Topical tetracycline: potential for allergic reaction or bacterial resistance

The high incidence of allergic reactions to some common dental antibiotics, primarily topical penicillins, has led to general concerns about all topical antibiotics. The development of resistant bacterial strains and efforts to reserve key antibiotics for life-threatening infections have also limited topical use of antibiotics. Delivery technologies providing for site-specific drug delivery have renewed interest in the use of topical antimicrobials to treat adult periodontitis. Topical tetracycline has an extremely low sensitizing potential and is not one of the antibiotics reserved by the medical community for use in life-threatening situations. Despite tetracycline's widespread dermatologic use and increasing use in adjunctive treatment of adult periodontitis, the incidence of allergic response to topical tetracycline is very low. Also, it is unlikely to cause resistance when used locally for short durations--particularly at the high per-site concentrations achieved with tetracycline periodontal fiber. Studies with tetracycline fiber showed no significant change in the tetracycline susceptibility of gram-negative periodontal microorganisms.

Enterotoxigenic Escherichia coli diarrhea in children less than five years of age in central Java

A community-based prospective study was performed from December 1993 through March 31, 1994 in Indonesia in children less than five years of age. Enterotoxigenic Escherichia coli (ETEC) was identified in diarrheic stool by colony hybridization assay, using toxin probes, and this bacterium was isolated from 19% of 340 episodes of diarrhea. Sixty-one percent of ETEC produced heat-labile toxin (LT) only, 325 LT and heat-stable toxin (ST), and 75 ST only. The age-specific incidence rates of diarrhea among children 0-1 and 2-3 years of age were 77% and 61%, respectively, during the study period; ETEC was isolated from 26% of children 0-1 years of age versus 53% for children 2-3 years of age. As many as seven episodes of diarrhea were repeatedly experienced by a single child during the four-month study period; however, only two children had more than one episode of known ETEC-associated diarrheal disease during the period of observation.

Molecular characterization of Vibrio cholerae O139 isolates from Asia

In 1992, a serologically novel clone of Vibrio cholerae, designated O139, caused large epidemics of diarrhea in India and Bangladesh. To determine the extent of the spread of V. cholerae O139 worldwide, 484 V. cholerae non-O1 strains isolated from different patients with diarrhea in Thailand, Indonesia, the Philippines, and Peru in 1993 were tested for agglutination in O139 antisera. One hundred fifty-one of these 484 isolates were examined for genes encoding cholera toxin, zonula occlulans toxin, the repetitive sequence 1, and the toxin coregulated pilin A (the V. cholerae virulence gene complex). Thirty-three percent (122 of 364) of V. cholerae non-O1 strains isolated from different patients with diarrhea in Thailand agglutinated in O139 antisera. Ninety-eight percent (120 of 122) of V. cholerae O139 contained the V. cholerae virulence gene complex. None of the 104 V. cholerae non-O1 strains isolated from patients with diarrhea in Indonesia or the 14 strains from patients with diarrhea in the Philippines were serotype O139. Four different ribotypes were found in V. cholerae O139 isolated in Asia. Twenty-three (47%) of 49 Thai O139 strains examined were of different ribotypes than isolates from India and Bangladesh; V. cholerae strains that were not O1 or O139 that were isolated from flies and water in Thailand 11 years previously in 1981 contained the same V. cholerae virulence gene complex found in V. cholerae O1 and O139. This suggests that other unidentified virulence determinants are involved in V. cholerae O139 pathogenesis.

Antimicrobial susceptibilities of Neisseria gonorrhoeae strains isolated in Surabaya, Indonesia

Until recently, the only common strains of antimicrobial agent-resistant Neisseria gonorrhoeae detected in Indonesia were penicillinase-producing N. gonorrhoeae (PPNG) strains. Despite the spread of resistance to other antimicrobial agents among N. gonorrhoeae in Southeast Asia, surveillance for such resistance in Indonesia has been limited. We evaluated the in vitro susceptibilities of 86 N. gonorrhoeae isolates from female sex workers in Surabaya, Indonesia, to 13 antimicrobial agents. Of the 86 isolates, 89% were resistant to penicillin (MIC, > or = 2.0 micrograms/ml), 98% were resistant to tetracycline (MIC, > or = 2.0 micrograms/ml), 18.1% were resistant to spectinomycin (MIC, > or = 128.0 micrograms/ml), and 97.7% showed decreased susceptibility to thiamphenicol (MIC, 1 to 2 micrograms/ml). Thus, thiamphenicol and spectinomycin may be approaching the end of their usefulness as the drugs of choice for the treatment of gonococcal infections in Surabaya. While the susceptibilities of N. gonorrhoeae to cephalosporins (ceftriaxone, cefixime, and cefoxitin) and fluoroquinolones (ciprofloxacin and ofloxacin) are universal, these drugs have not been used because they are more expensive in Indonesia than thiamphenicol. We conclude that Surabaya had the highest reported rate of penicillin and tetracycline resistance among the Southeast Asian countries and that cephalosporins or fluoroquinolones should be reasonable alternatives for the treatment of gonorrhea in this locale.

Safety, immunogenicity, and transmissibility of single-dose live oral cholera vaccine strain CVD 103-HgR in 24- to 59-month-old Indonesian children

Recombinant A-B+ Vibrio cholerae O1 strain CVD 103-HgR is a safe, highly immunogenic, single-dose live oral vaccine in adults in industrialized countries. Safety, excretion, immunogenicity, vaccine transmissibility, and environmental introduction of CVD 103-HgR were investigated among 24- to 59-month-old children in Jakarta. In 81 households, 1 child was randomly allocated a single dose of vaccine (5 x 10(9) cfu) and another, placebo. Additionally, 139 unpaired children were randomly allocated vaccine or placebo. During 9 days of follow-up, diarrhea or vomiting did not occur more often among vaccines than controls. Vaccine was minimally excreted and was isolated from no controls and from 1 (0.6%) of 177 unvaccinated family contacts. A 4-fold or higher rise in serum vibriocidal antibody was observed in 75% of vaccines (10-fold rise in geometric mean titer over baseline). Of 135 paired placebo recipients or household contacts, 5 had vibriocidal seroconversions. Moore swabs placed in sewers and latrines near 97 households failed to detect vaccine. These observations pave the way for a large-scale field trial of efficacy.

