Evaluation of polymyxin catheter lubricant and impregnated catheters

Biofilm and Foreign Body Infection the Significance to Capd-Associated Peritonitis

Microbial colonization of indwelling and implantable medical devices and prostheses is known to precede the formation of an adherent biofilm, such as is found on peritoneal catheters during CAPD. Micro-organismderived exopolysaccharides within the biofilm matrix seem to confer unique biological properties on this material, such as enhanced resistance to host defenses and antimicrobial agents. It has been proposed that an adherent biofilm is a major contributing factor in the development of foreign-body infections, including CAPD peritonitis. The source of organisms which lead to biofilm formation on peritoneal catheters is unknown but may include “seeding” at the time of surgical placement and migration from the subcutaneous tunnel via the inner cuff.

Strategies to inhibit biofilm development in industrial systems usually involve physical destruction of the biofilm and the use of biocides. Clinical success has been achieved by antimicrobial agents impregnated into or coated onto susceptible devices. Microbial adhesion to inanimate surfaces is a complex and multifaceted event. Continued research in this area, however, should increase our understanding of the factors involved underlying foreignbody infection.

Silver polymeric nanocomposites as advanced antimicrobial agents: classification, synthetic paths, applications, and perspectives

Utilization of metallic nanoparticles in various biotechnological and medical applications represents one of the most extensively investigated areas of the current materials science. These advanced applications require the appropriate chemical functionalization of the nanoparticles with organic molecules or their incorporation in suitable polymer matrices. The intensified interest in polymer nanocomposites with silver nanoparticles is due to the high antimicrobial effect of nanosilver as well as the unique characteristics of polymers which include their excellent structural uniformity, multivalency, high degree of branching, miscellaneous morphologies and architectures, and highly variable chemical composition. In this review, we explore several aspects of antimicrobial polymer silver nanocomposites, giving special focus to the critical analysis of the reported synthetic routes including their advantages, drawbacks, possible improvements, and real applicability in antibacterial and antifungal therapy. A special attention is given to "green" synthetic routes exploiting the biopolymeric matrix and to the methods allowing preparing magnetically controllable antimicrobial polymers for targeting to an active place. The controversial mechanism of the action of silver against bacteria, fungi and yeasts as well as perspectives and new applications of silver polymeric nanocomposites is also briefly discussed.

Catheter-associated urinary tract infections: diagnosis and prophylaxis

Catheter-associated urinary tract infections (CAUTI) are the commonest nosocomial infections worldwide. While they are often asymptomatic and frequently cost less than nosocomial surgical site infections or nosocomial pneumonia, they are major reservoirs of antimicrobial resistant pathogens. Numerous strategies have been devised in an attempt to reduce the incidence of CAUTI but few have proven effective. Novel technologies such as the potential use of antiseptic or antimicrobial coatings on catheters hold promise for possibly reducing these infections in the fight against antimicrobial resistance.

Prevention of catheter-related infections: the potential of a new nano-silver impregnated catheter

Contaminated or infected catheters are a major source of nosocomial infections responsible for >40% of all episodes of nosocomial sepsis in acute-care hospitals. Antibiotics as well as surface modifications with, for example, hydrogels proved to be of little value in preventing the contamination of indwelling catheters. The even distribution of 10(12-13) activated silver nanoparticles per gram in various polymers, e.g. polyurethane and silicone, results in an excellent antimicrobial activity against a broad spectrum of organisms in vitro. Substantial reduction of incrustation of these catheters was also observed. These preliminary experimental data warrant clinical studies.

Evaluation of the antimicrobial efficacy of urinary catheters impregnated with antiseptics in an in vitro urinary tract model

OBJECTIVES

To evaluate the long-term efficacy of urinary Foley catheters (latex and silicone) impregnated with (1) chlorhexidine and silver sulfadiazine (CXS) and (2) chlorhexidine, silver sulfadiazine, and triclosan (CXST) in inhibiting extra-luminal bacterial adherence and to compare their efficacy with that of silver hydrogel latex (SH) and nitrofurazone-treated silicone (NF) catheters.

