Virulence of Escherichia coli in relation to host factors in women with symptomatic urinary tract infection

α-Hemolysin promotes uropathogenic E. coli persistence in Bladder epithelial cells Via abrogating bacteria-harboring lysosome acidification

There is a growing consensus that a significant proportion of recurrent urinary tract infections are linked to the persistence of uropathogens within the urinary tract and their re-emergence upon the conclusion of antibiotic treatment. Studies in mice and human have revealed that uropathogenic Escherichia coli (UPEC) can persist in bladder epithelial cells (BECs) even after the apparent resolution of the infection. Here, we found that, following the entry of UPEC into RAB27b+ fusiform vesicles in BECs, some bacteria escaped into the cytoplasmic compartment via a mechanism involving hemolysin A (HlyA). However, these UPEC were immediately recaptured within LC3A/B+ autophagosomes that matured into LAMP1+ autolysosomes. Thereafter, HlyA+ UPEC-containing lysosomes failed to acidify, which is an essential step for bacterial elimination. This lack of acidification was related to the inability of bacteria-harboring compartments to recruit V-ATPase proton pumps, which was attributed to the defragmentation of cytosolic microtubules by HlyA. The persistence of UPEC within LAMP1+ compartments in BECs appears to be directly linked to HlyA. Thus, through intravesicular instillation of microtubule stabilizer, this host defense response can be co-opted to reduce intracellular bacterial burden following UTIs in the bladder potentially preventing recurrence.

Masquerading microbial pathogens: capsular polysaccharides mimic host-tissue molecules

The increasing prevalence of antibiotic-resistant bacteria portends an impending postantibiotic age, characterized by diminishing efficacy of common antibiotics and routine application of multifaceted, complementary therapeutic approaches to treat bacterial infections, particularly multidrug-resistant organisms. The first line of defense for most bacterial pathogens consists of a physical and immunologic barrier known as the capsule, commonly composed of a viscous layer of carbohydrates that are covalently bound to the cell wall in Gram-positive bacteria or often to lipids of the outer membrane in many Gram-negative bacteria. Bacterial capsular polysaccharides are a diverse class of high molecular weight polysaccharides contributing to virulence of many human pathogens in the gut, respiratory tree, urinary tract, and other host tissues, by hiding cell surface components that might otherwise elicit host immune response. This review highlights capsular polysaccharides that are structurally identical or similar to polysaccharides found in mammalian tissues, including polysialic acid and glycosaminoglycan capsules hyaluronan, heparosan, and chondroitin. Such nonimmunogenic coatings render pathogens insensitive to certain immune responses, effectively increasing residence time in host tissues and enabling pathologically relevant population densities to be reached. Biosynthetic pathways and capsular involvement in immune system evasion are described, providing a basis for potential therapies aimed at supplementing or replacing antibiotic treatment.

Do Escherichia coli strains causing acute cystitis have a distinct virulence repertoire?

Bacterial virulence factors influence the site and severity of urinary tract infections. While pyelonephritis-associated molecular traits have been defined, virulence factors specific for acute cystitis strains have not been identified. This study examined the virulence factor repertoire of 247 Escherichia coli strains, prospectively isolated from women with community-acquired acute cystitis. Fim sequences were present in 96% of the isolates, which also expressed Type 1 fimbriae. Curli were detected in 75%, 13% of which formed cellulose. Pap sequences were present in 47%, 27% were papG+, 23% were prsG+ and 42% expressed P fimbriae. TcpC was expressed by 33% of the strains, 32% in a subgroup of patients who only had symptoms of cystitis and 42% in patients with signs of upper urinary tract involvement; most frequently by the papG+/prsG+ subgroup. Strains with the full fim, pap and TcpC and curli virulence profile were more common in cystitis patients with than in patients without upper tract involvement (p < 0.05). The varied virulence profile of E. coli strains causing acute cystitis suggests that diverse bacterial strains, expressing Type 1 fimbriae trigger a convergent host response, involving pathways that give rise to the characteristic symptoms of acute cystitis.

A systematic review of outbreak and non-outbreak studies of extraintestinal pathogenic Escherichia coli causing community-acquired infections

A systematic review of outbreak and non-outbreak studies of infections caused by extraintestinal pathogenic Escherichia coli (ExPEC) was conducted. This review examines the epidemiology, seasonality, source or mode of transmission, and temporal changes, based on E. coli serogroup, in ExPEC causing sporadic vs. outbreak-associated infections. Twelve outbreak and 28 non-outbreak studies were identified. The existence of ExPEC outbreaks was well supported. Three of four outbreak reports indicated peak periods during the winter months. Serogroups associated with outbreak infections ranged from 1% to 26% (average 11·4%) vs. (range 1-15%, average 3·5%) for serogroups associated with sporadic infections; the distribution of serogroups also differed for outbreak and non-outbreak infections. Study authors indicated that the outbreaks may have resulted from foodborne transmission, but direct evidence was unavailable. This review provides evidence that the epidemiology of endemic vs. epidemic ExPEC infections differs; however, study reporting quality limited epidemiological inferences.

Pelvic floor dysfunction is not a risk factor for febrile urinary tract infection in adults

OBJECTIVE

To determine whether pelvic floor dysfunction (PFD) might be a risk factor for or consequence of febrile urinary tract infection (UTI), as UTI in adults is a common infection in which an underlying urological abnormality is often considered, and as in children, PFD is also thought to have a pathophysiological role in adults with UTI.

PATIENTS AND METHODS

A multicentre case-control study was conducted at 26 primary-care centres and at six Emergency Departments of regional hospitals. Cases were consecutive patients aged > or =18 years, who presented with febrile UTI. Controls were randomly selected subjects who visited their general practitioner for reasons other than UTI or fever. A validated pelvic floor questionnaire (the Pelvic Floor Inventories Leiden, PelFIs) was used to assess pelvic floor function.

RESULTS

Between October 2006 and December 2007, 153 cases were included; of these, the completed questionnaires of 102 (response rate 67%) were compared to those of 100 of 110 (response rate 91%) controls. The median age of cases and controls was 65 and 58 years, respectively; 40% of cases and controls were men. The percentage of PelFIs outcomes consistent with PFD were comparable between cases and controls, at 21% vs 23%, respectively (odds ratio 0.9, 95% confidence interval, CI, 0.4-1.78). In the multivariate analysis, comorbidity (odds ratio 4.9, 95% CI 2.2-11.1) and a history of UTI (odds ratio 2.5, 95% CI 1.0-6.1) were independent significant risk factors for febrile UTI, whereas PFD was not (odds ratio 1.0, 0.5-2.2). Within the group of cases, PFD was not associated with bacteriuria during assessment of PelFIs (odds ratio 1.1, 95% CI 0.4-3.5) and inversely related to a history of UTI within the previous year (odds ratio 0.2, 0.1-0.9).

