Bacterial adherence to periurethral epithelial cells in girls prone to urinary-tract infections

P-fimbriated Escherichia coli in adults with renal scarring and pyelonephritis

The commonest organism in urinary tract infections (UTI) is Escherichia coli. Pyelonephritogenic E.coli strains possess P-fimbriae which firmly attach to uroepithelial cells by recognition of a carbohydrate structure, alpha-D-Galp-(1-4)-beta-D-Galp, which is confined within all glycosphingolipids related to the human P-blood group antigens. Several investigators have studied virulence properties of E.coli and host resistance in relation to UTI. Uroepithelial cells from children and women with recurrent UTI have an increased capacity to bind E.coli. In contrast to previous studies the present one deals with patients with renal scarring, who constitute the major risk group among patients with UTI. P-fimbriae mediated binding to uroepithelial cells was studied and the risk of recurrent UTI in patients with renal scarring was determined. Ninety per cent of the E.coli isolates from female patients with acute non-obstructive pyelonephritis in this study possess P-fimbriae (I). The fecal E.coli colonies obtained from these patients were P-fimbriated in 55% compared to 11% of the fecal E.coli colonies from healthy controls. The P-blood group distribution in 56 female patients with renal scarring and a history of febrile UTI was the same as in a control group of 39 healthy subjects (II). A history of recurrent and/or early infections did not increase the percentage of the P1 blood group phenotype. Forty-nine female patients with renal scarring were prospectively investigated for the incidence of symptomatic UTI in relation to fecal colonization with P-fimbriated E.coli (III). Fifty-three per cent of the patients had altogether 65 episodes of symptomatic UTI during the three-year follow-up (0.036 infections per month). Eight patients (16%) had nine attacks of acute pyelonephritis and 4/5 of the tested E.coli strains from these patients were P-fimbriated. No relationship was demonstrated between the presence of P-fimbriated E.coli in the fecal flora and the development of subsequent acute pyelonephritis. The binding of P-fimbriated E.coli to uroepithelial cells from 19 female patients with renal scarring was studied with the fluorescence-activated cell sorting (FACS) analysis (IV). The uroepithelial cells from the patients with renal scarring exhibited a significantly higher binding capacity (p less than 0.01) than uroepithelial cells from healthy controls. Furthermore, uroepithelial cells from the patients with renal scarring and kidney insufficiency had a higher availability of P-fimbriae receptors on their uroepithelial cells than cells obtained from patients with renal scarring and normal renal function (r = -0.75, p less than 0.001) (V).(ABSTRACT TRUNCATED AT 400 WORDS)

Adhesion of Escherichia coli in urinary tract infection

In individuals prone to urinary tract infections the intestine is colonized by E. Coli strains that possess a combination of properties determining virulence. Such an E. coli strain may colonize the vaginal and periurethral area and ascend the urinary tract. The ability to attach to the mucosal surface is thought to be essential for E. coli to colonize and to remain in the urinary tract. Most E. coli from patients with urinary tract infection show one or both of two adherence properties. One may depend on the recognition by type 1 fimbriae of mannose-containing residues in the urinary slime. It is measured as mannose-sensitive haemagglutination and is found on most E. coli strains. The second adherence property is detected as attachment to human urinary tract epithelial cells and as mannose-resistant agglutination of human erythrocytes. This may depend on the recognition of globo-series glycolipids in the epithelial cell surface. Possession of this adherence factor is strongly related to virulence. Most strains from patients with acute pyelonephritis and cystitis have this property but it is rare in strains from patients with asymptomatic bacteriuria and strains from normal faeces. Local antibodies may interfere with bacterial attachment, thus possibly preventing the colonization that precedes urinary tract infection or modifying an established infection. Vaginal antibodies are known to coat E. coli from the stools. Antibodies in the urine of patients with acute pyelonephritis inhibit attachment of the infecting strain to uroepithelial cells. Antibodies directed against several bacterial surface structures, for example O antigen and fimbriae, are likely to inhibit attachment by steric hindrance or agglutination. The role of antibodies in adhesion-mediating structure such as fimbriae in susceptibility to and the outcome of human urinary tract infection remains to be investigated.

Ageing and infection

An increased morbidity and mortality due to infectious disease has been noted in the ageing. Two alternative explanations may account for this. Changes in the immune system and inflammatory responses with age or an increase in age-related diseases may underlie the increased susceptibility. A review of studies of healthy older individuals demonstrates changes in the immune system with ageing but minimal change in the inflammatory response. Investigations of severe infection in older nursing-home patients requiring hospitalization indicate that infection as a cause of admission and death is significantly more common in individuals who are bedridden because of serious cardiovascular or neurological disease and require urinary catheterization. The evidence indicates that underlying disease, not the senescence of host resistance, leads to severe infection in the ageing.

