Bacterial adherence to bladder uroepithelial cells in catheter-associated urinary tract infection

Use of Digital Healthcare Communication to Improve Urologists' Surveillance of Lithiasis Patients Treated with Internal Urinary Drainage Pre- and Post-COVID-19 Period

The COVID-19 pandemic has greatly affected lithiasis patients, which has led to an increase in the number of internal stents that have been installed. In this paper, two studies were carried out, a clinical study and a quantitative study. The aim of the first study was to evaluate the incidence and the prevalence of bacterial urinary colonization in patients with obstructive urolithiasis who needed internal stents implanted. In the second study, a multiple linear regression was created to identify the opinion of urologists regarding the importance of using digital technologies to improve the communication process. The result of the clinical study illustrates that the prevalence of urinary colonization in patients with internal stents carried out for obstructive urolithiasis was 35%, with this value being influenced by co-infection with COVID-19. The results of the quantitative study illustrated the fact that urologists are open to using new online technologies to facilitate communication with patients. The results have high importance for both doctors and patients, illustrating the main factors that have the ability to influence the communication process. The hospital managers should take into account the results obtained in this study when they choose to use certain online communication technologies with patients.

Comparison of uropathogens and antibiotic susceptibility patterns in catheterized ambulant middle-aged and elderly Nigerian patients with bladder outlet obstruction

OBJECTIVE

Advanced age is one of the notable risk factors for catheter-associated urinary tract infections (CAUTIs), and differences between middle aged and elderly men with CAUTIs is poorly understood. This study aimed at comparing the pattern of urinary pathogens and antibiotic susceptibility in ambulant catheterized middle-aged and elderly Nigerian men.

MATERIAL AND METHODS

One hundred and fifty-four patients catheterized for >48 hours had provided clean catch mid-stream urine samples for microscopic analysis, culture and sensitivity tests. Eighty-two men aged <65, and 72 men aged ≥65 years matched for age, level of education, occupation and marital status were compared.

RESULTS

Prevalence of CAUTIs among middle-aged men was middle-aged men was higher than the elderly (90.2% and 80.6% respectively) but this was not statistically significant (p=0.086). CAUTIs in middle-aged men with suprapubic catheters were significantly more frequent than those with urethral catheters (p=0.000). The prevalence of CAUTIs in middle-aged men with urethral stricture was different from other causes of bladder outlet obstruction (p=0.004). Men with indwelling catheters longer than 2 weeks had higher CAUTIs (p=0.000). Escherichia coli was the commonest pathogen in both groups while nitrofurantoin was the most sensitive drug.

CONCLUSION

There are differential rates of CAUTIs in both the middle-aged men and the elderly with bladder outlet obstruction in our environment. The knowledge of the common pathogens and the antibiotic susceptibility will prevent irrational antibiotic use. Middle-aged men had higher prevalence of CAUTIs when Proteus spp. was the infectious agent. However, E. coli was the commonest pathogen of CAUTIs in all men. Also, middle- aged men with suprapubic catheters had higher rates of CAUTIs. Nitrofurantoin was the best drug in all men with CAUTIs but elderly men had higher rates of multi-resistance.

Emerging medical and engineering strategies for the prevention of long-term indwelling catheter blockage

Urinary catheters have been used on an intermittent or indwelling basis for centuries, in order to relieve urinary retention and incontinence. Nevertheless, the use of urinary catheters in the clinical setting is fraught with complication, the most common of which is the development of nosocomial urinary tract infections, known as catheter-associated urinary tract infections. Infections of this nature are not only significant owing to their high incidence rate and subsequent economic burden but also to the severe medical consecutions that result. A range of techniques have been employed in recent years, utilising various technologies in attempts to counteract the perilous medical cascade following catheter blockage. This review will focus on the current advancement (within the last 10 years) in prevention of encrustation and blockage of long-term indwelling catheters both from engineering and medical perspectives, with particular emphasis on the importance of stimuli-responsive systems.