CONCLUSIONS

PFD is common among adults but it does not seem to be a risk factor for febrile UTI.

Uropathogenic Escherichia coli

The urinary tract is among the most common sites of bacterial infection, and Escherichia coli is by far the most common species infecting this site. Individuals at high risk for symptomatic urinary tract infection (UTI) include neonates, preschool girls, sexually active women, and elderly women and men. E. coli that cause the majority of UTIs are thought to represent only a subset of the strains that colonize the colon. E. coli strains that cause UTIs are termed uropathogenic E. coli (UPEC). In general, UPEC strains differ from commensal E. coli strains in that the former possess extragenetic material, often on pathogenicity-associated islands (PAIs), which code for gene products that may contribute to bacterial pathogenesis. Some of these genes allow UPEC to express determinants that are proposed to play roles in disease. These factors include hemolysins, secreted proteins, specific lipopolysaccharide and capsule types, iron acquisition systems, and fimbrial adhesions. The current dogma of bacterial pathogenesis identifies adherence, colonization, avoidance of host defenses, and damage to host tissues as events vital for achieving bacterial virulence. These considerations, along with analysis of the E. coli CFT073, UTI89, and 536 genomes and efforts to identify novel virulence genes should advance the field significantly and allow for the development of a comprehensive model of pathogenesis for uropathogenic E. coli.Further study of the adaptive immune response to UTI will be especially critical to refine our understanding and treatment of recurrent infections and to develop vaccines.

PapG II adhesin in the establishment and persistence of Escherichia coli infection in mouse kidneys

Most human pyelonephritogenic Escherichia coli express the PapG II adhesin. However, the role of the PapG II adhesin in enhancing the establishment and persistence of E. coli infection in the kidney is controversial. A pyelonephritogenic strain, EC114, which possesses one copy of the papG II gene, but without other virulence factors (such as S/F1C-fimbriae, hemolysin, and cytotoxic necrotizing factor 1) was selected for the construction of a papG II mutant. The resulting papG II mutant was confirmed by polymerase chain reaction, Southern hybridization, and agglutination assay, and designated as MEC114. We compared MEC114 with the parental strain (EC114) for colonization ability in the bladder and kidney of female BALB/c mice, which were challenged transurethrally with 50 microl of a low (5x10(4) CFU (colony-forming unit)) or high (5x10(8) CFU) dose of EC114 or MEC114 and assessed 1, 3, and 7 days after inoculation. Geometric means of quantitative bacterial counts in the kidney were significantly decreased when challenged with MEC114 on day 3 after inoculation, at both low and high dose (P<0.05), as compared with EC114. On the seventh day, both strains were mainly cleared from the kidney. Renal biopsy showed a similar degree of inflammatory response to both strains 1, 3, and 7 days after inoculation. In brief, the PapG II adhesin can enhance the early establishment of E. coli infection in the kidney, but the bacteria do not maintain infection owing to the host immune response.

Escherichia coli isolates associated with uncomplicated and complicated cystitis and asymptomatic bacteriuria possess similar phylogenies, virulence genes, and O-serogroup profiles

The genetic and serological characteristics of Escherichia coli isolates from patients with uncomplicated cystitis (UC), complicated cystitis (CC), and complicated asymptomatic bacteriuria (CASB) were determined. Phylogenetic group B2 was predominant in all categories. The prevalences of 14 out of 18 virulence factor genes were similar among the three categories, while pap, iha, ompT, and PAI were more frequently seen in isolates associated with UC than CC or CASB.

Virulence factors of uropathogenic Escherichia coli from a University Hospital in Ribeirão Preto, São Paulo, Brazil

The aim of the study was to determine the occurrence of virulence genes expressing fimbriae, production of hemolysin, colicin and aerobactin among a hundred Escherichia coli isolates obtained from in-and outpatients of a tertiary-care teaching hospital, between July and August 2000, showing clinical and laboratory signs of urinary tract infection (UTI). The presence of genes (pap, afa, sfa) for fimbriae expression was assayed using specific primers in a polymerase chain reaction. Among the isolates studied, the prevalence of the virulence factors was 96.0%, 76.0%, 24.0%, for hemolysin, aerobactin and colicin, respectively; the prevalence of genes coding for fimbrial adhesive systems was 32.0%, 19.0% and 11.0% for pap, sfa and afa respectively. The strains isolated from the outpatients displayed a greater number of virulence factors compared to those from hospitalized subjects, emphasizing the difference between these two kinds of patients.

Escherichia coli, fimbriae, bacterial persistence and host response induction in the human urinary tract

Urinary tract infections (UTI) are among the most common bacterial infections in humans. Symptomatic UTIs may be acute, recurrent or chronic but the most frequent form of UTI is asymptomatic bacteruria (ABU). In ABU, the mucosa remains inert, despite the presence of large bacterial numbers in urine. The difference in disease severity reflects the virulence of the infecting strain and the propensity of the host to respond to infection. It is essential to understand the molecular basis of disease diversity and the molecular interactions between bacteria and host that determine asymptomatic carriage and the transition to disease. We discuss the initial interactions between bacteria and the mucosal surfaces in the human urinary tract, and the bacterial factors involved in the breach of mucosal inertia. Specifically, the contribution of P and type 1 fimbriae to bacterial establishment and host response induction are investigated. The results show that P fimbriae serve as independent virulence factors when expressed by an ABU strain, by promoting the establishment of bacteriuria and the innate host response, which is the cause of symptoms and tissue damage. P fimbriae thus fulfil the molecular Koch postulates as independent virulence factors in the human urinary tract. Type 1 fimbriae, in contrast, did not act as virulence factors in this model, and thus appear to serve a different function in man than in the murine model.

