- Email: [email protected]
Prophylaxis of Indwelling Urethral Catheter Infection: Clinical Experience with A Modified Foley Catheter and Drainage System
0022-5347 /79/1211-0042$02.00/0 Vol. 121, January Printed in U.S.A.
THE JOURNAL OF UROWGY
Copyright © 1979 by The Williams & Wilkins Co.
PROPHYLAXIS OF INDWELLING URETHRAL CATHETER INFECTION: CLINICAL EXPERIENCE WITH A MODIFIED FOLEY CATHETER AND DRAINAGE SYSTEM HIROSHI AKIYAMA
AND
SHIGEHIRO OKAMOTO
From the Departments of Obstetrics and Gynecology, and Urology, St. Luke's International Hospital, Tokyo, Japan
ABSTRACT
With the application of the oligodynamic bactericidal property of silver ions, modification of the urinary catheter and drainage system has been found effective in the prevention of urinary tract infections owing to prolonged bladder catheterization. The newly devised catheter and open drainage system were used in 102 patients for bladder catheterization postoperatively or in those with urinary retention for periods ranging from 4 to 77 days. During the period of indwelling catheterization usually no antibiotics were administered and no patient had overt bacteriuria (more than 105 bacteria per ml.) or symptoms of urethritis. In contrast, all 20 patients in the control group who had the conventional type of indwelling catheters had bacteriuria within 4 days of catheterization. The data obtained indicate that effective prevention of urinary tract infection, which frequently is associated with indwelling urethral catheterization, can be achieved by the use of the modified catheter and drainage system. It is estimated that indwelling urethral catheterization is performed in approximately 10 to 15 per cent of hospitalized patients and about 25 per cent of these contract bacterial infection of the urinary tract. 1• 2 Despite various prophylactic measures, such as the application of antibiotic ointments or other bactericidal agents to the surface of the catheter or frequent bladder irrigation with concomitant prophylactic administration of antibiotics, the high incidence of catheterinduced urinary tract infection still remains a distressing problem. For indwelling bladder catheterization either the open or closed drainage system could be used. Recently, the closed drainage system has been preferred to delay infection in patients with long-term urethral catheterization. 3 However, about 50 per cent of the catheterized patients are infected after 10 to 13 days. 1, 2 The fact that most of these patients are given antibiotics also would result in the emergence of resistant organisms. The still high incidence of urinary tract infection in longterm catheterized patients, despite the use of the closed drainage system and the various prophylactic measures, has prompted one ofus (H. A.) to modify the catheter and devise a special connection for the drainage tube. MATERIALS AND METHODS
The modified drainage system includes the use of the socalled oligodynamic action of silver ions4 in preventing entry of infecting organisms. It consists of a Foley catheter coated in part with fine silver powder and a 6 cm. long, silver-plated connector fitted between the flared end of the catheter and the synthetic drainage tube (fig. 1). The distal end of the synthetic drainage tube is enlarged slightly in diameter and cut obliquely to prevent ascent of air bubbles from the urine collecting bag. The end of the drainage tube is inserted about 10 cm. into a disposable polyethylene bag that is taped to the side of the bed. This new open drainage system was used in 40 men and 62 women, including postoperative patients, and in those with urinary retention. The period of indwelling bladder catheterization ranged from 4 to 77 days. In none of these patients were
bacteria demonstrated in the urine before catheterization. When prolonged bladder catheterization was necessary the catheter and drainage tube were replaced at 7-day intervals. Usually, no antibiotic was given, except in 2 patients with pneumonia who received antibiotic treatment for short periods. The urine samples for culture were obtained by aspiration with a 24 gauge needle after sterilization of part of the catheter with 0.05 per cent l.6-di(4'-chlorophenyldiguanido) hexane solution. Initially, urine samples were cultured daily but since the cultures done for about a week were negative for bacteria in the first 5 cases they were done at intervals of 2 days to a week in the remaining patients. Quantitative urine cultures were done using heart infusion agar* plates that were incubated at 37C for 48 to 72 hours. An additional group of 20 patients served as controls. Bladder catheterization was done by the open drainage system with a conventional Foley catheter without concomitant antibiotic therapy. RESULTS
