Urovirulence determinants in Escherichia coli strains causing prostatitis

Extraintestinal Pathogenic Escherichia coli: Virulence Factors and Antibiotic Resistance

The One Health approach emphasizes the importance of antimicrobial resistance (AMR) as a major concern both in public health and in food animal production systems. As a general classification, E. coli can be distinguished based on the ability to cause infection of the gastrointestinal system (IPEC) or outside of it (ExPEC). Among the different pathogens, E. coli are becoming of great importance, and it has been suggested that ExPEC may harbor resistance genes that may be transferred to pathogenic or opportunistic bacteria. ExPEC strains are versatile bacteria that can cause urinary tract, bloodstream, prostate, and other infections at non-intestinal sites. In this context of rapidly increasing multidrug-resistance worldwide and a diminishingly effective antimicrobial arsenal to tackle resistant strains. ExPEC infections are now a serious public health threat worldwide. However, the clinical and economic impact of these infections and their optimal management are challenging, and consequently, there is an increasing awareness of the importance of ExPECs amongst healthcare professionals and the general public alike. This review aims to describe pathotype characteristics of ExPEC to increase our knowledge of these bacteria and, consequently, to increase our chances to control them and reduce the risk for AMR, following a One Health approach.

Screening of a Drug Library Identifies Inhibitors of Cell Intoxication by CNF1

Cytotoxic necrotizing factor 1 (CNF1) is a toxin produced by pathogenic strains of Escherichia coli responsible for extra-intestinal infections. CNF1 deamidates Rac1, thereby triggering its permanent activation and worsening inflammatory reactions. Activated Rac1 is prone to proteasomal degradation. There is no targeted therapy against CNF1, despite its clinical relevance. In this work we developed a fluorescent cell-based immunoassay to screen for inhibitors of CNF1-induced Rac1 degradation among 1120 mostly approved drugs. Eleven compounds were found to prevent CNF1-induced Rac1 degradation, and five also showed a protective effect against CNF1-induced multinucleation. Finally, lasalocid, monensin, bepridil, and amodiaquine protected cells from both diphtheria toxin and CNF1 challenges. These data highlight the potential for drug repurposing to fight several bacterial infections and Rac1-based diseases.

Phylogroup and virulence gene association with clinical characteristics of Escherichia coli urinary tract infections from dogs and cats

Escherichia coli isolates from infections outside the gastrointestinal tract are termed extra-intestinal pathogenic E. coli (ExPEC) and can be divided into different subpathotypes; one of these is uropathogenic E. coli (UPEC). The frequency with which UPEC strains cause urinary tract infections in dogs and cats is not well documented. We used an oligonucleotide microarray to characterize 60 E. coli isolates associated with the urinary tract of dogs ( n = 45) and cats ( n = 15), collected from 2004 to 2007, into ExPEC and UPEC and to correlate results with patient clinical characteristics. Microarray analysis was performed, and phylogroup was determined by a quadruplex PCR assay. Isolates that were missing 1 or 2 of the gene determinants representative of a function (capsule, iron uptake related genes, or specific adhesins) were designated as "non-classifiable" by microarray. Phylogroup B2 was positively associated with the UPEC subpathotype ( p < 0.0005) and negatively associated with "non-classifiable" isolates ( p < 0.0005). Phylogroup D was positively associated with ExPEC pathotype ( p = 0.025) and negatively associated with UPEC subpathotype ( p = 0.014). The ExPEC pathotype was positively associated with hospitalization for one or more days ( p = 0.031). The UPEC subpathotype was negatively associated with previous antimicrobial therapy ( p = 0.045) and previous hospitalization within the 3 mo prior to the positive culture ( p = 0.041). The UPEC subpathotype was positively associated with prostatitis ( p = 0.073) and negatively associated with current immunosuppressive therapy ( p = 0.090). Our results indicate that the case history observations may be critically important during the interpretation of laboratory results to encourage judicious use of antimicrobials.

Cytotoxic necrotizing factor 1 promotes prostate cancer progression through activating the Cdc42-PAK1 axis

Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections and plays a role in prostatic carcinogenesis and prostate cancer (PCa) progression. However, the mechanisms through which UPEC promotes PCa development and progression are unclear. Cytotoxic necrotizing factor 1 (CNF1) is one of the most important UPEC toxins and its role in PCa progression has never been studied. We found that UPEC-secreted CNF1 promoted the migration and invasion of PCa cells and PCa metastasis. In vitro studies showed that CNF1 promotes pro-migratory and pro-invasive activity through entering PCa cells and activating Cdc42, which subsequently induced PAK1 phosphorylation and up-regulation of MMP-9 expression. CNF1 also promoted pulmonary metastasis in a xenograft mouse model through these mechanisms. PAK1 phosphorylation correlated with advanced grades of PCa in human clinical PCa tissues. These results suggest that CNF1 derived from UPEC plays an important role in PCa progression through activating a Cdc42-PAK1 signal axis and up-regulating the expression of MMP-9. Therefore, surveillance for and treatment of cnf1-carrying UPEC strains may diminish PCa progression and thus have an important clinical therapeutic impact. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Uropathogenic Escherichia coli-Associated Exotoxins

Escherichia coli are a common cause of infectious disease outside of the gastrointestinal tract. Several independently evolved E. coli clades are common causes of urinary tract and bloodstream infections. There is ample epidemiological and in vitro evidence that several different protein toxins common to many, but not all, of these strains are likely to aid the colonization and immune-evasion ability of these bacteria. This review discusses our current knowledge and areas of ignorance concerning the contribution of the hemolysin; cytotoxic-necrotizing factor-1; and the autotransporters, Sat, Pic, and Vat, to extraintestinal human disease.

Cytotoxic Necrotizing Factor-1 (CNF1) does not promote E. coli infection in a murine model of ascending pyelonephritis

Background

Urinary tract infections (UTI) are among the most common and costly infections in both hospitalized and ambulatory patients. Uropathogenic E. coli (UPEC) represent the majority of UTI isolates and are a diverse group of bacteria that utilize a variety of virulence factors to establish infection of the genitourinary tract. The virulence factor cytotoxic necrotizing factor-1 (CNF1) is frequently expressed in clinical UPEC isolates. To date, there have been conflicting reports on the role of CNF1 in the pathogenesis of E. coli urinary tract infections.

Results

We examined the importance of CNF1 in a murine ascending kidney infection/ pyelonephritis model by performing comparative studies between a clinical UPEC isolate strain and a CNF1-deletion mutant. We found no alterations in bacterial burden with the loss of CNF1, whereas loss of the virulence factor fimH decreased bacterial burdens. In addition, we found no evidence that CNF1 contributed to the recruitment of inflammatory infiltrates in the kidney or bladder in vivo.

Conclusions

While further examination of CNF-1 may reveal a role in UTI pathogenesis, our data casts doubt on the role of CNF-1 in the pathogenesis of UPEC UTI. As with other infections, different models and approaches are needed to elucidate the contribution of CNF1 to E. coli UTI.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-017-1036-0) contains supplementary material, which is available to authorized users.

