Molecular basis of Escherichia coli colonization of the upper urinary tract in BALB/c mice. Gal-Gal pili immunization prevents Escherichia coli pyelonephritis in the BALB/c mouse model of human pyelonephritis

The frequency of expression of pyelonephritis-associated pili is under regulatory control

The Escherichia coli urinary tract isolate C1212 contains two pyelonephritis-associated pili (pap) DNA sequences designated here as pap-17 and pap-21. Each of these pap sequences encodes antigenically-distinct pilin monomers, pilin-17 and pilin-21, respectively. Most individual strain C1212 cells isolated from a single bacterial colony expressed pilin-21. Only a small fraction (5%) of strain C1212 cells expressed pilin-17. Most of the latter population simultaneously expressed pilin-21, but a low percentage of cells expressed pili composed of pilin-17 alone. In contrast, almost every E. coli K-12 cell containing multicopy pap-17 expressed pilin-17 at the cell surface. These results indicated that the regulation of pilin-17 expression observed for strain C1212 was lost when pap-17 was in the multicopy state. Transfer of pap-17 to a single copy vector resulted in a pilin-17 expression frequency lower than strain C1212 (1%). Using E. coli K-12 containing single copy pap-17, we found that the frequency of pilin-17 expression increased about 15-fold when pap-21 was present in multiple copies in trans. Subcloning of pap-21 showed that a 2.2 kilobase-pair DNA sequence adjacent to, but not including, the pilin-21 structural gene was sufficient for activation of pilin-17 expression.

Total and specific immunoglobulin response to acute and chronic urinary tract infections in a rat model

Total and specific levels of immunoglobulins IgG, A and M were determined by an enzyme-linked immunosorbent assay (ELISA) in a rat model of urinary tract infections (cystitis) during the early and late phases of infection. The early response was characterized by rapid rise in IgM in serum and urine. This response decreased rapidly and was undetectable in urine after eight weeks. Correlation between total serum and urine levels of IgM was not found although a chronological relationship was observed. Total and specific serum and urine IgA responses were erratic. Concentrations of IgA were low and this antibody class was undetectable in urine until the infection had been established for six weeks. In contrast, total serum and urine IgG increased in concentration at five days post infection and reached total maximum by weeks four to eight, then declined, but remained detectable over 24 weeks. Specific IgG titers remained elevated in serum but declined in urine between four and 10 weeks. A correlation between total serum and total urine IgG was found. Also, bacteria generated a concomitant nonspecific response, a part of which was detected against a common antigen expressed on E. coli J5 strain that cross-reacts with a number of gram negative genera. The results show that IgM chronologically is the first antibody to appear in increased amounts in the serum and urine, followed by IgG. The data also suggests a relationship exists between total serum IgG and total urine IgG which may affect the host's ability to eliminate urinary infection.

The O75X adhesin of uropathogenic Escherichia coli: receptor-active domains in the canine urinary tract and in-vitro interaction with laminin

The complementary binding sites for the purified O75X adhesin of uropathogenic Escherichia coli in canine urinary tract were determined by indirect immunofluorescence. The adhesin bound to the vascular basement membranes in the canine kidney, ureter, bladder and urethra. In the kidney, the adhesin bound also to the tubular basement membranes and to the Bowman's capsule and mesangium of the glomeruli. In the bladder and ureter, but not in the urethra, the O75X adhesin bound to the basal lamina of smooth muscle cells. Connective tissue was negative for the adhesin. Interestingly, considerable intraepithelial heterogeneity was revealed as the O75X adhesin bound to epithelium of the ureter but not to that of the kidney, bladder or urethra. The purified O75X adhesin bound specifically to laminin, a basement membrane glycoprotein, immobilized on nitrocellulose or polystyrene, suggesting that laminin is involved in the binding of the O75X adhesin to basement membranes.