The ages of the 102 patients ranged from 18 to 80 years. During catheterization none had bacteriuria (defined as containing a minimum of 105 bacteria per ml.) (tables 1 and 2) or pyrexia more than 38.5C. Of the patients 62 per cent showed an increase in temperature to 38.0C 1 or 2 days after catheterization, possibly owing to the influence of the preceding operation. In no case were there symptoms or signs of acute urethritis frequently associated with indwelling catheterization, that is urethral discharge, a constant itching or burning sensation in the urethra, and reddening and edema of the external meatus. Followup 1 to 4 months after removal of the catheter revealed no significant adverse findings in any of the 102 cases studied. In contrast, all of the 20 control patients had bacteriuria within 4 days (mean 48 hours) of indwelling catheterization. Pyrexia more than 38.5C occurred in 5 cases (25 per cent), urethral discharge in 15 (75 per cent), itching or burning sensation in the urethra in 4 (20 per cent) and reddening and edema of the external meatus in 2 (10 per cent).
* DIFCO Laboratories, Box 1058A, Detroit, Michigan.
Accepted for publication April 7, 1978.
40
PROPHYLAXIS OF INDWELLING URETHRAL CATHETER INFECTION
Fm. 1. Modified catheter and drainage system. A, modified indwelling catheter for urinary drainage. When coated portion of catheter and connector come in contact with urethral mucus or urine silver ions are liberated from their surfaces. B, silver-plated connector, 6 cm. in length and 6 mm. in caliber with total inner wall surface area of approximately 1,130 square mm. C, Foley catheter with fine silver powder coating over 6 cm. area. TABLE
1. Comparison of new open drainage system with conventional open system
2. Positive bacterial urine cultures (>10 3 bacteria/ml. urine) during catheterization with the modified Foley catheter and drainage system
TABLE
Open Drainage System New (102 cases)* Duration of catheterization (days) Bacteriuria (more than 105 bacteria per ml.) Fever (38.5C or more) Symptoms of urethritis: Urethral discharge Itching or burning sensation Reddening or edema of external meatus
4 to 77 None
Conventional (20 cases) 3 to 4 20 (within 4 days, av. 2 days)
None
5
None None None
15 4 2
* Antibiotics given to only 2 patients with pneumonia.
DISCUSSION
Since Kass defined overt bacteriuria as the presence of more than 105 bacteria per ml. urine on a single quantitative urine culture his criterion generally has been adopted in the diagnosis of urinary tract infection. 5 Because of the relatively great risk of causing urinary tract infection with open catheter drainage the closed drainage system has been used in recent years. 1- 3, H, 7 However, the closed drainage system does not provide satisfactory prevention of infection, despite various prophylactic attempts with systemic or external application of antibiotics, bladder irrigation with antibiotic solution, education and training in nursing care and so forth. It also has been indicated that female patients, especially those who are debilitated and have other serious advanced diseases, are at a particularly high risk for the development of urinary tract infection. 1 • 8 Urinary tract infections may occur by entry of bacteria from any or all of the following 3 sites: 1) via urethral fluid that surrounds the catheter, 2) junction between the flared end of the catheter and drainage tube and 3) ascent of bacteria conveyed along the inner wall surface of the drainage tube from the distal end. Heavy metals, such as gold, silver and copper, exert in the form of metal ions a profound bactericidal effect. These heavy metal ions are endowed with the so-called oligodynamic activity,4 inhibiting the growth of bacteria and acting bactericidally when applied at low concentrations of 1 times 10--s M. The catheter and connector described herein have been developed to prevent catheter-induced ascending urinary tract infection by the application of this phenomenon. The newly devised catheter has a sufficient degree of flexibility and is so designed as not to evoke any adverse reactions in the tissues, mucosa or epithelium of the urinary tract. Inas-
Bacterial Count
No. CasesSex
>10'
None
Between 104 and 105
3-F
Between 103 and 104
1-M 4-F
Day of Appearance of Bacteria in Culture (culture No.)
