In Vivo Consumption of Cranberry Exerts ex Vivo Antiadhesive Activity against FimH-Dominated Uropathogenic Escherichia coli: A Combined in Vivo, ex Vivo, and in Vitro Study of an Extract from Vaccinium macrocarpon

For investigation of the molecular interaction of cranberry extract with adhesins of uropathogenic Escherichia coli (UPEC), urine from four volunteers consuming standardized cranberry extract (proanthocyanidin content = 1.24%) was analyzed within ex vivo experiments, indicating time-dependent significant inhibition of 40-50% of bacterial adhesion of UPEC strain NU14 to human T24 bladder cells. Under in vitro conditions a dose-dependent increase in bacterial adhesion was observed with proanthocyanidin-enriched cranberry Vaccinium macrocarpon extract (proanthocyanidin content = 21%). Confocal laser scanning microscopy and scanning electron microscopy proved that V.m. extract led to the formation of bacterial clusters on the outer plasma membrane of the host cells without subsequent internalization. This agglomerating activity was not observed when a PAC-depleted extract (V.m. extract(≠PAC)) was used, which showed significant inhibition of bacterial adhesion in cases where type 1 fimbriae dominated and mannose-sensitive UPEC strain NU14 was used. V.m. extract(≠PAC) had no inhibitory activity against P- and F1C-fimbriae dominated strain 2980. Quantitative gene expression analysis indicated that PAC-containing as well as PAC-depleted cranberry extracts increased the fimH expression in NU14 as part of a feedback mechanism after blocking FimH. For strain 2980 the PAC-containing extract led to up-regulation of P- and F1C-fimbriae, whereas the PAC-depleted extract had no influence on gene expression. V.m. and V.m. extract(≠PAC) did not influence biofilm and curli formation in UPEC strains NU14 and 2980. These data lead to the conclusion that also proanthocyanidin-free cranberry extracts exert antiadhesive activity by interaction with mannose-sensitive type 1 fimbriae of UPEC.

Virulence factors, antibiotic resistance phenotypes and O-serogroups of Escherichia coli strains isolated from community-acquired urinary tract infection patients in Mexico

BACKGROUND/PURPOSE

Uropathogenic Escherichia coli (UPEC) strains isolated from patients with community-acquired urinary tract infections (UTIs) were assessed to determine the prevalence of virulence genes, antibiotic resistance, and the O-serogroup of the strains.

METHODS

Consenting patients with community-acquired UTI were enrolled at Unidad Médica Familiar Number 64 (Instituto Mexicano del Seguro Social, Estado de Mexico, Mexico) and 321 urine samples were collected. Polymerase chain reaction (PCR) was used to assess 24 virulence genes and 14 O-serogroups. The Kirby-Bauer method was used to evaluate the antibiotic susceptibility of the isolated strains to 12 commonly used antibiotics.

RESULTS

A total of 194 strains were identified as E. coli using standard biochemical tests, followed by PCR amplification of 16S ribosomal RNA gene. Only 58.2% of the strains belonged to the assessed 14 O-serogroups. The serogroups O25, O15, O8, and O75 were present in 20.6%, 17%, 6.1%, and 4.6% of strains, respectively. The most frequently occurring virulence genes among UPEC strains included kpsMT (92.2% strains), usp (87.1%), irp2 (79.3%), iha (64.9%), fim (61.3%), set (36%), astA (33.5%), pap (24.7%), and papGII (21.1%). In addition, 97% of the strains were multi-drug resistant (coresistance to 3-11 antibiotics).

CONCLUSION

The isolated UPEC strains predominantly belonged to three serogroups (O25, O15, and O8), harboured numerous virulence genes, and are multiresistant to antibiotics. The findings of this study could be used to orient UTI treatment strategies and in epidemiological studies in Mexico.

Hemolysin of uropathogenic Escherichia coli: A cloak or a dagger?