Solubilization and characterization of functionally coupled Escherichia coli heat-stable toxin receptors and particulate guanylate cyclase associated with the cytoskeleton compartment of intestinal membranes

1. Particulate guanylate cyclase and receptors for E. coli heat-stable enterotoxin were solubilized from the rat intestinal cytoskeletal compartment using Lubrol-PX and KCl. 2. Thirty to forty percent of the ST receptor and guanylate cyclase activities were extracted from the lipid layer with Lubrol-PX alone. 2. Seventy percent of the remaining activities were solubilized from the cytoskeleton with Lubrol-PX and KCl. 3. Guanylate cyclase solubilized from either compartment exhibited similar reaction kinetics. 4. Both high- and low-affinity classes of ST receptors were solubilized from the lipid and cytoskeleton compartments. 5. In the presence of ATP gamma S, ST selectively activated the guanylate cyclase solubilized from the cytoskeleton compared to that solubilized from the lipid bilayer. 6. Crosslinking experiments demonstrated a preferential solubilization of the 130 kDa receptor subunit from the cytoskeleton and the 56 kDa subunit from the lipid bilayer. 7. Development of a procedure to solubilize ST receptors and guanylate cyclase from the intestinal membrane cytoskeleton will permit purification and further detailed studies of the coupling of these activities.

Genetic conservation of hlyA determinants and serological conservation of HlyA: basis for developing a broadly cross-reactive subunit Escherichia coli alpha-hemolysin vaccine

The HlyA determinant among Escherichia coli isolates from patients with symptomatic urinary tract infection was compared in this report with a prototype HlyA encoded by pSF4000 by DNA-DNA hybridization tests with 20-base synthetic oligonucleotides and monoclonal antibody binding and neutralization assays. Hybridization results demonstrated that 349 (98%) of 357 definitive reactions among 54 hemolytic strains shared homology with seven DNA probes spanning many HlyA regions corresponding to residues (R) 41 to 47, 55 to 61, 248 to 254, 306 to 312, 336 to 343, 402 to 408, and 929 to 935. Genetic divergence was identified by lack of hybridization signals among 17 to 76% of the hemolytic strains within the distal portion of a predicted hydrophobic region corresponding to R491 to 319 and within a predicted hydrophilic region corresponding to R491 to 497 and R532 to 538. Serological studies demonstrated that 26 (81%) culture supernatants of 32 hemolytic strains were bound by all 12 monoclonal anti-HlyA antibodies. Among five of six remaining strains, the culture supernatants were bound by 3 to 11 monoclonal antibody preparations. There was only one hemolytic culture supernatant that failed to be bound by any monoclonal antibody, although the strain hybridized with nine hemolysin DNA probes. In addition, hemolytic activity of all 24 different culture supernatants tested was reduced by at least twofold by one monoclonal antibody specific for R2-161. These data extend and support previous views that the HlyA determinant is conserved among E. coli strains and suggest that a broadly cross-reactive HlyA subunit vaccine can be developed.

Pharmacokinetics of zidovudine alone and in combination with oxazepam in the HIV infected patient

This three-phase study was designed to determine if a pharmacokinetic drug-drug interaction exists between zidovudine and oxazepam. Six individuals infected with human immunodeficiency virus (HIV) and receiving zidovudine at 500 mg daily, with normal renal and hepatic function, were enrolled. During phase I, zidovudine pharmacokinetics were studied after steady-state oral administration (100 mg every 4 h) and after a single dose (70 mg) of intravenous zidovudine. Phase II consisted of a single oral dose (30 mg) of oxazepam followed by a 48-h blood sampling period. Phase III began with 48 h of concomitant zidovudine, 100 mg orally every 4 h, and oxazepam, 15 mg orally every 8 h, followed by concomitant dosing of intravenous zidovudine and oral oxazepam. Zidovudine concentrations were determined by radioimmunoassay. Oxazepam concentrations were determined with use of a fluorescence polarization immunoassay. The calculated bioavailability was 0.61 for zidovudine alone and 0.75 when administered in combination with oxazepam (p = 0.16). Plasma half-life for oral zidovudine alone and in combination with oxazepam was 1.17 h versus 0.99 h, respectively (p = 0.25), and 1.38 h versus 1.15 h (p = 0.38) for intravenous zidovudine during single and combination therapy, respectively. Total body clearance of zidovudine was not significantly altered by oxazepam (93 L/h vs. 109 L/h, p = 0.16). The mean pharmacokinetic parameters determined for a single 30-mg dose of oxazepam for oral clearance, apparent volume of distribution, and plasma half-life were 9.8 L/h, 65.7 L, and 5.1 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Local cytokine production in a murine model of Escherichia coli pyelonephritis

Cytokines may play an important role in the regulation of host defense against local bacterial infections. We have evaluated the local production of cytokines in a BALB/c mouse model of Escherichia coli pyelonephritis. Kidneys, draining lymph nodes, and spleens, were harvested at specific time intervals after bladder inoculation with E. coli corresponding to the stages of renal infection, infiltration, and bacterial clearance seen in this model. The presence of messenger RNA for specific cytokines (interleukins 1 through 6, chemotactic factors, granulocyte and granulocyte macrophage-colony stimulating factor (GM-CSF), tumor necrosis factor (TNF alpha) and beta, IFN gamma, transforming growth factor (TGF beta), and cytokine synthesis inhibitory factor (CSIF)/IL-10) was determined by polymerase chain reaction (PCR) amplification of reverse transcribed RNA. We have demonstrated mRNA encoding IL-1, IL-6, G-CSF, GM-CSF, TNF alpha, H400 (a protein homologous to a family of chemotactic factors and identical to MIP-1 beta), and CSIF/IL-10 in the kidney at 12 h and 1, 2, and 3 d after bacterial challenge. No signal was seen in normal animals or in mice after 5 d. This pattern of cytokine expression was observed only in renal tissues suggesting a localized response. IL-6 was present in the urine at 4 h with rapid resolution to baseline levels by 24 to 48 h. In contrast, IL-6 was not usually detectable in the serum. TNF alpha was not detectable in the serum or urine during the course of the infection. By immunohistochemical staining of kidney sections we have shown that IL-6 is produced predominantly by mesangial cells rather than by the inflammatory infiltrate. This study provides additional evidence utilizing novel techniques that specific cytokines are produced locally in response to bacterial infections. The time course of production demonstrated in this model supports the important role of cytokines in natural host resistance to local infection.