Antigenic analysis of Serratia marcescens fimbriae with monoclonal antibodies

Monoclonal antibodies (MAbs) were raised against the purified fimbriae of Serratia marcescens US46, a strain expressing three morphologically distinct fimbriae. The widths of these fimbriae were 7, 4.5, and 3 nm, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified fimbriae showed three bands with molecular weights of 21,000, 20,000, and 19,000, respectively. This strain had mannose-resistant (MR) hemagglutinating activity and was agglutinated by yeast cells. Therefore, strain US46 appeared to have both MR and mannose-sensitive fimbriae. In the immunoblot analysis, all MAbs reacted with the 20,000-molecular-weight subunit when given a choice of three differently sized subunits. Immunoelectron microscopy showed these MAbs attached to the MR fimbriae with the largest width (7 nm). The antigenic cross-reactivity of fimbriae was examined by an MAb-mediated agglutination test. All MR strains of S. marcescens and some mannose-sensitive strains were agglutinated by the MAbs. The serological homogeneity of MR fimbriae was confirmed by a spot test, using the crude purified fimbriae from several MR strains of S. marcescens. In other gram-negative rods, clinical isolates of Klebsiella spp. with hemagglutinating activity were agglutinated, but clinical isolates of Escherichia coli and Enterobacter spp. were not.

Administration in vivo of recombinant interleukin 2 protects mice against septic death

Administration in vivo of recombinant interleukin 2 (rIL-2) to mice induces a polyclonal IgM response. When co-administered with a specific antigen, rIL-2 can enhance concentrations of murine IgM antibodies specific for the antigen by fivefold within 7 d of initial treatment. IgM antibodies that are induced after injection of rIL-2 include antibodies specific for J5, a cell wall core lipopolysaccharide (LPS) antigen that is shared by the different members of the Enterobactericeae family. We report here that mice pretreated with rIL-2 or immunized with J5 antigen 7 d before bacterial challenge were protected from septic death that is caused by intraperitoneal challenges with Escherichia coli. Optimal protection was provided by a combined J5 antigen and rIL-2 treatment. Acquisition of the rIL-2 and J5 antigen-induced protection against lethal bacterial infection coincided temporally with maximal serum IgM titers that also contained IgM antibodies specific for the J5 antigen. In passive immunization experiments, the affinity-purified IgM fraction in sera of rIL-2-treated animals was identified as necessary and sufficient for protection. The IgM-depleted serum had no protective effect. The nonspecific augmentation of host-defense mechanisms without the induction of endotoxin manifestations makes rIL-2 a potential candidate to any alternative LPS-containing vaccines for the prevention of bacterial infections by gram-negative organisms since the core LPS antigen is shared among gram-negative bacteria.

Relationship of type 1 pilus expression in Escherichia coli to ascending urinary tract infections in mice

The role of type 1 pili and P adhesins during the in vivo growth of Escherichia coli inoculated into the urethras of BALB/c mice was studied. Strains which produced type 1 pili when grown in broth but lost this trait when grown on agar (regulated variants) were tested. Broth-grown organisms colonized the bladder of every animal tested, with counts of 10(3) to 10(4) viable organisms recovered from bladder homogenates. Agar-grown organisms gave lower rates of infection and the number of viable organisms recovered from bladders was significantly reduced. The degree of inoculum piliation influenced bladder colonization in a direct way: as piliation increased, the number of bacteria recovered from bladders also increased. After intraurethral inoculation, all of the bladders and 44% of the kidneys were colonized on day 1, and by day 5, 94% of the bladders and 16% of the kidneys were positive. Hemagglutination titers remained high for the bladder isolates, but the organisms colonizing the kidneys became significantly less piliated with time. Bacteriuria was unrelated to bladder or renal colonization. Strains that demonstrated random phase variation of type 1 pili during growth on agar produced similar colonizations of the urinary tract with broth- and agar-grown inocula. Strains that produced only P adhesins were less effective in colonizing the urinary tract than were type 1 piliated organisms. Other strains which did not produce pili only minimally colonized the bladder. The results suggest that type 1 pili play an essential role in ascending infections of the urinary tract.

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.