DESIGN

The antimicrobial spectrum of these catheters was evaluated using a zone of inhibition assay. A novel in vitro urinary tract model was developed to study the potential in vivo efficacy of antimicrobial catheters in preventing extraluminal bacterial colonization. The "meatus" was inoculated daily with Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Enterococcus faecalis, Pseudomonas aerginosa, and Candida albicans. The "bladder" portion of the model was cultured daily to determine bacterial growth.

RESULTS

Both CXS and CXST catheters had a broader antimicrobial spectrum than SH and NF catheters. In the in vitro model, CXST latex and silicone catheters exhibited significantly better efficacy (3 to 25days) against uropathogens, compared with CXS (1 to 14 days) and control (0 to 5 days) catheters (P = .01). CXST latex catheters exhibited significantly longer protection against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa, compared with SH catheters (P = .01). CXST silicone catheters resisted colonization with Staphylococcus aureus and Staphylococcus epidermidis for a significantly longer period (23 to 24 days) than did NF catheters (9 to 11 days) (P = .01).

CONCLUSION

Catheters impregnated with synergistic combinations of chlorhexidine, silver sulfadiazine, and triclosan exhibited broad-spectrum, long-term resistance against microbial colonization on their outer surfaces.

Prophylactic efficacy of a new gentamicin-releasing urethral catheter in short-term catheterized rabbits

OBJECTIVE

To describe an indwelling urethral catheter coated with gentamicin sulphate on the inner and outer surface of the catheter, and to evaluate the efficacy and safety of this catheter in preventing catheter-associated infections in rabbits. Materials and methods Sixty rabbits were divided equally into control and experimental groups which were then subdivided equally according to the duration of catheterization (1, 3 and 5 days). Silicone-treated latex catheters were used in the control group and gentamicin-releasing catheters in the experimental group. Urine samples and surface swabs from the catheter were cultured for bacteriological assessment, and the catheter surface examined by scanning electron microscopy to structurally analyse the biofilms.

RESULTS

The gentamicin-releasing catheter reduced the incidence of bacteriuria (defined as > or = 100 c.f.u./mL) after both 3 and 5 days of catheterization (eight and 10 rabbits, respectively, for the control catheter, vs two and four rabbits for the gentamicin-releasing catheter, P < 0.05). The surfaces of the gentamicin-releasing catheter were colonized less often than those of the control catheter after both 3 and 5 days (eight and 10, respectively, for the control, vs one and four for the gentamicin-releasing catheter, P < 0.05). Scanning electron microscopy showed the formation of bacterial biofilm throughout the 3-day and 5-day control catheters, but deterioration of the bacterial biofilm was visible on the surface of the gentamicin-releasing catheters.

CONCLUSION

This new gentamicin-releasing catheter produced an antibacterial barrier which inhibited catheter-associated urinary tract infection with no toxicity for at least 5 days. These in vivo studies suggest that this new catheter may be useful for controlling infection, with systemic and local safety, in patients undergoing short-term indwelling urethral catheterization.

Catheter-associated infections in urology: possible use of silver-impregnated catheters and the Erlanger silver catheter

Indwelling urinary catheters play a very important part in urology. However, their use is accompanied by a considerable increase in the risk of nosocomial urinary tract infections. The pathophysiological cause is ascribed to pathogens that adhere to the catheter surface, proliferate and produce a biofilm. In addition to aseptic techniques, modification of the catheter material to confer antimicrobial activity plays an essential part in the prevention of catheter-related urinary tract infections. The antimicrobial efficacy of silver against gram-positive and gram-negative bacteria is well known and amply shown in vitro. The efficacy of silver-impregnated catheters is critically dependent on both the chemical structure of the incorporated silver and the way the silver has been combined with the basic catheter material. Hence, clinical studies on silver-modified catheters have so far given inconsistent results. The new technology of the Erlanger silver catheter offers the opportunity of an effective reduction in catheter-related infections.

A prospective study of pathogenesis of catheter-associated urinary tract infections

OBJECTIVE

To determine the pathogenesis of catheter-associated urinary tract infection (CAUTI) and the relative importance of each of the possible mechanisms of entry of infecting microorganisms to the catheterized urinary tract.