[Recurrent urinary tract infections]

Recurrent urinary tract infections (RUTI) are a frequent clinical problem in sexually active young women, pregnant or postmenopausal women and in patients with underlying urological abnormalities. The present chapter reviews RUTI based on their classification: relapses, which usually occur early (< 1 month), are caused by the same microorganism and are associated with underlying urological abnormalities, and reinfections, which usually occur later and are caused by a new distinct microorganism (or by the same microorganism usually located in the rectum or uroepithelial cells). The pathogenesis of RUTI is reviewed and the risk factors associated with RUTI in premenopausal women (usually related to sexual activity), postmenopausal women (in whom estrogen deficiency has a significant effect on the vaginal Lactobacillus flora), and in pregnant women are discussed. Likewise, an extensive review of the distinct therapeutic strategies to prevent RUTI is provided: self-treatment of cystitis, continuous antibiotic prophylaxis, postcoital antibiotic prophylaxis, topical vaginal estrogens, Lactobacillus, cranberry juice, intravesical administration of non-virulent E. coli strains and vaccines, among others. Several diagnostic-therapeutic algorithms are included. These algorithms are based on the type of urinary infection (relapse-reinfection), on the type of patient (young, postmenopausal, or pregnant women) and on the number of episodes of RUTI.

Urinary Tract Infection in Pregnant Women: Old Dogmas and Current Concepts Regarding Pathogenesis

The dogma is that the higher risk of pyelonephritis in pregnant women is explained entirely by anatomic/obstructive changes. If so, gestational pyelonephritis should be caused by random, nonpathogenic bacteria. Instead, gestational pyelonephritis is associated with a narrow group of genetically related Escherichia coli and virulence factors, implicating a more complex pathophysiology. Current concepts in the pathogenesis of nongestational urinary tract infections propose receptor-mediated ascending infection. A pathogen with capacity to recognize various receptors may use receptors in the lower, rather than upper urinary tract, and ascend even the lumen of renal tubules. The immune system of a pregnant mother is modified to accommodate a semiallogeneic fetus. Gestational physiologic/immune adaptations may become additional risk factors, increasing sensitivity to urogenital infection. One could argue that it is not primarily the so-called "obstruction," but rather specific changes in the immune system and host receptors that act in concert with--or become exploited by--bacterial virulence that allow for infection in pregnancy to occur.

Adherence of type 1-fimbriated Escherichia coli to uroepithelial cells: more in diabetic women than in control subjects

OBJECTIVE

Women with diabetes have bacteriuria more often than women without diabetes. Because Escherichia coli adhere better to vaginal cells of nondiabetic patients with recurrent urinary tract infections (UTIs) than to those obtained from healthy control subjects, it was hypothesized that E. coli adhere more to the uroepithelial cells of diabetic women, either because of substances excreted in the urine (e.g., albumin, glucose, and Tamm Horsfall protein) or because of a difference in the uroepithelial cells.

RESEARCH DESIGN AND METHODS

A T24 bladder cell line and uroepithelial cells of 25 diabetic women and 19 control subjects were incubated with three different E. coli strains.

RESULTS

The mean numbers of type 1-fimbriated E. coli that adhered to diabetic and control cells were 12.9 and 6.1 (P = 0.001), respectively, whereas those of P-fimbriated E. coli were 8.8 and 8.1 (P = 0.8), and those of nonfimbriated E. coli were 2.7 and 3.4 (P = 0.4). The addition of various substances did not influence the adherence of E. coli to a T24 bladder cell line.

CONCLUSIONS

Type 1-fimbriated E. coli adhere more to diabetic than to control uroepithelial cells.

Pathogenesis of bacteriuria in women with diabetes mellitus

Women with diabetes mellitus (DM) have asymptomatic bacteriuria (ASB) and symptomatic urinary tract infections (UTIs) more often than women without DM. The increased prevalence of bacteriuria in diabetic patients can be the result of differences in the host responses between diabetic and nondiabetic patients, or a difference in the infecting bacterium itself. We have shown that the increased prevalence of ASB in diabetic women is not the result of a difference in bacteria, because the same number of virulence factors was found in the infecting Escherichia coli (most common causative microorganism of ASB) in our diabetic women with ASB, as listed in the literature for nondiabetic patients with ASB. We found that bacterial growth in vitro was increased after the addition of different glucose concentrations, as found in urine of poorly controlled patients. However, we could not confirm that glucosuria was a risk factor for ASB in vivo. In addition, we demonstrated that women with both DM and ASB have lower urinary cytokine and leukocyte concentrations than women without DM but with ASB. Finally, we found that E. coli expressing type 1 fimbriae (the virulence factor that plays an important role in the pathogenesis of UTIs) adhere better to uroepithelial cells of women with DM compared with the cells of women without DM.

Bacterial adherence and immune response in recurrent urinary tract infection

OBJECTIVE

To study the significance of bacterial adherence and humoral immune response in the pathogenesis of recurrent urinary tract infection in adult women.