Hemolysin from uropathogenic Escherichia coli (UPEC) is a hemolytic and cytotoxic protein active against a broad range of species and cell types. Expression of hemolysin correlates with severity of infection, as up to 78% of UPEC isolates from pyelonephritis cases express hemolysin. Despite decades of research on hemolysin activity, the mechanism of intoxication and the function of hemolysin in UPEC infection remain elusive. Early in vitro research established the role of hemolysin as a lytic protein at high doses. It is hypothesized that hemolysin is secreted at sublytic doses in vivo and recent research has focused on understanding the more subtle effects of hemolysin both in vitro and in elegant infection models in vivo, including inoculation by micropuncture of individual kidney nephrons. As the field continues to evolve, comparisons of hemolysin function in isolates from a range of UTI infections will be important for delineating the role of this toxin. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.

Presence of Virulence-Associated Genes and Ability to Form Biofilm among Clinical Isolates of Escherichia coli Causing Urinary Infection in Domestic Animals

Background:

Urinary tract infection caused by Escherichia coli is a frequently observed condition both in humans and animals. Uropathogenic E. coli (UPEC) has been shown to have a pathogenicity island that enables them to infect the urinary tract. Because there is little information about the presence of UPEC-associated virulent genes in animal isolates this work was carried out with the intent to enhance the understanding about the strains of E.coli that cause infections in animals.

Results:

We screened 21 E. coli strains isolated causing urinary tract infection in domestic animals. Primers were designed to amplify urinary infection-associated genes. Nine genes, papA, tcpC, fyuA, tpbA, Lma, hylA, picU, tonB, and flicC were then amplified and sequenced. Different from the human isolate CFT073, all the animals E. coli lack some of the pathogenesis-associated genes. Genes encoding for proteins used to scavenge iron appear not to be so necessary during animal infections as they are in human infection. In further investigation of phenotypic properties, it was observed that animal UPECs have significantly more impaired ability to form biofilms than human UPEC strain.

Conclusions:

This study identified significant differences between human and animal UPECs. This may have its roots in the fact that it is difficult to determine if an animal has symptoms. Future studies will focus on some of the observations.

Phylogenetic Distribution of Virulence Genes Among ESBL-producing Uropathogenic Escherichia coli Isolated from Long-term Hospitalized Patients

OBJECTIVES

The present study was aimed to investigate the antibiotic resistance, virulence potential and phylogenetic grouping of ESBL-producing uropathogenic Escherichia coli (EP-UPEC) isolated from long-term hospitalized patients.

MATERIALS AND METHODS

EP-UPEC isolates from September 2013 to June 2014 at a tertiary care hospital of China were screened for ESBL-production by the double disk diffusion test. Isolates with ESBL-phenotype were further characterized by antibiotic resistance testing, PCR of different ESBL and virulence genes, and phylogenetic grouping.

RESULTS

One hundred and twenty EP-UPEC were isolated from long-term hospitalized patients. All EP-UPEC isolates were resistant to Ampicillin, Cefazolin, Cefuroxime, Cefotaxime, Cefoperazone and Ceftriaxone, and the majority of EP-UPEC isolates were resistant to Piperacillin (82.5%), Ciprofloxacin (81.2%), Trimethoprim-Sulfamethoxazole (72.5%). The isolates showed the highest sensitivity against Imipenem (98.4%), Piperacillin/tazobactam (96.7%), Cefoperazone/sulbactam (91.7%), Amikacin (90.8%) and Cefepime (75.8%). Nine different ESBL genotype patterns were observed and CTX-M type was the most prevalent ESBL genotype (42.5%, 51/120). Majority of EP-UPEC isolates possess more than one ESBL genes. EP-UPEC isolates belonged mainly to phylogenetic group B2(36.7%) and D(35.0%). The prevalence of traT, ompT, iss, PAI, afa, fimH and papC were 75.8%, 63.3%, 63.3%, 60.8%, 40.8%, 19.2% and 6.7%, respectively. The number of virulence genes (VGs) detected was significantly higher in group B2 than in group A (ANOVA, p<0.001), group B1(ANOVA, p= 0.012) and D (ANOVA, p<0.001).

CONCLUSIONS

EP-UPEC strains showed multidrug resistance and co-resistance to other non β-lactam antibiotics. CTX-M was the most prevalent ESBL genotype and majority of EP-UPEC strains more than one ESBL genes. EP-UPEC strains belonged mainly to phylogenetic group B2 and D, and most of the virulence genes were more prevalent in group B2.

