Pathogenesis of urinary tract infection--experimental studies of vaginal resistance to colonization

Lactobacillus iners and genital health: molecular clues to an enigmatic vaginal species

Purpose of review

Vaginal lactobacilli are recognized as important drivers of genital health including protection against bacterial vaginosis and sexually transmitted infections. Lactobacillus iners is distinct from L. crispatus, L. gasseri, and L. jensenii by its high global prevalence in vaginal microbiomes, relatively small genome, production of only L-lactic acid, and inconsistent associations with genital health outcomes. In this review, we summarize our current understanding of the role of L. iners in the vaginal microbiome, highlight the importance of strain-level consideration for this species, and explain that while marker gene-based characterization of the composition of the vaginal microbiota does not capture strain-level resolution, whole metagenome sequencing can aid in expanding our understanding of this species in genital health.

Recent findings

L. iners exists in the vaginal microbiome as a unique combination of strains. The functional repertoires of these strain combinations are likely wide and contribute to the survival of this species in a variety of vaginal microenvironments. In published studies to date, strain-specific effects are aggregated and may yield imprecise estimates of risk associated with this species.

Summary

The worldwide high prevalence of Lactobacillus iners warrants more research into its functional roles in the vaginal microbiome and how it may directly impact susceptibility to infections. By incorporating strain-level resolution into future research endeavors, we may begin to appreciate L. iners more thoroughly and identify novel therapeutic targets for a variety of genital health challenges.

Efficacy and Safety of Carbapenems vs New Antibiotics for Treatment of Adult Patients With Complicated Urinary Tract Infections: A Systematic Review and Meta-analysis

This systematic review and meta-analysis evaluated the clinical efficacy and safety of carbapenems for the treatment of complicated urinary tract infections (cUTIs), with the comparators being new antibiotics evaluated for this indication. We searched 13 electronic databases for published randomized controlled trials (RCTs) and completed and/or ongoing trials. The search terms were developed using the Population, Intervention, Comparison, Outcomes, and Study framework. Pooled efficacy estimates of composite cure (clinical success and microbiological eradication) favored the new antibiotic groups, although this was not statistically significant (risk ratio [RR], 0.91; 95% CI, 0.79–1.04). A pooled estimate examining clinical response alone showed no difference between treatment arms (RR, 1.00; 95% CI, 0.96–1.05), however, new antibiotic treatments were superior to carbapenems for microbiological response (RR, 0.85; 95% CI, 0.79–0.91). New antibiotic treatments demonstrated a superior microbiological response compared with carbapenems in clinical trials of cUTI, despite an absence of carbapenem resistance. However, it is noteworthy that the clinical response and safety profile of new antibiotics were not different from those of carbapenems.

rUTI Resolution After FMT for Clostridioides difficile Infection: A Case Report

Clostridioides difficile infection (CDI) is the leading cause of nosocomial infectious diarrhea. Fecal microbiota transplantation (FMT) is a successful treatment for recurrent CDI (rCDI), and in some patients FMT has been associated with the resolution of recurrent urinary tract infections (rUTI). Recent evidence suggests that the origin of most bacterial infections in the urinary tract is the gut. Thus, the possibility of using FMT to displace pathogens commonly involved in rUTIs has major therapeutic implications. We report the case of a 93-year-old female patient with a rCDI and rUTI that underwent FMT and reported a complete clinical resolution of CDI; unexpectedly, no new symptomatic UTI episodes were diagnosed post-FMT. We characterized the gut microbiota of the stool donor and of the patient before and after the procedure. Our patient presented a dysbiosis with clear predominance of Enterobacteriaceae (74%) before FMT, which was significantly reduced to 0.07% after FMT. These findings were maintained for almost a year. We also observed an increase in microbial diversity indices compared with the pre-FMT sample reaching diversity values comparable to the donor stool samples. We reasoned that the disappearance of UTIs in our patient resulted from the reduction of Enterobacteriaceae in the gut microbiota. Our findings support previous evidence suggesting the potential of FMT for rUTI, particularly in cases due to multi-drug resistant pathogens where conventional antibiotic treatment is not an option.

Asymptomatic Bacteriuria and Pyuria in Premenopausal Women

BACKGROUND

Asymptomatic bacteriuria and pyuria in healthy women often trigger inappropriate antimicrobial treatment, but there is a paucity of data on their prevalence and persistence.