Bacteria
23 (VI) . . . . . . E. coli 7 (III) . . . . . . Grarn-pos. bacilli plus Candida 4 (II). . . . . . . Gram-pos. cocci plus Staph. epidermidis 12 (III) . . . . . . 5 (II) . . . . . . . 15 (IV) . . . . . . 14 (III) . . . . . . 8 (III) . . . . . .
E. coli Grarn-pos. bacilli Micrococci Klebsiella Grarn-pos. bacilli
much as, anatomically, the female urethra measures 3 to 4 cm. and the male urethra 15 to 20 cm. in length, prevention of bacterial intrusion into the bladder via the catheter surface can be achieved readily by coating the part of the catheter immediately before it reaches the bladder with fine silver powder. This fine silver powder dissolves and is ionized as it comes in contact with a small amount of urethral mucous secretion or urine that descends along the catheter surface from the bladder. A metal connector, 6 cm. long and 6 mm. in caliber (total inner wall surface area approximately 1,130 mm. 2 ), plated with silver over the entire surface, is used to connect the flared end of the catheter and the drainage tube. It serves to provide an effective barrier against bacterial intrusion from the junction and also to prevent ascent of bacteria along the inner wall surface of the drainage tube. Figure 2 shows complete inhibition of bacterial growth by the bactericidal effect of the heavy metal ions on heart infusion agar plates inoculated with smears of Escherichia coli, a principal pathogen responsible for urinary tract infection. The catheter and connector were placed on the inoculated agar surface and incubated at 37C for 24 hours. The silver-coated catheter is surrounded with a zone of bacterial growth inhibition about 2 mm. wide (fig. 2, A). Figure 2, B shows inhibition of growth of E. coli in the area where the catheter had been in contact with the inoculated agar surface and figure 2, C reveals similar inhibition of bacterial growth in the area where the connector had been placed. Patients who had bacterial infections (including those of the urinary tract) preoperatively were excluded from our
42
AKIYAMA AND OKAMOTO
Fm. 2. A, portion of modified catheter (upper half coated with fine silver powder) placed on heart infusion agar plate seeded over entire surface with E. coli and incubated at 37C for 24 hours. Note zones of bacterial growth inhibition about 2 mm. wide along both sides of catheter. B, after removal of catheter inhibition of bacterial growth is seen over area of agar surface previously in contact with catheter. Note zone of inhibition also under lower half of catheter, which resulted from seepage of silver ions along catheter surface after dissolution of fine silver powder coating upper half of catheter. C, inoculated heart infusion agar plate after removal of connector following incubation under same condition as in part A. Note zone ofE. coli growth inhibition over area previously in contact with silver-plated connector.
study. No antibiotic therapy was administered during indwelling catheterization with the new device, which in all cases was performed by the open drainage system. Throughout the use of catheter drainage the lower part of the drainage tube was fixed to the side of the bed in order not to allow bacteria to ascend from the distal end (urine draining spout). All 20 patients in the control group had overt bacteriuria within 4 days (mean 48 hours) of indwelling catheterization. This result is consistent with that of reports by other investigators. 9 Also, most of these patients had symptoms of urethritis. The duration of catheterization ranged from 4 to 77 days. Antibiotic therapy was administered for pneumonia in 2 cases. The fact that none of the 102 patients had bacteriuria during the indwelling catheter drainage indicates the remarkable effectiveness of the new catheter and connector for prevention of urinary tract infections, although it is important to exercise every possible precaution in the management of indwelling catheter drainage and to provide the patient with appropriate instructions. The results of our investigation suggest the potential usefulness of the modifieq. catheter and drainage system for wide clinica~ application. REFERENCES
1. Garibaldi, R. A., Burke, J. P., Dickman, M. L. and Smith, C.
B.: Factors predisposing to bacteriuria during indwelling urethral catheterization. New Engl. J. Med., 291: 215, 1974. 2. Kunin, C. M. and McCormack, R. C.: Prevention of catheter-
3. 4. 5. 6. 7. 8. 9.