Affinity purification of functional receptors for Escherichia coli heat-stable enterotoxin from rat intestine

Active receptors for Escherichia coli heat-stable enterotoxin (ST) were partially purified by ligand-affinity chromatography. The affinity column was prepared by coupling ST to biotin derivatized with an extended N-hydroxysuccinylated spacer arm prior to binding to monomeric avidin immobilized on agarose. Detergent extracts of rat intestinal mucosa membranes were quantitatively depleted of ST binding activity when chromatographed on this affinity matrix. Biotinylated ST-receptor complexes were eluted from affinity columns with 2 mM biotin and these complexes quantitatively dissociated with bile salts. Using this technique, functional ST receptors were purified maximally about 2000-fold, with about 3% of the total activity in crude extracts recovered in these purified preparations. Analysis of affinity-purified preparations by polyacrylamide gel electrophoresis and silver staining demonstrated a major protein subunit of 74 kDa. Affinity cross-linking of these preparations to 125I-ST demonstrated specific labeling predominantly of the 74-kDa subunit. In addition, lower amounts of labeled ST were incorporated into subunits of 164 and 45 kDa, confirming the heterogeneous nature of ST receptors. Purified receptors bound ST in a concentration-dependent fashion, with an IC50 of 10(-9) M. These studies demonstrate that ligand-affinity chromatography can be employed to purify ST receptors. The availability of purified receptors will facilitate further studies of mechanisms underlying ST-induced intestinal secretion.

Identification and characterization of a new family of high-affinity receptors for Escherichia coli heat-stable enterotoxin in rat intestinal membranes

Novel high-affinity, low-capacity binding sites in intestinal membranes for the heat-stable toxin produced by Escherichia coli have been defined. The appearance of these sites is observed in the presence of physiological concentrations of NaCl in binding reactions. Scatchard analyses of equilibrium binding in the absence of NaCl demonstrated a single class of binding sites with KD = 1.9 x 10(-9) M and Bmax = 0.75 pmol/mg of protein. In contrast, similar experiments in the presence of NaCl demonstrated, in addition to the previously described low-affinity site, a high-affinity site with a KD of 2.1 x 10(-11) M and a Bmax of 73 fmol/mg of protein. Confirmation of the presence of high- and low-affinity sites was obtained in studies of the kinetics of ST binding. These sites exhibited similar dissociation but markedly different association kinetics. Determination of the association and dissociation constants permitted calculation of the KD's for the high- and low-affinity sites, which were 1.15 x 10(-11) M and 1.89 x 10(-9) M, respectively. These data agree closely with those obtained in studies of equilibrium binding. Furthermore, similar values for the KD's of these sites were obtained in experiments of competitive displacement of labeled ST, confirming the presence of two receptors for this toxin. Binding of ST to high-affinity sites is completely reversible and does not appear to be coupled to activation of particulate guanylate cyclase. In contrast, binding of ST to low-affinity sites appears to be partially reversible and may be coupled to activation of guanylate cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of a Proteus mirabilis outer membrane protein vaccine in preventing experimental Proteus pyelonephritis in a BALB/c mouse model

A BALB/c mouse model of nonobstructive, ascending Proteus mirabilis pyelonephritis was characterized bacteriologically, histologically, and serologically from 3 to 28 days. Intravesicular administration of 2 X 10(8) P. mirabilis K7 resulted in the septic death of 9 (16%) of 57 mice by day 15. Among the survivors, K7 colonized the kidneys in great numbers until day 21. Histological examination of the kidneys revealed acute inflammation which was characterized by neutrophil infiltration by day 3, renal necrosis by day 7, and fibroblastic infiltration by day 14 which persisted at least until day 28. The immunoglobulin G response to the outer membrane proteins (OMP) was assessed by enzyme-linked immunosorbent assay and Western blotting (immunoblotting). Anti-OMP immunoglobulin G antibodies were detected as early as day 7, and the reciprocals of their titers rose progressively up to day 28 (i.e., greater than or equal to 500). This model was also used to assess the efficacy of OMP and lipopolysaccharide (LPS) immunization in preventing renal infection. K7 OMP or LPS (100 micrograms) preparations were administered intramuscularly in Freund's complete adjuvant. After 2 weeks, mice were intravesicularly challenged with 2 X 10(8) bacteria of the homologous K7 strain or one of four heterologous strains. Compared with the saline-immunized control group and K7 LPS-immunized mice, K7 OMP recipients were protected from death when challenged by homologous or heterologous strains. In addition, K7 OMP recipients were protected (P less than 0.003) from subsequent renal infection when challenged by the K7 strain and had more rapid bacterial renal clearance when challenged by three of four heterologous strains. OMP recipients produced antibodies which bound major OMP moieties (viz., 36- to 39-kDa cell wall constituents) as assessed by Western blotting. These results support the concept that immunization with selected bacterial protein surface coat constituents can prevent uromucosal infection by interfering with colonization or renal injury.

Frequency and organization of papA homologous DNA sequences among uropathogenic digalactoside-binding Escherichia coli strains

The frequency of selected papA DNA sequences among 89 digalactoside-binding, uropathogenic Escherichia coli strains was evaluated with 12 different synthetic 15-base probes corresponding to papA genes from four digalactoside-binding piliated recombinant strains (HU849, 201B, and 200A). The papA probes encode amino acids which are common at the carboxy terminus of all strains, adjacent to the proximal portion of the intramolecular disulfide loop of strain 210B, or predicted to constitute the type-specific epitope for each of the four recombinant strains or other epitopes of strain HU849. The presence among the strains of DNA sequence homology to the papA probes was determined by in situ colony hybridization. Hybridization data suggest that there is a high frequency of homologous papA DNA sequences corresponding to selected regions of the papA gene from strain HU849 among the clinical strains. The following nucleotide locations which encode portions of the mature HU849 PapA are detected in a high percentage (42 to 70%) of clinical isolates: 208 to 222, 310 to 324, 478 to 492, 517 to 531, 553 to 567, and 679 to 693. These sequences encode portions of the predicted protective, immunogenic, and/or antigenic epitopes of this PapA. The data also indicate considerable heterogeneity of papA sequences among the strains, especially in the region of nucleotide bases corresponding to positions 391 to 418. These oligonucleotides encode the predicted PapA type-specific immunogenic dominant epitope. Determination of the extent of genetic variability in the papA gene among digalactoside-binding strains will require more extensive DNA sequencing of prototypic papA genes, additional hybridization studies employing other papA gene oligonucleotide probes, and assessment of the different pap operons and their copy number in each strain.