METHODS

The study population consisted of 30 women with recurrent urinary tract infection (UTI) and 30 healthy women as controls. Bacterial adherence to vaginal epithelial cells was studied. The concentration of serum and urine antibodies against mixed coliform antigen and clinical isolate was determined by enzyme-linked immunosorbant assay (ELISA). The surface hydrophobicity of the organisms was determined. Student's unpaired t-test and Pearson's correlation coefficient test were used in the statistical analysis.

RESULTS

There was an increased adherence of bacteria to vaginal epithelial cells of women with recurrent UTI. The SIgA level in urine was low compared with other antibodies. There was good correlation between the level of free urinary IgG antibody and bacterial adherence.

CONCLUSIONS

This study showed that increased receptivity of vaginal epithelial cells to pathogens and lower local immunity may play an important role in the pathogenesis of recurrent UTI in females.

Recurrent urinary tract infection in women

Recurrent urinary tract infections (UTI) are common among young healthy women even though they generally have anatomically and physiologically normal urinary tracts. Women with recurrent UTI have an increased susceptibility to vaginal colonization with uropathogens, which is due to a greater propensity for uropathogenic coliforms to adhere to uroepithelial cells. Risk factors for recurrent UTI include sexual intercourse, use of spermicidal products, having a first UTI at an early age, and having a maternal history of UTIs. Inherited factors may be important in some women with recurrent UTI. Many factors thought to predispose to recurrent UTI in women, such as pre- and post-coital voiding patterns, frequency of urination, wiping patterns, and douching have not been proven to be risk factors for UTI. In contrast to the predominantly behavioral risk factors for young women, mechanical and/or physiological factors that affect bladder emptying are most strongly associated with recurrent UTI in healthy postmenopausal women. The management of recurrent UTI is the same as that for sporadic UTI except that the likelihood of infection with an antibiotic resistant uropathogen is higher in women who have received recent antimicrobials. Strategies to prevent recurrent UTI in young women should include education about the association of recurrent UTI with frequency of sexual intercourse and the usage of spermicide-containing products. Continuous or post-coital prophylaxis with low-dose antimicrobials or intermittent self-treatment with antimicrobials have all been demonstrated to be effective in managing recurrent uncomplicated UTIs in women. Estrogen use is very effective in preventing recurrent UTI in post-menopausal women. Exciting new approaches to prevent recurrent UTI include the use of probiotics and vaccines. Further understanding of the pathogenesis of UTI will lead to more effective and safer methods to prevent these frequent infections.

Secretory IGA differentially promotes adherence of type 1-piliated Escherichia coli to immortalized vaginal epithelial cell lines

OBJECTIVES

To elucidate the factors that influence bacterial adherence to vaginal epithelium. We developed an in vitro model to examine the interaction of type 1-piliated Escherichia coli, strain HB101/p1-17, with immortalized vaginal epithelial cells (VEC) from postmenopausal donors with (patient 1) and without (patient 2) clinical histories of urinary tract infections (UTI).

METHODS

The VEC were incubated in microtiter plates in the presence of E. coli HB101/p1-17, and factors such as time, mannose concentration, and secretory immunoglobulin A (sIgA) concentration were assessed. After incubation, the numbers of bacteria bound per VEC were counted on a scintillation counter.

RESULTS

The E. coli adhered to the VEC and the adherence was inhibited in the presence of 100-mM mannose solution. Clinical donor UTI histories were reflected in the binding characteristics of the VEC cell lines, with cells from patient 1 having a 30% higher baseline binding capacity than cells from patient 2 and an enhanced binding response in the presence of increasing sIgA concentrations. The sIgA concentration did not affect the patient 2 cell-bacterial binding.

CONCLUSIONS

These results indicate that our in vitro model is suitable for studying the factors influencing bacterial adherence to vaginal mucosa, and that after immortalization, vaginal mucosa maintains clinically relevant characteristics that can be studied. Our data suggest that E. coli adherence to vaginal mucosa from postmenopausal women susceptible to UTI is affected by intrinsic baseline bacterial binding capacity of the mucosa cells as well as by increased sIgA concentration in the women's vaginal fluid. Increasing vaginal fluid sIgA concentration in this population may have a deleterious rather than beneficial effect.