In vitro and in vivo effects of soluble, monovalent globotriose on bacterial attachment and colonization

Epithelial cells lining the urinary tract are rich in globo series glycolipids, structurally defined by a Galalpha1,4Gal motif in the oligosaccharide moiety of this glycolipid family. This Galalpha1,4Gal motif is the attachment target for the P-fimbrial adhesin of uropathogenic Escherichia coli. We investigated the ability of a trisaccharide analog of this core motif, globotriose (Galalpha1,4Galbeta1,4Glc), to interfere with uropathogen attachment and colonization in vitro and in vivo. We assessed the ability of globotriose to inhibit and reverse the binding and agglutination of a P-fimbriated strain of E. coli (JR1) using human erythrocytes and immortalized human colonic epithelial cells as targets. Globotriose (5 mg/ml) completely inhibited and reversed cell agglutination and caused a 10- to 100-fold reduction in JR1 binding to target cells, as determined by flow cytometry. In preparation for an in vivo efficacy study, we investigated the distribution and pharmacokinetics of globotriose in the BALB/c mouse. Globotriose was administered via the tail vein, targeting an instantaneous plasma concentration of 5 mg/ml, and in a different experiment, animals were gavaged at 10 times the intravenous (i.v.) dose. Globotriose was rapidly cleared from plasma (half-life [t1/2], 6 min) and slowly excreted via the kidney (t1/2, 4 h). Urine levels of >5 mg/ml were maintained from 4 to 12 h after the i.v. bolus dose, which resulted in a 1-log reduction in established bladder colonization by JR1. These results suggest that free, soluble globotriose is a feasible alternative therapy for urinary tract infections.

The pathogenicity island-associated K15 capsule determinant exhibits a novel genetic structure and correlates with virulence in uropathogenic Escherichia coli strain 536

The K15 capsule determinant of uropathogenic Escherichia coli strain 536 (O6:K15:H31) is part of a novel 79.6-kb pathogenicity island (PAI) designated PAI V536 that is absent from the genome of nonpathogenic E. coli K-12 strain MG1655. PAI V536 shows typical characteristics of a composite PAI that is associated with the pheV tRNA gene and contains the pix fimbriae determinant as well as genes coding for a putative phosphoglycerate transport system, an autotransporter protein, and hypothetical open reading frames. A gene cluster coding for a putative general secretion pathway system, together with a kps(K15) determinant, is localized downstream of a truncated pheV gene ('pheV) also present in this chromosomal region. The distribution of genes present on PAI V536 was studied by PCR in different pathogenic and nonpathogenic E. coli isolates of various sources. Analysis of the 20-kb kps locus revealed a so far unknown genetic organization. Generally, the kps(K15) gene cluster resembles that of group 2 and 3 capsules, where two conserved regions (regions 1 and 3) are located up- or downstream of a highly variable serotype-specific region (region 2). Interestingly, recombination of a group 2 and 3 determinant may have been involved in the evolution of the K15 capsule-encoding gene cluster. Expression of the K15 capsule is important for virulence in a murine model of ascending urinary tract infection but not for serum resistance of E. coli strain 536.

Vaginal Escherichia coli share common virulence factor profiles, serotypes and phylogeny with other extraintestinal E. coli

Characteristics of Escherichia coli residing in the vagina and their role in extraintestinal infections are largely unknown. In this study, 88 vaginal E. coli (VEC) isolates from Japanese women were characterized by extraintestinal virulence factor (VF) profiling, O:H serotyping and phylogenetic analysis. The prevalence of papC, hlyA, cnfI, PAI, ibeA and K1 antigen among the VEC strains were 45, 22, 19, 78, 32 and 44%, respectively. Phylogenetic analysis identified 76, 16 and 8% of the VEC strains in groups B2, D and A, respectively. The VEC strains were distributed into 31 serotypes, including 8 common serotypes (O1:K1:H1, O1:K1:H7, O2:K1:H7, O4:H5, O6:H1, O18ac:K1:H7, O25:H1 and O75:HNM) that were identified in three or more isolates. Comparative analysis with 61 stool isolates from healthy Japanese men and women, and with data from previous studies, revealed that, although some geographical specificities do exist, the VEC strains shared common VF profiles, O:K:H serotypes and phylogeny with uropathogenic E. coli and E. coli of neonatal septicaemia and meningitis. This study provides additional evidence for a link among extraintestinal E. coli, supporting the concept that the VEC are a reservoir along the 'faecal-vaginal-urinary/neonatal' course of transmission in the extraintestinal E. coli infections.

Roles of host and bacterial virulence factors in the development of upper urinary tract infection caused by Escherichia coli

Aims of this study are to identify host and Escherichia coli virulence factors associated with upper urinary tract infection (UTI) by comparing them with those for lower UTI and determining the association between major predisposing host factors for upper UTI and urovirulence genes for E coli. Host factors and urovirulence genes of E coli associated with bacteremia in patients with upper UTI and their interactions also were studied. One hundred thirty-nine adult patients who fulfilled clinical diagnostic criteria for upper (n = 81) or lower UTI (n = 58) caused by E coli between January 1997 and December 1999 were retrospectively enrolled into this study. Old age (> or =60 years), male sex, diabetes with poor blood glucose control (ie, glycosylated hemoglobin A1C > or = 8.1%), immunosuppression, and urinary tract obstruction were more frequently associated host factors for patients with upper UTI than for those with lower UTI. Using polymerase chain reaction, the papG class II allele was detected more frequently for E coli strains isolated from patients with upper UTI than for those from patients with lower UTI (85% versus 52%; P < 0.0001). Multivariate analysis showed that diabetes with poor blood glucose control, immunosuppression, urinary tract obstruction, and papG class II allele were independently associated with upper UTI. For patients without these three predisposing host factors, the prevalence of papG class II allele was significantly greater in those with upper UTI than those with lower UTI. However, the papG class II allele was less prevalent in strains isolated from patients with upper UTI with urinary tract obstruction or with two of the three predisposing host factors. In addition, both univariate and multivariate analyses showed that old age and papG class II allele were risk factors for the development of E coli bacteremia in patients with upper UTI. In conclusion, both host and E coli virulence factors contribute to the development of upper UTI, and less virulent strains can cause upper UTI in hosts with predisposing factors.