METHODS

To evaluate the prevalence and persistence of asymptomatic bacteriuria and pyuria in women at high risk of recurrent urinary tract infection, we conducted an observational cohort study in 104 healthy premenopausal women with a history of recurrent urinary tract infection with daily assessments of bacteriuria, pyuria, and urinary symptoms over a 3-month period.

RESULTS

The mean age of participants was 22 years, and 74% were white. Asymptomatic bacteriuria events (urine cultures with colony count ≥105 CFU/mL of a uropathogen on days with no symptomatic urinary tract infection diagnosed) occurred in 45 (45%) women on 159 (2.5%) of 6283 days. Asymptomatic bacteriuria events were most commonly caused by Escherichia coli, which was present on 1.4% of days, with a median duration of 1 day (range, 1-10). Pyuria occurred in 70 (78%) of 90 evaluable participants on at least 1 day and 25% of all days on which no symptomatic urinary tract infection was diagnosed. The positive predictive value of pyuria for E. coli asymptomatic bacteriuria was 4%.

CONCLUSIONS

In this population of healthy women at high risk of recurrent urinary tract infection, asymptomatic bacteriuria is uncommon and, when present, rarely lasts more than 2 days. Pyuria, on the other hand, is common but infrequently associated with bacteriuria or symptoms. These data strongly support recommendations not to screen for or treat asymptomatic bacteriuria or pyuria in healthy, nonpregnant women.

Mouthguards: does the indigenous microbiome play a role in maintaining oral health?

The existence of symbiotic relationships between bacteria and their hosts in various ecosystems have long been known to science. The human body also hosts vast numbers of bacteria in several habitats. Emerging evidence from the gastro-intestinal tract, genito-urinary tract and respiratory indicates that there are several health benefits to hosting a complex and diverse microbial community. Bacteria colonize the oral cavity within a few minutes after birth and form stable communities. Our knowledge of the oral microbiome has expanded exponentially with development of novel exploratory methods that allow us to examine diversity, structure, function, and topography without the need to cultivate the individual components of the biofilm. The purpose of this perspective, therefore, is to examine the strength of current evidence supporting a role for the oral microbiome in maintaining oral health. While several lines of evidence are emerging to suggest that indigenous oral microbiota may have a role in immune education and preventing pathogen expansion, much more work is needed to definitively establish whether oral bacteria do indeed contribute to sustaining oral health, and if so, the mechanisms underlying this role.

Daily Application of Alprostadil Topical Cream (Vitaros) Does Not Impact Vaginal pH, Flora, or Histology in Female Cynomolgus Monkeys

Topical alprostadil cream (Vitaros) is approved in Canada and Europe for the treatment of erectile dysfunction. To determine the effects on the female urogenital tract with repeated administration of the entire dose (300 μg alprostadil containing 2.5% dodecyl-2-n,n-dimethylaminopropionate hydrochloride), the vaginal pH, flora, and histology were assessed as a model for 100% transference from male to the female during unprotected sexual intercourse. Female cynomolgus monkeys were administered the entire dose of Vitaros for 14 days with a 7-day recovery. Relative to vehicle and placebo cream, the vaginal pH and microflora were determined at baseline and weekly, thereafter. Vaginal biopsies were evaluated at the end of dosing and recovery. All animals were clinically normal for the study duration, and the vaginal pH was consistent between dose groups and the dosing period. Vaginal microflora and histopathology findings of mild inflammation were generally similar across treatment groups. In conclusion, repeated vaginal exposure to Vitaros did not alter the pH, microflora, or histology after 14 daily doses, supporting the safety of Vitaros transference to the female partner.

The vaginal microbiota and susceptibility to HIV

There is some evidence that the risk of HIV infection per heterosexual act is higher in low-income countries than in high-income countries. We hypothesize that variations in per sex-act transmission probability of HIV may in part be attributed to differences in the composition and function of the vaginal microbiota between different populations. This paper presents data that are in support of this hypothesis. Experimental and clinical studies have provided evidence that the normal vaginal microbiota plays a protective role against acquisition of HIV and other sexually transmitted infections. Epidemiological studies have convincingly shown that disturbances of the vaginal microbiome, namely intermediate flora and bacterial vaginosis, increase the risk of acquisition of HIV infection. A review of the literature found large differences in prevalence of bacterial vaginosis between different populations, with the highest prevalence rates found in black populations. Possible explanations for these differences are presented including data suggesting that there are ethnic differences in the composition of the normal vaginal microbiota. Lastly, interventions are discussed to restore and maintain a healthy vaginal environment.