Environmental phosphate differentially affects virulence phenotypes of uropathogenic Escherichia coli isolates causative of prostatitis

K-12 Escherichia coli cells grown in static media containing a critical phosphate (Pi) concentration ≥25 mM maintained a high polyphosphate (polyP) level in stationary phase, impairing biofilm formation, a phenomenon that is triggered by polyP degradation. Pi concentration in human urine fluctuates according to health state. Here, the influence of environmental Pi concentration on the occurrence of virulence traits in uropathogenic E. coli (UPEC) isolated from acute prostatitis patients was evaluated. After a first screening, 3 isolates were selected according to differential biofilm formation profiles depending on media Pi concentration. For each isolate, biofilm positive and negative conditions were established. Regardless of the isolate, biofilm formation capacity was accompanied with curli and cellulose production and expression of some key virulence factors associated with adhesion. When the selected isolates were grown in their non-biofilm-forming condition, low concentrations of nalidixic acid and ciprofloxacin induced biofilm formation. Interestingly, similar to laboratory strains, polyP degradation induced biofilm formation in the selected isolates. Data demonstrated the complexity of UPEC responses to environmental Pi and the importance of polyP metabolism in the virulence of clinical isolates.

Evaluation of the effect of MPL and delivery route on immunogenicity and protectivity of different formulations of FimH and MrpH from uropathogenic Escherichia coli and Proteus mirabilis in a UTI mouse model

Urinary tract infections (UTIs) caused by Escherichia coli and Proteus mirabilis are an important cause of morbidity and with the high rate of relapse and spread of multi-drug resistant pathogens, pose a significant public health challenge worldwide. Lack of an efficacious commercial vaccine targeting both uropathogens makes development of a combined vaccine highly desirable. In this study the immunogenicity and protective efficacy of different formulations of FimH of UPEC, MrpH of P. mirabilis and their fusion protein (MrpH.FimH) subcutaneously administered with and without Monophosphoryl lipid A (MPL) adjuvant were evaluated. Our data showed that the subcutaneously administered proteins induced both serum and mucosal IgG, which MPL significantly improved developing a mixed Th1 and Th2 immune response. However, the preparations induced a higher systemic and mucosal IgG and IL-2 levels by this route compared to the intranasal. Immunization of mice with MrpH.FimH fusion with MPL or a mixture of FimH, MrpH and MPL conferred the highest protection of the bladder and kidneys when challenged with UPEC and P. mirabilis in a UTI mouse model. Therefore considering these results MrpH.FimH fusion with MPL administered subcutaneously or intranasally could be a promising vaccine candidate for elimination of UTIs caused by UPEC and P. mirabilis.

Anti-Adhesive Activity of Cranberry Phenolic Compounds and Their Microbial-Derived Metabolites against Uropathogenic Escherichia coli in Bladder Epithelial Cell Cultures

Cranberry consumption has shown prophylactic effects against urinary tract infections (UTI), although the mechanisms involved are not completely understood. In this paper, cranberry phenolic compounds and their potential microbial-derived metabolites (such as simple phenols and benzoic, phenylacetic and phenylpropionic acids) were tested for their capacity to inhibit the adherence of uropathogenic Escherichia coli (UPEC) ATCC^®53503™ to T24 epithelial bladder cells. Catechol, benzoic acid, vanillic acid, phenylacetic acid and 3,4-dihydroxyphenylacetic acid showed anti-adhesive activity against UPEC in a concentration-dependent manner from 100–500 µM, whereas procyanidin A2, widely reported as an inhibitor of UPEC adherence on uroepithelium, was only statistically significant (p < 0.05) at 500 µM (51.3% inhibition). The results proved for the first time the anti-adhesive activity of some cranberry-derived phenolic metabolites against UPEC in vitro, suggesting that their presence in the urine could reduce bacterial colonization and progression of UTI.