Biological and genetic characteristics of uropathogenic Escherichia coli strains

The aim of the present study was to determine biological characteristics such as expression of fimbriae, Congo red binding, production of hemolysin and aerobactin, adhesion to HeLa and uroepithelial cells and invasion of HeLa cells by Escherichia coli isolates obtained from patients showing clinical signs of urinary tract infection (UTI). Also, the presence of genes (apa, afa, spa) for fimbria expression and cytotoxic necrotizing factors (CNF1, CNF2) was assayed using specific primers in PCR. The data obtained were compared with the clonal relationships obtained by analysis of multilocus enzyme electrophoresis (MLEE), restriction fragment length polymorphism (RFLP) of the rDNA (ribotyping) and enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). All isolates but one presented a combination of at least two of the characteristics studied, a fact suggesting the presence of pathogenicity islands (PAIs). Diffuse adherence type to HeLa cells was observed to occur in most of the strains, but adhesion to uroepithelial cells seems to be a more reliable test to verify pathogenicity. Although four strains seemed to be able to invade HeLa cells when assayed by light microscopy, electron microscopy studies demonstrated that these strains were not invasive. MLEE, RFLP and ERIC-PCR were able to group the isolates differently into main clusters that were not correlated with the presence of pathogenic traits.

In vivo dynamics of type 1 fimbria regulation in uropathogenic Escherichia coli during experimental urinary tract infection

Escherichia coli is the primary cause of uncomplicated infections of the urinary tract including cystitis. More serious infections, characterized as acute pyelonephritis, can also develop. Type 1 fimbriae of E. coli contribute to virulence in the urinary tract; however, only recently has the expression of the type 1 fimbriae been investigated in vivo using molecular techniques. Transcription of type 1 fimbrial genes is controlled by a promoter that resides on a 314-bp invertible element capable of two orientations. One places the promoter in the ON orientation, allowing for transcription; the other places the promoter in the OFF orientation, preventing transcription. A PCR-based assay was developed to measure the orientation of the invertible element during an experimental urinary tract infection in mice. Using this assay, it was found that the percentage of the population ON in urine samples correlated with the respective CFU per gram of bladder (P = 0.0006) but not with CFU per gram of kidney (P > 0.069). Cystitis isolates present in the urine of mice during the course of infection had a higher percentage of their invertible elements in the ON orientation than did pyelonephritis isolates (85 and 34%, respectively, at 24 h; P < 0.0001). In general, cystitis isolates, unlike pyelonephritis isolates, were more likely to maintain their invertible elements in the ON orientation for the entire period of infection. E. coli cells expressing type 1 fimbriae, expelled in urine, were shown by scanning electron microscopy to be densely packed on the surface of uroepithelial cells. These results suggest that expression of type 1 fimbriae is more critical for cystitis strains than for pyelonephritis strains in the early stages of an infection during bladder colonization.

Development of a long-term ascending urinary tract infection mouse model for antibiotic treatment studies

A model of ascending unobstructed urinary tract infection (UTI) in mice was developed to study the significance of the antibiotic concentration in urine, serum, and kidney tissue for efficacy of treatment of UTI in general and pyelonephritis in particular. Outbred Ssc-CF1 female mice were used throughout the study, and Escherichia coli was used as the pathogen. The virulence of 11 uropathogenic E. coli isolates and 1 nonpathogenic laboratory E. coli strain was examined. Strain C175-94 achieved the highest counts in the kidneys, and this strain was subsequently used as the infecting organism. The model gave reproducible bladder infections, i.e., bacteria were recovered from 22 of 23 control mice after 3 days, and histological examination of kidney tissue showed that of 14 infected kidneys, 7 (50%) showed major histological changes, whereas 3 of 36 uninfected kidneys showed major histological changes (P = 0.018). Once the model was established, the efficacies of different doses of cefuroxime and gentamicin, corresponding to active concentrations in urine only or in urine, serum, and kidney tissue simultaneously, were examined. All cefuroxime doses resulted in significantly lower counts in urine than control treatments, but the dose which produced concentrations of cefuroxime only in urine and not in serum or kidney tissue had no effect on kidney infection. Even low doses of gentamicin (0.05 mg/mouse) resulted in concentrations in renal tissue for prolonged times due to accumulation. All gentamicin doses had a significant effect (compared to the effect of the control treatment) on bacterial counts in urine and kidneys. The antibiotic effect on bacterial counts in bladders was negligible for unknown reasons. Use of the mouse UTI model is feasible for study of the effect of an antibiotic in the urinary system, although the missing antibacterial effect in the bladder needs further evaluation.

Expression of virulence factors among Escherichia coli isolated from the periurethra and urine of children with neurogenic bladder on intermittent catheterization

BACKGROUND

Patients with neurogenic bladder caused by spinal cord injury or myelomeningocele empty their bladder several times a day by intermittent catheterization. Bacteriuria without symptoms of infection is frequently present in these patients. Occasionally a clone of Escherichia coli that has been carried for weeks without symptoms causes a symptomatic urinary tract infection. Virulence factors are commonly expressed among E. coli causing infection in patients with normal urinary tracts. However, it is unknown whether expression of virulence factors by an E. coli clone colonizing the neurogenic bladder increases the risk of subsequent infection. In this study we examined the prevalence of virulence factor expression among E. coli isolated from the periurethra and urine of patients with neurogenic bladder.

METHODS

The prevalence of virulence factors was examined among E. coli isolated from the periurethra and urine in patients with neurogenic bladder who received intermittent catheterization and were followed for 6 months. Representative isolates from the 37 clonal types of E. coli detected in the periurethra and urine of children with neurogenic bladder were assessed for O antigen, hemolysin, aerobactin, serum resistance and type I and P-adhesin.

RESULTS

All clones were serum-resistant and expressed type I adhesin, none expressed aerobactin and two expressed hemolysin. The presence of P-adhesin was not unique to clones associated with symptomatic infection. The presence of P-adhesin carried for weeks in a clone did not predict subsequent infection in the neurogenic bladder.

CONCLUSION

Bacterial virulence factors did not predict infection of the neurogenic bladder.

Effect of cranberry juice on bacteriuria in children with neurogenic bladder receiving intermittent catheterization

OBJECTIVE

To determine the effect of cranberry prophylaxis on rates of bacteriuria and symptomatic urinary tract infection in children with neurogenic bladder receiving clean intermittent catheterization.

DESIGN

Double-blind, placebo-controlled, crossover study of 15 children receiving cranberry concentrate or placebo concentrate for 6 months (3 months receiving one concentrate, followed by 3 months of the other). Weekly home visits were made. During each visit, a sample of bladder urine was obtained by intermittent catheterization. Signs and symptoms of urinary tract infection and all medications were recorded, and juice containers were counted.