Peptide display on bacterial flagella: principles and applications

Expression of foreign peptides as fusions to bacterial cell surface proteins has gained increasing attention in basic, as well as applied research during the last decade. A wide range of heterologous peptides have been expressed, and the spectrum of available carrier proteins is also wide. The choice of carrier protein is frequently ruled by the application of the fusion protein constructed. This review is focused on flagella display, which is based on genetic fusion of foreign peptides into a surface-exposed, dispensable region of flagellin, the flagellar major subunit present in thousands of copies per filament. Expression of these constructs in flagellin-deficient host strains results in hybrid flagella carrying the heterologous peptides in thousands of intimately-associated copies. The first and still most frequent application of flagella display is the construction of novel recombinant vaccines. Flagella display has also been used in peptide display as an alternative to the phage-display technique. One application involves fusion into a disulfide loop of Escherichia coli thioredoxin that has been inserted into flagellin, this system facilitates expression of random peptides in a conformationally constrained manner readily accessible on the flagellar surface. The random peptide library has been applied in antibody epitope mapping and is suitable for biopanning procedures in the study of ligand-receptor interactions. Many bacterial adhesins are of complex nature and thereby difficult to analyse by conventional methods. Direct flagella display has proven to be applicable also in bacterial adhesion technology since large fragments, up to 302 amino acid residues in length, of bacterial adhesins can be functionally expressed as fusions to flagellin. Hybrid flagella are easily purified and can easily be analysed for binding to various targets, such as immobilized proteins, tissue sections, as well as cell cultures.

Host defense mechanisms in urinary tract infections

The host response to urinary tract infections is directed against both bacterial surface antigens, as well as bacterial products. The local response is perhaps the most important, with prevention of binding and tissue invasion as the hallmarks. Once an infection is established, the humoral immune system is most active in curtailing the damage and clearing the infecting organism. The prostate has a specialized complex of defenses that serves to reduce the incidence of infections in males.

Bladder infection in the menopausal monkey

PURPOSE

The highest incidence of urinary tract infection in females occurs in elderly women. This study was done to determine whether this is due to the declining immune response that occurs during advancing age, or the menopausal state in the aged.

MATERIALS AND METHODS

Adult female monkeys (average age 19 years) were studied, half being subjected to bilateral oophorectomy to produce the menopause. In addition, old females (average age 29 years) already at menopause were studied before and after hormonal replacement with estradiol and progesterone. Bacterial adherence to vaginal cells was studied prior to and after urethral infection with E. coli. Plasma estradiol and progesterone levels were done, as well as white blood counts, plasma cytokine assays and serum antibody titers.

RESULTS

Bacteriuria was not prolonged, nor was there a significant difference in bacterial adherence to vaginal cells due to menopause. Interleukin-1 levels were depressed after surgical menopause but not as much as found in the old menopausal females and this low level was not corrected by hormonal replacement. The initial interleukin-2 levels were higher after spontaneous menopause, but the increasing plasma levels seen in cycling animals after infection did not occur in the aged menopausal females following infection even after hormone replacement. The antibody titers to the E. coli infection showed a trend to a lessened response to infection after menopause but were not significantly decreased.

CONCLUSIONS

The deficient Il-1, Il-2 and antibody response following infection was not corrected by hormone replacement and thus appears to be due to aging rather than lack of female hormones. These facts may be explained by the T cell senescence known to occur in aged individuals.

Pathogenesis of urinary tract infection. Role of host defenses

In the last decade, there have been modest strides made in our understanding of the pathogenesis of urinary tract infections (UTIs). Matching the advances achieved in unraveling the complexities of bacterial virulence factors using molecular-genetic techniques has been a parallel increase in knowledge of host defense mechanisms. Host susceptibility to UTI in the past has been predominantly studied in patients with structural (obstruction) or functional abnormalities (diabetes mellitus); however, most patients with UTIs have no such demonstrable abnormalities, hence attention has now focused on host behavioral factors in addition to genetically determined cellular mechanisms that predispose to sporadic and recurrent UTI.

Induction of protective immunity after escherichia coli bladder infection in primates. Dependence of the globoside-specific P-fimbrial tip adhesin and its cognate receptor

Clinical observations suggest that immune mechanisms affect etiology and course of recurrent cystitis. A primate infection model was used to show that primary bladder infection with a uropathogenic P-fimbriated strain (binding to globoside present in the bladder wall) protects against rechallenge with homologous as well as heterologous Escherichia coli strains for up to 5-6 mo. In contrast, mutant derivatives producing P-fimbriae either lacking the tip adhesin protein or carrying an adhesin for which no bladder receptor was present, were unable to induce protection, even though they generated bladder infections of similar duration as the wild type. Therefore, the protective effect mediated by the adhesin seemed to depend upon the presence of its cognate receptor. Since the wild strain also mediated protection against mutants that lacked the adhesin, our data suggest that the globoside-binding PapG adhesin acts as an adjuvant during infection to enhance a specific response against other bacterial antigens. In fact, the globoside-binding strain DS17, but not the mutant DS17-1, unable to bind to membrane-bound globoside, elicited a secretory IgA response to LPS in urine. These in vivo findings suggest that bacterial adhesin-ligand interactions may have signaling functions of importance for the immune response.