Antibiotic resistance patterns of bacteria isolated from indwelling Foley catheters following tube cystostomy in goats with obstructive urolithiasis

Tube cystostomy is a surgical method used for managing obstructive urolithiasis and involves placement of a Foley catheter into the urinary bladder. We identified and evaluated the antibiotic resistance patterns of bacteria isolated from indwelling Foley catheters following tube cystostomy in goats with obstructive urolithiasis. Urine samples collected over a 10-y period from catheter tips at the time of removal were submitted for bacteriologic culture and antibiotic susceptibility testing. Resistance patterns to antibiotics, trends in the resistance patterns over the study period, and the probability of a bacterial isolate being resistant as a function of the identity of the isolate and antibiotic tested were determined. A total of 103 urine samples from 103 male goats with obstructive urolithiasis managed surgically with tube cystostomy were included in the study. Aerococcus (36.9%) and Enterococcus (30.1%) were isolated most frequently. The susceptibility patterns of all bacteria isolated did not change over the study period ( p > 0.05). Proportions of isolates resistant to 1, 2, and ≥3 antibiotics were 36.9%, 18.5%, and 23.3%, respectively. Thus, 41.8% of bacterial isolates were resistant to 2 or more antibiotics tested. The probability of Aerococcus spp., Escherichia coli, and Pseudomonas aeruginosa isolates to be resistant to ampicillin, ceftiofur, erythromycin, penicillin, or tetracycline ranged from 0.59 to 0.76.

Leaf extract of Azadirachta indica (neem): a potential antibiofilm agent for Pseudomonas aeruginosa

Pseudomonas aeruginosa is well known for its ability to form biofilm on indwelling medical devices. These biofilms are difficult to remove because of their high tolerance to conventional antibiotics. Therefore, there is a need to look for alternative agents such as medicinal plants, which can eradicate or inhibit biofilm effectively. This study evaluated the role of neem in inhibiting biofilm formation by P aeruginosa Factors contributing to adherence and biofilm formation were also studied. Results demonstrated that neem leaves extract was quite effective in disrupting formation and structure of biofilms. Moreover, the level of exopolysaccharide, alginate, hydrophobic interactions and uroepithelial cell attachment, which contributes to biofilm formation, was also affected significantly. Results confirm the effectiveness of neem extract in inhibiting biofilm formation. Such studies can lead to the discovery of safe antimicrobial drugs from natural sources without the risk of resistance.

Bacterial biofilms and catheters: A key to understanding bacterial strategies in catheter-associated urinary tract infection

Despite major technological improvements in catheter drainage systems, the indwelling Foley catheter remains the most common cause of nosocomial infection in medical practice. By approaching this common complicated urinary tract infection from the perspective of the biofilm strategy bacteria appear to use to overcome obstacles to produce bacteriuria, one appreciates a new understanding of these infections. An adherent biofilm of bacteria in their secretory products ascends the luminal and external surface of the catheter and drainage system from a contaminated drainage spigot or urethral meatus into the bladder. If the intraluminal route of bacterial ascent is delayed by strict sterile closed drainage or addition of internal modifications to the system, the extraluminal or urethral route assumes greater importance in the development of bacteriuria, but takes significantly longer. Bacterial growth within these thick coherent biofilms confers a large measure of relative resistance to antibiotics even though the individual bacterium remains sensitive, thus accounting for the failure of antibiotic therapy. With disruption of the protective mucous layer of the bladder by mechanical irritation, the bacteria colonizing the catheter can adhere to the bladder's mucosal surface and cause infection. An appreciation of the role of bacterial biofilms in these infections should suggest future directions for research that may ultimately reduce the risk of catheter-associated infection.

Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America

Guidelines for the diagnosis, prevention, and management of persons with catheter-associated urinary tract infection (CA-UTI), both symptomatic and asymptomatic, were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic criteria, strategies to reduce the risk of CA-UTIs, strategies that have not been found to reduce the incidence of urinary infections, and management strategies for patients with catheter-associated asymptomatic bacteriuria or symptomatic urinary tract infection. These guidelines are intended for use by physicians in all medical specialties who perform direct patient care, with an emphasis on the care of patients in hospitals and long-term care facilities.