MATERIAL AND METHODS

We conducted a prospective study of 1,497 newly catheterized patients. Paired quantitative urine cultures were obtained daily, from the catheter specimen port and from the collection bag, using a technique that could detect 1 colony-forming unit/mL. We assumed that with extraluminal infections, caused by microorganisms ascending from the perineum in the mucous film contiguous to the external surface of the catheter, the organisms would be detected first in bladder urine or in far higher concentrations in urine from the specimen port than from the collection bag. With intraluminal CAUTIs, caused by microorganisms gaining access to the catheter lumen because of failure of closed drainage or contamination of collection bag urine, the organisms would be detected first or in far larger numbers in a collection bag specimen.

RESULTS

The probable mechanism of infection could be determined for 173 of 250 organisms (69.2 %) identified in 235 new-onset CAUTIs. Among these 173 cases, 115 (66%) were extraluminally acquired, and 58 (34%) were derived from intraluminal contaminants. For these determinable cases, CAUTIs caused by gram-positive cocci (enterococci and staphylococci) and yeasts were far more likely to be extraluminally acquired (extraluminal:intraluminal, 2.9) than were gram-negative bacilli, which caused CAUTIs by both routes equally (extraluminal: intraluminal, 1.2; P = 0.007). Surprisingly, no significant differences were noted in pathogenetic mechanisms between men and women.

CONCLUSION

We conclude that, in both men and women, CAUTIs occur by both extraluminal and intraluminal portals of entry but derive preponderantly from organisms that gain access extraluminally. Strategies for prevention of CAUTIs must focus on new technologies to prevent access of organisms by all possible routes.

A large randomized clinical trial of a silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection

PURPOSE

The antibacterial activity of silver-containing compounds has recently been employed in constructing medical devices, such as vascular and urinary catheters, that may be effective in blocking infection. The present study was designed to evaluate the efficacy of a silver oxide-coated urinary catheter.

PATIENTS AND METHODS

A total of 1,309 hospitalized patients who required placement of an indwelling urinary catheter for 24 hours or longer were randomly assigned to receive either a silicone catheter coated externally with 5% silver oxide or a standard silicone elastomer-coated latex catheter. Daily catheter-urine specimens were collected aseptically and catheter-care violations were monitored daily for the duration of the catheterization.

RESULTS

Bacteriuria developed in 85 of 745 patients (11.4%) in the silver-coated catheter group and in 73 of 564 patients (12.9%) in the control group (P = 0.45). In women who did not receive antibiotics, the rates were 29.3% and 30.4%, respectively (P = 0.98). In men who did not receive antibiotics, the rate of bacteriuria was significantly higher with the silver-coated catheter (29.4% compared to 8.3%, respectively, P = 0.02). Staphylococcal species were isolated more often from the silver-coated catheter group than from the control group (25% versus 8% of all isolates, respectively, P = 0.002).

CONCLUSIONS

This study, the largest ever reported evaluating any silver-impregnated device, has not only failed to demonstrate the efficacy of silver in prevention of catheter-associated bacteriuria, as suggested in prior studies, but it has also shown a significantly increased incidence of bacteriuria in male patients and a significantly increased occurrence of staphylococcal bacteriuria. These results suggest the need for caution and for similar large-scale trials before silver-containing compounds are widely used for preventing device-associated infections, both in vascular and urinary catheters.

Activity of a nitrofurazone matrix urinary catheter against catheter-associated uropathogens

Nitrofurazone-coated urinary catheter segments inhibited 51 (75%) of 70 urinary bacterial isolates from patients with indwelling catheters. Inhibition zones correlated significantly with the nitrofurazone MIC (r2 = 0.79, P = 0.0001). All strains except the Pseudomonas spp. were inhibited by < or = 64 micrograms of nitrofurazone per ml. MICs of nitrofurazone and nitrofurantoin correlated significantly (r2 = 0.93, P = 0.0001).

