Experimental Urinary Tract Infection Research Articles

[Combination antibacterial effects between aztreonam and eight other antibiotics].

In vitro interactions between aztreonam (AZT) and 8 other antibiotics were studied using the agar dilution checkerboard technique against 88 clinical isolates of Escherichia coli, Proteus vulgaris, Serratia marcescens and Pseudomonas aeruginosa. Combinations of AZT with 8 other antibiotics were generally additive or indifferent. Synergism was occasionally seen against S. marcescens or P. aeruginosa with AZT plus isepamicin (ISP). Antagonism was observed only between AZT and latamoxef against P. vulgaris. In a phase-contrast microscopic study, synergistic effects between AZT and aspoxicillin or ISP were confirmed against E. coli 177 and P. aeruginosa 15846. AZT in combination with ISP demonstrated a synergy against experimental urinary tract infection in mice caused by P. aeruginosa 15846. We believe that combinations of several antibiotics with AZT should be considered for initial therapy of infections because synergism and additive action were observed and antagonism was rarely found in our study.

The cell-bound hemolysin of Serratia marcescens contributes to uropathogenicity

The contribution of the cell-bound hemolysin of Serratia marcescens to uropathogenicity was studied in an experimental urinary tract infection in rats. The strain carrying the Serratia hemolysin colonized the urinary tract more and lead to a stronger inflammatory response compared to the isogenic hemolysin negative strain.

Study on pathogenesis of Enterococcus faecalis in urinary tract

The rate of isolation of Enterococcus faecalis as the causative bacterium of complicated urinary tract infections has been increasing. However, the pathogenicity of this bacterium in the urinary tract has not been clarified. Thus, the authors investigated how E. faecalis is pathogenic to the urinary tract, using mice with experimental urinary tract infection. The investigation revealed that this bacterium when sufficiently numerous can be directly pathogenic. The bacterium can be pathogenic indirectly when present with other typical urinary bacteria such as E. coli.

Staphylococcus saprophyticus urease: characterization and contribution to uropathogenicity in unobstructed urinary tract infection of rats.

We studied the biochemical properties of the urease of Staphylococcus saprophyticus and the possible role of the urease in experimental urinary tract infections. For this purpose, the nonhemagglutinating and nonadherent strain 9325, which was isolated from a case of symptomatic urinary tract infection, was used. The urease was shown to have a Km of 6.64 mM urea and a Vmax of 4.59 mumol NH3.min-1.mg-1. The enzyme was inhibited by acetohydroxamic acid in a noncompetitive manner. By means of Sephacryl S-300 column chromatography, we determined a mean molecular weight (+/- standard error of the mean) of 420,000 +/- 16,000. To assess the contribution of S. saprophyticus urease to uropathogenicity, a urease-negative mutant was constructed by nitrosoguanidine mutagenesis. In the rat model of ascending unobstructed urinary tract infection, higher numbers of CFU.gram of tissue-1 and more-severe lesions were detected with the parent strain. Moreover, bladder stones were found in animals infected with the urease-positive strain only. Interestingly, the difference in mean bacterial counts of the bladders was found to be significant by the Wilcoxon two-sample test (P less than 0.05), whereas that between the kidney bacterial counts was not. Immunoblot studies revealed a faint antibody response in rats infected with the mutant strain, although bacteria could still be detected in the kidneys after 7 days. Sera of animals challenged with the parent strain reacted strongly with many antigens of S. saprophyticus. Our data indicate that urease is a major factor for invasiveness of S. saprophyticus, especially in the tissue of the bladder, whereas persistence in the urinary tract and nephropathogenicity of this organism are governed by factors other than urease.

Hemagglutinating and adherence properties of Staphylococcus saprophyticus: epidemiology and virulence in experimental urinary tract infection of rats

We studied hemagglutinating and adherence properties in Staphylococcus saprophyticus isolates originating from symptomatic urinary tract infections. 12/13 (92%) of strains adhered to Hep cells and 11/13 (85%) were able to agglutinate sheep erythrocytes. Adherence properties differed markedly between strains ( P < 0.0001. Two strains, one hemagglutinating and adherent and one negative for both properties were chosen for experimental urinary tract infections. Results indicate that presence of the hemagglutinin favours colonization of kidney tissue.

Hemagglutinating and adherence properties of Staphylococcus saprophyticus: epidemiology and virulence in experimental urinary tract infection of rats.

We studied hemagglutinating and adherence properties in Staphylococcus saprophyticus isolates originating from symptomatic urinary tract infections. 12/13 (92%) of strains adhered to Hep cells and 11/13 (85%) were able to agglutinate sheep erythrocytes. Adherence properties differed markedly between strains (P less than 0.0001). Two strains, one hemagglutinating and adherent and one negative for both properties were chosen for experimental urinary tract infections. Results indicate that presence of the hemagglutinin favours colonization of kidney tissue.

