Increased Age, but Not Parity Predisposes to Higher Bacteriuria Burdens Due to Streptococcus Urinary Tract Infection and Influences Bladder Cytokine Responses, Which Develop Independent of Tissue Bacterial Loads.

Streptococcus agalactiae causes urinary tract infection (UTI) in pregnant adults, non-pregnant adults, immune-compromised individuals and the elderly. The pathogenesis of S. agalactiae UTI in distinct patient populations is poorly understood. In this study, we used murine models of UTI incorporating young mice, aged and dam mice to show that uropathogenic S. agalactiae causes bacteriuria at significantly higher levels in aged mice compared to young mice and this occurs coincident with equivalent levels of bladder tissue colonisation at 24 h post-infection (p.i.). In addition, aged mice exhibited significantly higher bacteriuria burdens at 48 h compared to young mice, confirming a divergent pattern of bacterial colonization in the urinary tract of aged and young mice. Multiparous mice, in contrast, exhibited significantly lower urinary titres of S. agalactiae compared to age-matched nulliparous mice suggesting that parity enhances the ability of the host to control S. agalactiae bacteriuria. Additionally, we show that both age and parity alter the expression levels of several key regulatory and pro-inflammatory cytokines, which are known to be important the immune response to UTI, including Interleukin (IL)-1ß, IL-12(p40), and Monocyte Chemoattractant Protein-1 (MCP-1). Finally, we demonstrate that other cytokines, including IL-17 are induced significantly in the S. agalactiae-infected bladder regardless of age and parity status. Collectively, these findings show that the host environment plays an important role in influencing the severity of S. agalactiae UTI; infection dynamics, particularly in the context of bacteriuria, depend on age and parity, which also affect the nature of innate immune responses to infection.

Uropathogenic Escherichia coli Engages CD14-Dependent Signaling to Enable Bladder-Macrophage-Dependent Control of Acute Urinary Tract Infection.

BACKGROUND: CD14, a coreceptor for several pattern recognition receptors and a widely used monocyte/macrophage marker, plays a key role in host responses to gram-negative bacteria. Despite the central role of CD14 in the inflammatory response to lipopolysaccharide and other microbial products and in the dissemination of bacteria in some infections, the signaling networks controlled by CD14 during urinary tract infection (UTI) are unknown. METHODS: We used uropathogenic Escherichia coli (UPEC) infection of wild-type (WT) C57BL/6 and Cd14(-/-) mice and RNA sequencing to define the CD14-dependent transcriptional signature and the role of CD14 in host defense against UTI in the bladder. RESULTS: UPEC induced the upregulation of Cd14 and the monocyte/macrophage-related genes Emr1/F4/80 and Csf1r/c-fms, which was associated with lower UPEC burdens in WT mice, compared with Cd14(-/-) mice. Exacerbation of infection in Cd14(-/-) mice was associated with the absence of a 491-gene transcriptional signature in the bladder that encompassed multiple host networks not previously associated with this receptor. CD14-dependent pathways included immune cell trafficking, differential cytokine production in macrophages, and interleukin 17 signaling. Depletion of monocytes/macrophages in the bladder by administration of liposomal clodronate led to higher UPEC burdens. CONCLUSIONS: This study identifies new host protective and signaling roles for CD14 in the bladder during UPEC UTI.

Urinary tract infection of mice to model human disease: Practicalities, implications and limitations.

Urinary tract infections (UTIs) are among the most common bacterial infections in humans. Murine models of human UTI are vital experimental tools that have helped to elucidate UTI pathogenesis and advance knowledge of potential treatment and infection prevention strategies. Fundamentally, several variables are inherent in different murine models, and understanding the limitations of these variables provides an opportunity to understand how models may be best applied to research aimed at mimicking human disease. In this review, we discuss variables inherent in murine UTI model studies and how these affect model usage, data analysis and data interpretation. We examine recent studies that have elucidated UTI host-pathogen interactions from the perspective of gene expression, and review new studies of biofilm and UTI preventative approaches. We also consider potential standards for variables inherent in murine UTI models and discuss how these might expand the utility of models for mimicking human disease and uncovering new aspects of pathogenesis.