RESULTS

During consumption of cranberry concentrate, the frequency of bacteriuria remained high. Cultures of 75% (114 of 151) of the 151 samples obtained during consumption of placebo were positive for a pathogen (>/=10(4) colony-forming units/mL) compared with 75% (120 of 160) of the 160 samples obtained during consumption of cranberry concentrate. Escherichia coli remained the most common pathogen during placebo and cranberry periods. Three symptomatic infections each occurred during the placebo and cranberry periods. No significant difference was observed in the acidification of urine in the placebo group versus the cranberry group (median, 5.5 and 6.0, respectively).

CONCLUSION

The frequency of bacteriuria in patients with neurogenic bladder receiving intermittent catheterization is 70%; cranberry concentrate had no effect on bacteriuria in this population.

Genomic analysis of a pathogenicity island in uropathogenic Escherichia coli CFT073: distribution of homologous sequences among isolates from patients with pyelonephritis, cystitis, and Catheter-associated bacteriuria and from fecal samples

Urinary tract infection is the most frequently diagnosed kidney and urologic disease and Escherichia coli is by far the most common etiologic agent. Uropathogenic strains have been shown to contain blocks of DNA termed pathogenicity islands (PAIs) which contribute to their virulence. We have defined one of these regions of DNA within the chromosome of a highly virulent E. coli strain, CFT073, isolated from the blood and urine of a woman with acute pyelonephritis. The 57,988-bp stretch of DNA has characteristics which define PAIs, including a size greater than 30 kb, the presence of insertion sequences, distinct segmentation of K-12 and J96 origin, GC content (42.9%) different from that of total genomic DNA (50.8%), and the presence of virulence genes (hly and pap). Within this region, we have identified 44 open reading frames; of these 44, 10 are homologous to entries in the complete K-12 genome sequence, 4 are nearly identical to the sequences of E. coli J96 encoding the HlyA hemolysin, 11 encode P fimbriae, and 19 show no homology to J96 or K-12 entries. To determine whether sequences found within the junctions of the PAI of CFT073 were common to other uropathogenic strains of E. coli, 11 probes were isolated along the length of the PAI and were hybridized to dot blots of genomic DNA isolated from clinical isolates (67 from patients with acute pyelonephritis, 38 from patients with cystitis, 49 from patients with catheter-associated bacteriuria, and 27 from fecal samples). These sequences were found significantly more often in strains associated with the clinical syndromes of acute pyelonephritis (79%) and cystitis (82%) than in those associated with catheter-associated bacteriuria (58%) and in fecal strains (22%) (P < 0.001). From these regions, we have identified a putative iron transport system and genes other than hly and pap that may contribute to the virulent phenotype of uropathogenic E. coli strains.

Comparison of Escherichia coli strains recovered from human cystitis and pyelonephritis infections in transurethrally challenged mice

Urinary tract infection, most frequently caused by Escherichia coli, is one of the most common bacterial infections in humans. A vast amount of literature regarding the mechanisms through which E. coli induces pyelonephritis has accumulated. Although cystitis accounts for 95% of visits to physicians for symptoms of urinary tract infections, few in vivo studies have investigated possible differences between E. coli recovered from patients with clinical symptoms of cystitis and that from patients with symptoms of pyelonephritis. Epidemiological studies indicate that cystitis-associated strains appear to differ from pyelonephritis-associated strains in elaboration of some putative virulence factors. With transurethrally challenged mice we studied possible differences using three each of the most virulent pyelonephritis and cystitis E. coli strains in our collection. The results indicate that cystitis strains colonize the bladder more rapidly than do pyelonephritis strains, while the rates of kidney colonization are similar. Cystitis strains colonize the bladder in higher numbers, induce more pronounced histologic changes in the bladder, and are more rapidly eliminated from the mouse urinary tract than pyelonephritis strains. These results provide evidence that cystitis strains differ from pyelonephritis strains in this model, that this model is useful for the study of the uropathogenicity of cystitis strains, and that it would be unwise to use pyelonephritis strains to study putative virulence factors important in the development of cystitis.

Bacterial virulence in urinary tract infection

Urinary tract infections (UTI) are caused by a variety of gram-negative bacteria that ascend into the urinary tract and establish bacteriuria often at levels greater than or equal to 10(5) bacteria/ mL of urine. Escherichia coli dominate as the causative agent in all patient groups, with Staphylococcus saprophyticus as the second most common, accounting for about 10% to 30% of the infections in young adult women depending on the season. This article covers the pathogenesis and inflammatory response of UTI and the virulence factors of uropathogenic E. coli.

Escherichia coli virulence factors and serotypes in acute bacterial prostatitis

BACKGROUND

Escherichia coli is the most frequent pathogen in both acute bacterial prostatitis and acute uncomplicated urinary infections. To assess the virulence profiles of E. coli in acute prostatitis, the serotypes and virulence factor (VF) genotypes were determined.

METHODS

We studied 107 E. coli isolates from cases of acute bacterial prostatitis, 76 isolates from acute pyelonephritis, 194 isolates from acute Cystitis and 80 fecal isolates from healthy people. All pyelonephritis and cystitis isolates were from women. Seven urovirulence determinants were analyzed by DNA colony hybridization, including the genes for type 1 fimbria (pil), P fimbria (pap), S fimbria (sfa), afimbrial adhesin AFA-I (afaI), alpha-hemolysin (hly), cytotoxic necrotizing factor 1 (cnf1) and aerobactin (aer). O:H:K serotypes were also determined.

RESULTS

With the exception of pil and afaI, all VFs were significantly more often associated with prostatitis, pyelonephritis and cystitis isolates than with the fecal isolates. The prevalence of sfa, hly and cnf1 was higher in prostatitis isolates than in pyelonephritis and cystitis isolates, and the pap+sfa+hly+cnf1+ genotype was dominant among prostatitis isolates (48.8%). Nine O serotype (O1, O2, O4, O6, O16, O18, O22, O25 and O75) accounted for 79.4%, 73.7% and 78.4% of the prostatitis, pyelonephritis and cystitis strains, respectively. There was an apparent correlation between serotype and genotype in uropathogenic E. coli.

CONCLUSION

The predominance of O serotypes in female urinary tract infections and a high percentage of multiple VFs among the prostatitis isolates suggested that VFs play important roles in the pathogenesis of acute bacterial prostatitis.