induced urinary-tract infections by sterile closed drainage. New Engl. J. Med., 274: 1155, 1966. Roberts, J.B. M., Linton, K. B., Pollard, B. R., Mitchell, J.P. and Gillespie, W. A.: Long-term catheter drainage in the male. Brit. J. Urol., 37: 63, 1965. Zimmermann, W.: Oligodynamishe Silberwirkung: ii.her der Wirkungsmechanismus. Z. Hyg., 135: 414, 1952. Kass, E. H.: Bacteriuria and the diagnosis of infections of the urinary tract. With observations on the use of methionine as a urinary antiseptic. Arch. Intern. Med., 100: 709, 1957. Desautels, R. E.: Aseptic management of catheter drainage. New Engl. J. Med., 263: 189, 1960. Thornton, G. F. and Andriole, V. T.: Bacteriuria during indwelling catheter drainage. II. Effect of a closed sterile drainage system. J.A.M.A., 214: 339, 1970. Fincke, B. G. and Friedland, G.: Prevention and management of infection in the catheterized patient. Urol. Clin. N. Amer., 3: 313, 1976. Kass, E. H.: Asymptomatic infections of the urinary tract. Trans. Ass. Amer. Phys., 69: 56, 1956. EDITORIAL COMMENT
The authors present an intriguing method to reduce urinary tract infection in patients with indwelling catheters. The colonization rate was extremely low which, coupled with the virtual absence of irritative symptoms, makes the use of this new system intriguing and :worthy of further examination. Rainer M. E. Engel 201 East 33rd Street Baltimore, Maryland
THE JOURNAL OF UROWGY
Copyright © 1979 by The Williams & Wilkins Co.
PROPHYLAXIS OF INDWELLING URETHRAL CATHETER INFECTION: CLINICAL EXPERIENCE WITH A MODIFIED FOLEY CATHETER AND DRAINAGE SYSTEM HIROSHI AKIYAMA
AND
SHIGEHIRO OKAMOTO
From the Departments of Obstetrics and Gynecology, and Urology, St. Luke's International Hospital, Tokyo, Japan
ABSTRACT
With the application of the oligodynamic bactericidal property of silver ions, modification of the urinary catheter and drainage system has been found effective in the prevention of urinary tract infections owing to prolonged bladder catheterization. The newly devised catheter and open drainage system were used in 102 patients for bladder catheterization postoperatively or in those with urinary retention for periods ranging from 4 to 77 days. During the period of indwelling catheterization usually no antibiotics were administered and no patient had overt bacteriuria (more than 105 bacteria per ml.) or symptoms of urethritis. In contrast, all 20 patients in the control group who had the conventional type of indwelling catheters had bacteriuria within 4 days of catheterization. The data obtained indicate that effective prevention of urinary tract infection, which frequently is associated with indwelling urethral catheterization, can be achieved by the use of the modified catheter and drainage system. It is estimated that indwelling urethral catheterization is performed in approximately 10 to 15 per cent of hospitalized patients and about 25 per cent of these contract bacterial infection of the urinary tract. 1• 2 Despite various prophylactic measures, such as the application of antibiotic ointments or other bactericidal agents to the surface of the catheter or frequent bladder irrigation with concomitant prophylactic administration of antibiotics, the high incidence of catheterinduced urinary tract infection still remains a distressing problem. For indwelling bladder catheterization either the open or closed drainage system could be used. Recently, the closed drainage system has been preferred to delay infection in patients with long-term urethral catheterization. 3 However, about 50 per cent of the catheterized patients are infected after 10 to 13 days. 1, 2 The fact that most of these patients are given antibiotics also would result in the emergence of resistant organisms. The still high incidence of urinary tract infection in longterm catheterized patients, despite the use of the closed drainage system and the various prophylactic measures, has prompted one ofus (H. A.) to modify the catheter and devise a special connection for the drainage tube. MATERIALS AND METHODS