Prognostic value of semi-quantitative bacteruria counts in the diagnosis of group B streptococcus urinary tract infection: a 4-year retrospective study in adult patients.

BACKGROUND: Semi-quantitative bacteruria counts (s-QBC) are important in the diagnosis of urinary tract infection (UTI) due to most uropathogens. The prognostic value of s-QBC for diagnosis of UTI due to group B streptococcus (GBS) is unknown. In this study, we assessed the value of s-QBC for differentiating acute GBS UTI from asymptomatic bacteruria (ABU), independent of other potential prognostic indicators. METHODS: Medical record review and urinalysis (UA) values for 1593 patients who had urinary GBS isolated (103 to ≥105 CFU/ml) during a four-year period were analyzed using binary logistic regression to determine the predictive values of s-QBC, age, and gender for infection category (acute UTI, ABU) based on the clinical diagnosis. RESULTS: s-QBC alone had a strong predictive value for infection category but only for ABU. Multivariate logistic regression showed similar predictive power of s-QBC for infection category using age as a co-predictor, which was also independently associated with infection category. Typical s-QBC cut-off values that are commonly used in diagnostic settings had no significant power in predicting infection category. Among other UA measures, proteinuria and hematuria were significantly associated with acute infection. CONCLUSIONS: Together, these data show that s-QBC is not useful in the differential diagnosis of GBS UTI. Among the patients in this study, age was an equally effective prognostic indicator compared to s-QBC for identifying high- and low-risk patients for acute GBS UTI. Collectively, these findings indicate that age-based associations may be equally as useful as s-QBC for predicting infection category in the setting of adult patients with GBS-positive urine cultures.

Group B streptococcus cystitis presenting in a diabetic patient with a massive abdominopelvic abscess: a case report.

INTRODUCTION: Streptococcus agalactiae or group B streptococcus is a Gram-positive pathogen that is typically associated with neonatal disease and infection in pregnant women. Group B streptococcus also causes invasive infections in non-pregnant adults including urinary tract infections. The spectrum of urinary tract infections caused by group B streptococcus includes cystitis, pyelonephritis, urosepsis and asymptomatic bacteriuria, which is particularly common among elderly individuals. A rare form of invasive group B streptococcus infection in adults is secondary abscess. Here, we present the first reported case of a patient who developed an unusual, massive abdominopelvic abscess secondary to acute group B streptococcus urinary tract infection. CASE PRESENTATION: A 46-year-old African-American woman presented to the University Emergency Department complaining of urinary tract infection symptoms and severe abdominal pain. Diagnostic imaging by transvaginal ultrasound and computed tomography revealed a massive peripherally-enhancing, low-attenuating fluid collection within her pelvis. The patient's abdominopelvic abscess was drained by ultrasound-guided drainage and this yielded a septic aspirate that was culture positive for abundant S. agalactiae. A recent history of urinary tract infection symptoms in the patient suggested that her abscess developed secondary to cystitis. Complete resolution of the abscess as a favorable outcome was achieved in this case following surgical drainage and appropriate antimicrobial therapy. CONCLUSION: Acute bacterial urinary tract infection leading to an abdominopelvic abscess has not previously been reported in the literature. This case report defines a new disease etiology associated with acute streptococcal cystitis and it will be of interest in cases of urinary tract infections where there is an association with abdominal and/or pelvic pain. A brief review of the literature on unusual secondary abscesses due to group B streptococcus is provided alongside this case to highlight the clinical significance and prognoses of these rare infections. Finally, this case emphasizes the requirement to distinguish unusual etiologies of pyogenic abscesses in order to guide successful clinical management and to treat patients with antibiotics active against the causal organism.

Escherichia coli 83972 expressing a P fimbriae oligosaccharide receptor mimic impairs adhesion of uropathogenic E. coli.