Alpha-hemolysin contributes to the pathogenicity of piliated digalactoside-binding Escherichia coli in the kidney: efficacy of an alpha-hemolysin vaccine in preventing renal injury in the BALB/c mouse model of pyelonephritis

Digalactoside-binding (Gal-Gal) pili and alpha-hemolysin of Escherichia coli have been implicated as important virulence determinants in the pathogenesis of human ascending, nonobstructive pyelonephritis. The pathogenic significance of these determinants was evaluated in vitro and in the BALB/c mouse pyelonephritis model by employing wild-type, avirulent laboratory, and genetically defined cosmids, transformants, and recombinant strains. In vitro data suggest that the cytolytic activity of hemolysin is significantly (P less than 0.05) enhanced among digalactoside-binding strains which agglutinate erythrocytes. The basis of increased hemolysis is related presumably to more efficient delivery of the toxin to target lipid substrate in the host plasma membrane. Intravesicular administration of bacteria that express both digalactoside binding and hemolysin generally resulted in greater mortality and renal parenchymal injury in mice than strains that expressed none or only one of these determinants. Analyses convincingly demonstrate that digalactoside-binding pili are correlated with upper urinary tract colonization and that hemolysin is correlated with septicemia and renal parenchymal damage. These determinants collectively constitute the minimal virulence factors to produce disease in this model. Their efficacy as vaccines for the prevention of pyelonephritis was also assessed. A purified Gal-Gal pilus vaccine prevented (P less than 0.05) subsequent colonization by a challenge wild-type strain that exhibited homologous pili. The hemolysin vaccine did not abrogate subsequent bacterial renal colonization on challenge, but it did protect (P less than 0.05) mice which survived challenge from subsequent renal injury compared with those in the saline control group. The combination of these determinants was also protective. The combination of Gal-Gal pili and hemolysin in a vaccine preparation represents a potentially worthwhile strategy for human immunoprophylaxis against pyelonephritis by interdicting several steps in the pathogenesis of a bacterial mucosal infection.

Efficacy and cost-effectiveness of antibiotic monitoring at a Veterans Administration hospital

A rigorous, continuously monitored antibiotic programme was initiated at our Veterans Administration hospital following evidence of inappropriate antibiotic usage. Seven hundred and thirty-one patients, mainly male, with an average age of 60 years were involved in the study; 378 were evaluable prior to policy implementation and 273 subsequently. The overall prevalence of deaths and average length of antibiotic therapy were less during the post-policy period. The number of antibiotic doses per patient was decreased by 24%. Drug costs were reduced by 32% post-policy, due largely to increased use of the longer-acting cephalosporins ceftriaxone and cefotetan. A 23% reduction in antibiotic acquisition costs was achieved over the 3-year period of the study, without detrimental effects on patient outcome.

Epitopes of Escherichia coli alpha-hemolysin: identification of monoclonal antibodies that prevent hemolysis

The antigenic regions of Escherichia coli alpha-hemolysin were determined by antibody binding to cyanogen bromide (CnBr) fragments of this protein under denatured conditions. Alpha-hemolysin was isolated from filtered culture supernatants of a recombinant strain by a combination of trichloroacetic acid precipitation and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Alpha-hemolysin was used to (i) produce polyclonal rabbit antisera and murine monoclonal immunoglobulin G (IgG) antibodies and (ii) generate CnBr fragments. Rabbit IgG and 13 murine IgG monoclonal antibodies (MAbs) were elicited to alpha-hemolysin as determined by enzyme-linked immunosorbent and immunoprecipitation assays. Antibodies bound to three specific CnBr fragments of alpha-hemolysin in Western blots (immuno-blots) from sodium dodecyl sulfate-polyacrylamide gels: CnBrII (encompassing residues [R] 2 to 160), CnBrV (R 425 to 892), and CnBrVI (R 893 to 1023). Five MAbs bound to CnBrII, seven MAbs bound to CnBrV, and one MAb bound to CnBrVI. These specific CnBr fragments are predicted to be hydrophilic and charged. There was no antibody binding to the highly hydrophobic CnBrIII (R 161 to 416). Similar binding patterns were observed when rabbit polyclonal anti-alpha-hemolysin IgG was used. Polyclonal antibodies to alpha-hemolysin readily inhibited hemolysis and its neutralization capacity was 4- to 64-fold more potent than neutralizing MAbs. The five MAbs that bind to CnBrII possessed hemolytic neutralizing activity to various degrees. In contrast, only three of seven MAbs that bind to CnBrV fragment exhibited neutralization capacity to various degrees; the MAb to CnBrVI did not exhibit this capacity. Based on these data, we predict that denatured alpha-hemolysin and its CnBrII and CnBrV fragments might be worthwhile immunoprophylactic candidates for the prevention of hemolysin-mediated E. coli tissue injury.

Rat intestinal cell atrial natriuretic peptide receptor coupled to guanylate cyclase

The present studies were initiated to determine if cells of intestinal origin possess the molecular components supporting a response to atrial natriuretic peptides. Specific binding in cultured rat ileal cells with 125I-labeled atrial natriuretic peptide was saturable and of high affinity. Scatchard analyses showed a single population of binding sites with a Kd of 2.1 nmol/L and a Bmax of 300 fmol/mg protein. Atrial natriuretic peptide activated particulate guanylate cyclase 5- to 10-fold in a concentration- and time-dependent fashion. The EC50 for activation of enzyme by atrial natriuretic peptide was 6 nmol/L. Accumulation of cyclic guanosine monophosphate stimulated by atrial natriuretic peptide was observed in the intracellular (25-fold) and extracellular (50-fold) compartments and was dependent on concentration and time. Half-maximum intracellular accumulation was observed with 10 nmol/L atrial natriuretic peptide. These data suggest a role for atrial natriuretic peptides in the gastrointestinal tract.