The pathogenesis of catheter-associated urinary tract infection

Catheter-associated urinary tract infection (CAUTI) remains one of the most common types of hospital-acquired infections. Further progress in the prevention of CAUTI requires a better understanding of its pathogenesis. Bacteria may enter the bladder through contamination of the tip during insertion with the flora of the distal urethra or from bacteria ascending the outside or the inside of the catheter. Residual urine in the bladder of catheterised patients increases the risk of bacteriuria. During the process of infection, bacteria need first to adhere to the epithelial cells of the urinary tract and/or the surface of the catheter. They will then develop into biofilms on the catheter surface and are resistant to the immune system and antibiotics. Catheters by themselves may cause immediate physical damage to the bladder epithelium; they may be toxic and also cause inflammation. Bacteria can also damage the epithelium and cause inflammation and the combination of both may be synergistic in producing symptoms in the patient. Most episodes of catheter-associated bacteriuria are asymptomatic but it is not known why some patients are symptomatic and others are not. Further research into the pathogenesis of CAUTI needs to be carried out. A suggestion for the prevention of CAUTI is the use of catheters with an additional eye-hole beneath the balloon to prevent residual urine in the bladder or to remove the tip and balloon altogether, with the additional benefit of having no tip to cause damage or inflammation to the bladder epithelium.

Complicated catheter-associated urinary tract infections due to Escherichia coli and Proteus mirabilis

Catheter-associated urinary tract infections (CAUTIs) represent the most common type of nosocomial infection and are a major health concern due to the complications and frequent recurrence. These infections are often caused by Escherichia coli and Proteus mirabilis. Gram-negative bacterial species that cause CAUTIs express a number of virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, and nutrient acquisition as well as factors that cause damage to the host. These infections can be reduced by limiting catheter usage and ensuring that health care professionals correctly use closed-system Foley catheters. A number of novel approaches such as condom and suprapubic catheters, intermittent catheterization, new surfaces, catheters with antimicrobial agents, and probiotics have thus far met with limited success. While the diagnosis of symptomatic versus asymptomatic CAUTIs may be a contentious issue, it is generally agreed that once a catheterized patient is believed to have a symptomatic urinary tract infection, the catheter is removed if possible due to the high rate of relapse. Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.

An outbreak of Pseudomonas aeruginosa because of inadequate disinfection procedures in a urology unit: a pulsed-field gel electrophoresis-based epidemiologic study

BACKGROUND

Pseudomonas aeruginosa is an opportunistic pathogen causing nosocomial infections in many hospitals. We aimed to investigate the source of urinary tract infections by determining clonal relationship of Pseudomonas aeruginosa strains with pulsed-field gel electrophoresis (PFGE).

METHODS

During a 2-month period, all postoperative infections because of P aeruginosa were investigated in the Urology Department. Patient data were collected from medical records. Surveillance samples were obtained from various places in urological operating rooms. PFGE typing was performed for all P aeruginosa isolates.

RESULTS

A total of 14 P aeruginosa strains (12 from patients and 2 from environmental samples) were isolated. PFGE typing of these 14 strains yielded 2 possibly related clones, which differed from each other by 4 major bands. Ten of the patient isolates were clonally identical with the strains of 2 forceps.

CONCLUSION

Typing results confirmed that inadequately disinfected surgical devices can be the source of outbreak. After institution of infection control measures and education, no further clusters of P aeruginosa infection were detected in the Urology Department.

Precise and rapid assessment of Escherichia coli adherence to vaginal epithelial cells by flow cytometry

BACKGROUND

In the pathogenesis of Escherichia coli urinary tract infections (UTIs) in women, infecting bacteria adhere to vaginal and periurethral epithelial cells prior to ascending to the bladder and causing infection. Complex interactions among specific bacterial adhesins and various host factors appear to influence adherence of E. coli to mucosal surfaces such as the urogenital epithelium. To conduct population-based studies assessing host epithelial cell determinants that influence bacterial attachment, a method of measuring bacterial adherence utilizing clinically derived epithelial cell samples is needed.

METHODS

We developed and standardized an efficient, accurate, high-throughput method for analyzing the adherence of uropathogenic E. coli to clinical samples containing a large number of exfoliated vaginal epithelial cells (VEC). Three wild-type E. coli strains isolated from women with UTI (IA2 expressing pap-encoded, class II fimbriae only; F24 expressing pap-encoded, class II and type 1 fimbriae; and F20, without pap-encoded or type I fimbriae) were transformed with gfpmut3, encoding green fluorescent protein, incubated with VECs, and analyzed by flow cytometry.

RESULTS

Enumeration of the binding of each E. coli strain to 10,000 VECs showed reproducible, highly significant strain-dependent differences in adherence to VECs. Differential analysis of the relative contributions of type 1 pili and P fimbrial-mediated binding to the adherence phenotype was performed. It demonstrated that IA2 binding was dependent entirely on P fimbriae, whereas F24 binding was dependent on both P and type 1 fimbriae.