Effects of anti-C5a antibodies on the adult respiratory distress syndrome in septic primates

In vitro and in vivo studies have suggested that human complement component C5a plays a key role in neutrophil injury in the adult respiratory distress syndrome (ARDS). First, using leukocyte aggregometry, we demonstrated that the addition of a recently developed rabbit anti-human polyclonal antibody to C5a des arg to endotoxin-activated plasma prevented leukocyte aggregation in vitro. We then administered the anti-C5a des arg antibody to septic primates (Macaca fascicularis). Three groups of primates, control, septic, and anti-C5a antibody treated septic, were studied (n = 4 in each group). A 30-min infusion of Escherichia coli (1 X 10(10)/kg) resulted in severe sepsis and ARDS. Primates were killed 4 h after completion of the E. coli infusion. Septic animals not treated with anti-C5a antibody had 75% mortality (3/4), decreased oxygenation, severe pulmonary edema, and profound hypotension. Septic primates treated with anti-C5a antibodies did not die and did not develop decreased oxygenation (P less than 0.05) or increased extravascular lung water (P less than 0.05). They also had a marked recovery in their mean arterial blood pressure (P less than 0.05). This study demonstrates that treatment with rabbit anti-human C5a des arg antibodies attenuates ARDS and some of the systemic manifestations of sepsis in nonhuman primates.

Pathogenesis of shigella diarrhea. XI. Isolation of a shigella toxin-binding glycolipid from rabbit jejunum and HeLa cells and its identification as globotriaosylceramide

A glycolipid that specifically binds shigella toxin was isolated from both HeLa cells and rabbit jejunal mucosa and identified as globotriaosylceramide (Gb3) by its identical mobility on HPTLC to authentic erythrocyte Gb3. Toxin also bound to a band tentatively identified as alpha-hydroxylated Gb3. In addition, toxin bound to P1 antigen present in group B human erythrocyte glycolipid extracts. The common feature of the three binding glycolipids is a terminal Gal alpha 1----4Gal disaccharide linked beta 1----4 to either Glc or GlcNAc. Globoisotriaosylceramide, which differs from Gb3 only in possessing a Gal alpha 1----3Gal terminal disaccharide, and LacCer, which lacks the terminal Gal residue of Gb3, were incapable of binding the toxin. Binding was shown to be mediated by the B subunit by the use of isolated toxin A and B subunits and monoclonal subunit-specific antibodies. Gb3-containing liposomes competitively inhibited the binding of toxin to HeLa cell monolayers but did not inhibit toxin-induced cytotoxicity. These studies show an identical carbohydrate-specific glycolipid receptor for shigella toxin in gut and in HeLa cells. The toxin B subunit that mediates this binding has also been shown to recognize a glycoprotein receptor with different sugar specificity. Thus, we have demonstrated that the same small (Mr 6,500) B subunit polypeptide has two distinctive carbohydrate-specific binding sites. The Gal alpha 1----4Gal disaccharide of the glycolipid toxin receptor is also recognized by the Gal-Gal pilus of uropathogenic E. coli. This suggests the possibility that the pilus and toxin B subunit contain homologous sequences. If this is true, it may be possible to use the purified Gal-Gal pilus to produce toxin-neutralizing antibodies.

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

To assess the role of bacterial adherence to uroepithelial cells in the pathogenesis of nosocomial urinary tract infection, we prospectively studied 55 patients with indwelling urinary catheters. We obtained uroepithelial cells from the bladder and urine for culture on the patients' entry into the study and every two to four days during catheterization. In all, 235 collections of uroepithelial cells from these patients were used in an in vitro adherence assay with six gram-negative bacterial strains. With uroepithelial cells from patients who did not have bacterial infections, the adherence of the bacteria used in the assay differed significantly according to species. The least adherence occurred with Escherichia coli GR12; the adherence increased with (in order) Proteus mirabilis, E. coli J96, Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas aeruginosa. With cells collected just before the onset of bacteriuria, adherence of these gram-negative strains was higher in patients in whom gram-negative rod infections developed than in those with gram-positive coccal infections (P = 0.005). Analysis with the Cox proportional-hazards model demonstrated that a significant increase in bacterial adherence to uroepithelial cells in the bladder occurred two to four days before the onset of bacteriuria, but that adherence returned to base-line values with the onset of bacteriuria. These results suggest that a transient increase in the adherence of gram-negative bacteria to bladder epithelial cells may be an important early event in the development of catheter-associated bacteriuria.