Catheter-associated urinary tract infections: epidemiology, pathogenesis, and prevention

Catheter-associated urinary tract infections (UTIc) remain the most common nosocomial infection. Although usually benign, UTIc cause bacteremia in 2-4% of patients and have been associated with a case fatality rate three times as high as nonbacteriuric patients. Risk factors for UTIc identified in multivariate analyses include increasing duration of use, female sex, absence of systemic antibiotics, and disconnection of the catheter-collecting tube junction. Recent studies suggest that most episodes of low colony count bacteriuria (10(2)-10(4) cfu/ml) rapidly progress to high (greater than or equal to 10(5)/ml) colony counts within 24-48 hours. In persons with long-term catheterization, bacteriuria inevitably develops and the infecting strains change frequently. In this setting, Proteus and Morganella species produce catheter encrustations and persistent bacteriuria. Routes of bacterial entry have been well defined and differ by gender, with the periurethral route predominating in women and the intraluminal route in men. Growth of bacteria in biofilms on the inner surface of catheters promotes encrustation and may protect bacteria from antimicrobial agents. Bacterial virulence factors have not been well characterized in UTIc, but fimbrial adhesins have been associated with bacterial persistence in the catheterized urinary tract, and urease production has been associated with stone formation and catheter encrustation. Recent efforts to prevent UTIc have focused mainly on preventing bacterial entry to the urinary tract or eradicating bacteriuria after its onset and have been largely unsuccessful. Systemic antimicrobials, sealed tubing and catheter junctions, silver ion-coated catheters, and antiseptics in the collecting bag have all been efficacious in one or more controlled trials. Failure to stratify patients by major risk factors, especially gender, antimicrobial exposure, and catheter duration, makes interpretation of many trials difficult. Further research in the areas of innovative catheter system design, bacterial-host epithelial cell interaction, and targeted antimicrobial prophylaxis seem the most likely approaches to controlling UTIc in the future.

Prevention of catheter-associated bacteriuria: clinical trial of methods to block three known pathways of infection

The simultaneous use of methods to block all three known pathways of bacterial entry into the bladders of catheterized patients has been suggested because of the limited effectiveness of individual methods that block single pathways. We conducted a randomized controlled trial to assess the prevention of bacteriuria in patients, using a three-way system that included a hydrophilic polymer-coated and preconnected sealed catheter system, daily catheter care, and disinfection of the outflow tube of the drainage bag with povidone-iodine (i.e., methods to block bacterial entry at the urethral insertion site, at the catheter drainage tube junction, and at the outflow tube). Among treated patients, 14 (4.7%) of 300 acquired bacteriuria as compared with 15 (4.9%) of 306 who did not receive the protocol treatments. Only 3 of 29 episodes of bacteriuria occurred in patients whose meatal cultures did not contain gram-negative bacilli or enterococci; thus migration of bacteria in the periurethral mucous sheath appeared to be the most common pathway by which bacteria gained entry into the bladder in this study. Catheter care and disinfection of the drainage bag outflow tube as used in this study remain unproven methods of preventing catheter-associated bacteriuria. Preconnected catheters with junction seals were used in both treated and untreated patients and, on the basis of previous studies, appear to be effective in reducing junction disconnections and bacteriuria. Therefore we conclude that the use of several simultaneous measures to prevent catheter-associated urinary infections is no more effective than the use of preconnected catheters with junction seals alone and is clearly more expensive.

Sustained in vitro activity of human albumin microspheres containing chlorhexidine dihydrochloride against bacteria from cultures of organisms that cause urinary tract infections

The potential of chlorhexidine dihydrochloride (CH HCl) incorporated into human albumin microspheres to provide sustained activity in vitro against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa from quality controls and from cultures of organisms that cause urinary tract infections was investigated. CH HCl was entrapped into five different formulations of human albumin microspheres. A technique was developed to evaluate the antibacterial activity of these microspheres and of controls (unloaded microspheres or gel). CH HCl microspheres exhibited antibacterial activity over a period of 16 days. Similar results were obtained with microspheres suspended in a methocel gel, and their antibacterial activity also continued for about 16 days. Empty microspheres or gel media alone were ineffective. The release rates of CH HCl from human albumin microspheres coated onto catheters by use of different gel formulations were also determined. The microsphere formulations were found to provide sustained antibacterial activity even at a low drug concentration.

Bacterial adherence to urethral catheters

Closed sterile catheter drainage has markedly reduced the incidence of nosocomial urinary tract infections. Infections that occur during closed drainage must ascend by colonizing the catheter or urethra. Our study compared adherence by different bacterial species to different catheter surfaces. We found no bacteria adhering to the hydrophilic catheter surface. Of the gram-negative bacteria Proteus mirabilis showed the greatest adherence to the other catheters and it, like most bacteria, showed the most marked adherence to the red rubber catheter.