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) are a significant health concern, exacerbated by the rapid emergence of multidrug resistant strains refractory to antibiotic treatment. P fimbriae are strongly associated with upper urinary tract colonization due to specific binding to α-D-galactopyranosyl-(1-4)-ß-D-galactopyranoside receptors in the kidneys. Thus, inhibiting P-fimbrial adhesion may reduce the incidence of UPEC-mediated UTI. E. coli 83972 is an asymptomatic bacteriuria isolate successfully used as a prophylactic agent to prevent UTI in human studies. We constructed a recombinant E. coli 83972 strain displaying a surface-located oligosaccharide P fimbriae receptor mimic that bound to P-fimbriated E. coli producing any of the 3 PapG adhesin variants. The recombinant strain, E. coli 83972::lgtCE, impaired P fimbriae-mediated adhesion to human erythrocytes and kidney epithelial cells. Additionally, E. coli 83972::lgtCE impaired urine colonization by UPEC in a mouse UTI model, demonstrating its potential as a prophylactic agent to prevent UTI.

Genome-wide mapping of cystitis due to Streptococcus agalactiae and Escherichia coli in mice identifies a unique bladder transcriptome that signifies pathogen-specific antimicrobial defense against urinary tract infection.

The most common causes of urinary tract infections (UTIs) are Gram-negative pathogens such as Escherichia coli; however, Gram-positive organisms, including Streptococcus agalactiae, or group B streptococcus (GBS), also cause UTI. In GBS infection, UTI progresses to cystitis once the bacteria colonize the bladder, but the host responses triggered in the bladder immediately following infection are largely unknown. Here, we used genome-wide expression profiling to map the bladder transcriptome of GBS UTI in mice infected transurethrally with uropathogenic GBS that was cultured from a 35-year-old women with cystitis. RNA from bladders was applied to Affymetrix Gene-1.0ST microarrays; quantitative reverse transcriptase PCR (qRT-PCR) was used to analyze selected gene responses identified in array data sets. A surprisingly small significant-gene list of 172 genes was identified at 24 h; this compared to 2,507 genes identified in a side-by-side comparison with uropathogenic E. coli (UPEC). No genes exhibited significantly altered expression at 2 h in GBS-infected mice according to arrays despite high bladder bacterial loads at this early time point. The absence of a marked early host response to GBS juxtaposed with broad-based bladder responses activated by UPEC at 2 h. Bioinformatics analyses, including integrative system-level network mapping, revealed multiple activated biological pathways in the GBS bladder transcriptome that regulate leukocyte activation, inflammation, apoptosis, and cytokine-chemokine biosynthesis. These findings define a novel, minimalistic type of bladder host response triggered by GBS UTI, which comprises collective antimicrobial pathways that differ dramatically from those activated by UPEC. Overall, this study emphasizes the unique nature of bladder immune activation mechanisms triggered by distinct uropathogens.

Clinical Escherichia coli isolates utilize alpha-hemolysin to inhibit in vitro epithelial cytokine production.

Uropathogenic Escherichia coli is the primary cause of urinary tract infections, which affects over 60% of women during their lifetime. UPEC exhibits a number of virulence traits that facilitate colonization of the bladder, including inhibition of cytokine production by bladder epithelial cells. The goal of this study was to identify the mechanism of this inhibition. We observed that cytokine suppression was associated with rapid cytotoxicity toward epithelial cells. We found that cytotoxicity, cytokine suppression and alpha-hemolysin production were all tightly linked in clinical isolates. We screened a UPEC fosmid library and identified clones that gained the cytotoxicity and cytokine-suppression phenotypes. Both clones contained fosmids encoding a PAI II(J96)-like domain and expressed the alpha-hemolysin (hlyA) encoded therein. Mutation of the fosmid-encoded hly operon abolished cytotoxicity and cytokine suppression. Similarly, mutation of the chromosomal hlyCABD operon of UPEC isolate F11 also abolished these phenotypes, and they could be restored by introducing the PAI II(J96)-like domain-encoding fosmid. We also examined the role of alpha-hemolysin in cytokine production both in the murine UTI model as well as patient specimens. We conclude that E. coli utilizes alpha-hemolysin to inhibit epithelial cytokine production in vitro. Its contribution to inflammation during infection requires further study.