Use of transfer factor for the treatment of recurrent non-bacterial female cystitis (NBRC): a preliminary report

Results of conventional treatment of female non-bacterial recurrent cystitis (NBRC) are discouraging. Most patients show an unexpected high incidence of vaginal candidiasis, while their cell mediated immunity to Herpes simplex viruses (HSV) and Candida antigens seems impaired, and it is known that the persistence of mucocutaneous chronic candidiasis is mainly due to a selective defect of CMI to Candida antigens. Twenty nine women suffering of NBRC, and in whom previous treatment with antibiotics and non-steroid anti-inflammatory drugs was unsuccessful, underwent oral transfer factor (TF) therapy. TF specific to Candida and/or to HSV was administered bi-weekly for the first 2 weeks, and then once a week for the following 6 months. No side effects were observed during treatment. The total observation period of our cohort was 24379 days with 353 episodes of cystitis recorded and a cumulative relapse index (RI) of 43. The observation period during and after treatment was 13920 days with 108 relapses and a cumulative RI of 23 (P < 0.0001). It, thus, seems that specific TF may be capable of controlling NBRC and alleviate the symptoms.

Antibacterial activity of the bladder mucosa

Antibacterial activity of bladder mucosa is believed to be a host defense against infection. In this study we examined the antibacterial activity of the bladder mucosa without the effect of voiding. In addition we examined whether the property of adherence was advantageous for the organism in contact with the bladder mucosa. For this, three adhering and three nonadhering strains of E. coli were placed in contact with the bladder mucosa for 4 h in an in vivo rabbit model. E. coli grown in broth and applied to 32 bladders increased in titer by 1 log. E. coli grown in rabbit urine and applied to seven bladders increased in titer by 1.2 log. In contrast E. coli inoculated into control vials containing broth increased in titer by 2.3 log (P = 0.01). There was no significant difference in the titer between adhering and nonadhering strains of E. coli after 4 h of contact with the bladder mucosa. Bladder mucosa may have an inhibitory effect on bacterial growth (regardless of adherence characteristics) and with urine flow serves to prevent infection of the bladder urine.

Vesicoureteral reflux and pyelonephritis in the monkey: a review

P-fimbriated Escherichia coli, which cause nonobstructive pyelonephritis, adhere to a specific urothelial glycolipid receptor. In either the presence or absence of reflux (in the area of turbulent urine flow) these bacteria ascend the ureter and cause a decrease in ureteral motility. Endotoxin causes peristalsis to cease, leading to ureteral dilatation and change in papillary shape, thus allowing intrarenal reflux and adherence of the bacteria to renal tubules. Bacterial infection of a refluxing ureter may cause reflux to persist. Once the bacteria reach the kidney rapid effects occur at the cellular level with activation of complement followed by granulocytic aggregation and capillary obstruction, causing renal ischemia and damage during reperfusion. In addition, during phagocytosis the respiratory burst occurs, releasing toxic oxygen molecules, which leads to renal tubular death, invasion of the interstitium, microabscess and renal scar formation, that is chronic pyelonephritis, which equates with reflux nephropathy.

Urinary tract infections in the 90s: pathogenesis and management

Urinary tract infections are one of the most common types of infection encountered in the practice of medicine. Recent discussions have focused on our current knowledge of natural host defenses that function during normal physiologic conditions in an attempt to prevent urinary infections. However, increased susceptibility to these infections may result from intrinsic risk factors that alter host defenses, or from extrinsic risk factors. Advances in the treatment of urinary infections have focused on short course therapy for women with uncomplicated lower tract infections, and on oral therapy in women with mild acute uncomplicated pyelonephritis. Also, in the area of prevention, reasonable candidates for antimicrobial prophylaxis have been identified. Even so, further studies are needed to define more clearly our understanding of the pathogenesis, treatment, and prevention of infections of the urinary tract.

Impact of site release vaginal pH buffer cream on introital colonization by gram-negative bacilli

Colonization of the vaginal introitus by gram-negative bacilli is a critical event in the pathogenesis of bacteriuria and is promoted by an abnormal pH elevation. To determine whether a pH reduction might inhibit colonization we conducted a placebo controlled, crossover study of a site release vaginal pH buffer cream. A total of 12 premenopausal women with a history of urinary tract infection participated in the 12-week investigation. The mean introital pH during application of the placebo and buffer was 4.87 and 4.61, respectively (p less than 0.01). However, the percentage of positive introital cultures during application of the placebo and buffer (40.3 and 35.3, respectively) and the mean density of colonization (23,600 and 22,700 bacteria per ml., respectively) were not significantly different. The percentage of positive introital cultures and the mean colonization density were also not different during application of the placebo and buffer when the patients were retrospectively stratified as light and heavy colonizers. These data suggest that alteration of the introital pH within a range of 4.5 to 5.0 does not influence the growth of uropathogens on the vaginal mucosa.

Virulence factors in Escherichia coli urinary tract infection

Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans.