Escherichia coli sequence type 73 as a cause of community acquired urinary tract infection in men and women in Rio de Janeiro, Brazil

Escherichia coli clones ST131, ST69, ST95, and ST73 are frequent causes of urinary tract infections (UTI) and bloodstream infections. Specific clones and virulence profiles of E. coli causing UTI in men has been rarely described. The aim of this study was to characterize patient and clonal characteristics of community-acquired UTI caused by E. coli in men (n=12) and women (n=127) in Rio de Janeiro, Brazil, complementing a previous work. We characterized isolates in phylogenetic groups, ERIC2-PCR and PFGE types, MLST, genome similarity and virulence gene-profiles. UTI from men were more frequently caused by phylogenetic group B2 isolates (83% versus 42%, respectively, P = 0.01), a group with significantly higher virulence scores compared with women. ST73 was the predominant clone in men (50%) and the second most frequent in women (12%), with the highest virulence score (mean and median=9) among other clones. ST73 gnomes formed at least six clusters. E. coli from men carried significantly higher numbers of virulence genes, such as sfa/focDE (67% versus 27%), hlyA (58% versus 24%), cnf 1 (58% versus 16%), fyuA (100% versus 82%) and MalX (92% versus 44%), compared with isolates from women. These data suggest the predominance and spread of ST73 isolates likely relates to an abundance of virulence determinants.

Cellular and Humoral Systemic and Mucosal Immune Responses Stimulated by an Oral Polybacterial Immunomodulator in Patients with Chronic Urinary Tract Infections

An oral polybacterial immunomodulator Urostim (U), composed of killed cells and their lysates from E. coli expressing type 1 and P-pili, E. coli Re mutant, P. mirabilis, K. pneumoniae and E. faecalis was created for immunoprophylaxis and immunotherapy of urinary tract infections (UTIs). In experimental animal models, the stimulating effect of U on lymphocyte functional activity, macrophage phagocytosis and antibody producing cells, was established. In this study the immuno-modulating effects of U on the proliferating capacity and ultrastructural morphologic changes of lymphocytes, cytokine production and specific systemic humoral and mucosal immune responses in patients with UTIs have been evaluated. Patients enrolled in the study, received orally 50 mg U daily for a period of three months. On days 0,30 and 90 a quantitative analysis was performed on lymphoproliferative responses to polyclonal mitogens, IL-2 and the specific antigen U, the production of specific serum and saliva IgA, IgM and IgG antibodies to all components of U and the concentration of pro-inflammatory cytokines. There was significant improvement of non-specific and specific lymphoproliferative responses on days 30 and 90 after the onset of treatment with U, confirmed by electron-microscopic studies. The highest concentrations of serum proinflammatory cytokines TNF-α, IL-1β, and IL-6 were registered at baseline followed by a decrease until the end of the observation period. This finding correlates with the gradual decrease of immune activation as measured by the spontaneous lymphocyte proliferation. Data from the production of specific antibacterial antibodies in serum and saliva show two types of reactions. The first type was registered in patients with low pre-treatment levels in whom the concentration of specific antibodies increased on days 30 and 90. The second type of reaction was observed in patients with high pre-treatment levels, which dropped on day 30 and were usually followed by an increase at the end of the study. These results provide evidence for the immuno-modulating effect of U. Our data show that the oral administration of the polybacterial immunomodulator Urostim stimulates adequate cellular and humoral systemic and mucosal immune responses in patients with chronic UTIs.

Bacterial Prostatitis: Bacterial Virulence, Clinical Outcomes, and New Directions

Four prostatitis syndromes are recognized clinically: acute bacterial prostatitis, chronic bacterial prostatitis, chronic prostatitis/chronic pelvic pain syndrome, and asymptomatic prostatitis. Because Escherichia coli represents the most common cause of bacterial prostatitis, we investigated the importance of bacterial virulence factors and antimicrobial resistance in E. coli strains causing prostatitis and the potential association of these characteristics with clinical outcomes. A structured literature review revealed that we have limited understanding of the virulence-associated characteristics of E. coli causing acute prostatitis. Therefore, we completed a comprehensive microbiological and molecular investigation of a unique strain collection isolated from healthy young men. We also considered new data from an animal model system suggesting certain E. coli might prove important in the etiology of chronic prostatitis/chronic pelvic pain syndrome. Our human data suggest that E. coli needs multiple pathogenicity-associated traits to overcome anatomic and immune responses in healthy young men without urological risk factors. The phylogenetic background and accumulation of an exceptional repertoire of extraintestinal pathogenic virulence-associated genes indicate that these E. coli strains belong to a highly virulent subset of uropathogenic variants. In contrast, antibiotic resistance confers little added advantage to E. coli strains in these healthy outpatients. Our animal model data also suggest that certain pathogenic E. coli may be important in the etiology of chronic prostatitis/chronic pelvic pain syndrome through mechanisms that are dependent on the host genetic background and the virulence of the bacterial strain.

Escherichia coli isolates from patients with bacteremic urinary tract infection are genetically distinct from those derived from sepsis following prostate transrectal biopsy

BACKGROUND

Transrectal ultrasound-guided (TRUS) prostate biopsy is a very common procedure that is generally considered relatively safe. However, severe sepsis can occur after TRUS prostate biopsies, with Escherichia coli being the predominant causative agent. A common perception is that the bacteria that cause post-TRUS prostate biopsy infections originate in the urinary tract, but this view has not been adequately tested. Yet other authors believe on the basis of indirect evidence that the pathogens are introduced into the bloodstream by the biopsy needle after passage through the rectal mucosa.

METHODS

We compared E. coli isolates from male patients with bacteremic urinary tract infection (B-UTI) to isolates of patients with post prostate biopsy sepsis (PPBS), in terms of their sequence types, determined by multi-locus sequence typing (MLST) and their virulence markers.

RESULTS

B-UTI isolates were much richer in virulence genes than were PPBS isolates, supporting the hypothesis that E. coli causing PPBS derive directly from the rectum. Sequence type 131 (ST131) strains and related strain from the ST131 were common (>30%) among the E. coli isolates from PPBS patients as well as from B-UTI patients and all these strains expressed extended spectrum beta-lactamases.

CONCLUSIONS

Our finding supports the hypothesis that E. coli causing PPBS derive directly from the rectum, bypassing the urinary tract, and therefore do not require many of the virulence capabilities necessary for an E. coli strain that must persist in the urinary tract. In light of the increasing prevalence of highly resistant E. coli strains, a new approach for prevention of PPBS is urgently required.

Prostatic inflammation induces urinary frequency in adult mice

Lower urinary tract symptoms (LUTS) including urinary frequency and nocturia are common in aging men. Recent studies have revealed a strong association of prostatic inflammation with LUTS. We developed an animal model of bacterial induced, isolated prostatic inflammation and examined the effect of prostatic inflammation on voiding behavior in adult C57BL/6J mice. Prostatic inflammation was induced by transurethral inoculation of uropathogenic E. coli—1677. Bacterial cystitis was prevented by continuous administration of nitrofurantoin. Hematoxylin and eosin (H&E) staining and bacterial culture were preformed to validate our animal model. Voiding behavior was examined by metabolic cage testing on post-instillation day 1 (PID 1), PID 4, PID 7 and PID 14 and both voiding frequency and volume per void were determined. Mice with prostatic inflammation showed significantly increased voiding frequency at PID 1, 7 and 14, and decreased volume per void at all time points, as compared to mice instilled with saline and receiving nitrofurantoin (NTF). Linked analysis of voiding frequency and voided volumes revealed an overwhelming preponderance of high frequency, low volume voiding in mice with prostatic inflammation. These observations suggest that prostatic inflammation may be causal for symptoms of urinary frequency and nocturia.