Signature-tagged mutagenesis and co-infection studies demonstrate the importance of P fimbriae in a murine model of urinary tract infection

Escherichia coli is the leading cause of urinary tract infections (UTIs), one of the most common infections in humans. P fimbria was arguably the first proposed virulence factor for uropathogenic E. coli, based on the capacity of E. coli isolated from UTIs to adhere to exfoliated epithelial cells in higher numbers than fecal strains of E. coli. Overwhelming epidemiologic evidence has been presented for involvement of P fimbriae in colonization. It has been difficult, however, to demonstrate this requirement for uropathogenic strains in animal models of infections or in humans. In this study, a signature-tagged mutagenesis screen identified a P-fimbrial gene (papC) and 18 other genes as being among those required for full fitness of cystitis isolate E. coli F11. A P-fimbrial mutant was outcompeted by the wild-type strain in cochallenge in the murine model of ascending UTI, and this colonization defect could be complemented with the cloned pap operon. To our knowledge, this study is the first to fulfill molecular Koch's postulates in which a pathogenic strain was attenuated by mutation of pap genes and then complemented to restore fitness, confirming P fimbria as a virulence factor in a pathogenic clinical isolate.

Urinary tract infections attributed to diverse ExPEC strains in food animals: evidence and data gaps

Between 70 and 95% of urinary tract infections (UTI) are caused by strains of Escherichia coli. These strains, often termed Extraintestinal Pathogenic E. coli (ExPEC), possess specific virulence traits allowing them to colonize more inhospitable environments, such as the urogenital tract. Some ExPEC isolates from humans have similar virulence factor profiles to ExPEC isolates from animals, and because of the potential for these strains to cause UTI in people, these infections have been referred to as foodborne UTI, or FUTI. Finding similarities in ExPEC in animals and humans is not necessarily proof of transmission, particularly a unidirectional pathway from animals to humans; similarities in virulence factor profiles should be expected given the specific bacterial requirements for colonizing physiological compartments with similar characteristics in all animals. Many of the most important strains of human ExPEC globally, such as ST131, are highly virulent and clonal implying routes of transmission other than food. Documenting routes of transmission is particularly difficult due to the wide range of potential ExPEC sources, including the human intestinal tract, and non-human reservoirs such as food animals and retail meat products, sewage and other environmental sources, and companion animals. The significant environmental reservoir of ExPEC, including strains such as ST131, could potentially explain much more completely the global dissemination of virulent ExPEC clones and the rapid dissemination of new strains within the community. Taken in its totality, the link between ExPEC in animals and UTI in humans might exist, but studies conducted to date do not enable an estimation of the relative importance of this route of transmission. To reduce the burden of illness associated with ExPEC, the scientific community needs to push forward with ecologically-based, scientifically-sound study designs that can address the plethora of ways in which E. coli can spread.

Role of uropathogenic Escherichia coli outer membrane protein T in pathogenesis of urinary tract infection

OmpT is one of the members of the outer membrane protein family that has been identified as a virulence factor in most of the uropathogenic Escherichia coli (UPEC). However, the exact role of OmpT in the urinary tract infections (UTIs) remains unclear. To determine the role of OmpT in the pathogenesis of UPEC, an isogenic deletion mutant of ompT (COTD) was constructed by the λ Red recombination. Human bladder epithelial cell line 5637(HBEC 5637) was used to evaluate the ability of bacterial adhesion/invasion. A murine model of UTI was established to study the formation of intracellular bacterial communities (IBCs) in the process of UTIs. The cytokines were also examined during the pathogenesis. The results showed that the COTD strain was deficient in bacterial adhesion and invasion as well as in IBC formation compare to the parent strain. ELISA quantification analysis of cytokines showed that the levels of TNF-α, IL-6 and IL-8 in the serum, bladder and kidney tissues of the mice infected with COTD were lower than that of the CFT073 group. In summary, these results suggest that OmpT plays a multifaceted role in pathogenesis of UTI, including increased bacterial adhesiveness/invasiveness, formation of IBCs and upregulated proinflammatory cytokines.

Intranasal immunization with fusion protein MrpH·FimH and MPL adjuvant confers protection against urinary tract infections caused by uropathogenic Escherichia coli and Proteus mirabilis