Secretory immunoglobulin A and inhibitory activity of bacterial adherence to epithelial cells in urine from patients with urinary tract infections

To assess the role of local immune response against bacterial invasion of the urinary tract we studied 168 patients with bacteriuria. Urinary secretory immunoglobulins A (sIgA) were measured using radial immunodiffusion or enzyme-linked immunosorbent assay (ELISA). In particular, ELISA is a very suitable assay for measuring the low levels of sIgA in urine. Furthermore, we used a quantitative in vitro adherence assay to investigate the attachment of Escherichia coli to human uroepithelial cells after incubation in urine from patients with urinary tract infection. Urine from patients with ileocystoplasty was significantly more potent in inhibiting bacterial adherence than was urine from other groups of patients with urinary tract infection. The presence of high urinary sIgA may help explain the increased antiadherence activity of urine in patients with ileocystoplasty. Mean urinary sIgA in patients with upper urinary tract infection was higher than in patients with uncomplicated infection in the lower urinary tract. Alterations in mucosal immune functions may account for the propensity toward bacterial colonization in women prone to uncomplicated urinary tract infection.

P blood group and proneness to urinary tract infection in Japanese children

The globoseries of glycolipids are antigens in the P blood group system as well as epithelial cell receptors for uropathogenic Escherichia coli. The P1 blood group is overrepresented in Swedish girls with recurrent pyelonephritis. In this study, Japanese children with urinary tract infection (UTI) were analyzed for P blood group phenotype. Out of 26 children with recurrent UTI, 50% were of the P1 blood group compared to the 31% of P1 individuals in the Japanese population at large (p less than 0.05). Of children defined as having febrile UTI 62% were P1. The P1 blood group was thus significantly enriched (3.5 times) in the children with febrile UTI. These results support the hypothesis that individuals of blood group P1 run an increased risk for recurrent pyelonephritis.

Virulence of wild-type E. coli uroisolates in experimental pyelonephritis

This study was designed to analyze the colonizing and invasive properties of wild-type bacteriuric E. coli possessing a variety of phenotypic characteristics in experimental nonobstructive pyelonephritis (P and Type 1 [T] fimbriae, hemolysin [Hly], presence of K capsules, flagella [H], serotype, biotype, human and mouse serumcidal resistance). Special emphasis was on the role of Gal-Gal adhesin (P fimbriae) of non-genetically engineered uroisolates. It was shown that organisms that are P+ or T+ or Hly+ are more likely to colonize bladders than strains negative for those parameters (P less than 0.001). Additionally, P+ strains were more often associated with kidney histopathology than P- E. coli (P less than 0.05). However, the data also indicated that fimbriae (P and Type 1) were not sole determinants of virulence since two strains devoid of fimbriae, hemolysin, K capsules and sensitive to human serumcidal activity caused incipient and acute pyelonephritis. Even among identical serotypes and biotypes, the presence/absence of fimbriae did not appear to be the critical factor in urovirulence, nor did the presence of several positive characteristics (hemolysin, K capsule, flagella, serum resistance) in a given strain enhance uropathogenicity. Therefore, these properties do not need to work together to render an E. coli urovirulent. These phenotypic characters may simply represent associated or serologic markers with the host serving as the dominant determinant of susceptibility to urinary infection. The findings emphasize the inherent limitations in relating and extrapolating colonizing and invasive properties of genetically engineered strains to those of naturally occurring, wild-type E. coli human uroisolates causing pyelonephritis.

Adherence of bacteria to human foreskins

The mucosal surface of the human foreskin from newborns shows a propensity to be colonized by pathogenic bacteria. Bacteria with P fimbriae and type 1 fimbriae adhere. However, hydrophobic interaction as well as electrostatic charge appear to be as important in this adherence as are fimbriae. Since bacterial adherence has been shown to precede urinary tract infection in female patients it is assumed that this adherence to the foreskin in male patients also may be necessary before initiation of the disease. The high incidence of urinary tract infection in uncircumcised male patients combined with these findings of adherence of pathogenic bacteria to the mucosal surface of the foreskin, thus, would seem to be related. Prevention of urinary tract infection and acute pyelonephritis in male neonates then may require either circumcision or the prevention of bacterial adherence to the human foreskin.

Pathogenesis of urinary tract infections--amoxicillin induces genital Escherichia coli colonization

The aim of this study was to examine whether a vaginal Escherichia coli colonization, mimicking the one seen in UTI-prone females, could be induced by amoxicillin administration. In adult cynomolgus monkeys, who carry the alpha-Gal-1-4-beta-Gal receptor for P-fimbriae, we have investigated the ability of a clinical isolate of P-fimbriated E. coli to colonize the mucous membranes of the genital tract. When the vagina was washed with a suspension of the P-fimbriated strain, a persistent colonization was obtained in only 17% (4/24) of the experiments. When such colonization attempts were performed during vaginal amoxicillin administration, a persistent and heavy colonization of the vagina occurred in 5/5 attempts. The findings do not contradict our hypothesis that antibiotics given to UTI-prone females may facilitate the establishment of the abnormal colonization of the genital tract.