CONCLUSIONS

This method has great potential for use in high-throughput analyses of clinically derived epithelial cell samples and will be valuable in population-based investigations of host-parasite interactions in UTI utilizing VECs collected from specific patient groups.

Effects of subinhibitory concentrations of nitroxoline on the surface properties of Escherichia coli

Nitroxoline (5-nitro-8-quinolinol; NIQ) at subinhibitory concentrations (sub-MIC) decreased the adherence of uropathogenic Escherichia coli to catheter surface and significantly enhanced cell surface hydrophobicity. The surface hydrophobicity increased in the presence of sub-MIC of NIQ and also in an excess of Mg2+. The effect of NIQ on the cell surface was not related to the bacteriostatic effect of this agent. The increase in nitrogen and decrease in phosphate content in the cell surface was found in the presence of NIQ. NIQ did not inhibit the expression of fimbriae.

Hydrogel/silver ion-coated urinary catheter reduces nosocomial urinary tract infection rates in intensive care unit patients: a multicenter study

OBJECTIVES

Indwelling urinary catheters are the leading source of nosocomial urinary tract infections (NUTIs). The Bardex I.C. catheter is a hydrogel latex Foley catheter with a monolayer of silver metal applied to the inner and outer surfaces of the catheter. We investigated the Bardex I.C. catheter for its ability to decrease the NUTI rate in critical care units.

METHODS

Five hospitals participated in a blind prospective study, exchanging the standard latex Foley catheter for the Bardex I.C. Foley catheter. The device use rate and NUTI rate were monitored. Data were collected and analyzed using Wilcoxon rank sum test and four-way analysis of variance. A cost analysis was also performed.

RESULTS

The baseline period, intervention period, and number of device days was similar for both periods. The unadjusted catheter-associated infection rate during the baseline and intervention periods was 7.1 and 4.5 infections per 1000 catheter days, respectively (P <0.01). The adjusted catheter-associated infection rate during the baseline and intervention periods was 8.1 and 4.9 infections per 1000 catheter days, respectively. This was not statistically significant (P = 0. 13).

CONCLUSIONS

A trend toward a reduction in NUTIs with the use of the hydrogel/silver-coated catheter was noted in all intensive care units at each institution as shown by the unadjusted and adjusted catheter-associated infection rates. One hospital demonstrated a statistically significant reduction in NUTIs. However, statistical significance was not met when the results were adjusted. The cost analysis at one institution demonstrated cost savings with the use of the silver-coated catheter. Future analysis may require a double-blind, prospective-controlled study of longer duration to reach statistical significance.

Hospital-acquired urinary tract infections associated with the indwelling catheter

Indwelling urethral catheters are commonly used in patients admitted to acute care hospitals. Forty percent of nosocomial infections occur in the urinary tract, and greater than 80% of these infections are secondary to an indwelling urethral catheter. Fortunately, the majority of catheters are left indwelling for a short period of time. The duration of catheterization is directly related to the development of bacteriuria, nosocomial infection, and possible bacteremia with sepsis. A relatively low percentage of patients become infected during the first 3 to 5 days if sterile technique and proper maintenance of a closed system are performed. Bacteria may grow in the urine (planktonic) and ascend via the lumen, or bacteria in the biofilm around the outside of the catheter may infect the bladder. Most organisms are from the patient's intestinal flora, but exogenous sources on or near the patient may be involved. The major morbid events associated with the catheter are fever and the possible progression to bacteremia and sepsis. Early recognition of complications and arresting their progression, especially in the high-risk patient, are essential. Current research is directed at developing ways to reduce infection beyond the sterile closed system.

Outbreak of nosocomial urinary tract infections due to Pseudomonas aeruginosa in a paediatric surgical unit associated with tap-water contamination

An outbreak of 14 cases of urinary tract infections by Pseudomonas aeruginosa, including six symptomatic infections, occurred from September to November 1994 in a paediatric surgical unit. During the outbreak, urine samples from patients and multiple samples from the environment of patients were tested for the presence of P. aeruginosa. Bacterial isolates were studied by pulsed-field gel electrophoresis. Genotypic analysis showed that most of the isolates from children were different. Multiple P. aeruginosa isolates were also found in the tap water, as the only putative source of contamination. Two of these isolates were identified in two infected patients, indicating possible direct contamination of patients via tap water and this was related to the distal colonization of faucets. Bacteria were eradicated from tap water by replacement of taps. The cluster of cases of P. aeruginosa urinary infection was, therefore, related to multiple contaminations through tap water. These results illustrate an unexpected risk of nosocomial infection and emphasizes the importance of checking tap water to prevent bacterial contamination through handwashing in contaminated water.