Characterization of urinary Escherichia coli O75 strains

Forty-four Escherichia coli O75 strains from patients with urinary tract infections were characterized by a variety of methods to obtain evidence of their clonal distribution and uropathogenic properties. By K and H antigen typing, the strains were divided into the following serotypes: O75:K5:H- (18 strains), O75:K95:H- (10 strains), O75:K95:H5 (7 strains), O75:K100:H5 (4 strains), and O75:K-:H55 (5 strains). Generally, biotyping proved to be of no discriminative value. With two exceptions the strains were found to be sensitive to the bactericidal effect of normal human serum. As shown by multilocus enzyme electrophoresis, the whole-cell protein profile (WCPP), and the patterns of the outer membrane proteins and lipopolysaccharides, all but the five O75:H55 strains were genetically closely related to each other and could be classified into one clonal group. The O75:K-:H55 strains proved to be quite different and lacked type 1 fimbriae. All 17 K95 (H-, H5) strains produced hemolysin and P fimbriae. Five of the O75:K5:H- strains were different from the other K5 strains by showing hemagglutinating properties, on the basis of the presence of the OX adhesin. The last two groups are suggested to be uropathogenic and are proposed to represent separate clonal groups or subgroups.

Host defense within the urinary tract. I. Bacterial adhesion initiates an uroepithelial defense mechanism

Uroepithelial defense has ben suggested to contribute to the local host resistance against ascending urinary tract infection. The cellular mechanism, however, is not known. In this study, bacterial growth was measured under the direct and indirect influence of uroepithelial cells. To study if a specific ligand-receptor interaction is required for uroepithelial cell (UEC) activation, isogenic Escherichia coli mutants expressing either mannose-sensitive, mannose-resistant (p), or mannose resistant (s) pili were tested for their capacity to induce the UEC defense mechanism. The antibacterial effect of UEC was abolished either by performing coculture in chambers with a fluid-permeable membrane which separates UEC from bacteria or by inhibiting membrane contact using the antiadherence factor pentosane polysulfate. No difference between the various types of pili could be shown. All E. coli strains adhered comparably to the UEC and were subsequently suppressed in their growth. Even a "naked" mutant without expression of common pili showed a similar behavior. In conclusion, bacterial growth suppression depends on direct contact between the UEC and bacteria, but is independent of common pili expressed on E. coli.

The O4 specific antigen moiety of lipopolysaccharide but not the K54 group 2 capsule is important for urovirulence of an extraintestinal isolate of Escherichia coli

Group 2 capsules and lipopolysaccharides are regarded as important virulence factors in extraintestinal isolates of Escherichia coli, but their specific contributions to bladder and renal infections, if any, are unknown. Proven isogenic derivatives deficient in the K54 antigen alone (CP9.137), the O4 antigen alone (CP921), or both the K54 and O4 antigens (CP923) were compared with their wild-type parent (CP9 [O4/K54JH5]) for growth in human urine in vitro and for virulence in vivo in a mouse model of ascending urinary tract infection (UTI). Growth of CP9.137 and CP921 was equivalent to that of CP9 in human urine. CP923 demonstrated a small but reproducible decrease in log-phase growth but achieved the same plateau density. In the mouse model of UTI, the isogenic mutant deficient in the 04 antigen alone (CP921) and, to a greater degree, the derivative deficient in both the K54 and O4 antigens (CP923) were significantly less virulent in nearly all parameters measured. In contrast, the K54 knockout derivative was as virulent as its parent, CP9, in causing bladder infection and nearly as virulent in causing renal infection. These results demonstrate an important role for the O4 antigen moiety of lipopolysaccharide in the pathogenesis of UTI. The possibility that the K54 antigen also plays a minor role cannot be excluded.

Virulence factors and O groups of Escherichia coli isolates from patients with acute pyelonephritis, cystitis and asymptomatic bacteriuria

The relationship between the presence of bacterial virulence factors and the severity of urinary tract infection (UTI) was analized in this study. The production of alpha-hemolysin (Hly), the expression of P-fimbriae and the mannose-resistant hemagglutination (MRHA) type IVa (associated with the presence of P-fimbriae), were all detected more frequently in Escherichia coli strains from acute pyelonephritis than in strains isolated from cystitis and asymptomatic bacteriuria. In contrast, the production of cytotoxic necrotizing factor type 1 (CNF1) and the expression of MRHA types III and IVb were distributed uniformly between strains causing different clinical categories of UTI. Thus 88% of the E. coli strains from acute pyelonephritis showed some of the virulence factors investigated in this study, whereas only 60% (p < 0.01) and 56% (p < 0.01) repectively of the strains isolated from cystitis and asymptomatic bacteriuria possessed virulence factors. There were no significant differences in the prevalence of virulence properties between strains isolated from patients with or without complicating factors. Only 16% (p < 0.001) of the fecal isolates from healthy individuals showed virulence factors. The virulence factors were concentrated in strains belonging to 10 (O1, O2, O4, O6, O7, O14, O18, O22, O75 and O83) of the 12 serogroups most frequently detected in uropathogenic E. coli strains. The majority of uropathogenic O4, O6, O14, O22, O75 and O83 E.coli strains were Hly+CNF1+ and expressed P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly+CNF1- and P-fimbriated. Among O1 and O7 strains we found Hly-CNF1-strains that expressed P-fimbriae. Among O2 strains we found Hly+CNF1+ strains that expressed P-fimbriae or MRHA type III and other Hly-CNF1-strains that possessed P-fimbriae. We conclude that E.coli strains isolated from pyelonephritis show virulence factors more frequently than those from cystitis and asymptomatic bacteriuria, and that strains that cause urinary tract infections in Spain belong to the same serogroups as uropathogenic E.coli isolated in other areas of the world. Our results support the special pathogenicity theory and suggest that many cases of serious urogenital disease may be caused by a limited number of P-fimbriated E.coli strains that usually produce alpha-hemolysin.

Gestational pyelonephritis--associated Escherichia coli isolates represent a nonrandom, closely related population

OBJECTIVE

A select group of Escherichia coli strains known as uropathogenic cause pyelonephritis in nonpregnant individuals. We investigated whether Escherichia coli from gestational pyelonephritis represent a random population or possess common uropathogenic characteristics.

STUDY DESIGN

Repetitive element sequence-based polymerase chain reaction, plasmid profiles, hemolysin, and O serotypes were assayed from Escherichia coli isolates of 57 pregnant patients with acute pyelonephritis at different gestational ages.