Ciprofloxacin for 7 days versus 14 days in women with acute pyelonephritis: a randomised, open-label and double-blind, placebo-controlled, non-inferiority trial

BACKGROUND

Acute pyelonephritis is a common infection in adult women, but there is a paucity of controlled trials of its treatment and the optimum duration of antibiotic treatment has not been properly defined. We compared the efficacy of ciprofloxacin for 7 days and 14 days in women with community-acquired acute pyelonephritis.

METHODS

In a prospective, non-inferiority trial undertaken at 21 centres of infectious diseases in Sweden, women (aged ≥18 years) who were not pregnant and had a presumptive diagnosis of acute pyelonephritis were randomly assigned to oral treatment with ciprofloxacin 500 mg twice daily for 7 days or 14 days. The first week was open label. A computer-generated randomisation list in block sizes of two was used for treatment allocation in a 1:1 ratio. The study was double-blind and placebo-controlled during the second week of treatment, which was either continuation of ciprofloxacin 500 mg or placebo tablets twice daily according to the randomisation code. Patients, carers, site investigators, and trial coordinating centre staff were masked to group assignment. The primary endpoint was the clinical and bacteriological outcome 10-14 days after completion of treatment with active drug. Analysis was by per protocol. This trial is registered with EudraCT, number 2005-004992-39, and ClinicalTrials.gov, number ISRCTN73338924.

FINDINGS

126 of 248 patients were randomly assigned to 7 days and 122 to 14 days of ciprofloxacin. 73 and 83 patients, respectively, were analysed. Short-term clinical cure occurred in 71 (97%) patients treated with ciprofloxacin for 7 days and 80 (96%) treated for 14 days (difference -0·9%; 90% CI -6·5 to 4·8; p=0·004; non-inferiority test). Cumulative efficacy at long-term follow-up was 93% in each group (68 of 73 vs 78 of 84; -0·3%; -7·4 to 7·2; p=0·015). Both regimens were well tolerated. Two patients discontinued ciprofloxacin because of myalgia with 7 days of treatment and itching exanthema with 14 days. Four (5%) of 86 patients assigned to 7 days of treatment who complied with study criteria and six (6%) of 93 assigned to 14 days reported an adverse event after the first week of treatment that was possibly or probably related to the study drug. In those assigned to 7 days, no patient had mucosal candida infection after the first week versus five treated for 14 days (p=0·036).

INTERPRETATION

Our results show that acute pyelonephritis in women, including older women and those with a more severe infection, can be treated successfully and safely with oral ciprofloxacin for 7 days. Short courses of antibiotics should be favoured in an era of increasing resistance.

FUNDING

Swedish Strategic Programme against Antibiotic Resistance (Strama).

Comparison of the gut microbe profiles and numbers between patients with liver cirrhosis and healthy individuals

Human liver was closely associated with gut through various biological mechanisms, such as bacterium-gut interactions. Alterations of gut microbiota seemed to play an important role in induction and promotion of liver damage progression. The aim of this study was to characterize the gut microbiota in liver cirrhosis patients and assess whether there are alterations in the diversity and similarity of intestinal flora in cirrhotic patients when compared with healthy individuals. PCR-denaturing gradient gel electrophoresis (DGGE) with universal primers targeting V3 region of the 16S rRNA gene was employed to characterize the overall intestinal microbiota composition, and some excised gel bands were cloned for sequencing. Real-time PCR was further utilized to quantitatively analyze the subpopulation of microbiota using group-specific primers targeting the Enterobacteriaceae, Enterococcus and Bifidobacterium genus. The DGGE profiles of two groups demonstrated significant differences between cirrhotic and healthy groups (P < 0.05). While real-time PCR revealed significant increase of Enterobacteriaceae and Enterococcus (P < 0.05) in the cirrhotic group compared with the healthy group. The ratio of Bifidobacterium genus and Enterobacteriaceae decreased in the cirrhotic patients group, but no statistical significance. This study revealed strong relationship between alterations of gut microbiota and liver cirrhosis.

Effects of treatment with antimicrobial agents on the human colonic microflora

Antimicrobial agents are the most valuable means available for treating bacterial infections. However, the administration of therapeutic doses of antimicrobial agents to patients is a leading cause of disturbance of the normal gastrointestinal microflora. This disturbance results in diminishing the natural defense mechanisms provided by the colonic microbial ecosystem, making the host vulnerable to infection by commensal microorganisms or nosocomial pathogens. In this minireview, the impacts of antimicrobials, individually and in combinations, on the human colonic microflora are discussed.