Heterogeneity of intestinal receptors for Escherichia coli heat-stable enterotoxin

The structure of rat intestinal cell receptors for Escherichia coli heat-stable enterotoxin (ST) was investigated by affinity cross-linking to 125I-ST and analysis by denaturing gel electrophoresis. Cross-linking of labeled toxin to intestinal membranes and analysis by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed five specifically labeled proteins with molecular masses of 160, 136, 78, 71, and 56 (kilodaltons) kDa. Exhaustive reduction of these samples resulted in a similar pattern of labeling. Affinity-labeled proteins were further analyzed by nonreducing SDS-PAGE, reduction of the resulting separated proteins, and further separation by SDS-PAGE in the presence of beta-mercaptoethanol. Thus, the 160-kDa band on nonreducing gels consisted of two different receptors: a 160-kDa polypeptide not further reducible and one composed of at least two subunits, one of which was the 78-kDa subunit. Similarly, the 136-kDa band on nonreducing gels consisted of a 136-kDa polypeptide not further reducible and one composed of at least two subunits, one of which was the 71-kDa subunit. The 78-, 71-, and 56-kDa subunits were not further reducible. These data suggest heterogeneity of the ST receptor subunit structure and organization in rat intestinal epithelia.

Infectious disease management of adult leukemic patients undergoing chemotherapy: 1982 to 1986 experience at Stanford University Hospital

PURPOSE

The purpose of this study was to determine the recent incidence of infection and to evaluate antimicrobial usage among adult leukemic patients undergoing chemotherapy for acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) at Stanford University Hospital.

PATIENTS AND METHODS

The records of 142 adult patients from a consecutive series of 226 induction or consolidation/maintenance chemotherapy courses for AML or ALL between 1982 to 1986 were reviewed retrospectively. Data were analyzed to compare the infectious disease complications and antimicrobial usage for patients receiving identical chemotherapy for a specific phase of leukemia treatment. Evaluation for each chemotherapy course included assessments for the following: compliance with criteria for initiating antibiotics, incidence of infection that was documented by culture or clinical criteria, predictive value of surveillance cultures, incidence of superinfection, survival outcomes, antimicrobial usage, antibiotic-related adverse effects, and cost for antibiotics and diagnostic studies.

RESULTS

Antimicrobials were employed in 190 (84%) of 226 chemotherapy courses. Broad-spectrum antibiotics were regularly begun within the first five days of admission and they were continued for an average of 3.5 weeks until the granulocyte count was greater than 1,000/microL after discontinuation of chemotherapy. There were no differences in the types of infection or outcomes among the patient groups. There was only a 37% rate of documented infections by culture or clinical signs among these patients during their entire hospital stay. Bacterial infections, especially those caused by coagulase-negative staphylococci in patients with Hickman catheters, accounted for 93% of the episodes. Viral and fungal infections accounted for 4% and 3% of documented cases, respectively, and occurred more than 10 days after the institution of broad-spectrum antibiotic therapy. A total of 922 different antimicrobials were employed in 190 courses (average 4.9 per course). The rationale for excessive usage and multiple changes was a persistent or intermittent fever, rather than documented infection(s). This practice led to usage of more broad-spectrum and expensive antibiotics. Further analyses indicate that the greater number of antibiotics employed correlated with apparent increased toxicity, especially renal and hepatic adverse reactions. These toxicities were associated with higher rates of fatal outcomes, i.e., 12 (39%) of 31 patients died with antibiotic-associated hepatic and/or renal insufficiency, compared with 12 (7.5%) of 159 patients who died without antibiotic-associated organ damage.

CONCLUSION

Excessive antibiotic usage and multiple antibiotic changes among adult leukemic patients undergoing chemotherapy appear to increase the risks of adverse hepatic and renal effects and death. Furthermore, this practice leads to use of more broad-spectrum and expensive antibiotics...

Transformation of Actinobacillus pleuropneumoniae and analysis of R factors by electroporation

An efficient method for DNA transfer is essential for the genetic manipulation of any organism. Such a capacity will be required for the genetic analysis of Actinobacillus pleuropneumoniae as a swine pathogen, as well as for its manipulation for vaccination purposes. For this reason, the use of electroporation as a means of plasmid DNA introduction into this species was examined. The multiple antibiotic-resistant strain 80-8141 of Actinobacillus pleuropneumoniae harbors 3 plasmids: pYG10, pYG15, and pYG12 of 5.0, 2.7, and 2.5 kb, respectively. Electroporation of A pleuropneumoniae strain 4074 with a plasmid extract of strain 80-8141 showed that pYG10 encodes chloramphenicol resistance and that pYG12 encodes ampicillin resistance. Electrical pulse conditions for efficient electroporation of strain 4074 were examined by use of pYG10 DNA isolated from a 4074 transformant. Efficiency, expressed as transformants per microgram of plasmid DNA, increased directly with pulse amplitude. However, high efficiencies were only observed in a narrow window of pulse duration (tau = 12 to 22 ms at 6.25 kV/cm). Longer pulse durations resulted in cell death. Electroporation efficiencies increased with cell density. Yield of transformants increased directly with DNA concentration. Results indicate that electroporation can be used to efficiently transform A pleuropneumoniae and that pYG10 and pYG12 are suitable plasmid vectors for use in the genetic manipulation of this organism.

Influence of a glycine or proline substitution on the functional properties of a 14-amino-acid analog of Escherichia coli heat-stable enterotoxin

Analogs of Escherichia coli heat-stable enterotoxin (ST) differing in chain length or the presence of turn-forming residues were assessed for binding to receptors, activation of particulate guanylate cyclase, and stimulation of secretion in suckling mice. These analogs included the native 18-amino-acid peptide (ST), the 14-amino-acid carboxy terminus of this native peptide with a proline at position 12 (ST[5-18]proline), and the 14-amino-acid carboxy terminus in which the proline at position 12 was substituted with glycine (ST[5-18]glycine). Each analog bound to the receptor in a dose-dependent fashion, completely displacing [125I]ST in competitive binding assays. However, their potencies differed significantly: ST demonstrated the highest affinity (inhibition constant [Ki], 10(-9) M), followed by ST[5-18]proline (Ki, 10(-7) M) and ST[5-18]glycine (Ki, 10(-6) M). Similarly, these peptides maximally activated particulate guanylate cyclase and stimulated intestinal secretion in suckling mice. Their rank order of potency in these assays was similar to that described for receptor binding: ST greater than ST[5-18]proline greater than ST[5-18]glycine. These data demonstrate that the full peptide structure is not absolutely required for pharmacological, biochemical, or biological activity. However, the four amino-terminal residues contribute significantly to the potency of these peptides. In addition, the turn imposed by the proline residue at position 12 is not absolutely required for receptor occupancy or activation of the biochemical cascade that results in intestinal secretion. However, it significantly increases the potency of the toxin. These data illustrate the importance of primary and secondary structures to the biochemical, pharmacological, and physiological activities of the ST produced by E. coli.