RESULTS

The majority of the first trimester isolates fell primarily into repetitive element sequence-based patterns 1 and 3 and O6, O15, and O75 serotypes. Second-trimester isolates had multiple patterns with high-frequency repetitive element sequence-based polymerase chain reaction 1 and 5 and an unknown (OX) serotype. Pattern 3, predominantly O75 serotype, was found primarily among third-trimester isolates.

CONCLUSION

It is likely that Escherichia coli associated with acute pyelonephritis during different trimesters of pregnancy represents nonrandom closely related isolates, and some of these strains may be characteristic in pregnant patients only.

Detection of Escherichia coli K95 strains by bacteriophages

A set of three bacteriophages (phi K5, phi K20, and phi K95) was used to discriminate between Escherichia coli K5 and K95 strains isolated from patients with urinary tract infections. All the strains tested were detected primarily by phi K5 and thought to carry the capsular antigen K5. Ten O2, 33 O6, and 32 O18 strains proved to be sensitive to the three phages. Eleven of 44 O75:H- strains, all 8 O75:H5 strains, 1 O17 strain, and 1 OR strain were not lysed by phage phi K20, the only phage without activity toward the K95 test strain. It has been suggested that the phi K20-resistant strains carry K95. These findings were confirmed by countercurrent immunoelectrophoresis with K-antigen extracts and anti-K95 serum. These preliminary data indicate the usefulness of these phages to detect K95 strains among K5 isolates.

Characterization of adhesion associated surface properties of uropathogenic Escherichia coli

Escherichia coli was isolated from the urine of patients with pyelonephritis, with urinary tract infections other than pyelonephritis and with asymptomatic bacteriuria. Surface properties of the strains were analyzed by the salting-out aggregation test (SAT), hydrophobic interaction chromatography (HIC), Congo red binding (Crb), agglutination of erythrocytes (MRHA) and latex particles covered by digalactoside (PF) and by adherence to tissue culture cells. In addition, a DNA probe for the pap gene was used. The DNA probe detected the highest proportion of strains with pap gene in the group of patients with pyelonephritis, lower in the urinary tract infections other than pyelonephritis and the lowest in the group with asymptomatic bacteriuria. Tests for P-fimbriae (PF, MRHA) showed a similar distribution. Hydrophobicity measured by SAT and by HIC did not show differences among the tested groups of strains. The results suggest that factors other than the P-fimbriae and hydrophobicity may contribute to the persistence of E. coli in the urinary tract.

Applications from bacterial adhesion and biofilm studies in relation to urogenital tissues and biomaterials: a review

The urogenital tract, particularly of the adult female, is the habitat for many species of microorganisms. These populations are in a state of flux, are susceptible to disruption by antibiotics and spermicides, and are exposed to many different biomaterial substrata. Infections of the genital area and bladder are common, and are invariably initiated by microbial adhesion to surfaces. This review examines the actual and potential applications to industry and to patients emerging from the study of bacterial adhesion to surfaces.

Suppressed antibody and interleukin-6 responses to acute pyelonephritis in pregnancy

This study examined the effect of pregnancy on the host response to acute pyelonephritis. Urine and serum samples were obtained at the time of diagnosis and after two weeks, from non-pregnant and pregnant women with acute pyelonephritis. The samples were analyzed for interleukin-6 (IL-6) and specific antibody activity to antigens extracted from the Escherichia coli strain infecting each patient. The host response to infection was further quantitated as fever, C-reactive protein, and renal concentrating capacity. Acute pyelonephritis in non-pregnant and pregnant women was accompanied by a significant serum and urine antibody response. The serum antibody response was significantly lower in the pregnant group. The IL-6 levels in serum and urine at diagnosis were significantly higher in the non-pregnant compared to the pregnant women. These results demonstrate that the immunosuppression of pregnancy includes the mucosal IL-6 and specific antibody responses to acute pyelonephritis caused by E. coli.

Community-acquired pyelonephritis in adults: characteristics of E. coli isolates in bacteremic and non-bacteremic patients

Escherichia coli strains isolated from the urine in 49 consecutive episodes of community-acquired pyelonephritis in adult women were characterized for adhesins and hemolysin production. The mean age of the patients was 56 years and 47% had at least 1 compromising condition. P fimbriae was found in 67% and hemolysin production in 35% of the strains; these figures were significantly (p < 0.001) higher than the corresponding figures (11% for each) among 287 strains isolated from stool of healthy adults (Siitonen A. J Infect Dis 1992; 166: 1058-1065). The prevalence of Non-P mannose-resistant adhesins and type 1C fimbriae was low (4 and 8%, respectively) and did not differ significantly from the corresponding prevalences (1 and 7%) in healthy adults. 74% fo the pyelonephritic (but only 22% of the stool) isolates had at least 1 of these 4 virulence factors (p < 0.001) and 37% and 7%, respectively, had at least 2 (p < 0.001). Nevertheless, the strains represented a wide variety of O:K serotypes without any indication of specially virulent clones. Of the 49 patients 15 had concomitant bacteremia, and in all except 2 compromised elderly patients the urinary and blood isolates were identical.

P1-antigen-containing avian egg whites as inhibitors of P adhesins among wild-type Escherichia coli strains from patients with urosepsis

Among 58 Escherichia coli urosepsis isolates, P1-antigen-containing dove and pigeon egg whites were significantly more effective inhibitors of P-adhesin-specific agglutination than were chicken egg whites or globoside. Globoside's inefficacy may have resulted from a proadherence effect of globoside's lipid tail. Adhesin phenotypes determined with dove and pigeon egg whites as as agglutination inhibitors corresponded closely with phenotypes defined by comparative hemagglutination of human P1 and p erythrocytes. These data suggest that avian P1-antigen-containing substances may provide a useful alternative method for P adhesin inhibition among uropathogenic E. coli strains.