IraL is an RssB anti-adaptor that stabilizes RpoS during logarithmic phase growth in Escherichia coli and Shigella

RpoS (σ(S)), the general stress response sigma factor, directs the expression of genes under a variety of stressful conditions. Control of the cellular σ(S) concentration is critical for appropriately scaled σ(S)-dependent gene expression. One way to maintain appropriate levels of σ(S) is to regulate its stability. Indeed, σ(S) degradation is catalyzed by the ClpXP protease and the recognition of σ(S) by ClpXP depends on the adaptor protein RssB. Three anti-adaptors (IraD, IraM, and IraP) exist in Escherichia coli K-12; each interacts with RssB and inhibits RssB activity under different stress conditions, thereby stabilizing σ(S). Unlike K-12, some E. coli isolates, including uropathogenic E. coli strain CFT073, show comparable cellular levels of σ(S) during the logarithmic and stationary growth phases, suggesting that there are differences in the regulation of σ(S) levels among E. coli strains. Here, we describe IraL, an RssB anti-adaptor that stabilizes σ(S) during logarithmic phase growth in CFT073 and other E. coli and Shigella strains. By immunoblot analyses, we show that IraL affects the levels and stability of σ(S) during logarithmic phase growth. By computational and PCR-based analyses, we reveal that iraL is found in many E. coli pathotypes but not in laboratory-adapted strains. Finally, by bacterial two-hybrid and copurification analyses, we demonstrate that IraL interacts with RssB by a mechanism distinct from that used by other characterized anti-adaptors. We introduce a fourth RssB anti-adaptor found in E. coli species and suggest that differences in the regulation of σ(S) levels may contribute to host and niche specificity in pathogenic and nonpathogenic E. coli strains.

IMPORTANCE

Bacteria must cope with a variety of environmental conditions in order to survive. RpoS (σ(S)), the general stress response sigma factor, directs the expression of many genes under stressful conditions in both pathogenic and nonpathogenic Escherichia coli strains. The regulation of σ(S) levels and activity allows appropriately scaled σ(S)-dependent gene expression. Here, we describe IraL, an RssB anti-adaptor that, unlike previously described anti-adaptors, stabilizes σ(S) during the logarithmic growth phase in the absence of additional stress. We also demonstrate that iraL is found in a large number of E. coli and Shigella isolates. These data suggest that strains containing iraL are able to initiate σ(S)-dependent gene expression under conditions under which strains without iraL cannot. Therefore, IraL-mediated σ(S) stabilization may contribute to host and niche specificity in E. coli.

Genotypic and phenotypic characterization of Escherichia coli isolates from children with urinary tract infection and from healthy carriers

BACKGROUND

Urinary tract infections (UTI) are common in children and contribute significantly to morbidity and mortality. The major cause is Escherichia coli, carrying multiple virulence-associated factors (VFs). However, the specific traits that distinguish childhood uropathogenic E. coli from fecal commensals of healthy children are incompletely defined.

METHODS

We used a multiplex polymerase chain reaction-based reverse line blot assay, several additional polymerase chain reactions and phenotypic methods to compare distributions of virulence traits (22 VF genes, UTI-associated O types, phylogenetic groups, sequence type 131 and expression of selected VFs), between 212 E. coli isolates from children ≤ 5 years with UTI (109 cystitis and 103 pyelonephritis) and 115 fecal isolates from healthy children of similar age, collected during the same time period.

RESULTS

The studied traits were most prevalent among pyelonephritis, followed closely by cystitis isolates and were uncommon among fecal isolates. Eight VF genes differentiated pyelonephritis from cystitis isolates, but aggregate VF scores in these 2 UTI groups were similar. Most of the studied phenotypic characteristics showed a similar descending prevalence gradient from pyelonephritis, through cystitis, to fecal isolates. Coexpression of biofilm components, curli and cellulose, was strongly associated with pyelonephritis, phylogenetic group B2, individual VF genes and higher VF scores. Two-thirds (67%) of clinical isolates belonged to phylogenetic group B2 and, of these, 12% belonged to the sequence type 131 clonal group, compared with 14% and 1%, respectively, of fecal isolates.

CONCLUSIONS

These findings identify specific virulence factors, O types and a virulent clonal group (sequence type 131), as potential targets for UTI prevention strategies in children.

Acute Escherichia coli prostatitis in previously health young men: bacterial virulence factors, antimicrobial resistance, and clinical outcomes

OBJECTIVES

To investigate clinical outcomes, bacterial virulence factors, and antimicrobial resistance in E. coli from young men presenting with acute bacterial prostatitis.

METHODS

Initial E. coli isolates from previously healthy young men with no factors compromising urinary tract anatomy or function were tested for virulence-associated genes by polymerase chain reaction (PCR) assays, phylogenetic grouping by triplex polymerase PCR, and antibiotic resistance.

RESULTS

All 18 patients responded to treatment, including 2 who required long-term therapy. E. coli were allocated to phylogenetic groups B2 (13 strains) and D (5 strains). Prostatitis isolates belonged to clones mainly represented by extraintestinal pathogenic E. coli (ExPEC) and preferentially uropathogenic E. coli and displayed marked accumulation of virulence genes (hly, cdt1, clb, pap, sfa/foc, fyuA, iroN, kpsMT(II), and traT) characteristic of highly virulent ExPEC. All phylogenetic group B2 strains coded for at least 1 toxin with carcinogenic potential (Colibactin, cytolethal distending toxins, or cytotoxic necrotizing factor). In contrast to their accumulation of virulence-associated traits, prostatitis strains were sensitive to standard antibiotics.

CONCLUSIONS

The phylogenetic background and accumulation of an exceptional repertoire of extraintestinal pathogenic virulence-associated genes indicate that these E. coli strains belong to a highly virulent subset of uropathogenic variants. In contrast, antibiotic resistance was minimal in these E. coli strains from previously healthy, young outpatients.

Uropathogenic Escherichia coli induces chronic pelvic pain

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a debilitating syndrome of unknown etiology often postulated, but not proven, to be associated with microbial infection of the prostate gland. We hypothesized that infection of the prostate by clinically relevant uropathogenic Escherichia coli (UPEC) can initiate and establish chronic pain. We utilized an E. coli strain newly isolated from a patient with CP/CPPS (strain CP1) and examined its molecular pathogenesis in cell culture and in a murine model of bacterial prostatitis. We found that CP1 is an atypical isolate distinct from most UPEC in its phylotype and virulence factor profile. CP1 adhered to, invaded, and proliferated within prostate epithelia and colonized the prostate and bladder of NOD and C57BL/6J mice. Using behavioral measures of pelvic pain, we showed that CP1 induced and sustained chronic pelvic pain in NOD mice, an attribute not exhibited by a clinical cystitis strain. Furthermore, pain was observed to persist even after bacterial clearance from genitourinary tissues. CP1 induced pelvic pain behavior exclusively in NOD mice and not in C57BL/6J mice, despite comparable levels of colonization and inflammation. Microbial infections can thus serve as initiating agents for chronic pelvic pain through mechanisms that are dependent on both the virulence of the bacterial strain and the genetic background of the host.

Do Escherichia coli extract and cranberry exert preventive effects on chronic bacterial prostatitis? Pilot study using an animal model

Traditional first-line treatment of chronic bacterial prostatitis (CBP) is administration of empirical antibiotics. However, the efficacy rate is low and long-term antibiotic therapy can result in adverse events and bacterial resistance. For these reasons, a new treatment or preventive modality that can replace traditional antibiotic therapy is required. There are several reports that E. coli extract has a preventive effect on recurrent urinary tract infection (UTI). Cranberries are also known to have beneficial effects in preventing UTI. To evaluate the preventive effect of E. coli extract and cranberries on CBP, 48 rats were randomly divided into 4 groups; control, ciprofloxacin, E. coli extract, and cranberry groups. All drug treatments were conducted for 3 weeks, and then we developed a CBP rat model. After 4 weeks, the results of microbiological culture of prostate and urine samples as well as histological findings for the prostate were analyzed for each group. The infection rate in the ciprofloxacin group was significantly lower than that in the control group. The microbiological cultures of the prostate and urine samples demonstrated reduced bacterial growth in all experimental groups compared with the control group. Histopathologic examination showed significantly decreased prostatic inflammation in all groups compared with the control group. These results suggest that E. coli extract has a potential preventive effect on the development of CBP, and cranberry also exhibits promising activity in this context.