Silver alloy coated catheters reduce catheter-associated bacteriuria

The tendency of indwelling catheters to cause urinary tract infection was evaluated in a randomised clinical study of 223 patients. A Foley catheter coated with silver alloy on both inner and outer surfaces was used in 60 patients; 60 others received a Teflonised latex Foley's catheter and the remaining 103 patients were excluded because of antibiotic treatment, diabetes, etc. There was a statistically significant difference in the incidence of catheter-associated bacteriuria (greater than 10(5) organisms/ml) in the 2 groups after 6 days' catheterisation: 6 patients with the silver coated catheter developed bacteriuria compared with 22 who had the Teflonised latex catheter. This suggests that the silver impregnated urethral catheters reduce the incidence of catheter-associated urinary tract infection.

Evaluation of the retrograde contamination guard in a bacteriologically challenged rabbit model

We compared a newly developed closed urinary drainage system incorporating a retrograde contamination guard (RCG) with the conventional closed drainage system. The new system contains a solid bactericide (povidone iodine) pellet enclosed in a porous cartridge at the drain port of the urine collection bag. A catheterised rabbit model was used. The urine drainage bags were challenged daily for 8 days with an auxotrophically marked uropathogenic strain of Escherichia coli at the outlet tube. The bag urine was infected with the marked organism in 10 of the 11 rabbits in the control group (conventional collection bags) in 3.8 +/- 1.03 days and in only 1 of the 13 rabbits fitted with the RCG. The RCG effectively prevents contamination of the urine drainage bag and thus may play an important role in reducing the incidence of nosocomial urinary tract infections.

Postoperative pneumonia and urinary-tract infection: epidemiology and prevention

Hospital-acquired pneumonias and urinary-tract infections are important causes of morbidity and mortality in surgical patients, and a great deal of effort has been expended on infection control strategies to prevent their occurrence. Prophylactic antibiotics, used either systemically or topically, are not routinely recommended for the prevention of either of these infections. The beneficial effects of these agents are transient, and they are often in association with the acquisition of colonization or infection with resistant bacteria. New approaches for infection control, not involving antibiotic agents, are being developed to lower the infection rates of both hospital-acquired pneumonias and urinary-tract infections to an irreducible minimum.

Effect of silver oxide/trichloroisocyanuric acid antimicrobial urinary drainage system on catheter-associated bacteriuria

We assessed the efficacy of silver oxide coating of the indwelling urethral catheter and catheter adapter, and instillation of trichloroisocyanuric acid into the urinary drainage bag in the prevention of catheter-associated bacteriuria in a prospective and randomized study of 74 patients. Bacteriuria was documented in 29 of the 74 patients (39 per cent). There was a significant difference between the attack rates, with 11 of 41 patients (27 per cent) in the test group and 18 of 33 (55 per cent) in the control group having bacteriuria (p equals 0.02) after a median time to bacteriuria of 36 and 8 days, respectively (p equals 0.01). Urethral meatal colonization was implicated as the source of bladder bacteriuria in 12 of 18 patients (67 per cent) in the control group and 5 of 11 (45 per cent) in the test group. Trichloroisocyanuric acid significantly reduced drainage bag contamination but bag contamination with the same microorganism responsible for bacteriuria preceded infection in only 2 of the 29 patients (7 per cent), 1 in each group. Patients who received systemic antimicrobial agents acquired bacteriuria less frequently than those who did not. The apparent protective effect of systemic antimicrobials was strongest during the first 4 days of catheterization. The data indicate that episodes of bacteriuria arising from the urethral meatus are common among catheterized patients and that the antimicrobial catheter is effective in reducing the incidence of catheter-associated bacteriuria.