Urinary tract infections (UTIs) caused by Uropathogenic Escherichia coli (UPEC) and Proteus mirabilis are among the most common infections in the world. Currently there are no vaccines available to confer protection against UTI in humans. In this study, the immune responses and protection of FimH of UPEC with MrpH antigen of P. mirabilis in different vaccine formulations with and without MPL adjuvant were assessed. Mice intranasally immunized with the novel fusion protein MrpH·FimH induced a significant increase in IgG and IgA in serum, nasal wash, vaginal wash, and urine samples. Mice immunized with fusion MrpH·FimH also showed a significant boost in cellular immunity. Addition of MPL as the adjuvant enhanced FimH and MrpH specific humoral and cellular responses in both systemic and mucosal samples. Vaccination with MrpH·FimH alone or in combination with MPL showed the highest efficiency in clearing bladder and kidney infections in mice challenged with UPEC and P. mirabilis. These findings may indicate that the protection observed correlates with the systemic, mucosal and cellular immune responses induced by vaccination with these preparations. Our data suggest MrpH·FimH fusion protein with or without MPL as adjuvant could be potential vaccine candidates for elimination of UPEC and P. mirabilis. These data altogether are promising and these formulations are good candidates for elimination of UPEC and P. mirabilis.

Comparative analysis of the uropathogenic Escherichia coli surface proteome by tandem mass-spectrometry of artificially induced outer membrane vesicles

Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections. For successful colonisation of the urinary tract, UPEC employ multiple surface-exposed or secreted virulence factors, including adhesins and iron uptake systems. Whilst individual UPEC strains and their virulence factors have been the focus of extensive research, there have been no outer membrane (OM) proteomic studies based on large clinical UPEC collections, primarily due to limitations of traditional methods. In this study, a high-throughput method based on tandem mass-spectrometry of EDTA heat-induced outer membrane vesicles (OMVs) was developed for the characterisation of the UPEC surface-associated proteome. The method was applied to compare the OM proteome of fifty-four UPEC isolates, resulting in the identification of 8789 proteins, consisting of 619 unique proteins, which were subsequently interrogated for their subcellular origin, prevalence and homology to characterised virulence factors. Multiple distinct virulence-associated proteins were identified, including two novel putative iron uptake proteins, an uncharacterised type of chaperone-usher fimbriae and various highly prevalent hypothetical proteins. Our results give fundamental insight into the physiology of UPEC and provide a framework for understanding the composition of the UPEC OM proteome.

BIOLOGICAL SIGNIFICANCE

In this study a high-throughput method based on tandem mass-spectrometry of EDTA heat-induced outer membrane vesicles was used to define the outer membrane proteome of a large uropathogenic E. coli (UPEC) collection. Our results provide an inventory of proteins expressed on the surface of UPEC, and provide a framework for understanding the composition of the UPEC OM proteome. The method enables the rapid characterisation of the E. coli surface proteome and could easily be applied to the large-scale outer membrane protein profiling of other Gram-negative bacteria.

Selective autophagy: xenophagy

Xenophagy is an autophagic phenomenon that specifically involves pathogens and other non-host entities. Although the understanding of the relationship between autophagosomes and invading organisms has grown significantly in the past decade, the exact steps to confirm xenophagy has been not been thoroughly defined. Here we describe a methodical approach to confirming autophagy, its interaction with bacterial invasion, as well as the specific type of autophagic formation (i.e. autophagosome, autolysosome, phagolysosome). Further, we argue that xenophagy is not limited to pathogen interaction with autophagosome, but also non-microbial entities such as iron.

Host-specific induction of Escherichia coli fitness genes during human urinary tract infection

Uropathogenic Escherichia coli (UPEC) is the predominant etiological agent of uncomplicated urinary tract infection (UTI), manifested by inflammation of the urinary bladder, in humans and is a major global public health concern. Molecular pathogenesis of UPEC has been primarily examined using murine models of UTI. Translational research to develop novel therapeutics against this major pathogen, which is becoming increasingly antibiotic resistant, requires a thorough understanding of mechanisms involved in pathogenesis during human UTIs. Total RNA-sequencing (RNA-seq) and comparative transcriptional analysis of UTI samples to the UPEC isolates cultured in human urine and laboratory medium were used to identify novel fitness genes that were specifically expressed during human infection. Evidence for UPEC genes involved in ion transport, including copper efflux, nickel and potassium import systems, as key fitness factors in uropathogenesis were generated using an experimental model of UTI. Translational application of this study was investigated by targeting Cus, a bacterial copper efflux system. Copper supplementation in drinking water reduces E. coli colonization in the urinary bladder of mice. Additionally, our results suggest that anaerobic processes in UPEC are involved in promoting fitness during UTI in humans. In summary, RNA-seq was used to establish the transcriptional signature in UPEC during naturally occurring, community acquired UTI in women and multiple novel fitness genes used by UPEC during human infection were identified. The repertoire of UPEC genes involved in UTI presented here will facilitate further translational studies to develop innovative strategies against UTI caused by UPEC.

