Relationship among bacterial virulence, bladder dysfunction, vesicoureteral reflux and patterns of urinary tract infection in children

Urine Cytokine and Chemokine Levels Predict Urinary Tract Infection Severity Independent of Uropathogen, Urine Bacterial Burden, Host Genetics, and Host Age

Urinary tract infections (UTIs) are among the most common infections worldwide. Diagnosing UTIs in older adults poses a significant challenge as asymptomatic colonization is common. Identification of a noninvasive profile that predicts likelihood of progressing from urine colonization to severe disease would provide a significant advantage in clinical practice. We monitored colonization susceptibility, disease severity, and immune response to two uropathogens in two mouse strains across three age groups to identify predictors of infection outcome. Proteus mirabilis caused more severe disease than Escherichia coli, regardless of mouse strain or age, and was associated with differences in interleukin-1β (IL-1β), beta interferon (IFN-β), CXCL5 (LIX), CCL5 (RANTES), and CCL2 (MCP-1). In a comparison of responses to infection across age groups, mature adult mice were better able to control colonization and prevent progression to kidney colonization and bacteremia than young or aged mice, regardless of mouse strain or bacterial species, and this was associated with differences in IL-23, CXCL1, and CCL5. A bimodal distribution was noted for urine colonization, which was strongly associated with bladder CFU counts and the magnitude of the immune response but independent of age or disease severity. To determine the value of urine cytokine and chemokine levels for predicting severe disease, all infection data sets were combined and subjected to a series of logistic regressions. A multivariate model incorporating IL-1β, CXCL1, and CCL2 had strong predictive value for identifying mice that did not develop kidney colonization or bacteremia, regardless of mouse genetic background, age, infecting bacterial species, or urine bacterial burden. In conclusion, urine cytokine profiles could potentially serve as a noninvasive decision support tool in clinical practice and contribute to antimicrobial stewardship.

Interleukin-6/Stat3 signaling has an essential role in the host antimicrobial response to urinary tract infection

The signaling networks regulating antimicrobial activity during urinary tract infection (UTI) are incompletely understood. Interleukin-6 (IL-6) levels increase with UTI severity, but the specific contributions of IL-6 to host immunity against bacterial uropathogens are unknown. To clarify this we tested whether IL-6 activates the Stat3 transcription factor, to drive a program of antimicrobial peptide gene expression in infected urothelium during UTI. Transurethral inoculation of uropathogenic Escherichia coli led to IL-6 secretion, urothelial Stat3 phosphorylation, and activation of antimicrobial peptide transcription, in a Toll-like receptor 4-dependent manner in a murine model of cystitis. Recombinant IL-6 elicited Stat3 phosphorylation in primary urothelial cells in vitro, and systemic IL-6 administration promoted urothelial Stat3 phosphorylation and antimicrobial peptide expression in vivo. IL-6 deficiency led to decreased urothelial Stat3 phosphorylation and antimicrobial peptide mRNA expression following UTI, a finding mirrored by conditional Stat3 deletion. Deficiency in IL-6 or Stat3 was associated with increased formation of intracellular bacterial communities, and exogenous IL-6 reversed this phenotype in IL-6 knockout mice. Moreover, chronic IL-6 depletion led to increased renal bacterial burden and severe pyelonephritis in C3H/HeOuJ mice. Thus, IL-6/Stat3 signaling drives a transcriptional program of antimicrobial gene expression in infected urothelium, with key roles in limiting epithelial invasion and ascending infection.

A study of asymptomatic bacteriuria in Egyptian school-going children

BACKGROUND

Urinary tract infections (UTI) are a common and important clinical problem in childhood. Upper urinary tract infections (i.e., acute pyelonephritis) may lead to renal scarring, hypertension, and end-stage renal disease. Despite the presence of simple and reliable methods of preliminary screening of children's urine, urinary tract infection continues to be under diagnosed.

OBJECTIVES

The aim of this study was to establish prevalence rates of significant bacteriuria in asymptomatic school children by simple urine tests in comparison to standard urine culture techniques in Giza, Egypt.

PATIENTS AND METHODS

A total of 1000 apparently healthy school going children (6-12) years, 552 boys (55.2%) and 448 girls (44.8%), were enrolled in this cross-sectional prevalence survey.

RESULTS

Overall prevalence of significant bacteriuria was 6%. Higher prevalence occurred in girls (11.4%) than boys (1.6%). Escherichia coli was isolated in 35(58%) cases (3 boys and 32 girls), Staph. aureus in 13 (22%) cases (3 boys and 10 girls), Enterobacter in 6 girls (10%), Kelbsiella pneumoniae in 3 boys (5%) and Proteus vulgaris in 3 girls (5%).

CONCLUSION

Asymptomatic bacteriurea could be detected by urine screening program at school age. Overall prevalence of significant bacteriuria was 6%, with predominance in girls than boys.