P-fimbriae receptors in patients with chronic pyelonephritis

The adherence of fluorescein isothiocyanate-labeled P-fimbriated Escherichia coli to uroepithelial cells from 19 women with chronic pyelonephritis was determined with the fluorescence-activated cell sorting technique. The application of this method has made it possible to study bacterial binding to a large number of cells. Renal function was determined in all patients and the recurrences of P-fimbriated Escherichia coli bacteriuria, cystitis and acute pyelonephritis during a 3-year followup were studied. We found a significant correlation between the P-fimbriae receptor accessibility on uroepithelial cells and glomerular filtration rate (r equals -0.75, p less than 0.001). Uroepithelial cells from the patients with chronic pyelonephritis and renal insufficiency had a higher binding capacity of P-fimbriated Escherichia coli than uroepithelial cells from patients with a normal glomerular filtration rate. There was no correlation between kidney function and the availability of P-fimbriae receptors in a control group of patients with polycystic kidney disease.

The ecology and pathogenicity of urease-producing bacteria in the urinary tract

Urease activity is a physiological function of many bacteria that enables these organisms to utilize urea as a source of nitrogen. The association of ureolytic bacteria with human or animal hosts varies widely from a commensal relationship as demonstrated with skin microflora, a symbiotic relationship in the gastrointestinal tract, to a pathogenic relationship in the urinary tract. Since similar or identical species of bacteria such as Staphylococcus aureus are found in all three environments, the effect of urease activity on the host must be solely a function of the environment of these organisms. In this review, the importance of urease to bacteria is discussed, identifying the gastrointestinal tract as a major reservoir of ureolytic bacteria and investigating the urinary tract environment and the infectious struvite stone production that often accompanies urease-producing bacteria there. Finally, an infection model is presented which explains the development and growth of these urinary calculi and their remarkable persistence in spite of modern urological treatments.

Host parasite interaction in urinary tract infection

The last decade has provided new insight into the mechanisms of host-parasite interactions in the urinary tract. Reduction of host resistance appears to reduce the requirement for bacterial virulence, whereas the resistant host becomes infected with bacteria of high virulence. In the resistant host, bacterial virulence can be defined as the sum of properties required to colonize the urinary tract and induce tissue reactions. The ability to attach to uroepithelial cells is the single property most frequently associated with pyelonephritogenic clones. Attachment to the Gal alpha 1-4Gal beta-containing receptors promotes localization of bacteria to the kidney and the induction of lipopolysaccharide-mediated inflammation. Other virulence factors, defined by increased frequency in acute pyelonephritis compared with asymptomatic bacteriuria, include haemolysin and aerobactin production. Among the factors which influence the natural resistance to urinary tract infection are urinary flow and reactivity to endotoxin. The resistance induced by natural exposure to infection or immunization may be protective in experimental models, but the importance of this is not yet defined. The localization, severity and sequelae of urinary tract infection are determined by the balance between bacterial virulence and host resistance. Although disease is a result of the interaction between bacterial virulence and host resistance, these components are discussed separately for clarity.

P-fimbriated Escherichia coli in children with acute cystitis

P-fimbriation of Escherichia coli is an important factor in the pathogenesis of childhood pyelonephritis. The present study investigates children with single episodes of symptomatic non-febrile urinary tract infection, i.e. cystitis, with respect to clinical appearance and bacteriology, especially the frequency of P-fimbriated E. coli. The study included 75 children, 57 of whom had their first attack of urinary tract infection. E. coli was the causative agent in 88% (66/75) of the infections, and 48% (32/66) of E. coli strains were P-fimbriated. No association was found between identification of P-fimbriated E. coli at index infection and proneness to reinfection during the following six-month period. It is suggested that P-fimbriated E. coli is a virulence factor even in lower urinary tract infections, when occurring in single, symptomatic episodes.

Interaction of urinary Tamm-Horsfall protein with transitional cells and transitional epithelium

Uropathogenic E. coli that express mannose sensitive adhesins adhere to agglutinated urinary Tamm-Horsfall protein (THP) and to exfoliated transitional epithelial cells coated with THP. Whether THP interacts with the transitional epithelium in vivo and facilitates adhesin mediated attachment of E. coli is not known. Using immunohistochemical techniques we could not identify THP associated with formalin-fixed, paraffin-embedded transitional epithelium from a variety of sites within the urinary tract. However, varying levels of THP associated with the washed exfoliated transitional cells from 10 different subjects were detected by indirect radioimmunoassay methodologies. After in vitro incubation in human urine the mean interaction of THP with the exfoliated transitional cells increased significantly but closely paralleled the mean interaction of THP with exfoliated vaginal and buccal epithelial cells after identical incubation. We conclude that the interaction of THP with transitional cells in vivo is nonspecific and occurs after detachment from the mucosa. THP may act as a natural host defense against E. coli bacteriuria by inhibition of adhesion mediated bacterial adherence to the urothelium.