Gal-Gal pili vaccines prevent pyelonephritis by piliated Escherichia coli in a murine model. Single-component Gal-Gal pili vaccines prevent pyelonephritis by homologous and heterologous piliated E. coli strains

The initial pathogenic step in nonobstructive Escherichia coli pyelonephritis usually involves the binding of a bacterial adhesin with host uroepithelial glycoprotein receptors containing the D-Gal p alpha 1----4 D-Gal p beta 1 (Gal-Gal) moiety. In this study, groups of mice were immunized with Gal-Gal pili and challenged 2 wk later intravesicularly with E. coli strains expressing homologous or heterologous pili. 63 of 129 pili-immunized mice (49%) were protected from subsequent E. coli renal colonization compared with 5 of 85 control mice (6%). Among mice that had E. coli cultured from their right kidney, control mice had greater bacterial colony counts than pili-immunized animals (P less than 0.05). Light microscopic examination of kidneys demonstrated less histopathology among pili immunized mice than among control mice (P less than 0.05). Protection correlated with the presence of specific IgG antibodies in the urine and serum that bind to the major pilin structural polypeptide and not to the Gal-Gal pili tip adhesin per se. These results support the concept that immunization with a bacterial surface-coat constituent can prevent mucosal infection by interfering with colonization. Also Gal-Gal pili of E. coli represent a suitable candidate for immunoprophylaxis against pyelonephritis.

Use of a Chlamydia trachomatis DNA probe for detection of ocular chlamydiae

We examined the efficacy of a Chlamydia trachomatis DNA probe in detecting ocular chlamydiae by comparing it with tissue culture isolation, direct fluorescent-antibody cytology, and clinical eye exams. In a trachoma-endemic area of Nepal, 430 Nepalese villagers were examined according to the World Health Organization trachoma grading scale. Upper tarsal conjunctival specimens from each subject were obtained for DNA probing, tissue culture, and fluorescent-antibody screening. Moderate to severe intensity of inflammation was found in 85 (21%) of 430 people studied. An additional 25 (7.2%) of 345 people with low or no intensity of inflammation also had microbiologically proven infection, which may reflect asymptomatic carriage. Compared with culture, the DNA probe had a sensitivity of 86.9% and a specificity of 91%. For direct fluorescent antibody versus culture, the values were 47.8 and 96.9%, respectively. Results from this study indicate that the DNA probe for C. trachomatis might be considered a valuable epidemiologic tool in screening trachoma-endemic populations for ocular chlamydiae.

Improved sensitivity of a modified polymerase chain reaction amplified DNA probe in comparison with serial tissue culture passage for detection of Chlamydia trachomatis in conjunctival specimens from nepal

A sensitive means for detecting ocular chlamydial infections is needed to accurately define the epidemiology of trachoma. Tissue culture is considered the "gold standard," yet it is less than 50% sensitive for ocular specimens. The purpose of this study was to improve the detection rate of culture by serial passage and thereby provide a more reliable basis for comparing polymerase chain reaction (PCR) amplified and 32P DNA probes and direct fluorescent antibody (DFA) tests with culture. Ocular exams on 1043 individuals were scored for trachoma; 252 (24%) had moderate/severe intensity. A total of 1214 conjunctival samples were collected and passaged twice. Of 1053 samples, 276 negative at second passage were passaged an additional two times. The vast majority (93%) of all culture-positive samples were recovered by first passage. Only 80 of 252 cases (32%) with moderate/severe intensity were diagnosed by culture. The sensitivity of the 32P and PCR probes were 87% and 90%, respectively. For DFA versus culture, the sensitivity rate was 48%. Our results indicate that true rates of infection can not be accurately determined by culture even with serial passage. The sensitivity of the probes and DFA tests may, therefore, be higher. The PCR probe holds promise as an epidemiologic tool for studying chlamydial ocular infections.

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.

Pulmonary edema after Escherichia coli peritonitis correlates with thiobarbituric-acid-reactive materials in bronchoalveolar lavage fluid

We developed a new model of acute lung injury caused by live Escherichia coli peritonitis in guinea pigs. Arterial blood gas determinations, arterial blood pressure, and white blood cell counts were monitored serially for 12 h after the injection of either 2 x 10(9) E. coli J96 or saline. Lung water, albumin concentration in bronchoalveolar lavage fluid (BALF) and in lung tissue, WBC counts in BALF, and thiobarbituric-acid-reactive materials (TBARM) in plasma, lung tissue, and BALF were examined. Increased TBARM might be associated with pulmonary injury and are produced either by the generation of lipoperoxides secondary to oxygen-free radicals or as metabolic byproducts of prostanoid metabolism. Lung tissue sections were studied by light microscopy. E. coli peritonitis, as compared with control animals, caused significant peripheral neutropenia, histopathologic evidence of lung inflammation, acidosis, and hypotension. The wet-to-dry lung ratio was increased in the peritonitis group when compared with that in the control group (p less than 0.01). Pulmonary edema in the peritonitis group was associated with significantly increased albumin concentrations in BALF and lung tissue. We report the new finding of increased TBARM concentrations in BALF after E. coli peritonitis (p less than 0.01 and p less than 0.05, respectively). In contrast, plasma TBARM concentrations were unchanged. The levels of TBARM in the BALF correlated significantly with both lung water (p less than 0.01) and lung tissue albumin concentration (p less than 0.01). The measurement of elevated TBARM in BALF may allow acute lung injury to be detected. We conclude that this model may be useful for further studies of acute lung injury caused by E. coli peritonitis.