Inhibition of Cyclooxygenase-2 Prevents Chronic and Recurrent Cystitis

The spread of multidrug-resistant microorganisms globally has created an urgent need for novel therapeutic strategies to combat urinary tract infections (UTIs). Immunomodulatory therapy may provide benefit, as treatment of mice with dexamethasone during acute UTI improved outcome by reducing the development of chronic cystitis, which predisposes to recurrent infection. Here we discovered soluble biomarkers engaged in myeloid cell development and chemotaxis that were predictive of future UTI recurrence when elevated in the sera of young women with UTI. Translation of these findings revealed that temperance of the neutrophil response early during UTI, and specifically disruption of bladder epithelial transmigration of neutrophils by inhibition of cyclooxygenase-2, protected mice against chronic and recurrent cystitis. Further, proteomics identified bladder epithelial remodeling consequent to chronic infection that enhances sensitivity to neutrophil damage. Thus, cyclooxygenase-2 expression during acute UTI is a critical molecular trigger determining disease outcome and drugs targeting cyclooxygenase-2 could prevent recurrent UTI.

Antibiotic resistance in uropathogenic e. Coli strains isolated from non-hospitalized patients in pakistan

PURPOSE

To study multidrug-resistance in Uropathogenic E. Coli (UPEC) isolated from non-hospitalized patients.

MATERIALS AND METHODS

Altogether, 250 bacterial samples were collected from non-hospitalized patients. Their identifications were done on basis of Gram-staining, colony morphology, biochemical testing and PCR. Susceptibility testing was performed by using standard protocols which were recommended by CLSI.

STATISTICAL ANALYSIS

For comparisons, statistical analysis was performed by using software, Graphpad Prism 5.0 RESULTS: In total, 32% (n = 80) of the isolates were identified as E. Coli strains and their susceptibility patterns for different antibiotics were determined. The data indicated least resistance against tazocin [(TZP) -1.25%], amikacin [(AK) -1.8%], tigecycline [(TGC)- 2.5%] and nitrofurantoin [(F) -3.75%]. For both minocycline (MH) and sulzone (SUL), resistance rate was 5%, for gentamicin (CN), it was 16.25%, while higher resistances were observed against cephalothine [(KF)- 70%], cefotaxime [(CTX) -58.5%], ceftazidime [(CAZ)- 57.5%], cefepime [(FEP) -55%], cefuroxime and cefixime [(CXM) (CFM)- 53.75 %]. Resistance against ciprofloxacin (CIP) was 57.5%, for norfloxacine (NOR), it was 52.5% and incase of sparfloxacin (SPX), it remained 55%. High percentage of the isolates were resistant to cotrimoxazole [(SXT) -86%] and Amoxicillin [AMX-CLA (AMC)- 76%]. No resistance against meropenem (MEM) was observed.

CONCLUSION

Highest level of drug-resistance was observed against trimethoprim-sulfamethoxazole (TMP-SMZ) among clinical isolates of uropathogenic E. Coli collected from non-hospitalized patients.

Urinary tract infection in Uruguayan children: Aetiology, antimicrobial resistance and uropathogenic Escherichia coli virulotyping