A systematic review of outbreak and non-outbreak studies of extraintestinal pathogenic Escherichia coli causing community-acquired infections

A systematic review of outbreak and non-outbreak studies of infections caused by extraintestinal pathogenic Escherichia coli (ExPEC) was conducted. This review examines the epidemiology, seasonality, source or mode of transmission, and temporal changes, based on E. coli serogroup, in ExPEC causing sporadic vs. outbreak-associated infections. Twelve outbreak and 28 non-outbreak studies were identified. The existence of ExPEC outbreaks was well supported. Three of four outbreak reports indicated peak periods during the winter months. Serogroups associated with outbreak infections ranged from 1% to 26% (average 11·4%) vs. (range 1-15%, average 3·5%) for serogroups associated with sporadic infections; the distribution of serogroups also differed for outbreak and non-outbreak infections. Study authors indicated that the outbreaks may have resulted from foodborne transmission, but direct evidence was unavailable. This review provides evidence that the epidemiology of endemic vs. epidemic ExPEC infections differs; however, study reporting quality limited epidemiological inferences.

Loss of Nkx3.1 expression in bacterial prostatitis: a potential link between inflammation and neoplasia

NKX3.1 is a homeodomain protein that functions as a dosage sensitive prostate-specific transcription factor. Diminished NKX3.1 expression is associated with prostate epithelial cell proliferation in vitro and with increasing Gleason grade in patient samples. Mouse Nkx3.1 also functions as a negative regulator of prostate cell growth in prostate cancer models. Identifying biological and environmental factors that modulate NKX3.1 accumulation is therefore central to efforts aimed at elucidating prostate growth control mechanisms. To determine the effect of inflammation on Nxk3.1 accumulation, bacterial prostatitis was induced by intraurethral inoculation of a uropathogenic E. coli strain in mice. Nkx3.1 expression was profoundly reduced in infected prostate lobes and correlated with increased expression of a proliferation marker. Androgen receptor levels were also reduced in concert with Nkx3.1, and a marked increase in the basal cell marker p63 was observed. Analyses of the inflammatory infiltrate revealed a classic acute inflammatory response that attained characteristics of a chronic state within fourteen days postinoculation. Comparison of the four prostate lobes revealed clear differences in the extent of inflammation. These data demonstrate that acute inflammation in response to a bacterial agent in the prostate is associated with a significant diminution in the level of a key regulator of prostate cell proliferation. These observations provide a plausible mechanism whereby prostate inflammation may establish a local environment conducive to epithelial cell growth.

Uropathogenic Escherichia coli

The urinary tract is among the most common sites of bacterial infection, and Escherichia coli is by far the most common species infecting this site. Individuals at high risk for symptomatic urinary tract infection (UTI) include neonates, preschool girls, sexually active women, and elderly women and men. E. coli that cause the majority of UTIs are thought to represent only a subset of the strains that colonize the colon. E. coli strains that cause UTIs are termed uropathogenic E. coli (UPEC). In general, UPEC strains differ from commensal E. coli strains in that the former possess extragenetic material, often on pathogenicity-associated islands (PAIs), which code for gene products that may contribute to bacterial pathogenesis. Some of these genes allow UPEC to express determinants that are proposed to play roles in disease. These factors include hemolysins, secreted proteins, specific lipopolysaccharide and capsule types, iron acquisition systems, and fimbrial adhesions. The current dogma of bacterial pathogenesis identifies adherence, colonization, avoidance of host defenses, and damage to host tissues as events vital for achieving bacterial virulence. These considerations, along with analysis of the E. coli CFT073, UTI89, and 536 genomes and efforts to identify novel virulence genes should advance the field significantly and allow for the development of a comprehensive model of pathogenesis for uropathogenic E. coli.Further study of the adaptive immune response to UTI will be especially critical to refine our understanding and treatment of recurrent infections and to develop vaccines.

Amyloid formation by the pro-inflammatory S100A8/A9 proteins in the ageing prostate

Background

The conversion of soluble peptides and proteins into polymeric amyloid structures is a hallmark of many age-related degenerative disorders, including Alzheimer's disease, type II diabetes and a variety of systemic amyloidoses. We report here that amyloid formation is linked to another major age-related phenomenon − prostate tissue remodelling in middle-aged and elderly men.

Methodology/Principal Findings

By using multidisciplinary analysis of corpora amylacea inclusions in prostate glands of patients diagnosed with prostate cancer we have revealed that their major components are the amyloid forms of S100A8 and S100A9 proteins associated with numerous inflammatory conditions and types of cancer. In prostate protease rich environment the amyloids are stabilized by dystrophic calcification and lateral thickening. We have demonstrated that material closely resembling CA can be produced from S100A8/A9 in vitro under native and acidic conditions and shows the characters of amyloids. This process is facilitated by calcium or zinc, both of which are abundant in ex vivo inclusions. These observations were supported by computational analysis of the S100A8/A9 calcium-dependent aggregation propensity profiles. We found DNA and proteins from Escherichia coli in CA bodies, suggesting that their formation is likely to be associated with bacterial infection. CA inclusions were also accompanied by the activation of macrophages and by an increase in the concentration of S100A8/A9 in the surrounding tissues, indicating inflammatory reactions.

Conclusions/Significance

These findings, taken together, suggest a link between bacterial infection, inflammation and amyloid deposition of pro-inflammatory proteins S100A8/A9 in the prostate gland, such that a self-perpetuating cycle can be triggered and may increase the risk of malignancy in the ageing prostate. The results provide strong support for the prediction that the generic ability of polypeptide chains to convert into amyloids could lead to their involvement in an increasing number of otherwise apparently unrelated diseases, particularly those associated with ageing.

Virulence Traits in Escherichia Coli Strains Isolated from Outpatients with Urinary Tract Infections

This study aims to characterize phenotypic and genotypic virulence traits in Escherichia coli strains, isolated from outpatients with urinary tract infections, comparing with those obtained from inpatients. Information on the pathogenic behavior of the uropathogenic strains was obtained by monitoring different biological properties, such as autoagglutination, hemagglutination, adhesiveness to and invasion of human bladder (HT1376) cells, biofilm formation, phylogenetic grouping, and virulence-related genes. The results show similar behavior in the two groups concerning autoagglutination, hemagglutination, and biofilm formation. None of the strains examined was invasive. However, in strains from outpatients there was an increased adhesion to HT1376 cells compared with clinical strains, a significant higher presence of genes codifying for adhesins and cell protection factors, and a lower proportion of strains belonging to B1 group. These findings add further information on the pathogenic traits of community E. coli, since strains isolated from the outpatients' group were differently “armed” in comparison with those of clinical cases, and more suitable to infect healthy individuals.