Microbial and host factors that influence adherence of Escherichia coli to kidney epithelium

The adherence of Escherichia coli 06K13H1 to punch biopsy specimens of rabbit renal pelvic tissue and isolated epithelial cells was examined quantitatively. Organisms with pili adhered readily to kidney tissue, whereas organisms without pili (nonpiliated or grown in glucose-containing media) had significantly less adherence. Adherence was inhibited by antibody to pili antigen but not by mannose (a determinant of adherence to buccal mucosal cells). Studies were done to evaluate adherence under conditions operative in the renal medulla. The combination of hypertonic salt or urea solutions in acid pH interfered with adherence of the mannose-resistant strain. In additional studies of kidneys from humans, a similar effect of antipili serum and mannose was seen. These studies provide further evidence that pili are important in the initiation of upper urinary tract infection and define host factors that may inhibit initiation of infection.

Location of adhesion sites for P-fimbriated and for 075X-positive Escherichia coli in the human kidney

High-affinity binding sites for P-fimbriated and for 075X-positive Escherichia coli were located in the human kidney. Frozen sections of normal human kidney were double-stained first with fluorochrome-labelled bacteria and then with fluorochrome-labelled nephron site-specific lectins or antibodies. The P-fimbriate recombinant E. coli strain used showed specific adherence to glomerular structures, to the lumen of proximal and sital tubules and to vascular endothelium but did not adhere to collecting ducts or to peritubular sites. Two E. coli strains having the 075X adhesin showed specific adherence to renal interstitium, to glomerular elements and to Bowman's capsule. The method described allows the detailed determination of tissue-substructure specificity of bacterial adhesion. Our results demonstrate tissue tropism in the adhesion of E. coli to human kidneys and suggest a pathogenetic role for X adhesins.

Analysis of P fimbriae on Escherichia coli O2, O4, and O6 strains by immunoprecipitation

P fimbriae on Escherichia coli O2, O4, and O6 strains were analyzed by immunoprecipitation. Fimbrial extracts were prepared from a total of 35 strains and tested for precipitation with four anti-P-fimbria sera. The overall fimbrial composition of the strains was related to the O:K:H serotype, and two to three P fimbrial variants per strain were found on most of the O4 and some of the O6 strains. The O2 strains, in contrast, showed only one antigenic variant of P fimbriae per strain, which was serologically unrelated to those of the O4 and O6 strains. The results stress the multiplicity and serological complexity of E. coli P fimbriae.

Chromosomal map position of genes encoding P adhesins in uropathogenic Escherichia coli

Escherichia coli isolates from upper urinary tract infections frequently express adherence to human uroepithelium and D-mannose-resistant hemagglutination of human erythrocytes. Such adherence is usually associated with P pili encoded by the pap operon(s). In this paper, we report approximate chromosomal map positions for two copies of the pap operon. Only one copy expressed an adhesin capable of D-mannose-resistant hemagglutination, although both expressed P-related antigen.

Escherichia coli in extra-intestinal infections

When Theodor Escherich (1885a, b) first describedEscherichia colihe looked on it as a saprophytic organism. Soon several investigators found that colibacteria could be isolated from intestinal infections and from many infections outside the intestine, like urinary tract infections (UTI), cholecystitis, wound infections, meningitis, septicaemia, pulmonary infections, and many more. Uhlenhuth (1897) showed that coli strains from pathological processes were more pathogenic in animal experiments than strains isolated from the normal intestine. Smith (1927), who examined strains from white scours in calves, showed that spontaneous acapsular mutants could be obtained from certain colibacteria, and that such mutants were less virulent when injected intra-peritoneally into guinea-pigs.

Gal-Gal binding and hemolysin phenotypes and genotypes associated with uropathogenic Escherichia coli