Urinary tract infection in the immunocompromised host. Lessons from kidney transplantation and the AIDS epidemic

The occurrence of urinary tract infection and its clinical impact is determined, as with any infectious disease, by the interaction between the virulence of the infecting organism and the host defense mechanisms that can be mobilized. In the case of urinary tract infections, an anatomically and functionally intact kidney and urinary tract are the primary host defenses, with phagocytic function and immune mechanisms coming into play to limit the consequences of those infections. Of all the categories of immunocompromised hosts, the renal transplant patient is the one most susceptible to the direct and indirect consequences of urinary tract infections. In the first 3 months post transplant, the incidence of urinary tract infection is greater than 30%, and there is a relatively high rate of bacteremia and overt pyelonephritis of the allograft. After this time period, unless anatomic or functional derangement of the urinary tract is present, the direct clinical manifestations are far more benign. In addition to the direct effects of urinary tract infection on these patients, indirect effects are also important. These include the activation of CMV by TNF released as a consequence of a urinary tract infection and the initiation of allograft injury. Fortunately, low-dose trimethoprim-sulfamethoxazole or fluoroquinolones are safe and effective prophylactic strategies for preventing the direct and indirect consequences of urinary tract infections. Although the pathogenetic mechanisms are incompletely understood, data are emerging that AIDS patients have both an increased incidence and severity of urinary tract infection. The risk for urinary tract infections seem to be correlated with the degree of immune compromise and, perhaps, the amount of malnutrition and wasting that are present. The best strategies for preventing urosepsis in AIDS patients remain to be defined.

Catheter-associated urinary tract infections

Millions of urethral catheters are used each year. This device subverts several host defenses to allow bacterial entry at the rate of 3% to 10% incidence per day, and its presence encourages the organism's persistent residence in the urinary tract. Most catheter-associated bacteriurias are asymptomatic. The complications in short-term catheterized patients include fever, acute pyelonephritis, bacteremia, and death; patients with long-term catheters in place are at risk for these complications and catheter obstruction, urinary tract stones, local periurinary infections, chronic renal inflammation, chronic pyelonephritis, and, over years, bladder cancer. The closed catheter system has been a magnificant step forward in the prevention of catheter-associated bacteriuria. Indeed, only two catheter principles are universally recommended: keep the closed catheter system closed and remove the catheter as soon as possible. Most modifications of the closed catheter system have not improved markedly on its ability to postpone bacteriuria. On first inspection, systemic antibiotics seem to be an exception to this rule, but their use results in infection of the bladder with resistant organisms, including candida. This and the effect of side effects on the patient and emergence of resistant bacteria in the medical unit have led most authorities to conclude that antibiotics are not useful for prevention of bacteriuria, nor for treatment of bacteriuria in the asymptomatic catheterized patient. For symptomatic patients, usually with fever or signs of sepsis, treatment of bacteriuria with appropriate systemic antibiotics and removal or replacement of the urethral catheter are indicated. Gloves, hand washing, and segregation of catheterized patients can minimize nosocomial clusters. Because clinicians can only postpone bacteriuria, and once it occurs, clinicians seem unable to prevent its complications, methodologies other than urethral catheters should be used for urine drainage assistance whenever possible. These options include condom, intermittent, suprapubic, and intraurethral catheterization for appropriate patients. The few data available suggest that each one of these catheterization options yields a lower incidence of bacteriuria-and its consequent complications-than urethral catheterization.

Microflora persistence on duodenojejunal flat or normal mucosa in time after a meal in children