Synthetic peptides corresponding to protective epitopes of Escherichia coli digalactoside-binding pilin prevent infection in a murine pyelonephritis model

Synthetic peptides corresponding to five segments of a globoside (Gal-Gal)-binding pilin sequence [residues 5-12 (R5-12), R65-75, R93-104, R103-116, and R131-143], cyanogen bromide fragment II (CNBr-II, R53-163), and purified, intact Gal-Gal pili were prepared as vaccines and tested for their efficacy in a BALB/c murine model of pyelonephritis. Intact Gal-Gal pili, CNBr-II, and synthetic peptides R5-12 and R65-75 engendered antibodies that bound the homologous pilin protein and prevented urine and renal colonization in most vaccine recipients. Protection correlated with serum anti-pilus IgG ELISA titers greater than or equal to 1:250. The efficacy afforded by synthetic peptides R5-12 and R65-75 in vaccinated mice indicates that linear "antigenic" determinants in separate cyanogen bromide fragments encode "protective" epitopes. Peptides R93-104, R103-116, and R131-143 lacked efficacy, indicating that not all regions of the sequence are serologically equivalent. The crossreactivity of the peptide antisera for different Gal-Gal pilins was also assessed and correlated with the sequence homology of the corresponding regions. Antiserum to peptide R65-75, which corresponds to a region of unconserved sequence in heterologous pilins, bound only the homologous pilin. Thus, it specifies a type-specific protective epitope. Antiserum to synthetic peptide R5-12, which corresponds to a region of conserved sequence, bound Gal-Gal pilins from seven of eight pyelonephritis strains, indicating that it specifies a crossreacting protective epitope.

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.

Adult respiratory distress syndrome. A live E coli septic primate model

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The effects of prostaglandin E1 on the adult respiratory distress syndrome in septic primates

The effects of prostaglandin E1 (PGE1) on the adult respiratory distress syndrome were studied in the septic primate (Macaca fascicularis). A 30-min infusion of Escherichia coli (1 X 10(10)/kg) resulted in severe septic shock and adult respiratory distress syndrome. Primates, if living, were killed 4 h after completion of the E. coli infusion. Three groups of primates were studied (n = 4 in each group). The control group (Group 1) received PGE1 at 100 ng/kg/min throughout the experiment. The septic group (Group 2) received a 30-min infusion of E. coli. The treatment group (Group 3) received a continuous PGE1 infusion (100 ng/kg/min) along with the E. coli infusion which was begun 30 min after the PGE1 infusion was started. Control primates had hemodynamic changes consistent with the vasodilatory effect of PGE1 (heart rate and cardiac output increased; blood pressure and systemic vascular resistance (SVR) decreased). All control animals survived the experiment and had no evidence of pulmonary damage. Primates given E. coli developed severe hypotension, decreased SVR, and lung injury evidenced by pulmonary edema, decreased oxygenation, and increased extravascular lung water. Primates treated with both PGE1 and E. coli developed similar cardiovascular and pulmonary changes as the septic group. There was no statistically significant difference between Group 2 and Group 3 animals with regard to mean arterial blood pressure, SVR, extravascular lung water, alveolar-arterial oxygen difference, or survival.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Intestinal receptor for heat-stable enterotoxin of Escherichia coli is tightly coupled to a novel form of particulate guanylate cyclase

A novel form of particulate guanylate cyclase tightly coupled by cytoskeletal components to receptors for heat-stable enterotoxin (ST) produced by Escherichia coli can be found in membranes from rat intestinal mucosa. Intestinal particulate guanylate cyclase was resistant to solubilization with detergent alone, with only 30% of the total enzyme activity being extracted with Lubrol-PX. Under similar conditions, 70% of this enzyme was solubilized from rat lung membranes. The addition of high concentrations of sodium chloride to the extraction buffer resulted in greater solubilization of particulate guanylate cyclase from intestinal membranes. Although extraction of intestinal membranes with detergent and salt resulted in greater solubilization of guanylate cyclase, a small fraction of the enzyme activity remained associated with the particulate fraction. This activity was completely resistant to solubilization with a variety of detergents and chaotropes. Particulate guanylate cyclase and the ST receptor solubilized by detergent retained their abilities to produce cyclic GMP and bind ST, respectively. However, ST failed to activate particulate guanylate cyclase in detergent extracts. In contrast, guanylate cyclase resistant to solubilization remained functional and coupled to the ST receptor since enzyme activation by ST was unaffected by various extraction procedures. The possibility that the ST receptor and particulate guanylate cyclase were the same molecule was explored. ST binding and cyclic GMP production were separated by affinity chromatography on GTP-agarose. Similarly, guanylate cyclase migrated as a 300,000-dalton protein, while the ST receptor migrated as a 240,000-dalton protein on gel filtration chromatography. Also, thiol-reactive agents such as cystamine and N-ethylmaleimide inhibited guanylate cyclase activation by ST, with no effect on receptor binding of ST. These data suggest that guanylate cyclase and the ST receptor are independent proteins coupled by cytoskeletal components in membranes of intestinal mucosa.

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.

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.

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

Most human pyelonephritis Escherichia coli isolates express both mannose (MS)- and globoside (Gal-Gal)-binding pili. An ascending E. coli urinary tract infection model was established in the 16-wk-old female BALB/c mouse to compare the pathogenic significance of MS and Gal-Gal pili and their efficacy as vaccines for the prevention of pyelonephritis. The distribution and density of pilus receptor compounds in urogenital tissues and as soluble compounds in urine were determined with antibodies to the synthetic receptor analogues, alpha D-Gal(1----4) beta D-Gal and alpha D-Man(1----2) alpha D-Man. Both carbohydrates were detected in vagina, bladder, ureter, and renal pelvis epithelium and in collecting duct and tubular cells. A pilus receptor compound also was detected in urine. It competitively inhibited the binding capacity of MS pili and was found to be physically, chemically, and immunologically related to Tamm-Horsfall uromucoid. Infectivity and invasiveness were quantitatively and histologically characterized for four E. coli strains: J96, a human pyelonephritis strain that expresses both MS and Gal-Gal pili; two recombinant strains prepared from J96 chromosomal DNA encoding MS pili or Gal-Gal pili; and the nonpiliated K12 recipient. Intravesicular administration of J96 (10(6) colony-forming units [CFU]) resulted in renal colonization and invasion in each of nine mice. The Gal-Gal clone (10(6) CFU) colonized the kidneys in each of 10 mice but did not invade. In contrast, the MS clone (10(6) CFU) did not colonize renal epithelium or invade. This effect was superceded when larger doses (greater than or equal to 10(10) CFU) of the MS clone were administered in volumes that cause acute vesicoureteric reflux. The efficacy was determined of vaccines composed of pure MS or Gal-Gal pili or the lipopolysaccharide containing O somatic antigen of the challenge strain, J96. The Gal-Gal pilus vaccine blocked renal colonization in 19 of 22 mice and renal invasion in 10 of 11 mice. Gal-Gal pili may be useful immunogens for the prevention of pyelonephritis in anatomically normal urinary tracts.