Hemolysin of uropathogenic Escherichia coli evokes extensive shedding of the uroepithelium and hemorrhage in bladder tissue within the first 24 hours after intraurethral inoculation of mice

Many uropathogenic Escherichia coli (UPEC) strains produce both hemolysin (Hly) and cytotoxic necrotizing factor type 1 (CNF1), and the loci for these toxins are often linked. The conclusion that Hly and CNF1 contribute to urovirulence is supported by the results of epidemiological studies associating the severity of urinary tract infections (UTIs) with toxin production by UPEC isolates. Additionally, we previously reported that mouse bladders and rat prostates infected with UPEC strain CP9 exhibit a more profound inflammatory response than the organs from animals challenged with CP9cnf(1) and that CNF1 decreases the antimicrobial activities of polymorphonuclear leukocytes. More recently, we created an Hly mutant, CP9Delta hlyA(1)::cat, and showed that it was less hemolytic and destructive for cultured bladder cells than CP9 was. Here we evaluated the relative effects of mutations in hlyA(1) or cnf(1) alone or together on the pathogenicity of CP9 in a mouse model of ascending UTI. To do this, we constructed an hlyA(1)-complemented clone of CP9Delta hlyA(1)::cat and an hlyA(1) cnf(1) CP9 double mutant. We found that Hly had no influence on bacterial colonization of the bladder or kidneys in single or mixed infections with the wild type and CP9Delta hlyA(1)::cat but that it did provoke sloughing of the uroepithelium and bladder hemorrhage within the first 24 h after challenge. Finally, we confirmed that CNF1 expression induces bladder inflammation and, in particular, as shown in this study, submucosal edema. From these data, we speculate that Hly and CNF1 may be largely responsible for the signs and symptoms of cystitis in humans infected with toxigenic UPEC.

In vitro activity of prulifloxacin against Escherichia coli isolated from urinary tract infections and the biological cost of prulifloxacin resistance

Minimum inhibitory concentrations (MICs) and mutant prevention concentrations (MPCs) of prulifloxacin against 30 strains of Escherichia coli isolated from urinary tract infections as well as the 'biological cost' related to acquisition of resistance to the same drug in 10 uropathogenic E. coli were assessed. In terms of MIC(90), prulifloxacin was more potent than ciprofloxacin and levofloxacin. Prulifloxacin produced lower or equal MPC values than the other two fluoroquinolones (93.3% and 73.3% compared with levofloxacin and ciprofloxacin, respectively). Compared with susceptible strains, prulifloxacin-resistant mutants showed a reduced rate of growth (ranging from 20.0% to 98.0% in different culture media and incubation conditions) and a decreased fitness index (ranging from 0.959 to 0.999). They were also impaired in their ability to adhere to uroepithelial cells and urinary catheters (11.7-66.4% and 16.3-78.3% reduction, respectively) and showed a lower surface hydrophobicity (51.2-76.0%). They were more susceptible to ultraviolet irradiation (30.6-93.8% excess mortality), showed increased resistance to colicins and diminished transfer of plasmids (<1-8.5x10(-8) vs. 3.3x10(-7)-2.4x10(-4)). Synthesis of haemolysin and type I fimbriae and production of flagella were also adversely affected. This study demonstrates a strict relationship between acquisition of prulifloxacin resistance and loss of important virulence traits. In this transition, E. coli pays a severe biological cost that entails a general reduction of fitness, thus compromising competition with susceptible wild-type strains in the absence of the drug.

Biofilm formation in uropathogenic Escherichia coli strains: relationship with prostatitis, urovirulence factors and antimicrobial resistance

PURPOSE

Escherichia coli strains are the most frequent cause of urinary tract infections. Biofilm formation allows the strains to persist a long time in the genitourinary tract and interfere with bacterial eradication. We determined the possible relationships between the different urinary tract infections, and in vitro biofilm formation, the presence of urovirulence factors and nalidixic acid resistance.

MATERIALS AND METHODS

A total of 151 E. coli strains collected from patients with cystitis (44 strains), pyelonephritis (75) and prostatitis (32) were analyzed for in vitro biofilm formation, the phylogenetic group, the presence of several urovirulence factors and resistance to nalidixic acid.

RESULTS

E. coli strains causing prostatitis produced biofilm in vitro more frequently than those causing other urinary tract infections and had a higher frequency of hemolysin (p = 0.03 and 0.0002, respectively). However, only hemolysin was independently associated with prostatitis. On the other hand, strains forming biofilm presented a significantly higher frequency of hemolysin and type 1 fimbriae expression.

CONCLUSIONS

Although hemolysin is the main virulence factor by which E. coli causes acute prostatitis, the association between hemolysin and biofilm formation may result in increased ability of E. coli strains to persist in the prostate.

Escherichia coli isolates associated with uncomplicated and complicated cystitis and asymptomatic bacteriuria possess similar phylogenies, virulence genes, and O-serogroup profiles

The genetic and serological characteristics of Escherichia coli isolates from patients with uncomplicated cystitis (UC), complicated cystitis (CC), and complicated asymptomatic bacteriuria (CASB) were determined. Phylogenetic group B2 was predominant in all categories. The prevalences of 14 out of 18 virulence factor genes were similar among the three categories, while pap, iha, ompT, and PAI were more frequently seen in isolates associated with UC than CC or CASB.

Pathogenicity island markers in commensal and uropathogenic Escherichia coli isolates

Uropathogenic isolates of Escherichia coli (UPEC) contain blocks of DNA, termed pathogenicity islands (PAIs), that contribute to their virulence. Two multiplex PCR assays were developed to detect eight PAI markers among 50 commensal E. coli and 100 UPEC isolates. In total, 40% of commensal isolates and 93% of UPEC carried PAIs. Despite this difference, the distribution of various PAIs showed the same pattern in both groups, with the most prevalent being PAI IV(536) (38% commensal vs. 89% UPEC), followed by PAI I(CFT073) (26% vs. 73%), PAI II(CFT073) (14% vs. 46%), PAI II(J96) (8% vs. 34%), PAI I(536) (8% vs. 33%) and PAI II(536) (4% vs. 20%). PAI III(536) was detected only in UPEC (2%), while PAI I(J96) was not detected in any isolate. Although the mean number of PAIs per isolate was higher among UPEC (2.97) than in commensal (0.98) isolates, there were no statistical differences among group B2 E. coli from the two origins; however, commensal isolates from groups D and B1 appeared to be less virulent than pathogenic isolates. Regardless of their phylogenetic group, nearly all the commensal and UPEC isolates with the same number of PAIs had the same PAI combinations. Although group B2 E. coli are uncommon among commensal intestinal flora, they are highly virulent when present, suggesting that the intestinal flora may act as a reservoir for bacteria that can cause urinary tract infection.

Caracterización de Escherichia coli de los grupos filogenéticos A y B1 causantes de infección extraintestinal

INTRODUCTION

Escherichia coli isolates from the non-pathogenic phylogenetic groups A and B1 rarely cause extraintestinal infections. The aim of this study was to analyze 37 E. coli isolates pertaining to phylogenetic groups A and B1 and compare them with 37 E. coli isolates from group B2 and 31 from group D, which caused the same infections.

METHODS

Among 105 E. coli isolated from the urine of patients with cystitis and pyelonephritis and from the blood of patients with urinary-source and other-source bacteriemia, the E. coli phylogenetic groups, 15 virulence-associated genes, 7 O-antigens and fluoroquinolone resistance were analyzed.