Immunization with killedEscherichia coliincreases resistance of lipopolysaccharide-hyporesponsive C3H/HeJ mice to experimental urinary tract infection

C3H/HeJ mice are highly susceptible to experimental ascending urinary tract infection. After a 4-week intraperitoneal immunization regimen with killed Escherichia coli, these mice became more resistant to urinary tract infection. The level of resistance induced by this regimen in this strain was similar to that of the normally more resistant C3HeB/FeJ strain of mouse and was evident from 3 to 14 days after transurethral challenge with E. coli. Increased resistance also developed after a 2- or 3-week immunization regimen, but this resistance was not apparent until 14 days after challenge.

Immunization with killed Escherichia coli increases resistance of lipopolysaccharide-hyporesponsive C3H/HeJ mice to experimental urinary tract infection

C3H/HeJ mice are highly susceptible to experimental ascending urinary tract infection. After a 4-week intraperitoneal immunization regimen with killed Escherichia coli, these mice became more resistant to urinary tract infection. The level of resistance induced by this regimen in this strain was similar to that of the normally more resistant C3HeB/FeJ strain of mouse and was evident from 3 to 14 days after transurethral challenge with E. coli. Increased resistance also developed after a 2- or 3-week immunization regimen, but this resistance was not apparent until 14 days after challenge.

[Experimental urinary tract infection in mice to evaluate the pathogenicity of Escherichia coli isolated from newborn infants and their mothers].

[Experimental urinary tract infection in mice to evaluate the pathogenicity of Escherichia coli isolated from newborn infants and their mothers].

[Experimental urinary tract infection in compromised mice to evaluate the pathogenicity of Escherichia coli].

[Experimental urinary tract infection in compromised mice to evaluate the pathogenicity of Escherichia coli].

Bacterial virulence versus host resistance in the urinary tracts of mice.

The relative contributions of host resistance and bacterial virulence were analyzed in a mouse model for ascending urinary tract infection. The congenic mouse strains C3H/HeJ and C3H/HeN were used in parallel. They differ in their reactivity to lipopolysaccharide (LPS) and susceptibility to experimental urinary tract infection. C3H/HeJ cells are susceptible to infection and are nonresponders to LPS (Lpsd Lpsd), whereas C3H/HeN cells respond to LPS and are resistant to infection (Lpsn Lpsn). The Escherichia coli pyelonephritis isolate GR-12, serotype O75K5, expressing adhesins specific for globoseries glycolipids (P fimbriae) and for mannosides (type-1 fimbriae), and its derivatives deficient in these factors were used, either singly or in combination, to establish experimental infections. In C3H/HeN mice, the relative persistence of E. coli was inversely proportional to its phagocytosis in vitro. Loss of the O75 and K5 antigens increased the tendency toward hydrophobic interaction, promoted phagocytosis, and reduced persistence in the kidneys. This was not the case in C3H/HeJ mice, in which O75- and K5- serotypes persisted in the same extent as did the parent strain. The total number of bacteria recovered from the kidneys of C3H/HeJ mice was about 1,000-fold higher than the number recovered from kidneys of C3H/HeN mice 24 h after infection. Previous studies have demonstrated a delayed influx of polymorphonuclear leukocytes into the urinary tracts of C3H/HeJ mice. The results are consistent with the hypothesis that phagocyte activation through LPS is a major defense mechanism against E. coli in the kidney, a property in which C3H/HeJ mice are deficient.

マウス実験的尿路感染症による大腸菌の尿路病原性の評価

マウス実験的尿路感染症による大腸菌の尿路病原性の評価

Population shift in mannose-specific fimbriated phase of Klebsiella pneumoniae during experimental urinary tract infection in mice.

The infection rate (percentage of mice shedding 10(5) organisms per ml of urine) in 27 mice infected intravesicularly with a mannose-specific (MS+) phenotype of Klebsiella pneumoniae was 85% at day 7, and all the bacteria shed during the 7 days exhibited strong MS activity as estimated by a yeast aggregation assay. In contrast, the outcome of infection with an MS- phenotype of the same strain in 47 mice was heterogeneous: one group of 25 mice continued to shed the originally injected phenotype (MS-) throughout the investigation period, whereas the second group (22 mice) shed bacteria with various degrees of phenotypic conversion to MS+. In the first group, the rate of infection at day 7 was significantly reduced (28%) compared with that of the second group (68%). Mice infected with a mixture of 5% MS+ bacteria and 95% of an MS- variant which lost its ability to undergo phase variation had an infection rate of 89%, but at day 7 95% of the excreted bacteria were MS+. The infection rate of mice injected with the MS- variant was 14%, and none of the mice shed MS+ bacteria. The incidence of kidney pathology was higher in mice inoculated with the MS+ phenotype (3 of 10) or in the group in which the MS+ overgrew the MS- phenotype (4 of 10) as compared with the group of mice in which no such shift occurred (1 of 11). The kidneys of four mice which excreted mostly MS+ organisms harbored a population predominantly of the MS- phenotype. These results suggest that the MS adhesin confers an advantage in the initial steps of the infectious process in the bladder but not in later stages of infection in the kidney, emphasizing the importance of phase variation in the survival of bacteria at the various stages of the infectious process.