From structure to function: the ecology of host-associated microbial communities

In the past several years, we have witnessed an increased interest in understanding the structure and function of the indigenous microbiota that inhabits the human body. It is hoped that this will yield novel insight into the role of these complex microbial communities in human health and disease. What is less appreciated is that this recent activity owes a great deal to the pioneering efforts of microbial ecologists who have been studying communities in non-host-associated environments. Interactions between environmental microbiologists and human microbiota researchers have already contributed to advances in our understanding of the human microbiome. We review the work that has led to these recent advances and illustrate some of the possible future directions for continued collaboration between these groups of researchers. We discuss how the application of ecological theory to the human-associated microbiota can lead us past descriptions of community structure and toward an understanding of the functions of the human microbiota. Such an approach may lead to a shift in the prevention and treatment of human diseases that involves conservation or restoration of the normal community structure and function of the host-associated microbiota.

Robustness of the bacterial community in the cabbage white butterfly larval midgut

Microbial communities typically vary in composition and structure over space and time. Little is known about the inherent characteristics of communities that govern various drivers of these changes, such as random variation, changes in response to perturbation, or susceptibility to invasion. In this study, we use 16S ribosomal RNA gene sequences to describe variation among bacterial communities in the midguts of cabbage white butterfly (Pieris rapae) larvae and examine the influence of community structure on susceptibility to invasion. We compared communities in larvae experiencing the same conditions at different times (temporal variation) or fed different diets (perturbation). The most highly represented phylum was Proteobacteria, which was present in all midgut communities. The observed species richness ranged from six to 15, and the most abundant members affiliated with the genera Methylobacteria, Asaia, Acinetobacter, Enterobacter, and Pantoea. Individual larvae subjected to the same conditions at the same time harbored communities that were highly similar in structure and membership, whereas the communities observed within larval populations changed with diet and over time. In addition, structural changes due to perturbation coincided with enhanced susceptibility to invasion by Enterobacter sp. NAB3R and Pantoea stewartii CWB600, suggesting that resistance to invasion is in part governed by community structure. These findings along with the observed conservation of membership at the phylum level, variation in structure and membership at lower taxonomic levels, and its relative simplicity make the cabbage white butterfly larval community an attractive model for studying community dynamics and robustness.

Ceftibuten versus trimethoprim-sulfamethoxazole for oral treatment of febrile urinary tract infection in children

A randomized, open, coordinated multi-center trial compared the bacteriological and clinical efficacy and safety of orally administered ceftibuten and trimethoprim-sulfamethoxazole (TMP-SMX) in children with febrile urinary tract infection (UTI). Children aged 1 month to 12 years presenting with presumptive first-time febrile UTI were eligible for enrollment. A 2:1 assignment to treatment with ceftibuten 9 mg/kg once daily (n = 368) or TMP-SMX (3 mg + 15 mg)/kg twice daily (n = 179) for 10 days was performed. Escherichia coli was recovered in 96% of the cases. Among the E. coli isolates, 14% were resistant to TMP-SMX but none to ceftibuten. In the modified intention-to-treat population, the bacteriological elimination rates at follow-up did not differ significantly between patients treated with ceftibuten and those treated with TMP-SMX [91 vs. 95%, with a 95% confidence interval (CI) for difference of -9.7 to 1.0]. However, the clinical cure rate was significantly higher among those treated with ceftibuten (93 vs. 83%, with a 95% CI for difference of 2.4 to 17.0). Adverse events were similar for both regimens and consisted mainly of gastrointestinal disturbances. In conclusion, ceftibuten is a safe and effective drug for the empirical treatment of febrile UTI in young children.

Receptors for Escherichia coli adhesins in the genitourinary tract in a non-human primate

OBJECTIVE

To study the expression of receptors allowing adhesin-mediated binding of Escherichia coli to urogenital tissues ranging from the kidney to the vagina in cynomolgus monkeys using an in situ assay.

MATERIAL AND METHODS

Receptors specific for four relevant adhesins were investigated: PapG and PrsG of P-fimbriae binding to gal-alpha(1-4)gal glycosphingolipids (preferentially globoside and the Forssman antigen, respectively): and two variants of FimH of type 1 fimbriae, one binding to monomannose/trimannose and the other to trimannose only. To ascertain the specificity of the observed bindings we used adhesion inhibition by receptor analogues as well as E. coli adhesin knockout mutants.