Association of O-Antigen Serotype with the Magnitude of Initial Systemic Cytokine Responses and Persistence in the Urinary Tract

Urinary tract infection (UTI) is one of the most common ailments requiring both short-term and prophylactic antibiotic therapies. Progression of infection from the bladder to the kidney is associated with more severe clinical symptoms (e.g., fever and vomiting) as well as with dangerous disease sequelae (e.g., renal scaring and sepsis). Host-pathogen interactions that promote bacterial ascent to the kidney are not completely understood. Prior studies indicate that the magnitude of proinflammatory cytokine elicitation in vitro by clinical isolates of uropathogenic Escherichia coli (UPEC) inversely correlates with the severity of clinical disease. Therefore, we hypothesize that the magnitude of initial proinflammatory responses during infection defines the course and severity of disease. Clinical UPEC isolates obtained from patients with a nonfebrile UTI elicited high systemic proinflammatory responses early during experimental UTI in a murine model and were attenuated in bladder and kidney persistence. Conversely, UPEC isolates obtained from patients with febrile UTI elicited low systemic proinflammatory responses early during experimental UTI and exhibited prolonged persistence in the bladder and kidney. Soluble factors in the supernatant from saturated cultures as well as the lipopolysaccharide (LPS) serotype correlated with the magnitude of proinflammatory responses in vitro. Our data suggest that the structure of the O-antigen sugar moiety of the LPS may determine the strength of cytokine induction by epithelial cells. Moreover, the course and severity of disease appear to be the consequence of the magnitude of initial cytokines produced by the bladder epithelium during infection.

IMPORTANCE

The specific host-pathogen interactions that determine the extent and course of disease are not completely understood. Our studies demonstrate that modest changes in the magnitude of cytokine production observed using in vitro models of infection translate into significant ramifications for bacterial persistence and disease severity. While many studies have demonstrated that modifications of the LPS lipid A moiety modulate the extent of Toll-like receptor 4 (TLR4) activation, our studies implicate the O-antigen sugar moiety as another potential rheostat for the modulation of proinflammatory cytokine production.

Incidence, admission rates, and economic burden of pediatric emergency department visits for urinary tract infection: data from the nationwide emergency department sample, 2006 to 2011

BACKGROUND

The Emergency Department (ED) is being increasingly utilized as a pathway for management of acute conditions such as the urinary tract infections (UTIs).

OBJECTIVE

We sought to assess the contemporary trends in pediatric UTI associated ED visits, subsequent hospitalization, and corresponding financial expenditure, using a large nationally representative pediatric cohort. Further, we describe the predictors of admission following a UTI associated ED visit.

METHODS

The Nationwide Emergency Department Sample (NEDS; 2006-2011) was queried to assess temporal-trends in pediatric (age ≤17 years) ED visits for a primary diagnosis of UTI (ICD9 CM code 590.X, 595.0, and 599.0), subsequent hospital admission, and total charges. These trends were examined using the estimated annual percent change (EAPC) method. Multivariable regression models fitted with generalized estimating equations (GEE) identified the predictors of hospital admission.

RESULTS

Of the 1,904,379 children presenting to the ED for management of UTI, 86 042 (4.7%) underwent hospital admission. Female ED visits accounted for almost 90% of visits and increased significantly (EAPC 3.28%; p = 0.003) from 709 visits per 100 000 in 2006 to 844 visits per 100 000 in 2011. Male UTI incidence remained unchanged over the study-period (p = 0.292). The overall UTI associated ED visits also increased significantly during the study-period (EAPC 3.14%; p = 0.006) because of the increase in female UTI associated ED visits. Overall hospital admissions declined significantly over the study-period (EAPC -5.59%; p = 0.021). Total associated charges increased significantly at an annual rate of 18.26%, increasing from 254 million USD in 2006 to 464 million USD in 2011 (p < 0.001; Figure). This increase in expenditure was likely driven by increased utilization of diagnostic CT scanning in these patients (EAPC 22.86%; p < 0.001). Ultrasonography (p = 0.805), X-ray (p = 0.196), and urine analysis/culture use (p = 0.121) did not change over the study-period. In multivariable analysis, the independent predictors of admission included younger age (p < 0.001), male gender (OR = 2.05, p < 0.001), higher comorbidity status (OR = 14.81, p < 0.001), pyelonephritis (OR = 4.45, p < 0.001) and concurrent hydronephrosis (OR = 49.42, p < 0.001), stone disease (OR = 6.44, p < 0.001), or sepsis (OR = 18.83, p < 0.001).

DISCUSSION

We show that the incidence of ED visits for pediatric UTI is on the rise. This rise in incidence could be due to several factors, including increasing prevalence of metabolic conditions such as obesity, diabetes and metabolic syndrome in children predisposing them to infections, or could be secondary to increasing sexual activity amongst adolescents and changing patterns of contraceptive use (increased use of OCP in place of condoms), or more simply might just be a reflection of changing practice patterns. Second, we demonstrate that total charges for management of UTI in the ED setting are increasing rapidly; the increase is primarily driven by increasing utilization of diagnostic imaging in the ED setting, as has been demonstrated in other ED based studies as well.