The modified drainage system includes the use of the socalled oligodynamic action of silver ions4 in preventing entry of infecting organisms. It consists of a Foley catheter coated in part with fine silver powder and a 6 cm. long, silver-plated connector fitted between the flared end of the catheter and the synthetic drainage tube (fig. 1). The distal end of the synthetic drainage tube is enlarged slightly in diameter and cut obliquely to prevent ascent of air bubbles from the urine collecting bag. The end of the drainage tube is inserted about 10 cm. into a disposable polyethylene bag that is taped to the side of the bed. This new open drainage system was used in 40 men and 62 women, including postoperative patients, and in those with urinary retention. The period of indwelling bladder catheterization ranged from 4 to 77 days. In none of these patients were
bacteria demonstrated in the urine before catheterization. When prolonged bladder catheterization was necessary the catheter and drainage tube were replaced at 7-day intervals. Usually, no antibiotic was given, except in 2 patients with pneumonia who received antibiotic treatment for short periods. The urine samples for culture were obtained by aspiration with a 24 gauge needle after sterilization of part of the catheter with 0.05 per cent l.6-di(4'-chlorophenyldiguanido) hexane solution. Initially, urine samples were cultured daily but since the cultures done for about a week were negative for bacteria in the first 5 cases they were done at intervals of 2 days to a week in the remaining patients. Quantitative urine cultures were done using heart infusion agar* plates that were incubated at 37C for 48 to 72 hours. An additional group of 20 patients served as controls. Bladder catheterization was done by the open drainage system with a conventional Foley catheter without concomitant antibiotic therapy. RESULTS
The ages of the 102 patients ranged from 18 to 80 years. During catheterization none had bacteriuria (defined as containing a minimum of 105 bacteria per ml.) (tables 1 and 2) or pyrexia more than 38.5C. Of the patients 62 per cent showed an increase in temperature to 38.0C 1 or 2 days after catheterization, possibly owing to the influence of the preceding operation. In no case were there symptoms or signs of acute urethritis frequently associated with indwelling catheterization, that is urethral discharge, a constant itching or burning sensation in the urethra, and reddening and edema of the external meatus. Followup 1 to 4 months after removal of the catheter revealed no significant adverse findings in any of the 102 cases studied. In contrast, all of the 20 control patients had bacteriuria within 4 days (mean 48 hours) of indwelling catheterization. Pyrexia more than 38.5C occurred in 5 cases (25 per cent), urethral discharge in 15 (75 per cent), itching or burning sensation in the urethra in 4 (20 per cent) and reddening and edema of the external meatus in 2 (10 per cent).
* DIFCO Laboratories, Box 1058A, Detroit, Michigan.
Accepted for publication April 7, 1978.
40
PROPHYLAXIS OF INDWELLING URETHRAL CATHETER INFECTION
Fm. 1. Modified catheter and drainage system. A, modified indwelling catheter for urinary drainage. When coated portion of catheter and connector come in contact with urethral mucus or urine silver ions are liberated from their surfaces. B, silver-plated connector, 6 cm. in length and 6 mm. in caliber with total inner wall surface area of approximately 1,130 square mm. C, Foley catheter with fine silver powder coating over 6 cm. area. TABLE
1. Comparison of new open drainage system with conventional open system
2. Positive bacterial urine cultures (>10 3 bacteria/ml. urine) during catheterization with the modified Foley catheter and drainage system
TABLE
Open Drainage System New (102 cases)* Duration of catheterization (days) Bacteriuria (more than 105 bacteria per ml.) Fever (38.5C or more) Symptoms of urethritis: Urethral discharge Itching or burning sensation Reddening or edema of external meatus
4 to 77 None
Conventional (20 cases) 3 to 4 20 (within 4 days, av. 2 days)
None
5
None None None
15 4 2
* Antibiotics given to only 2 patients with pneumonia.