A pathogenic role for high numbers of bacteria in the small intestine had been suggested previously by bacterial counts on luminal aspirates, but these investigations were flawed by the sampling device "contamination" in the mouth and the changing nature of fluent intestinal content. A procedure was developed to sterilize the Watson biopsy capsule with HCl in the upper portion of the duodenum. Bacteria were counted in the mucosal homogenate of the first (diagnostic) duodenojejunal biopsy in 80 untreated celiac children, and in 46 children with irritable bowel syndrome (IBS) in a four-cell, controlled, randomized investigation. Persistence of bacteria on the mucosa for 20 h after the last meal was investigated in 62 subjects, and for 26 h after the last meal in 64 subjects. Bacteria, mainly streptococci and staphylococci, persisted at a concentration of 10(6) per gram of mucosa 20 h after the last meal. The number of bacteria per gram of mucosa was 24 times higher in all 62 children of the 20-h fast groups than in all 64 children of the 26-h fast groups (p < 0.001). The bacteria count in celiac children was 39 times higher in the 20-h fast group than in the 26-h one. This difference was significantly higher than the 11 times difference that was found on the normal mucosa between the 20- and 26-h fast IBS groups (p < 0.001), which was still significant. The number of bacteria on duodenojejunal mucosa depends on nutrient absorption and persists longer than the intermeal interval in these subjects.

Adherence to urethral catheters by bacteria causing nosocomial infections

Previous clinical studies of catheters with hydrophilic coating have, in some instances, shown a delay in the onset of significant bacteriuria, while others reported no such effect. To attempt to determine reasons for these differences we decided to study bacterial adherence of bacteria obtained from nosocomial urinary tract infections associated with catheters. Almost all strains adhered to the silicone catheter and none of them adhered to the catheter with the hydrophilic surface whether incubated in urine or serum. When incubated in urine, all strains adhered to the red rubber catheters. Adherence was variable to the Teflon and elastomer surfaces.

Binding of uropathogenic Escherichia coli R45 to glycolipids extracted from vaginal epithelial cells is dependent on histo-blood group secretor status

Women with a history of recurrent Escherichia coli urinary tract infections (UTIs) are two to three times more likely to be nonsecretors of histo-blood group antigens than are women without such a history. Further, uroepithelial cells from women who are nonsecretors show enhanced adherence of uropathogenic E. coli compared with cells from secretors. To investigate the hypothesis that nonsecretors express unique receptors for uropathogenic E. coli related to their genetic background, we extracted glycosphingolipids (GSLs) from vaginal epithelial cells collected from nonsecretors and secretors and used an assay in which radiolabeled uropathogenic E. coli were bound to these GSLs separated on TLC plates. An E. coli strain (R45) expressing both P and F adhesins, which was isolated from one of these patients' UTIs, was metabolically labeled with 35S for the TLC binding assay. The radiolabeled E. coli R45 bound to two extended globo-series GSLs, sialosyl gal-globoside (SGG) and disialosyl gal-globoside (DSGG), found in the GSL extracts from nonsecretors but not from secretors. The identity of SGG in the nonsecretor GSL extracts was confirmed in radioimmunoassays using an mAb to SGG and in immunofluorescence assays with this mAb and native vaginal epithelial cells. We show that SGG and DSGG are selectively expressed by epithelial cells of nonsecretors, presumably as a result of sialylation of the gal-globoside precursor glycolipid, which in secretors is fucosylated and processed to ABH antigens. The presence of SGG and DSGG may account for the increased binding of E. coli to uroepithelial cells from nonsecretors and for their increased susceptibility to recurrent UTI.

Movement of pseudomonas aeruginosa along catheter surfaces. A mechanism in pathogenesis of catheter-associated infection

The etiologic mechanism involved in the establishment of catheter-associated bacteriuria is suggested in this in vitro study of the movement of Pseudomonas aeruginosa along a catheter surface against a flowing artificial urine milieu in the presence and absence of antibiotics. Following a lag phase, during which a bacterial biofilm becomes firmly established at a site of contamination, the bacteria ascend the surface of the Foley catheters in a rapidly expanding coherent biofilm. The speed of the bacterial ascent is increased as a result of turbulence-associated planktonic saltatory bacterial movement within the urine column. Bacteriocidal concentrations of antibiotics in the urine can slow down the bacterial ascent, but they do not preclude it.

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.

Effect of a siliconized latex urinary catheter on bacterial adherence and human neutrophil activity

The effect of a siliconized latex urinary catheter on the in vitro adherence and growth of Pseudomonas aeruginosa and Escherichia coli and on the activity of human polymorphonuclear leukocytes (PMNs) was assessed. The adherence of P. aeruginosa to latex catheters was significantly greater than that of E. coli, being 30 times higher at 6 hr of incubation. The survival of E. coli (10(8) CFU/ml) in phosphate-buffered saline (PBS) containing segments of siliconized latex catheters was lower than in the controls. This effect seems to be due to a toxic effect produced by substances eluted into the medium from the catheters, as the viability of E. coli (10(3) CFU/ml) in eluates obtained from the incubation of catheters in PBS (24 hr; 37 degrees C) was significantly lower than in the controls. These phenomena were not observed with P. aeruginosa. The incubation of human PMNs with either catheter segments or eluates did not affect the uptake of opsonized E. coli but significantly decreased the production of superoxide radicals by these phagocytes. It is concluded that the adherence of P. aeruginosa to these catheters is higher than that of E. coli and that the latex urinary catheter used herein elutes substances that are in vitro toxic for E. coli and the oxygen-dependent bactericidal mechanisms of human PMNs.