Reduction of bacterial adherence to catheter surface with heparin

Despite many advances in catheter design and use, the most common cause of hospital-acquired infections is catheterization of the urinary tract. In the present investigation the adherence of bacteria to catheters coated with heparin was studied. Since heparin itself does not coat the plastic catheter surface, a complex of heparin with tridodecylmethylammonium chloride (TDMAC) was used which results in hydrophobic association of hydrocarbon chains of the TDMAC with the catheter leaving the quaternary ammonium moiety of TDMAC exposed to the surface forming ionic bonds with the highly anionic sulfate groups of heparin. Coating latex catheter material with TDMAC without heparin resulted in 3.6-fold higher adherence whereas coating with the TDMAC-heparin complex reduced adherence to less than 10% of control untreated latex. TDMAC-heparin also significantly reduced bacterial adherence to teflon coated latex (Bardex) and vinyl catheter material. Less than 30% of the original heparin was removed after wash periods of up to one week. These results indicate that TDMAC-heparin coating of urethral catheters reduces bacterial adherence and thereby may delay the acquisition of catheter associated urinary tract infection.

Nosocomial bacteriuria: estimating the potential for prevention by closed sterile urinary drainage

Urinary tract infections associated with the temporary use of indwelling bladder catheters remain a vexing problem in acute care hospitals. The appreciable morbidity and mortality from these infections are still under active investigation. Because of the large numbers of patients at risk, increased attention is also being given to the costs for prevention, detection, treatment, and follow-up of catheter-associated infections.

Before the advent of commercially available systems for maintaining closed sterile urinary drainage, infection was believed to be inevitable. In the past 25 years, the successful prevention of infection in 70% to 80% of catheterized patients by aseptic methods has undoubtedly prevented thousands of deaths from gram-negative bacteremia and stimulated efforts to further reduce the infection rate.

Short-term versus prolonged systemic antibiotic prophylaxis in patients treated with indwelling catheters

Newly hospitalized patients with stroke treated by indwelling catheters were assigned randomly to 3 treatment groups. Group 1 (24 patients) received 3 gm. ampicillin intramuscularly in divided doses 1 hour before, at the time of and 6 hours after insertion of the catheter. Group 2 (28 patients) received daily 1 gm. ampicillin intramuscularly every 8 hours. Group 3 (26 patients) was not subjected to any antimicrobial prophylaxis. Within 1 week after catheter insertion significant bacteriuria developed in 12.5 per cent of the patients in group 1, 42.8 per cent in group 2 and 45.1 per cent in group 3. The difference in the incidence between group 1 and either group 2 or 3 was statistically significant (p less than 0.02 and p less than 0.01, respectively). The mean number of strains (plus or minus standard error of mean) isolated per case of bacteriuria in group 3 (1.25 plus or minus 0.18) was significantly lower (p less than 0.05) and antimicrobial resistant strains were fewer (4 of 15) than in group 2 (1.75 plus or minus 0.13 and 12 of 21, respectively).

Genitourinary infections in the patient at risk: extrinsic risk factors

The indwelling urinary catheter is an essential part of modern medical care. It is widely used to relieve temporarily anatomic or physiologic urinary obstruction, to facilitate surgical repair of the urethra and surrounding structures, to provide a dry environment for comatose or incontinent patients, and to permit accurate measurement of urinary output in severely ill patients. Unfortunately, when poorly managed, the indwelling catheter may present a hazard to the very patients it is designed to protect. It is the leading cause of nosocomial induced urinary tract infections and the most common prediposing factor in fatal gram-negative sepsis in hospitals. Catheters drain the bladder, but they obstruct the urethra, producing other major problems such as urethral strictures and epididymitis. Advances in catheter care since the introduction of closed drainage are reviewed. The best means of prevention is the avoidance of use when unnecessary and prompt removal when the need no longer exists. This practice is of particular importance in long-term care institutions. Alternate methods include intermittent catheterization in the paraplegic patient, condom drainage in the nonobstructed patient, and direct drainage of the bladder through the skin. Most recent studies have attempted to improve care of the indwelling catheter by either prevention of periurethral infection (the most common route of acquisition) or sterilization of the drainage bag to prevent ascending infection and cross infection. Thus far, these methods have been unsatisfactory. A new approach to designing drainage systems is clearly needed. Finally, all studies failed to demonstrate the ability of systemic antimicrobial therapy to eradicate catheter-associated infections other than temporarily. Instead, excessive use of antibiotics has led to the emergence of resistant strains that may be spread to other patients through contaminated urine.