A common antigenic determinant found in two functionally unrelated toxins

The heat-stable enterotoxin ST Ib produced by enterotoxigenic E. coli strains shares a sequence homology with the sea snail neurotoxin, conotoxin GI. Rabbit antisera were raised against synthetic analogs of these toxins and to a six-residue peptide representing the region common to both toxins. Results from enzyme-linked immunosorbent assays indicate that the homologous region of both toxins represents part of their antigenic site. The lack of cross-reactivity exhibited by the six-residue common domain with serum directed against either toxin suggests that this region probably retains a similar conformation in the intact toxins but not in the isolated fragment.

Mutations in E coli cistrons affecting adhesion to human cells do not abolish Pap pili fiber formation

A chromosomal DNA fragment which mediates Pap (pili associated with pyelonephritis) pili formation, mannose-resistant hemagglutination ( MRHA ) and binding to uroepithelial cells has been isolated from the uropathogenic Escherichia coli clinical isolate J96 , and genetically studied. Analysis of polypeptides expressed by the Pap DNA led to detection of a number of polypeptides ranging in mol. wt. from 13 000 to 81 000 daltons. The gene order and transcriptional orientation for four of the corresponding cistrons was: 13 000 ( papB ) 19 500 ( papA , structural gene for the Pap pilus subunit), 81 000 ( papC ) and 28 500 ( papD ). Analyses of a lacZ- papA gene fusion located a promoter upstream from papA within the cloned DNA. Transposon Tn5 insertions in any of these four cistrons decreased or eliminated Pap pili formation. A number of transposon Tn5 mutations were identified in a region distal to papD that expressed normal levels of the papA protein on the cell surface in the form of recognizable pili structures but did not agglutinate human erythrocytes or adhere to uroepithelial cells. This region expressed polypeptides of 15 000, 24 000, 26 000 and 35 000 daltons. This finding shows that Pap pili formation and binding properties can be genetically dissociated.

A simple, sensitive, and specific assay for the heat-stable enterotoxin of Escherichia coli

A simple assay for the heat-stable enterotoxin (ST) of Escherichia coli was developed on the basis of ST activation of guanylate cyclase in membranes from the intestinal mucosa of mice. ST activated guanylate cyclase in mucosal membranes in a linear fashion over a 50-fold range of toxin concentrations with Mg++-guanosine 5'-triphosphate as substrate. Activation of guanylate cyclase was detectable at concentrations of ST that were five- to 10-fold lower than those resulting in increases in the ratio of gut weight to carcass weight of mice. This assay was used to quantify ST in crude and purified samples from culture filtrates of wild-type strains and recombinant strains of E coli containing the gene for ST. Activation of guanylate cyclase was specific for ST; purified cholera toxin and E coli heat-labile enterotoxin did not activate guanylate cyclase. Thus, this assay for ST is sensitive, specific, and will facilitate rapid analysis of samples for quantification of ST.

Nucleotide sequence of the papA gene encoding the Pap pilus subunit of human uropathogenic Escherichia coli

The papA gene of the uropathogenic strain Escherichia coli J96, coding for the Pap pili subunit, was subjected to DNA sequencing, and found to code for an 185-amino acid-long polypeptide with a 22-amino acid-long signal peptide. Here we present the primary sequence, the hydrophilicity profile, and the predicted polypeptide secondary structure of the Pap pili subunit.

Mannose-sensitive and Gal-Gal binding Escherichia coli pili from recombinant strains. Chemical, functional, and serological properties

Chromosomal genes encoding the MS and Gal-Gal binding properties have been cloned into separate recombinants and their respective pili characterized. Hapten inhibition of hemagglutination with synthetic carbohydrate receptor analogues and carbohydrate-adsorbed latex agglutination studies indicate that Gal-Gal and MS pili collectively exhibit the binding properties of the parent strain. MS pili migrated in SDS-PAGE with an Mr of 19 kdaltons and 17 kdaltons; the Mr of Gal-Gal pili was 17.5 kdaltons. The pili are chemically similar by amino acid composition and when the N-terminal cysteines are aligned, 8 of the 13 residues between positions 9 and 22 are homologous. Further, carboxy-terminal sequence homology was inferred from the carboxypeptidase digestion of a MS pili and the sequence of a carboxy-terminal tryptic peptide from Gal-Gal pili.

Genetics of digalactoside-binding adhesin from a uropathogenic Escherichia coli strain

The uropathogenic strain Escherichia coli J96 mediates mannose-resistant hemagglutination owing to production of a digalactoside-binding adhesin. A cosmid clone from this strain has been isolated that, when harbored in E. coli K-12, expressed Pap pili and this adhesin (R. Hull et al., Infect. Immun. 33:933-938, 1981). By transposon mutagenesis and by the construction of a number of hybrid plasmid derivatives, we have demonstrated that about 8.5 kilobases of DNA is required to generate a mannose-resistant hemagglutination-positive phenotype in E. coli K-12 strain P678-54. The structural gene for the Pap pili monomer, papA, has been identified and mapped close to the promotor-proximal end of the Pap operon. Although strain P678-54 that harbored a Tn5 insertion within papA showed a mannose-resistant hemagglutination-positive phenotype, it was negative in a competitive enzyme-linked immunosorbent assay with anti-Pap pilus serum. This could mean that a Pap adhesin is encoded by a region on the Pap operon that is distinct from papA.