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.

Stimulation of epithelial hyperplasia in rat urinary bladder by Escherichia coli cystitis

Using heterotopically transplanted rat urinary bladder, experiments were conducted to develop a reproducible animal model of bacterial cystitis-associated urothelial hyperplasia without calculus formation, and to elucidate which bacterial component(s) might induce urothelial hyperplasia. Bladder instillation of live Escherichia coli (E. coli) resulted in persistent infection and inflammation and also diffuse urothelial hyperplasia. Instillation of killed E. coli also induced diffuse hyperplasia. Hyperplastic changes regressed following withdrawal of the killed E. coli treatment. Urothelial hyperplasia was also induced by repeated instillation of protein-rich lipopolysaccharide (LPS), the endotoxin derived from gram-negative bacterial wall component, but not by protein-free LPS. A finding common to bladders showing hyperplasia was the infiltration of neutrophils into intercellular spaces of the urothelium. We conclude that urothelial hyperplasia is induced by E. coli cystitis, that LPS plays a significant role in the hyperplastic response, and that neutrophils may mediate the response.

Isolation and comparison of Escherichia coli strains from canine and human patients with urinary tract infections

We analyzed Escherichia coli strains isolated from dogs with urinary tract infections (UTIs) in an attempt to determine if any of these strains were similar to E. coli isolated from humans with UTIs. Using genotypic and phenotypic traits, we identified four canine and six human E. coli UTI isolates that all appeared to be closely related or identical. All isolates shared similar DNA sequences for pyelonephritis-associated pili (pap), alpha-hemolysin (hly), and insertion sequence 5 (IS5), on the basis of Southern blot analysis. Similar outer membrane protein, pilin, and plasmid profiles were obtained for each of the isolates, although minor heterogeneity was observed. All of these isolates expressed a neuraminidase-sensitive binding phenotype in contrast to the majority of human isolates, which are known to express an adhesin that recognizes terminal digalactoside residues. Taken together, these results suggest that similar E. coli uropathogens may be capable of infecting both dogs and humans. To determine if the intestinal tracts of dogs were a reservoir for uropathogenic E. coli, eight paired rectal and urine pap+ E. coli strains were cultured from dogs with UTIs. By using the same genotypic and phenotypic criteria described above as a basis for strain identity, seven of eight urine-rectal pairs showed intrapair identity. However, each urine-rectal pair displayed a unique overall profile and could be distinguished from the other pairs. We conclude that the uropathogen colonizing the bladders of dog can also be the predominant strain colonizing the intestinal tracts.

Role of Escherichia coli adhesins in urethral colonization of catheterized patients

Escherichia coli is a major cause of catheter-associated urinary tract infection and frequently colonizes the urethra prior to invading the urinary tract. Bacterial pili, filamentous protein cell surface-associated appendages, have been shown to mediate colonization of epithelial cells. Pili associated adhesins can be detected in vitro by their ability to mediate bacterial hemagglutination of erythrocytes. We have assessed the role of bacterial adhesins in supporting urethral colonization by determining the hemagglutination reactions of 56 E. coli isolates from the urethra of patients with indwelling urethral catheters. The adhesin detected most frequently was the type 1 mannose-sensitive hemagglutinin (43%), and 43% of isolates failed to hemagglutinate guinea pig or human erythrocytes. E. coli hemagglutinins were no more common on urethral isolates from patients that were persistently colonized (E. coli present 70% of the time catheterized), than from those that were transiently colonized (E. coli present 30% of the time catheterized). Analysis of the HA reactions and DNA plasmid profiles of multiple isolates from persistently colonized patients suggested that the E. coli strain colonizing the urethra changed over time. The data suggest that bacterial colonization of the urethra is mediated in part by adhesins and changes over time.