RESULTS

The distributions of PapG and FimH receptors in monkey tissues showed great similarities to available data in humans. Whilst monomannose receptors were expressed on the surface epithelium in both the monkey bladder and ureter, trimannose receptors were not. The different distribution of FimH isoreceptors and the heterogeneity of FimH adhesin variants among E. coli may explain contradictory earlier findings in type 1 fimbriae-mediated adhesion to the human bladder and to renal tissues. We also found evidence of a hitherto unknown type of host-aggressor interaction on vaginal and urethral mucosa, which was not discovered until type 1 fimbriae had been eliminated.

CONCLUSIONS

A precise molecular fit between host receptors and bacterial lectins is important in infectious pathogenesis. We conclude that urinary tract infection in the cynomolgus monkey is a relevant model of the human disease because of the similarity in the expression of receptors for E. coli adhesins on epithelial surfaces in the two species.

Probiotics and prebiotics: A brief overview

Probiotics and prebiotics are 2 food ingredients that confer physiologic effects through the gastrointestinal tract. Probiotics have been defined as viable microorganisms that (when ingested) have a beneficial effect in the prevention and treatment of specific pathologic conditions. These microorganisms are believed to exert biological effects through a phenomenon known as colonization resistance, whereby the indigenous anaerobic flora limits the concentration of potentially pathogenic (mostly aerobic) flora in the digestive tract. Other modes of action, such as supplying enzymes or influencing enzyme activity in the gastrointestinal tract, may also account for some of the other physiologic effects that have been attributed to probiotics. Conversely, prebiotics are nondigestible food ingredients that beneficially affect host health by selectively stimulating the growth and/or activity of 1 or a limited number of bacteria in the colon. The prebiotic, fructooligosaccharide (FOS), is found naturally in many foods, such as wheat, onions, bananas, honey, garlic, or leeks. They can also be isolated from chicory root or synthesized enzymatically from sucrose. Fermentation of FOS in the colon results in a large number of physiologic effects including increasing the numbers of bifidobacteria in the colon, increasing calcium absorption, increasing fecal weight, shortening of gastrointestinal transit time, and possibly lowering blood lipid levels. Other effects that have been observed in animal models include an increase in cecal weight and an increase in fecal nitrogen excretion. The increase in bifidobacteria has been assumed to benefit human health by producing compounds to inhibit potential pathogens, by reducing blood ammonia levels, and by producing vitamins and digestive enzymes.

Aspects on feed related prophylactic measures aiming to prevent post weaning diarrhoea in pigs

The ability of feed related measures to prevent or reduce post weaning diarrhoea (PWD) was examined in a split litter study including 30 pigs from 6 litters allotted into 5 groups. Four groups were exposed to 3 pathogenic strains of E. coli via the environment at weaning. Three of them were given zinc oxide, lactose+fibres or non-pathogenic strains of E. coil as probiotics. The challenged and the unchallenged control groups were given a standard creep feed. Diarrhoea was observed in all challenged groups but not among uninfected animals, and the incidence of diarrhoea was lower in the group given nonpathogenic E. coli compared to all other challenged groups. The severity of PWD also differed between litters. When corrected for mortality due to PWD, a decreased incidence of diarrhoea was also seen in the groups given zinc oxide or lactose+fibres. The dominating serotype of E. coil within faecal samples varied from day to day, also among diarrhoeic pigs, indicating that diarrhoea was not induced by one single serotype alone. The diversity of the faecal coliform populations decreased in all piglets during the first week post weaning, coinciding with an increased similarity between these populations among pigs in the challenged groups. This indicated an influence of the challenge strains, which ceased during the second week. The group given lactose+fibres was least affected with respect to these parameters. In conclusion feed related measures may alleviate symptoms of PWD.

Microbial flora of the cervix assessed at the time of embryo transfer adversely affects in vitro fertilization outcome

OBJECTIVE

To investigate whether the presence of cervical microorganisms, as detected on catheters used for ET, alters the outcome of IVF-ET.

DESIGN

Prospective analysis.

SETTING

The assisted reproduction unit of a hospital in Clamart, France.

PATIENT(S)

Two hundred seventy-nine controlled ovarian hyperstimulation (COH) cycles performed for IVF-ET. Inclusion criteria were a patient age of < or =38 years, a morphologically normal uterus, and > or =2 good-quality embryos transferred.