DISCUSSION
Since Kass defined overt bacteriuria as the presence of more than 105 bacteria per ml. urine on a single quantitative urine culture his criterion generally has been adopted in the diagnosis of urinary tract infection. 5 Because of the relatively great risk of causing urinary tract infection with open catheter drainage the closed drainage system has been used in recent years. 1- 3, H, 7 However, the closed drainage system does not provide satisfactory prevention of infection, despite various prophylactic attempts with systemic or external application of antibiotics, bladder irrigation with antibiotic solution, education and training in nursing care and so forth. It also has been indicated that female patients, especially those who are debilitated and have other serious advanced diseases, are at a particularly high risk for the development of urinary tract infection. 1 • 8 Urinary tract infections may occur by entry of bacteria from any or all of the following 3 sites: 1) via urethral fluid that surrounds the catheter, 2) junction between the flared end of the catheter and drainage tube and 3) ascent of bacteria conveyed along the inner wall surface of the drainage tube from the distal end. Heavy metals, such as gold, silver and copper, exert in the form of metal ions a profound bactericidal effect. These heavy metal ions are endowed with the so-called oligodynamic activity,4 inhibiting the growth of bacteria and acting bactericidally when applied at low concentrations of 1 times 10--s M. The catheter and connector described herein have been developed to prevent catheter-induced ascending urinary tract infection by the application of this phenomenon. The newly devised catheter has a sufficient degree of flexibility and is so designed as not to evoke any adverse reactions in the tissues, mucosa or epithelium of the urinary tract. Inas-
Bacterial Count
No. CasesSex
>10'
None
Between 104 and 105
3-F
Between 103 and 104
1-M 4-F
Day of Appearance of Bacteria in Culture (culture No.)
Bacteria
23 (VI) . . . . . . E. coli 7 (III) . . . . . . Grarn-pos. bacilli plus Candida 4 (II). . . . . . . Gram-pos. cocci plus Staph. epidermidis 12 (III) . . . . . . 5 (II) . . . . . . . 15 (IV) . . . . . . 14 (III) . . . . . . 8 (III) . . . . . .
E. coli Grarn-pos. bacilli Micrococci Klebsiella Grarn-pos. bacilli
much as, anatomically, the female urethra measures 3 to 4 cm. and the male urethra 15 to 20 cm. in length, prevention of bacterial intrusion into the bladder via the catheter surface can be achieved readily by coating the part of the catheter immediately before it reaches the bladder with fine silver powder. This fine silver powder dissolves and is ionized as it comes in contact with a small amount of urethral mucous secretion or urine that descends along the catheter surface from the bladder. A metal connector, 6 cm. long and 6 mm. in caliber (total inner wall surface area approximately 1,130 mm. 2 ), plated with silver over the entire surface, is used to connect the flared end of the catheter and the drainage tube. It serves to provide an effective barrier against bacterial intrusion from the junction and also to prevent ascent of bacteria along the inner wall surface of the drainage tube. Figure 2 shows complete inhibition of bacterial growth by the bactericidal effect of the heavy metal ions on heart infusion agar plates inoculated with smears of Escherichia coli, a principal pathogen responsible for urinary tract infection. The catheter and connector were placed on the inoculated agar surface and incubated at 37C for 24 hours. The silver-coated catheter is surrounded with a zone of bacterial growth inhibition about 2 mm. wide (fig. 2, A). Figure 2, B shows inhibition of growth of E. coli in the area where the catheter had been in contact with the inoculated agar surface and figure 2, C reveals similar inhibition of bacterial growth in the area where the connector had been placed. Patients who had bacterial infections (including those of the urinary tract) preoperatively were excluded from our
42
AKIYAMA AND OKAMOTO
Fm. 2. A, portion of modified catheter (upper half coated with fine silver powder) placed on heart infusion agar plate seeded over entire surface with E. coli and incubated at 37C for 24 hours. Note zones of bacterial growth inhibition about 2 mm. wide along both sides of catheter. B, after removal of catheter inhibition of bacterial growth is seen over area of agar surface previously in contact with catheter. Note zone of inhibition also under lower half of catheter, which resulted from seepage of silver ions along catheter surface after dissolution of fine silver powder coating upper half of catheter. C, inoculated heart infusion agar plate after removal of connector following incubation under same condition as in part A. Note zone ofE. coli growth inhibition over area previously in contact with silver-plated connector.