Randomized controlled trials in hospital epidemiology. Sixth annual National Foundation for Infectious Diseases lecture

Randomized controlled trials (RCTs) are useful in the evaluation of both new and well-established hospital infection control practices for which the benefit is unproven and not obvious. RCTs are often undertaken to resolve controversies, and many of them have a "negative" or inconclusive outcome. Well-designed RCTs with a negative outcome have the potential for reducing health care costs by identifying widely used preventive measures that are not cost effective. ICPs should appreciate that RCTs have important limitations, may contain serious flaws in design, and are subject to exploitation by pharmaceutical and equipment manufacturers. Knowledge of the principles of RCTs can lead to improved scientific standards for all research--nonrandomized as well as randomized--in hospital epidemiology.

Intractable urinary incontinence in geriatric patients. A management approach

Care of the permanently incontinent patient is aimed at collection or controlled release of urine and maintenance of personal hygiene. Before the patient is submitted to long-term catheterization and its attendant risks of infection, incrustation, and urethritis, alternatives should be explored. These include condom catheters, penile clamps, incontinence underpants, and various surgical procedures. Management is much the same for men and women, except that incontinence underpants are employed more often for women. In all patients, long-term catheterization should always be considered a last resort.

An evaluation of daily bacteriologic monitoring to identify preventable episodes of catheter-associated urinary tract infection

We evaluated the efficacy of a daily bacteriologic monitoring program for preventing symptomatic urinary tract infections (UTI) in hospitalized patients with temporary indwelling urethral catheters. We identified 99 instances in which bacteriuria was present at the time of catheter insertion among 1,140 catheterizations. Of those, 62 patients were asymptomatic and 37 patients had fever or symptoms attributable to UTI. Of the 37 symptomatic episodes, only 14 developed symptoms 24 hours or more after the first culture and might be considered potentially preventable. We also identified 76 episodes of acquired bacteriuria among 608 catheterizations that were initially nonbacteriuric in which at least two cultures were available. Of these 76 patients, 51 (67%) remained asymptomatic throughout their period of hospitalization. Of the 25 patients who developed symptomatic infections, only ten were potentially preventable. In all, only 24 symptomatic episodes among 1,140 catheterizations (2%) occurred 24 hours or more after colonization was first detected and might be considered potentially preventable. Our data suggest that routine daily bacteriologic monitoring of urine from all catheterized patients is not an efficient way to decrease the incidence of symptomatic, catheter-associated UTI.

The bacteriuria in long-stay geriatric inpatients with an indwelling catheter

Long-stay geriatric inpatients with an indwelling urinary catheter are harassed by foul-smelling urine, urine leakage, and frequent catheter blockages. It is reasonable to assume that catheter-induced bacteriuria plays an essential role in the catheter problems of these patients. An attempt to reduce the catheter-induced bacteriuria was made by the introduction of a latex catheter coated with a layer of copper metal. The antibacterial properties of the copper-coated catheters studied were, however, insufficient, probably due to too small amount of copper on the catheter. The copper layer was dissolved from the catheter in a few days. The effective time of copper treatment thus became too short.

Evaluation of a vented drainage system in prevention of bacteriuria

A vented urinary drainage system was compared to an otherwise identical non-vented system in a prospective, randomized, double-blind study. Among the 316 female patients evaluated there was a significant reduction in the rate of bacteriuria after 10 days using the vented system (66 per cent in the non-vented group versus 26 per cent in the vented group, p less than 0.05), while no significant difference could be demonstrated among the 190 male patients. We used urine hemoglobin as an indicator of mucosal trauma that might predispose to bacteriuria and no significant difference could be shown between the 2 drainage systems.

Comparison of hydrophilic polymer-coated latex, uncoated latex and PVC indwelling balloon catheters in the prevention of urinary infection

Latex, hydrophilic polymer-coated latex and PVC balloon indwelling urethral catheters were compared in respect of the urinary tract infections arising in association with their use in male patients. The polymer (Hydron) coating conferred no benefit over uncoated latex which in turn was indistinguishable from PVC. No significant differences in the spectra of infecting organismns were observed between the 3 catheter types.