Recent insights into microbial triggers of interleukin-10 production in the host and the impact on infectious disease pathogenesis.

Since its initial description as a Th2-cytokine antagonistic to interferon-alpha and granulocyte-macrophage colony-stimulating factor, many studies have shown various anti-inflammatory actions of interleukin-10 (IL-10), and its role in infection as a key regulator of innate immunity. Studies have shown that IL-10 induced in response to microorganisms and their products plays a central role in shaping pathogenesis. IL-10 appears to function as both sword and shield in the response to varied groups of microorganisms in its capacity to mediate protective immunity against some organisms but increase susceptibility to other infections. The nature of IL-10 as a pleiotropic modulator of host responses to microorganisms is explained, in part, by its potent and varied effects on different immune effector cells which influence antimicrobial activity. A new understanding of how microorganisms trigger IL-10 responses is emerging, along with recent discoveries of how IL-10 produced during disease might be harnessed for better protective or therapeutic strategies. In this review, we summarize studies from the past 5 years that have reported the induction of IL-10 by different classes of pathogenic microorganisms, including protozoa, nematodes, fungi, viruses and bacteria and discuss the impact of this induction on the persistence and/or clearance of microorganisms in the host.

Infection-induced IL-10 and JAK-STAT: A review of the molecular circuitry controlling immune hyperactivity in response to pathogenic microbes.

Generation of effective immune responses against pathogenic microbes depends on a fine balance between pro- and anti-inflammatory responses. Interleukin-10 (IL-10) is essential in regulating this balance and has garnered renewed interest recently as a modulator of the response to infection at the JAK-STAT signaling axis of host responses. Here, we examine how IL-10 functions as the "master regulator" of immune responses through JAK-STAT, and provide a perspective from recent insights on bacterial, protozoan, and viral infection model systems. Pattern recognition and subsequent molecular events that drive activation of IL-10-associated JAK-STAT circuitry are reviewed and the implications for microbial pathogenesis are discussed.

Innate transcriptional networks activated in bladder in response to uropathogenic Escherichia coli drive diverse biological pathways and rapid synthesis of IL-10 for defense against bacterial urinary tract infection.

Early transcriptional activation events that occur in bladder immediately following bacterial urinary tract infection (UTI) are not well defined. In this study, we describe the whole bladder transcriptome of uropathogenic Escherichia coli (UPEC) cystitis in mice using genome-wide expression profiling to define the transcriptome of innate immune activation stemming from UPEC colonization of the bladder. Bladder RNA from female C57BL/6 mice, analyzed using 1.0 ST-Affymetrix microarrays, revealed extensive activation of diverse sets of innate immune response genes, including those that encode multiple IL-family members, receptors, metabolic regulators, MAPK activators, and lymphocyte signaling molecules. These were among 1564 genes differentially regulated at 2 h postinfection, highlighting a rapid and broad innate immune response to bladder colonization. Integrative systems-level analyses using InnateDB (http://www.innatedb.com) bioinformatics and ingenuity pathway analysis identified multiple distinct biological pathways in the bladder transcriptome with extensive involvement of lymphocyte signaling, cell cycle alterations, cytoskeletal, and metabolic changes. A key regulator of IL activity identified in the transcriptome was IL-10, which was analyzed functionally to reveal marked exacerbation of cystitis in IL-10-deficient mice. Studies of clinical UTI revealed significantly elevated urinary IL-10 in patients with UPEC cystitis, indicating a role for IL-10 in the innate response to human UTI. The whole bladder transcriptome presented in this work provides new insight into the diversity of innate factors that determine UTI on a genome-wide scale and will be valuable for further data mining. Identification of protective roles for other elements in the transcriptome will provide critical new insight into the complex cascade of events that underpin UTI.