Symptomatic recurrent urinary tract infections in patients with renal scarring in relation to fecal colonization with P-fimbriated Escherichia coli

We evaluated prospectively 49 women with renal scarring and a history of febrile urinary tract infections in regard to the incidence of recurrent symptomatic urinary tract infection and fecal colonization with P-fimbriated Escherichia coli. During a 3-year followup 26 patients (53 per cent) had symptomatic urinary tract infection (0.036 infections per patient-month), including 8 (16 per cent) who had 9 new episodes of febrile urinary tract infection, while 33 (67 per cent) had Escherichia coli bacteriuria (10(5) bacteria per ml. urine in pure culture). Thus, patients with previous febrile urinary tract infections and renal scarring have a high risk for recurrent infections. For comparison, the incidence of symptomatic urinary tract infection also was determined in 35 women with a recent episode of acute nonobstructive pyelonephritis and with normal kidneys on excretory urography. These patients had 0.031 symptomatic infections per patient-month. The fecal flora were examined twice a year for P-fimbriated Escherichia coli in 48 patients with renal scarring. Of these patients 21 (44 per cent) had at least 1 fecal colonization with a P-fimbriated Escherichia coli strain. However, in only 1 instance was a relationship detected between the presence of P-fimbriated Escherichia coli in the fecal flora and the development of subsequent febrile urinary tract infection. The findings indicate that fecal sampling twice a year is not of value to predict future urinary tract infections in adults with renal scarring.

Vaginal immunization against induced cystitis in monkeys

Cynomolgus monkeys received either vaginal immunization with formalin-killed E. coli or vaginal instillation of excipient without the bacteria. At 2, 7, 14 and 21 days after induction of a urinary tract infection with live E. coli, immunized monkeys showed enhanced clearance of bacteriuria compared to non-immunized controls. Immunized monkeys also showed increased levels of urinary anti-E. coli IgA and IgG after the immunizing and infecting procedures. Induction of heightened local immunity by vaginal immunization may lessen host susceptibility to urinary tract infections.

Fluorescence-activated cell analysis of P-fimbriae receptor accessibility on uroepithelial cells of patients with renal scarring

Pyelonephritogenic Escherichia coli possess P-fimbriae that bind to uroepithelial cells by recognizing a receptor containing the alpha-D-Galp-(1-4)-beta-D-Galp carbohydrate structure. The accessibility of P-fimbriae receptors was determined using uroepithelial cells from 19 female patients with verified renal scarring and a history of febrile urinary tract infection, and 13 healthy controls. The binding of fluorescein isothiocyanate labeled P-fimbriated Escherichia coli to a large number of uroepithelial cells from each individual was studied using the method of fluorescence-activated cell sorting analysis, which allows examination of a large number of cells and selection of cells of a given size. The uroepithelial cells from the patients exhibited a significantly higher binding capacity to P-fimbriated Escherichia coli than did uroepithelial cells from healthy controls (p less than 0.01). The determination of P-fimbriae receptor accessibility on uroepithelial cells may be useful for detecting risk groups among patients with recurrent urinary tract infections.

Localization of binding sites for purified Escherichia coli P fimbriae in the human kidney

Binding sites in the human kidney for purified P fimbriae of pyelonephritogenic Escherichia coli were determined. The purified KS71A (F7(1)) fimbriae bound only to epithelial elements of the kidney, i.e., to the apical aspect of proximal and distal tubular cells, as well as to the apical and cytoplasmic sites of collecting ducts. In addition, binding was seen at the vascular endothelium throughout the kidney and at the parietal epithelium of the glomeruli. The binding was specifically inhibited by the receptor analog of E. coli P fimbriae, globotriose. The binding sites identified suggested a possible pathogenetic mechanism for the invasion of P-fimbriated bacteria into the renal parenchyma, as well as for their subsequent spread into the circulatory system.

Binding of Escherichia coli S fimbriae to human kidney epithelium

Purified S fimbriae and an Escherichia coli strain carrying the recombinant plasmid pANN801-4 that encodes S fimbriae were tested for adhesion to frozen sections of human kidney. The fimbriae and the bacteria bound to the same tissue domains, and in both cases the binding was specifically inhibited by the receptor analog of S fimbria, sialyl(alpha 2-3)lactose. S fimbriae bound specifically to the epithelial elements in the kidneys; to the epithelial cells of proximal and distal tubules as well as of the collecting ducts and to the visceral and parietal glomerular epithelium. In addition, they bound to the vascular endothelium of glomeruli and of the renal interstitium. No binding to connective tissue elements was observed. The results suggest that the biological function of S fimbriae is to mediate the adhesion of E. coli to human epithelial and vascular endothelial cells.