RESULTS

E. coli from groups A and B1 showed fewer virulence determinants (median 3.5) than E. coli from group B2 (8.6, P < 0.01) or D (5.3, P < .001); however, a subgroup containing 3 isolates from group A and 5 from B1 harbored 5 or more factors. E. coli from groups A/B1 were associated with resistance to fluoroquinolones (74%, P < .001), whereas E. coli from group B2 were associated with susceptibility to this antibiotic (76%, P = .003). E. coli from groups A/B1 were isolated significantly more frequently in patients with pyelonephritis or sepsis and local or general factors favoring infection, association not observed in patients with cystitis.

CONCLUSIONS

Even though most of the E. coli isolates from phylogenetic groups A and B1 presented a low virulence potential, they were able to cause extraintestinal infections, particularly in compromised patients.

A single amino acid substitution in the enzymatic domain of cytotoxic necrotizing factor type 1 of Escherichia coli alters the tissue culture phenotype to that of the dermonecrotic toxin of Bordetella spp

Cytotoxic necrotizing factor type 1 (CNF1) and dermonecrotic toxin (DNT) share homology within their catalytic domains and possess deamidase and transglutaminase activities. Although each toxin has a preferred enzymatic activity (i.e. deamidation for CNF1 and transglutamination for DNT) as well as target substrates, both modify a specific glutamine residue in RhoA, Rac1 and Cdc42, which renders these GTPases constitutively active. Here we show that despite their similar mechanisms of action CNF1 and DNT induced unique phenotypes on HEp-2 and Swiss 3T3 cells. CNF1 induced multinucleation of HEp-2 cells and was cytotoxic for Swiss 3T3 cells (with binucleation of the few surviving cells) while DNT showed no morphological effects on HEp-2 cells but did induce binucleation of Swiss 3T3 cells. To determine if the enzymatic domain of each toxin dictated the induced phenotype, we constructed enzymatically active chimeric toxins and mutant toxins that contained single amino acid substitutions within the catalytic site and tested these molecules in tissue culture and enzymatic assays. Moreover, both site-directed mutant toxins showed reduced time to maximum transglutamination of RhoA compared with the parent toxins. Nevertheless, the substitution of threonine for Lys(1310) in the DNT-based mutant, while affecting transglutamination efficiency of the toxin, did not abrogate that enzymatic activity.

Escherichia coli cytotoxic necrotizing factor 1 blocks cell cycle G2/M transition in uroepithelial cells

Evidence is accumulating that a growing number of bacterial toxins act by modulating the eukaryotic cell cycle machinery. In this context, we provide evidence that a protein toxin named cytotoxic necrotizing factor 1 (CNF1) from uropathogenic Escherichia coli is able to block cell cycle G(2)/M transition in the uroepithelial cell line T24. CNF1 permanently activates the small GTP-binding proteins of the Rho family that, beside controlling the actin cytoskeleton organization, also play a pivotal role in a large number of other cellular processes, including cell cycle regulation. The results reported here show that CNF1 is able to induce the accumulation of cells in the G(2)/M phase by sequestering cyclin B1 in the cytoplasm and down-regulating its expression. The possible role played by the Rho GTPases in the toxin-induced cell cycle deregulation has been investigated and discussed. The activity of CNF1 on cell cycle progression can offer a novel view of E. coli pathogenicity.

Detection of Escherichia coli 16S RNA and cytotoxic necrotizing factor 1 gene in benign prostate hyperplasia

OBJECTIVES

Inflammation and occasionally necrosis is observed in the prostate tissue from patients with benign prostate hyperplasia (BPH). The etiology of prostatic inflammation/necrosis is unknown, but bacteria may be involved.

MATERIALS AND METHODS

Retrospective analysis of archival prostate tissue samples collected during 1982-1997 was undertaken. Three hundred fifty-two specimens from patients with BPH obtained via transurethral resection of prostate (TURP) were studied for the presence of Escherichia coli 16S RNA and E. coli virulence factor genes: cytotoxic necrotizing factor (cnf1), alpha-hemolysin (hly), an autotransported protein (sat), and P fimbriae (papC).

RESULTS

E. coli 16S RNA was detected in 12 (3%) samples and cnf1 gene in six (1.5%) samples, with two samples being positive for both markers. hly, sat, papC genes were not detected. Of 6 cnf1-positive samples, severe inflammation and necrosis were present in four and three samples, respectively. Of eight E. coli-positive/cnf1-negative samples, five showed signs of severe inflammation and two showed severe necrosis.

CONCLUSIONS

A small proportion of patients with BPH undergoing TURP are positive for E. coli 16S RNA and cnf1 gene in the prostate tissue. Further studies are needed to show that particular E. coli genotypes are involved in the development of prostatic inflammation/necrosis in BPH.

Quinolone, fluoroquinolone and trimethoprim/sulfamethoxazole resistance in relation to virulence determinants and phylogenetic background among uropathogenic Escherichia coli

INTRODUCTION

The goal of this study was to assess how resistance to quinolones, fluoroquinolones and trimethoprim/sulfamethoxazole relates to the virulence potential and phylogenetic background of clinical Escherichia coli isolates.

METHODS

Among 150 uropathogens (21% resistant to quinolones, 12% resistant to fluoroquinolones and 29.3% resistant to trimethoprim/sulfamethoxazole), E. coli phylogenetic group, 15 virulence-associated genes and 7 O antigens were analysed. Clonal group A (CGA) and genomic PCR profiles were studied among trimethoprim/sulfamethoxazole-resistant isolates.

RESULTS

Isolates susceptible to the three antimicrobial agents were significantly associated with phylogenetic group B2, whereas resistant isolates exhibited shifts to non-B2 groups (quinolone and fluoroquinolone-resistant isolates to group A; trimethoprim/sulfamethoxazole-resistant isolates to group D). Diverse virulence traits, including UTI-associated O antigens, were significantly less frequent among resistant isolates, particularly those resistant to fluoroquinolones (median score, 3.9 virulence factors/strain) and also to quinolones (5.2) or trimethoprim/sulfamethoxazole (6.4), as compared with the corresponding drug-susceptible isolates (median scores of 7.9, 8.6 and 7.9, respectively). Among 44 trimethoprim/sulfamethoxazole-resistant isolates, 3 (6.8%) belonged to CGA. All these 3 CGA strains caused pyelonephritis (P=0.02) and exhibited the consensus virulence profile of previously described CGA strains from abroad.

CONCLUSIONS

E. coli isolates resistant to quinolones, trimethoprim/sulfamethoxazole and especially fluoroquinolones were associated with reductions in virulence traits and shifts to non-B2 phylogenetic groups. Moreover, fluoroquinolone resistance usually occurred in low-virulence E. coli group A isolates rather than in isolates from groups B2 and D which had lost virulence traits. CGA accounted for 23% of trimethoprim/sulfamethoxazole-resistant E. coli producing pyelonephritis.

[Pathogenesis of urinary tract infections]

"Uropathogenic Escherichia coli" has been the term used to describe E. coli strains able to cause urinary tract infections. Their molecular characterization has demonstrated that these strains are the same as those causing infections in non-urinary extraintestinal locations, and it has been proposed thus the more inclusive term "extraintestinal pathogenic E. coli" or "ExPEC" to use. ExPEC derive mainly from the phylogenetic B2 group and harbor genes that codify virulence, such as fimH, papA, papG allele II, kspM II, hlyA, cnf1, fyuA, iutA, and traT, which are grouped in pathogenicity islands (PAIs). The vaginal ecosystem and especially Lactobacillus, as well as intestinal populations of E. coli, coitus and the physiological and anatomical conditions of the urinary tract also play a major role in the pathogenesis of urinary tract infections. The persistence of E. coli in bladder "biofilms" or "pods" or in the fecal reservoir could explain recurrent infections in young women.