Isogenic P-fimbrial deletion mutants of pyelonephritogenic Escherichia coli: the role of alpha Gal(1-4) beta Gal binding in virulence of a wild-type strain

Escherichia coli strains causing acute pyelonephritis often express multiple fimbrial types and haemolysin, which may contribute to their ability to adhere to, and interact with, kidney epithelial cells. Strain CFT073, a pap+, sfa+, pil+, hly+ pyelonephritis strain, previously established as virulent in the CBA mouse model of ascending urinary tract infection and cytotoxic for cultured human renal epithelial cells, was selected for construction of isogenic strains. From a gene bank of this strain, two distinct copies of the pap operon were isolated. The two P-fimbrial determinants were subcloned into pCVD442, a positive selection suicide vector containing the sacB gene of Bacillus subtilis. Deletion mutations were introduced into each of the two constructs, within papEFG of one operon and papDEFG of the other. Suicide vectors carrying pap deletions were mobilized from E. coli SM10 lambda pir into CFT073 (NalR) and cointegrates were passaged on non-selective medium. The first pap mutation was identified by screening a Southern blot of DNA from sucrose-resistant colonies using a papEFG probe. This mutant retained the MRHA+ phenotype since a second functional copy of pap was still present. A double pap-deletion mutant, UPEC76, confirmed by Southern blotting, was unable to agglutinate human type O erythrocytes or alpha Gal(1-4)beta Gal-coated latex beads. CBA mice (N = 100) were challenged transurethrally with 10(5), 10(6), 10(7), or 10(9) cfu of strains CFT073 or UPEC76. After one week, quantitative cultures of urine, bladder, and kidney were done and histologic changes were examined. No substantive differences in organism concentration or histological findings between parent and mutant were detected in urine, bladder, or kidney at any challenge concentration. We conclude that adherence by P fimbriae of uropathogenic E. coli strain CFT073 plays only a subtle role in the development of acute pyelonephritis in the CBA mouse model.

Characteristics of haemolytic Escherichia coli with particular reference to production of cytotoxic necrotizing factor type 1 (CNF1)

A total of 1,106 Escherichia coli strains isolated in Spain between 1986 and 1991 from extraintestinal infections and faeces of healthy controls were examined for production of alpha-haemolysin (Hly). Among strains causing urinary tract infections, sepsis and other extraintestinal infections, Hly production was detected in 51% (P < 0.001), 32% (P < 0.001) and 18% (P < 0.02), respectively. In contrast, only 9% of faecal isolates from healthy individuals synthesized Hly. The 356 haemolytic E. coli strains characterized in this study belonged to 28 different serogroups. However, 284 (80%) were of one of eight serogroups (02, 04, 06, 08, 018, 022, 075 and 083); 40% and 31% of haemolytic strains expressed P fimbriae and mannose-resistant haemagglutination (MRHA) type III, respectively. We have found that haemolytic isolates of E. coli may clearly be divided into two categories on the basis of the ability to produce cytotoxic necrotizing factor type 1 (CNF1). The serogroups and adhesins determined in Hly+CNF1+ strains were generally different from those found in Hly+CNF1- strains. Thus, serogroups 02, 06 and 075 were associated with haemolytic E. coli producing CNF1+, whereas serogroups 01, 08, 018, 028 and 086 were established more frequently among Hly+CNF1- strains. While expression of P fimbriae was more frequently detected in Hly+CNF1- strains (70 versus 29%, P < 0.001), MRHA type III was usually identified in Hly+CNF1+ E. coli (42 versus 1%, P < 0.001). Furthermore, the sonic extracts of Hly+CNF1+ strains caused necrosis in rabbit skin (96 versus 25%, P < 0.001) and death in intraperitoneally injected mice (73 versus 11%, P < 0.001) more frequently than sonic extracts of Hly+CNF1- strains.

Influence of some bacterial and host factors on colonization and invasiveness of Escherichia coli K1 in neonatal rats

Of 209 healthy infants examined, 44 (21.1%) carried Escherichia coli K1 in their feces. Of these 44 isolates, 36 (81.8%) were attributed to 10 different known clonal groups of E. coli K1 and 4 isolates represented unknown types. The influence of mannose-resistant (MR) adhesins, aerobactin production, and resistance to serum on colonization and invasiveness of E. coli K1 in orally infected inbred LEW baby rats was investigated. Strains expressing MR adhesins had significantly higher colonization and invasion rates than non-MR strains did. Mixed-infection experiments of LEW rats revealed interactions between different types of E. coli K1 strains affecting colonization and invasion rats. P-fimbriated strains appeared to have a selective advantage for colonization. The bacteremic potentials of different E. coli K1 strains could not be associated with their resistance to sera from LEW rats free of members of the family Enterobacteriaceae. No differences in virulence between fecal E. coli K1 isolates and clinical isolates from diseased humans were found. An influence of the major histocompatibility complex on host susceptibility to invasive E. coli K1 was indicated by comparing the parental LEW rat strain with different congenic LEW strains (RT1).

Characteristics of Escherichia coli in acute community-acquired cystitis of adult women

The characteristics of Escherichia coli isolated from the urine in 178 consecutive episodes of community-acquired cystitis in adult women were studied and compared with strains isolated from stools of 287 healthy adults. The prevalence of each of the previously described virulence-associated factors for urinary tract infection was significantly higher in the cystitis than in the stool isolates. The figures were 25.3% and 10.8%, respectively, for P fimbriation; 19.7% and 1% for Non-P MR adhesins, 13.5% and 7.3% for type 1C fimbriae and 22.5% and 10.8% for hemolysin production. 54% of the cystitis strains (but only 21.6% of the stool isolates) had at least 1 of these virulence-associated factors. These factors were mutually associated in a non-random manner; the association of P fimbriae with K1 and of Non-P MR adhesins and type 1C fimbriae with K5 capsules were highly significant. However, no clones specifically associated with cystitis could be identified. No significant differences were found between isolates from the first or recurrent UTI, or from younger or older, compromised or non-compromised patients. We conclude that P fimbriae, Non-P MR adhesins, type 1C fimbriae and hemolysin production all contribute to the establishment of cystitis in adults.

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.

Bacteremic and non-bacteremic febrile urinary tract infection--a review of 168 hospital-treated patients

Patients with febrile urinary tract infections with (80 patients) or without (88 patients) positive blood cultures were reviewed. Eighty-nine percent of the infections were community acquired. The bacteremic patients were older, Escherichia coli was the most commonly found organism in both groups. The most important finding in this study was increased frequency of resistance to three common urinary tract antibiotics (ampicillin, cephalothin and trimethoprim-sulfamethoxazole) in E. coli from patients with non-bacteremic compared with bacteremic infections. Complications occurred in 28 bacteremic and in three non-bacteremic patients. Six patients died, all with bacteremia. The significantly higher temperature at admittance among patients with gram-negative versus gram-positive bacteremic infection possibly reflects an effect by endotoxin.