types of organisms present on the urinary catheter. Because of the low efficacy of antibiotics in preventing catheter-associated UTI, antimicrobial-impregnated urinary catheters have been considered as a preventative therapy for catheter-associated UTI and biofilm formation. Antiseptic and antimicrobial agents such as silver and nitrofurazone previously have been assessed as urinary catheter-coating materials but were associated with variable success. Chlorhexidine is widely used as an antiseptic agent in veterinary medicine. It has low toxicity to mammals and a broad antimicrobial spectrum. Chlorhexidine might be an effective coating material to prevent catheter-associated UTI. The development of sustained-release varnish (SRV) of chlorhexidine for use on urinary catheters had been reported recently.
Objectives To assess the efficacy of urinary catheters coated with SRV of chlorhexidine in
decreasing catheter-associated biofilm formation in dogs.
Procedure Thirteen dogs were catheterized with urinary catheters coated with SRV of chlorhexidine (study group), and 13 dogs were catheterized with an untreated urinary catheter (control group). Presence and intensity of biofilm formation on the urinary catheters were assessed and compared between the groups by evaluating colonyfoaming units (CFU) of biofilm bacteria, and semiquantitatively using confocal laser scanning microscopy and electron microscopy.
Results None of the dogs experienced adverse effects associated with the presence of the urinary catheters. Median CFU count of biofilm bacteria at all portions of the urinary catheter was significantly lower in the study group compared with the control group. The degree of biofilm formation on the urinary catheters as evaluated by confocal laser scanning microscopy and electron microscopy was significantly lower in the study group compared with the control group. Electron microscopy examination identified crystals on some of the urinary catheters. The proportion of catheters on which crystals were observed was significantly lower on the distal part of the urinary catheters in the study group compared to the control group (16.7% versus 66.7%, respectively).
Author Conclusion Chlorhexidine SRV urinary catheters effectively decrease urinary catheterassociated biofilm formation in dogs.
Inclusions Three figures, 2 tables, 32 references.
Editor Annotation This study evaluated the use of urinary catheters coated with SRV of chlorhexidine in mitigating biofilm formation on urinary catheters in dogs. UTIs are a common disorder in dogs. Bacteria within biofilm are more protected from antibiotics. Results revealed that there was a significant decrease in biofilm bacteria on all proportions of the urinary catheters in the study group versus the control group. With electron microscopy, crystals were identified on some urinary catheters which were
significantly lower on the distal part of the urinary catheter in the study group compared to the control group. Bacterial colonization on the crystalline layer can render the coated catheters less effective, since bacteria adhere to the crystals rather than the antimicrobial-coated catheter. The conclusion was that the SRV-chlorhexidine coated catheters did decrease urinarycatheter-associated biofilm formation in dogs. If commercially available, the use of SRV of chlorhexidine on urinary catheters could significantly reduce the risk of catheter-induced UTIs in dogs. (MM) Segev G, Bankirer T, Steinberg D, et al. Evaluation of urinary catheters coated with sustainedrelease varnish of chlorhexidine in mitigating biofilm formation on urinary catheters in dogs. J Vet Intern Med 2013;27:39-46.