EXPERIMENTAL AND CLINICAL STUDIES ON KW-1100 IN URINARY TRACT INFECTIONS

EXPERIMENTAL AND CLINICAL STUDIES ON KW-1100 IN URINARY TRACT INFECTIONS

Relevance of in vitro antibacterial activities and pharmacokinetic properties of antipseudomonal .BETA.-lactam antibiotics to their therapeutic effects on urinary tract infection caused by Pseudomonas aeruginosa P 9 in mice.

The therapeutic effects of seven antipseudomonal beta-lactam antibiotics on experimental urinary tract infection caused by Pseudomonas aeruginosa P 9 in mice were compared, and the results were analyzed in relation to their in vitro antibacterial activities and pharmacokinetic properties. The CD50 values were (mg/kg): cefsulodin, 6.19; cefoperazone, 162; sulbenicillin, 167; ticarcillin, 184; azlocillin, 121; mezlocillin, 390; and piperacillin, 227. Cefsulodin was more active than the other antibiotics not only in therapeutic effects but also in in vitro antibacterial effects evaluated according to growth inhibitory, bactericidal, and bacteriolytic activities. It also penetrated and persisted well in the kidney of mice. The therapeutic effects of cefoperazone, azlocillin, and piperacillin were much less than expected from their in vitro antibacterial activities; the CD50 values were more than 18-fold as large as that of cefsulodin, whereas the differences of their MIC values were less than four-fold.

Noninvasive Localization of Urinary Tract Infection: Clinical Investigations and Experience

Previously we evaluated new methods to localize the source of bacteriuria in monkeys with experimental urinary tract infection. A high level of diagnostic accuracy was obtained with studies of antibody coating of urinary bacteria by immunofluorescence, 131iodine hippuran quantitative scintillation camera studies with the patient in the hydropenic state and 67gallium citrate scintiphotos. We identified unique patterns that differentiated cystitis, ureteritis, pyelonephritis and renal or perinephric abscess.Herein we review our clinical experience with these combined techniques in 40 patients and correlate the degree of accuracy of these studies with that of standard radiographic examinations. In 20 patients diagnostic studies also were compared to the findings of split ureteral urine cultures or bacteriologic culture of renal tissue obtained from surgical specimens or autopsy. The use of the quantitative scintillation camera studies done with the patient in a state of controlled hydropenia increased clearly the level of diagnostic sensitivity in demonstrating the source of a urinary tract infection compared to urine culture and excretory urography alone. In patients with an abnormal 131iodine hippuran study the performance of 67gallium renal imaging on the same day usually provided information that allowed specific localization of the source and extent of an infection. Both studies must be performed with a high degree of resolution over the renal areas and then must be interpreted carefully to ensure accuracy. Study of antibody coating of urinary bacteria was helpful in suggesting the presence or absence of upper urinary tract disease but was less sensitive and accurate than the combined radionuclide studies.

Experimental urinary tract infection in rabbits by a group D Streptococcus sp.: A study of serum immunoglobulin classes by enzyme-linked immunosorbent assay

After induction of pyelonephritis and cystitis in rabbits by a group D streptococcus, the authors measured the specific serum antibody response in the three major immunoglobulin classes. The enzyme-linked immunosorbent assay was performed using group D streptococcal antigen extracted by phenol. Before experimentation, all rabbits had low IgM, IgG and IgA titres against group D streptococcal antigen. A marked increase in IgM antibodies was detected during the first month of experimental pyelonephritis. A poor IgM antibody response was observed in rabbits with cystitis. During the three months of experimentation, a significant difference in mean IgG levels was observed between rabbits with pyelonephritis and those with cystitis.

Experimental urinary tract infection in rabbits by a group D Streptococcus sp.: A study of serum immunoglobulin classes by enzyme-linked immunosorbent assay

After induction of pyelonephritis and cystitis in rabbits by a group D streptococcus, the authors measured the specific serum antibody response in the three major immunoglobulin classes. The enzyme-linked immunosorbent assay was performed using group D streptococcal antigen extracted by phenol. Before experimentation, all rabbits had low IgM, IgG and IgA titres against group D streptococcal antigen. A marked increase in IgM antibodies was detected during the first month of experimental pyelonephritis. A poor IgM antibody response was observed in rabbits with cystitis. During the three months of experimentation, a significant difference in mean IgG levels was observed between rabbits with pyelonephritis and those with cystitis.

Estrogens influence antibody coating in experimental urinary tract infection.

Female rats were infected with E. coli 0.25 by intravesical instillation. After 4 weeks, significantly higher bacterial counts (bladder puncture and renal homogenates) were found in estradiol treated rats (0.5 mg/kg/week) than in solvent controls, but the proportion of antibody-coated bacteria was significantly (P less than 0.01) lower in bladder urine and renal homogenates. There was no influence of estrogens on renal histology or ureteral width. The results are compatible with an effect of estrogens on local immune response in the urinary tract.

[Experimental urinary tract infection with Proteus mirabilis in mice (author's transl)].

[Experimental urinary tract infection with Proteus mirabilis in mice (author's transl)].