Mouse model for acute bacterial prostatitis in genetically distinct inbred strains

OBJECTIVES

Prostatitis is a common urologic disease seen in adult men. As many as 50% of men will experience an episode of prostatitis in their lifetime, and 2% to 3% of men will have bacterial prostatitis. Because the pathogenic mechanisms of prostatitis remain unclear, we developed a reproducible mouse model of bacterial prostatitis in which to study the etiology and host factors associated with infection susceptibility.

METHODS

Male BALB/c, C3H/HeJ, C3H/HeOuJ, C57BL/6J, and (BALB/c x C3H/HeJ)F1 mice 13 weeks old were inoculated intraurethrally with 2 x 10(6) or 2 x 10(8) Escherichia coli. Control mice were inoculated with phosphate-buffered saline. The animals were killed at 5 days after inoculation to assess the intensities of the bladder and prostate infections.

RESULTS

Significant bladder or prostate infections were not present in the BALB/c, C57BL/6J, or (BALB/c x C3H/HeJ)F1 mice at either inoculum dose. In contrast, both C3H/HeJ and C3H/HeOuJ mice developed high bladder infections and severe, acute prostatitis at both doses. Control mice infected with phosphate-buffered saline had no bladder or prostate infections. The P values were less than 0.01 for the comparison of bladder and prostate colony-forming units between C3H/HeJ or C3H/HeOuJ and BALB/c, C57BL/6J, or F1 mice.

CONCLUSIONS

The strain-dependent differences in susceptibility indicate that genetic factors may play a major role in the etiology of bacterial prostatitis. Because F1 mice did not develop significant bladder and prostate infections, similar to the BALB/c parents, it appears that infection susceptibility is a recessive trait. The availability of this model will allow us to investigate the immunology, genetics, and histopathologic features of bacterial infection of the prostate.

Comparative study of Escherichia coli virulence determinants in strains causing urinary tract bacteremia versus strains causing pyelonephritis and other sources of bacteremia

To assess the role of phylogenetic background and putative virulence factors (VFs) in Escherichia coli causing urinary bacteremia, 50 strains isolated from this condition were compared with 50 strains isolated from pyelonephritis and 50 from other sources of bacteremia. papA and papGII were significantly more prevalent in urinary bacteremia and pyelonephritis (78%, 66% and 70%, 58%) than in other-source bacteremia (48% and 24%), whereas sfa/focDE and cnf1 were more prevalent in urinary-source bacteremia (56% and 44%) than in pyelonephritis and other-source bacteremia (28%, 42% and 20%, 28%). Group B2 was the most frequent in all conditions (63% of isolates) and exhibited the greatest concentration of VFs. Urinary tract bacteremia, pyelonephritis, and other-source bacteremia isolates presented similar virulence scores (7.8, 7.0, and 6.6); however, there were striking differences among the phylogenetic groups (8.7 in group B2 versus 3.4 in group A; P < .001). Group A and B1 strains almost exclusively infected compromised hosts.

Phylogenetic and pathotypic comparison of concurrent urine and rectal Escherichia coli isolates from men with febrile urinary tract infection

Among men with febrile urinary tract infection (FUTI), whether the host's fecal flora is the source for the urine strain ("fecal-urethral" hypothesis), and whether pathogenesis is driven by prevalence versus special pathogenicity, are unknown. Accordingly, pretherapy urine isolates from 65 men with FUTI were compared with concurrent rectal isolates from the same hosts according to serotype, genomic profile, phylogenetic group, and virulence genotype. The host's multiple rectal colonies included only the urine clone in 25% of subjects, the urine clone plus additional clones in 22%, and only nonurine clones in 54%. Compared with the 67 unique rectal clones, the 65 urine isolates were significantly enriched for phylogenetic group B2, virulence-associated serotypes, and specific virulence genes and contained more virulence genes (median, 10 versus 6: P < 0.001). In multivariable models, phylogenetic group B2, hlyD (hemolysin), cnf1 (cytotoxic necrotizing factor), iroN (siderophore receptor), ompT (outer membrane protease), and malX (pathogenicity island marker) most strongly predicted urine source. These findings challenge the fecal-urethral and prevalence hypotheses for FUTI pathogenesis and instead strongly support the possibility of alternate infection routes in some men and the special pathogenicity hypothesis. They also identify specific bacterial traits as potential targets for anti-FUTI interventions.

Bacterial toxins that modulate host cell-cycle progression

The mammalian cell cycle is involved in many processes--such as immune responses, maintenance of epithelial barrier functions, and cellular differentiation--that affect the growth and colonization of pathogenic bacteria. Therefore it is not surprising that many bacterial pathogens manipulate the host cell cycle with respect to these functions. Cyclomodulins are a growing family of bacterial toxins and effectors that interfere with the eukaryotic cell cycle. Here, we review some of these cyclomodulins such as cytolethal distending toxins, vacuolating cytotoxin, the polyketide-derived macrolide mycolactone, cycle-inhibiting factor, cytotoxic necrotizing factors, dermonecrotic toxin, Pasteurella multocida toxin and cytotoxin-associated antigen A. We describe and compare their effects on the mammalian cell cycle and their putative role in disease, commensalism and symbiosis. We also discuss a possible link between these cyclomodulins and cancer.

Detection of virulence factors in alpha-haemolytic Escherichia coli strains isolated from various clinical materials

In total, 201 alpha-haemolytic Escherichia coli isolates from various clinical materials (urine samples and vaginal and rectal swabs) were examined by PCR for the presence of genes for the virulence factors alpha-haemolysin (hly), cytotoxic necrotising factor type 1 (cnf1), P-fimbriae (pap), S/F1C-fimbriae (sfa/foc), aerobactin (aer) and afimbrial adhesin (afaI). Among vaginal isolates, 96% were positive for cnf1, compared with 80% of urine strains (p 0.02) and 63% of rectal strains (p 0.0001). Similarly, sfa/foc-specific DNA sequences were found in 97% of vaginal isolates compared with 75% of rectal strains (p 0.004). The afa1 and aer genes were associated more with rectal alpha-haemolytic E. coli strains than with extra-intestinal isolates. The results suggested that CNF1 and/or S/F1C-fimbriae contribute to colonisation and persistence of alpha-haemolytic E. coli strains in the vaginal environment.

Cytotoxic necrotizing factor 1 enhances reactive oxygen species-dependent transcription and secretion of proinflammatory cytokines in human uroepithelial cells

Uropathogenic Escherichia coli strains frequently produce a Rho-activating protein toxin named cytotoxic necrotizing factor type 1 (CNF1). We herein report that CNF1 promotes transcription and release of tumor necrosis factor alpha, gamma interferon, interleukin-6 (IL-6), and IL-8 proinflammatory cytokines and increases the production of reactive oxygen species (ROS) in uroepithelial T24 cells. The antioxidant N-acetyl-L-cysteine counteracts these phenomena, a fact which suggests a role for ROS-mediated signaling in CNF1-induced proinflammatory cytokine production.

Microbial virulence determinants and the pathogenesis of urinary tract infection

The most frequent and best-studied agent of urinary tract infection (UTI) is Escherichia coli, which serves as a useful model pathogen for understanding microbial virulence in relation to UTI pathogenesis. The E. coli strains that cause most UTIs and other extraintestinal E. coli infections represent a highly specialized subset of the total E. coli population. The enhanced virulence potential of such strains, which collectively are known as uropathogenic E. coli or extraintestinal pathogenic E. coli (ExPEC), is thought to be caused mainly by their multiple virulence factors. These virulence factors include diverse adhesins, siderophores, toxins, polysaccharide coatings, and other properties that assist the bacteria in avoiding or subverting host defenses, injuring or invading host cells and tissues, and stimulating a noxious inflammatory response. Although the true evolutionary basis for ExPEC is unknown, the virulence factors of ExPEC serve as useful epidemiologic markers and in the future may provide effective targets for anti-UTI interventions.