CONCLUSIONS

In children presenting to the ED with a primary diagnosis of UTI, total ED charges are increasing at an alarming rate not commensurate with the increase in overall ED visits. While the preponderance of children presenting to the ED for UTI are treated and discharged, 4.7% of patients were admitted to the hospital for further management. The strongest predictors of inpatient admission were pyelonephritis, younger age, male gender, higher comorbidity status, and concurrent hydronephrosis, stone disease, or sepsis. Managing these at-risk patients more aggressively in the outpatient setting may prevent unnecessary ED visits and subsequent hospitalizations, and reduce associated healthcare costs.

Urinary tract infections in children with myelodysplasia in whom clean intermittent catheterization was administered

AIM

In this study, it was aimed to evaluate the frequency of significant bacteriuria and antibiotic resistance characteristics in children with myelodysplasia in whom clean intermittent catheterization was administered.

MATERIAL AND METHODS

The study group was composed of 71 patients with myelodysplasia who were found to have significant bacteriuria (age: 8.20±4.57 years; 39 girls) and the control groups was composed of 49 children who were diagnosed with community-acquired urinary tract infection (age: 7.94±4.17 years; 29 girls). The patient and control groups were evaluated in terms of the microorganisms grown in urinary cultures and antibiotic resistance characteristics. The study approved by the ethics committe (14/02/2012-19/E).

RESULTS

Growth of Escherichia coli (E. coli) was found with the highest rate in myelodysplasic patients. However, when compared with the control group in terms of microorganism types, an increase in the growth rates of the microorganisms excluding E. coli was observed in the patients with myelodysplasia which was close to the significance limit (p=0.055). When antibiotic resistance properties were examined, a significantly increased resistance against cotrimaxazole was found in the patient group compared to the control group (p=0.001). 84.5% of the patients were using prophylactic antibiotic including mainly co-trimoxazole. A significantly increased co-trimoxazole resistance was also found in the patients who were using prophylactic antibiotic compared to the patients who were not using prophylactic antibiotic (p=0.025). The rate of symptomatic UTI was found to be 21% in the patients with myelodysplasia and a significant increase was found in the complaints of abdominal/side pain and nausea/vomiting as well as fever in these patients compared to the patients with asymptomatic bacteriuria (p=0.029 and p=0.032, respectively).

CONCLUSION

Our results show that UTI is still a significant problem in patients with myelodysplasia. In addition, they show that use of prophylactic antibiotic may increase the frequency of development of resistance and co-trimoxazole used for this objective is not a good option..

Expression and antimicrobial function of beta-defensin 1 in the lower urinary tract

Beta defensins (BDs) are cationic peptides with antimicrobial activity that defend epithelial surfaces including the skin, gastrointestinal, and respiratory tracts. However, BD expression and function in the urinary tract are incompletely characterized. The purpose of this study was to describe Beta Defensin-1 (BD-1) expression in the lower urinary tract, regulation by cystitis, and antimicrobial activity toward uropathogenic Escherichia coli (UPEC) in vivo. Human DEFB1 and orthologous mouse Defb1 mRNA are detectable in bladder and ureter homogenates, and human BD-1 protein localizes to the urothelium. To determine the relevance of BD-1 to lower urinary tract defense in vivo, we evaluated clearance of UPEC by Defb1 knockout (Defb1^-/-) mice. At 6, 18, and 48 hours following transurethral UPEC inoculation, no significant differences were observed in bacterial burden in bladders or kidneys of Defb1^-/- and wild type C57BL/6 mice. In wild type mice, bladder Defb1 mRNA levels decreased as early as two hours post-infection and reached a nadir by six hours. RT-PCR profiling of BDs identified expression of Defb3 and Defb14 mRNA in murine bladder and ureter, which encode for mBD-3 and mBD-14 protein, respectively. MBD-14 protein expression was observed in bladder urothelium following UPEC infection, and both mBD-3 and mBD-14 displayed dose-dependent bactericidal activity toward UPEC in vitro. Thus, whereas mBD-1 deficiency does not alter bladder UPEC burden in vivo, we have identified mBD-3 and mBD-14 as potential mediators of mucosal immunity in the lower urinary tract.

Update on recent guidelines for the management of urinary tract infections in children: the shifting paradigm

PURPOSE OF REVIEW

Recent guidelines on the management of urinary tract infections (UTIs) in children have seen a shift from aggressive imaging studies and the use of prophylactic antibiotics to a more restrictive and targeted approach. This review focuses on new additions to the literature on management of UTI from January 2011 to September 2012.

RECENT FINDINGS

The causal relationship between UTI-vesicoureteral reflux (VUR) and renal scarring has been challenged by several studies. Concerns about unnecessary exposure to ionizing radiation, invasiveness of some of the procedures, and risk of infection have also been raised. With improved prenatal ultrasound, a 'top-down' approach to investigating febrile UTI in children using renal bladder ultrasound alone as an initial study has become popular. Several studies have reported that prophylactic antibiotics and imaging studies after first UTI can be reduced substantially without affecting the risk of recurrent UTI or renal scarring.

SUMMARY

The use of targeted imaging approach in evaluating febrile UTI in children may lead to improved resource use and reduction of potential harmful procedures and interventions, without affecting outcomes of UTI in children. Providers using current guidelines should endeavor to collect practice-based evidence to validate and inform future guidelines.