Attachment of Giardia lamblia to rat intestinal epithelial cells

The human enteric protozoan, Giardia lamblia, has surface membrane lectin activity which mediates parasite adherence to erythrocytes. To determine whether an intestinal binding site exists for this lectin we have studied the interaction in vitro between axenically cultured Giardia trophozoites and isolated rat intestinal epithelial cells. Scanning electron microscopy showed that Giardia attached to the apical microvillus membrane and basolateral membrane of rat enterocytes. Any location on the parasite surface could mediate attachment without predeliction for the ventral disc. Trophozoites attached more avidly to jejunal compared with colonic epithelial cells. Attachment was inhibited at 4 degrees C, by sugars and glycoproteins containing D-mannosyl residues and by subagglutinating concentrations of anti-Giardia rabbit serum and two monoclonal antibodies, all with reactivity to parasite surface membrane determinants. Trypsinisation of trophozoites also reduced attachment but the ability to attach was rapidly restored after returning trophozoites to TYI-S culture medium for 4 h at 37 degrees C. Attachment was unaltered by the presence of the microfilament inhibitor cytochalasin B and in the absence of Ca++ and Mg++ ions. These findings support previous work that Giardia possesses a surface membrane mannose binding lectin and indicate that appropriate binding sites are present on rat intestinal epithelial cells. This lectin may play a part in mediating adherence of Giardia to mammalian intestine and could be a target for host immune defence.

The management of children with spinal dysraphism

Improvements in technology have dramatically increased the survival of children with spinal dysraphism. Because this complex condition affects multiple organ systems as well as the psychosocial functioning of the child and family, these children require care from a host of specialists in order to achieve optimum functioning. This article reviews the pathophysiology and discusses the current management of the medical and psychosocial effects of spinal dysraphism. It also briefly discusses strategies for intervention, long-term outcomes, and some controversies regarding care and screening.

Complications of chronic indwelling urinary catheters among male nursing home patients: a prospective study

We studied prospectively the incidence of symptomatic infections of presumed urinary tract origin requiring antimicrobial therapy among 54 male nursing home patients with chronic indwelling bladder catheters. During 514 patient-months at risk there were 106 episodes of symptomatic infection, for an incidence of 0.21 per patient-month at risk. Of the patients 80 per cent had at least 1 episode and 48 per cent had 2 or more. None of the clinical factors we examined, including age, nutritional status, stool incontinence, diabetes mellitus, episodes of catheter blockage and the use of chronic suppressant antimicrobial therapy, was associated with the development of symptomatic infection. Further research on host and pathogen-related factors that increase the risk for symptomatic infection, and improvements in infection control and catheter care protocols are necessary to decrease catheter-associated morbidity among male nursing home patients who must be managed by chronic indwelling catheterization.

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.

Aromatic alpha-glycosides of mannose are powerful inhibitors of the adherence of type 1 fimbriated Escherichia coli to yeast and intestinal epithelial cells

Adherence of bacteria via their surface lectins to host epithelial cells is considered an important initial event in bacterial pathogenesis. Mannose-specific (type 1) fimbriae are among the most commonly found lectins in enterobacteria. We studied the effect of aromatic alpha-glycosides of mannose on the agglutination of mannan-containing yeasts by different strains of Escherichia coli and on the adherence of the bacteria to guinea pig ileal epithelial cells. In both systems these compounds were considerably more effective inhibitors than methyl alpha-mannoside, with 4-methylumbelliferyl alpha-mannoside and p-nitro-o-chlorophenyl alpha-mannoside being the strongest inhibitors. Both compounds were approximately 400-times stronger inhibitors of yeast agglutination by E. coli O128 than was methyl alpha-mannoside and 1,000- and 470-fold stronger, respectively, than was methyl alpha-mannoside in inhibiting the adherence of the bacteria to ileal epithelial cells. 4-Methylumbelliferyl alpha-mannoside was 540 to 1,000 times more effective in inhibiting yeast agglutination by four additional strains of mannose-specific E. coli. It was also more efficient than methyl alpha-mannoside in removing adherent E. coli O128 from ileal epithelial cells. Our results provide further evidence that type 1 fimbriae of E. coli possess a hydrophobic region next to the mannose-binding site. The results suggest that 4-methylumbelliferyl alpha-mannoside and p-nitro-o-chlorophenyl alpha-mannoside are good candidates for the design of therapeutic agents that may prevent adherence in vivo and infection by E. coli strains that express type 1 fimbriae.