Occurrence and genetic association of selected virulence factors in clinical Escherichia coli isolates

Occurrence of cnf1+ E. coli pathogenic strains among extraintestinal E. coli isolates was evaluated to explain an impact of cytotoxic necrotizing factor type 1 (CNF1) in human infections. A total of 120 E. coli isolates were characterized for presence of virulence factors cnf1- and pap--specific sequences by PCR, and the production of alpha-hemolysin using blood agar-plate test. Different association patterns among the detected virulence factors were obtained by comparison of various groups of clinical E. coli isolates. These differences probably reflect a potential impact of CNF1 in the colonization of vaginal environment.

[The treatment of prostatitis]

PURPOSE

Prostatitis are frequently recognized in general practice and often are a diagnosis and therapeutic challenge. We review here the updated knowledge on diagnosis and therapy of prostatitis.

CURRENT KNOWLEDGE AND KEY POINTS

Prostatitis are divided into acute bacterial prostatitis (I), chronic bacterial prostatitis (II), chronic prostatitis/ chronic pelvic pain syndrome (III) and asymptomatic inflammatory prostatitis. Chronic prostatitis/ chronic pelvic pain syndrome are divided into : inflammatory (IIIA) and noninflammatory (IIIB). Treatment of prostatitis should follow evidence based guidelines recently published. Acute prostatitis should be treated by ciprofloxacine 500 mg tid or ofloxacine 200 mg bid or cotrimoxazole 960 mg bid for 4 weeks (CIII). When bacteremia occurs third generation cephalosporin with gentamicin should be used (CIII). In chronic bacterial prostatitis ciprofloxacine 500 mg tid or ofloxacine 200 mg bid or norfloxacine 400 mg bid or cotrimoxazole 960 mg bid for 4 weeks may be used (BIII).

FUTURE PROSPECTS AND PROJECTS

Molecular techniques should improve the etiological diagnosis of prostatitis and their treatment.

Differences in virulence factors among clinical isolates of Escherichia coli causing cystitis and pyelonephritis in women and prostatitis in men

Differences in the presence of nine urovirulence factors among clinical isolates of Escherichia coli causing cystitis and pyelonephritis in women and prostatitis in men have been studied. Hemolysin and necrotizing factor type 1 occur significantly more frequently among isolates causing prostatitis than among those causing cystitis (P < 0.0001) or pyelonephritis (P < 0.005). Moreover, the papGIII gene occurred more frequently in E. coli isolates associated with prostatitis (27%) than in those associated with pyelonephritis (9%) (P < 0.05). Genes encoding aerobactin and PapC occurred significantly less frequently in isolates causing cystitis than in those causing prostatitis (P < 0.01 and P < 0.0001, respectively) and pyelonephritis (P < 0.01 and P < 0.0001, respectively). No differences in the presence of Sat or type 1 fimbriae were found. Finally, AAFII and Bfp fimbriae are no longer considered uropathogenic virulence factors since they were not found in any of the strains analyzed. Overall, the results showed that clinical isolates producing prostatitis need greater virulence than isolates producing pyelonephritis in women or, in particular, cystitis in women (P < 0.05). Overall, the results suggest that clinical isolates producing prostatitis are more virulent that those producing pyelonephritis or cystitis in women.

Cytotoxic necrotizing factor from Escherichia coli induces RhoA-dependent expression of the cyclooxygenase-2 Gene

Cytotoxic necrotizing factor 1 (CNF) is a toxin produced by some isolates of Escherichia coli that cause extraintestinal infections. CNF can initiate signaling pathways that are mediated by the Rho family of small GTPases through a covalent modification that results in constitutive activation. In addition to regulating the assembly of actin stress fibers and focal adhesion complexes, RhoA can also regulate gene expression at the level of transcription. Here we demonstrate for the first time, by using a luciferase-based reporter system, that the transcription of cyclooxygenase-2 (COX-2) is strongly upregulated in NIH 3T3 fibroblasts treated with CNF and that this effect is dependent upon the activation of RhoA by the toxin. Subsequent protein tyrosine phosphorylation events modulate the induction, but the transcription signal is not mediated by Rho-associated kinase (p160/ROCK) and so must rely upon another effector that is activated by RhoA. CNF therefore induces COX-2 expression via a RhoA-dependent signaling pathway that diverges from the pathway that regulates cytoskeletal rearrangements in response to RhoA activation.

Cytotoxic necrotizing factor type 1-positive Escherichia coli causes increased inflammation and tissue damage to the prostate in a rat prostatitis model

Infection of rat prostates with cytotoxic necrotizing factor type 1 (CNF1)-positive uropathogenic Escherichia coli caused more inflammation-mediated morphological and histological tissue damage than did infection with isogenic CNF1-negative mutants. These striking differences occurred despite the finding that bacterial counts for the strain pairs were indistinguishable. We conclude that CNF1 contributes to E. coli virulence in a model of acute prostatitis. To our knowledge, the results of this study provide the first demonstration of a role for any uropathogenic E. coli virulence factor in acute prostatitis.

Mutation of the gene encoding cytotoxic necrotizing factor type 1 (cnf(1)) attenuates the virulence of uropathogenic Escherichia coli

Cytotoxic necrotizing factor type 1 (CNF1) is a 115-kDa toxin that activates Rho GTPases and is produced by uropathogenic Escherichia coli (UPEC). While both epidemiological studies that link CNF1 production by E. coli with urinary tract disease and the cytopathic effects of CNF1 on cultured urinary tract cells are suggestive of a role for the toxin as a UPEC virulence factor, few in vivo studies to test this possibility have been reported. Therefore, in this investigation, we evaluated the importance of CNF1 in a murine model of urinary tract infection (UTI) by comparing the degree of colonization and damage induced by three different CNF1-producing E. coli strains with isogenic CNF1-deficient derivatives. The data from single-strain challenge experiments with C3H/HeOuJ mice indicated a trend toward higher counts of the wild-type strains in the urine and bladders of these animals up to 3 days after challenge in two of three strain pairs. Furthermore, this difference was statistically significant at day 2 of infection with one strain pair, C189 and C189cnf(1). To control for the animal-to-animal variability inherent in this model, we infected C3H/HeOuJ mice with a mixture of CNF1-positive and -negative isogenic derivatives of CP9. The CNF1-positive strain was recovered in higher numbers than the CNF1-negative strain in the urine, bladders, and kidneys of the mice up to 9 days postinfection. These striking coinfection findings, taken with the trends observed in single-strain infections, led us to conclude that CNF1-negative strains were generally attenuated compared to the wild type in the C3H/HeOuJ mouse model of UTI. Furthermore, histopathological examination of bladder specimens from mice infected with CNF1-positive strains consistently showed deeper, more extensive inflammation than in those infected with the isogenic mutants. Lastly, we found that CNF1-positive strain CP9 was better able to resist killing by fresh human neutrophils than were CP9cnf(1) bacteria. From these data in aggregate, we propose that CNF1 production increases the capacity of UPEC strains to resist killing by neutrophils, which in turn permits these bacteria to gain access to deeper tissue and persist better in the lower urinary tract.