study. No antibiotic therapy was administered during indwelling catheterization with the new device, which in all cases was performed by the open drainage system. Throughout the use of catheter drainage the lower part of the drainage tube was fixed to the side of the bed in order not to allow bacteria to ascend from the distal end (urine draining spout). All 20 patients in the control group had overt bacteriuria within 4 days (mean 48 hours) of indwelling catheterization. This result is consistent with that of reports by other investigators. 9 Also, most of these patients had symptoms of urethritis. The duration of catheterization ranged from 4 to 77 days. Antibiotic therapy was administered for pneumonia in 2 cases. The fact that none of the 102 patients had bacteriuria during the indwelling catheter drainage indicates the remarkable effectiveness of the new catheter and connector for prevention of urinary tract infections, although it is important to exercise every possible precaution in the management of indwelling catheter drainage and to provide the patient with appropriate instructions. The results of our investigation suggest the potential usefulness of the modifieq. catheter and drainage system for wide clinica~ application. REFERENCES
1. Garibaldi, R. A., Burke, J. P., Dickman, M. L. and Smith, C.
B.: Factors predisposing to bacteriuria during indwelling urethral catheterization. New Engl. J. Med., 291: 215, 1974. 2. Kunin, C. M. and McCormack, R. C.: Prevention of catheter-
3. 4. 5. 6. 7. 8. 9.
induced urinary-tract infections by sterile closed drainage. New Engl. J. Med., 274: 1155, 1966. Roberts, J.B. M., Linton, K. B., Pollard, B. R., Mitchell, J.P. and Gillespie, W. A.: Long-term catheter drainage in the male. Brit. J. Urol., 37: 63, 1965. Zimmermann, W.: Oligodynamishe Silberwirkung: ii.her der Wirkungsmechanismus. Z. Hyg., 135: 414, 1952. Kass, E. H.: Bacteriuria and the diagnosis of infections of the urinary tract. With observations on the use of methionine as a urinary antiseptic. Arch. Intern. Med., 100: 709, 1957. Desautels, R. E.: Aseptic management of catheter drainage. New Engl. J. Med., 263: 189, 1960. Thornton, G. F. and Andriole, V. T.: Bacteriuria during indwelling catheter drainage. II. Effect of a closed sterile drainage system. J.A.M.A., 214: 339, 1970. Fincke, B. G. and Friedland, G.: Prevention and management of infection in the catheterized patient. Urol. Clin. N. Amer., 3: 313, 1976. Kass, E. H.: Asymptomatic infections of the urinary tract. Trans. Ass. Amer. Phys., 69: 56, 1956. EDITORIAL COMMENT
The authors present an intriguing method to reduce urinary tract infection in patients with indwelling catheters. The colonization rate was extremely low which, coupled with the virtual absence of irritative symptoms, makes the use of this new system intriguing and :worthy of further examination. Rainer M. E. Engel 201 East 33rd Street Baltimore, Maryland