To determine whether uropathogenic strains of Escherichia coli exhibit a distinctive constellation of phenotypes, we examined 44 urinary isolates from women with radiologically normal urinary tracts and pyelonephritis, cystitis, or asymptomatic bacteriuria and 73 fecal isolates from healthy control subjects. The strains were characterized by their O serogroup, by their binding specificity (as determined by adhesins), and by their production of hemolysin and colicin V. In addition, the strains were assessed for homologous gene sequences by means of DNA-hybridization probes prepared from cistrons that encode hemolysin and the Gal-Gal binding adhesin--two determinants of virulence, which cause tissue injury and promote bacterial colonization of uroepithelia, respectively. In contrast to most isolates from normal feces and from the urine of patients with asymptomatic bacteriuria, pyelonephritis strains belong to a small number of O serogroups; all express the Gal--Gal binding adhesin and 75 per cent are hemolytic. A gene probe for the Gal--Gal binding adhesin, derived from the chromosome of one strain from a patient with pyelonephritis, hybridized with the DNA of all other pyelonephritis strains. The probe for the hemolysin gene hybridized with DNA from all other hemolytic strains. These data indicate that most cases of pyelonephritis are due to a small number of pathogenic clones that express critical determinants of virulence, and that the nucleotide sequences for hemolysin and the Gal--Gal binding adhesin in heterologous strains share homology. We are tempted to speculate that the gene products of these shared regions of the genome might form the basis for a vaccine against pyelonephritis.

Pili of Neisseria meningitidis. Analysis of structure and investigation of structural and antigenic relationships to gonococcal pili

To provide information useful for the design of a pilus vaccine effective for the prevention of both meningococcal and gonococcal disease, the electron microscopic morphology of meningococcal pili and the structural and antigenic relationships of meningococcal pili to gonococcal pili were investigated. Meningococcal pili were 4-6 nm in width, extended 500-6,000 nm from the organism surface, and occurred singly or in bundles composed of 8-10 pili per bundle. Meningococcal pilin varied between 17,250 and 20,600 daltons. Pilin was present in outer membrane preparations of some meningococcal isolates that were nonpiliated by electron microscopic examination. Antibodies to gonococcal pili, cyanogen bromide cleavage fragments of gonococcal pilin, or synthetic peptide analogues corresponding to regions of the gonococcal pilin sequence, were used to detect common meningococcal and gonococcal antigenic determinants that might indicate the existence of a conserved sequence beyond residue 29. Antibody to intact gonococcal pili or to the variable CNBR-3 region of gonococcal pilin detected little shared antigenicity with meningococcal pilin. However, pilin from all tested meningococcal isolates reacted with antibody to the CNBR-2 fragment of gonococcal pilin, a region highly conserved among gonococcal strains. Meningococcal pilins were also broadly crossreactive with antibody to a synthetic peptide corresponding to residues 69-84 of the gonococcal sequence, a part of the CNBR-2 region that appears to be critical for gonococcal receptor-binding function. If a sequence similar to 69-84 is also important for receptor-binding function in meningococcal pili, a peptide corresponding to this region may elicit antibodies that block the adherence function of pili elaborated by both Neisseria gonorrhoeae and N. meningitidis.

Gal-Gal pyelonephritis Escherichia coli pili linear immunogenic and antigenic epitopes

The linear immunogenic and antigenic structure of E. coli Gal-Gal pili from the recombinant strain HU 849 was investigated with nine synthetic peptides corresponding to regions of the pilus sequence predicted to contain hydrophilic beta-turns. Five peptides, as bovine serum albumin conjugates, were found by anti-HU 849 pilus serum and were thus designated "immunogenic epitopes." Peptides corresponding to R 25-38, R 38-50, and R 48-61 (which jointly comprise the single intramolecular disulfide loop), and R 103-116, were bound in low titer. A prominent immunogenic epitope was specified by a peptide corresponding to R 65-75. Four peptides, as thyroglobulin conjugates, elicited antisera in rabbits that bound intact HU 849 pili. These were designated "antigenic epitopes." Two prominent antigenic epitopes were localized to peptides corresponding to R 5-12 and R 93-104, whereas peptides corresponding to R 65-75 and R 119-131 represented two minor antigenic epitopes. None of the peptide antisera bound Gal-Gal pili from heterologous strains except anti-R 93-104 and anti-R 5-12. In 8 of the 10 Gal-Gal-binding pyelonephritis isolates tested, anti-R 5-12 detected a protein with an apparent molecular weight of 18,000 co-migrating with several Gal-Gal pili. Anti-R 93-104 detected a corresponding protein in 4 of 8 fecal and 7 of 12 pyelonephritis Gal-Gal-binding isolates; however, it also bound apparently unrelated proteins of higher molecular weight.