INTERVENTION(S)

The tips of catheters used for ruling out possible cervical obstruction before ET were subjected to quantitative (> or =10 colonies = positive culture group; <10 colonies = negative culture group) and qualitative microbial assessment.

MAIN OUTCOME MEASURE(S)

Pregnancy and implantation rates.

RESULT(S)

In 143 (51%) of 279 ETs, cultures were positive, predominantly for Escherichia coli (64%) and Streptococcus species (8%). Although data on patients, COH, and embryology were similar in both culture groups, clinical and ongoing pregnancy rates as well as implantation rates were significantly lower in the positive culture group than in the negative culture group (24% versus 37%; 17% versus 28%; and 9% versus 16%, respectively).

CONCLUSION(S)

The presence of microbial flora of the cervix on ET catheters is associated with poor IVF-ET outcome.

Prevention of urinary tract infection

Recurrent UTI remains an exceedingly common clinical problem among women of all ages. Among otherwise healthy premenopausal and postmenopausal women, increased susceptibility to recurrences seems to be conferred by intrinsic host factors, such as nonsecretor genotype or estrogen status, and by exogenous exposures or behaviors, such as use of a diaphragm with spermicide, antimicrobial use, and sexual behavior. The natural history of recurrent UTIs is notable for a temporal clustering phenomenon, the tendency of women to revert to a baseline infection pattern after the cessation of preventive interventions, and repeated serial reinfections of the urinary tract from the fecal reservoir, often by genetically identical organisms. Low-dose antimicrobial regimens given daily, three times weekly, or postcoitally are effective in preventing recurrences in most women with a predisposition to frequent infection. Intermittent patient-initiated self-treatment is an appropriate and effective option in some patients with lower recurrence rates. In postmenopausal women, estrogen replacement therapy, particularly vaginally applied estriol creams, may also significantly reduce the rate of recurrent UTI. Ongoing investigations in the areas of microbial ecology of the vaginal flora, the molecular basis for host-parasite interactions within the urinary tract, and vaccine development may eventually lead to improved means to prevent recurrent urinary tract infections more effectively.

Aminoglycosides do not improve the efficacy of cephalosporins for treatment of acute pyelonephritis in women

A prospective, coordinated, randomized multicentre trial was conducted to determine whether tobramycin 160 mg intravenously (i.v.) once daily for 2 days would improve the efficacy of cefotaxime 1 g i.v. twice daily for 2 days followed by a 10-day course of oral cefadroxil 1 g twice daily, in the treatment of community-acquired acute pyelonephritis in women. Of 73 patients enrolled in the study, 51 could be evaluated according to the protocol. There were no significant differences in bacteriological cure rates between the combined treatment with tobramycin/cefotaxime and cefotaxime alone, either at short-term follow-up (63.0% vs 59.1%; 95% confidence interval (CI) for difference in proportions -23.4% to 31.2%), or up to 7 weeks after cessation of treatment (42.9% vs 52.2%; 95% CI, -18.0% to 36.6%). A modified intention-to-treat analysis showed no difference in clinical efficacy between the two regimens (68.6% vs 69.2%; 95% CI, -22.9% to 24.1%). Tobramycin seemed to enhance the resolution of inflammation by a more rapid decline in C-reactive protein levels. The high recurrence rates after treatment with beta-lactam antibiotics in this and previous studies of acute pyelonephritis may be explained by adverse ecological effects rather than failure to eradicate the infection.

Management of primary vesico-ureteric reflux in children--operation ineffective in preventing progressive renal damage

Four studies comprising 606 children and with a follow-up of 4-5 years have shown that operation and long-term antibiotic prophylaxis are equally ineffective in preventing post-infectious, progressive renal damage in children with grade III-IV reflux. To consider only the grade of reflux in the choice of management is too simple an approach. Other aspects of the complex biology of UTI should also be considered. Another important aspect concerns the organization of the care. Efficient and robust routines for a thorough follow-up and measures to guarantee immediate diagnosis and treatment of recurrent infections in children known to be at risk may be more important for the preservation of the kidneys than a stereotyped policy of operation or "endless" antibiotic prophylaxis. Specialized teams should be used as in the treatment of other long-term diseases. Parents should be educated and made active participants in the supervision of children at risk. Controlled multicentre studies are powerful scientific instruments, but appear to have too little impact on clinical practice. The responsibility of clinical scientists to make important results known and understood among those concerned is discussed from the ethical point of view.