Uropathogenic Escherichia coli (UPEC) is the most frequent cause of urinary tract infection (UTI). Virulence factors (VFs) of UPEC in children are not well known. Circulating antibiotic resistance mechanisms in the community are increasing. In this study, the aetiological agents of UTI and antibiotic resistance mechanisms of 124 strains isolated from urine cultures from children with community-acquired UTI were determined. Virulotyping of isolated E. coli strains was also described. β-Lactam, fluoroquinolone and sulfonamide resistance genes as well as integrons were detected by PCR. E. coli phylogenetic groups and 25 VFs were sought by multiplex PCR. E. coli was the most frequent aetiological agent (88.7%), of which 48.2% belonged to phylogenetic group D and 35.5% to group B2. Moreover, 81.8% were considered UPEC and >93% had virulence structures, with kpsMTII, fimH and iutA being the most frequent. Most of the E. coli isolates were susceptible to amoxicillin/clavulanic acid (AMC) (87.3%), nitrofurantoin (97.3%), cefuroxime and third-generation cephalosporins (100%). Resistance levels to oxyimino-cephalosporins were higher in non-E. coli isolates, with circulation of integrons, bla_CTX-M-2 and bla_CMY-2 detected in the community. Moreover, 8.1% of isolates were resistant to fluoroquinolones, with qnrB found in two isolates. Resistance to trimethoprim/sulfamethoxazole was found in 37.9% of isolates, with 85.5% harbouring sul genes. E. coli isolated from children with UTI presented high rates of VFs. Nitrofurantoin, AMC and cefuroxime would be suitable antibiotics to treat UTI in children. However, the presence of integrons (fundamentally class 1) and circulation of broad-spectrum β-lactamases in the community makes continuous surveillance necessary.

A simple in vitro acylation assay based on optimized HlyA and HlyC purification

HlyA is a toxin secreted by uropathogenic Escherichia coli strains. HlyA belongs to the repeats in the toxin protein family and needs (i) a posttranslational, fatty acylation at two internal lysines by the acyltransferase HlyC and (ii) extracellular ion binding to achieve its active conformation. Both processes are not fully understood and experiments are often limited due to the low amounts of protein available. Here, we present an optimized purification protocol for the proteins involved in HlyA activation as well as a quick and nonradioactive assay for in vitro HlyA acylation. These may simplify future experiments, e.g., activity scanning and characterization of HlyA or HlyC mutants as demonstrated with single and double HlyA lysine mutants.

Suppression of type 1 pilus assembly in uropathogenic Escherichia coli by chemical inhibition of subunit polymerization

Objectives

To identify and to characterize small-molecule inhibitors that target the subunit polymerization of the type 1 pilus assembly in uropathogenic Escherichia coli (UPEC).

Methods

Using an SDS–PAGE-based assay, in silico pre-filtered small-molecule compounds were screened for specific inhibitory activity against the critical subunit polymerization step of the chaperone–usher pathway during pilus biogenesis. The biological activity of one of the compounds was validated in assays monitoring UPEC type 1 pilus biogenesis, type 1 pilus-dependent biofilm formation and adherence to human bladder epithelial cells. The time dependence of the in vivo inhibitory activity and the overall effect of the compound on UPEC growth were determined.

Results

N-(4-chloro-phenyl)-2-{5-[4-(pyrrolidine-1-sulfonyl)-phenyl]-[1,3,4]oxadiazol-2-yl sulfanyl}-acetamide (AL1) inhibited in vitro pilus subunit polymerization. In bacterial cultures, AL1 disrupted UPEC type 1 pilus biogenesis and pilus-dependent biofilm formation, and resulted in the reduction of bacterial adherence to human bladder epithelial cells, without affecting bacterial cell growth. Bacterial exposure to the inhibitor led to an almost instantaneous loss of type 1 pili.

Conclusions

We have identified and characterized a small molecule that interferes with the assembly of type 1 pili. The molecule targets the polymerization step during the subunit incorporation cycle of the chaperone–usher pathway. Our discovery provides new insight into the design and development of novel anti-virulence therapies targeting key virulence factors of bacterial pathogens.

Strong cross-system interactions drive the activation of the QseB response regulator in the absence of its cognate sensor

Bacterial two-component systems (TCSs) mediate specific responses to distinct conditions and/or stresses. TCS interactions are highly specific between cognate partners to avoid unintended cross-talk. Although cross-talk between a sensor kinase and a noncognate response regulator has been previously demonstrated, the majority of reported interactions have not been robust. Here, we report that in the case of the quorum-sensing Escherichia coli (Qse)BC TCS, absence of the cognate sensor QseC leads to robust, constitutive activation of the QseB response regulator by the noncognate polymyxin resistance (Pmr) sensor kinase PmrB. Remarkably, the noncognate PmrB exhibits a kinetic preference for QseB that is similar to QseC. However, although PmrB readily phosphorylates QseB in vitro, it is significantly less efficient at dephosphorylating QseB, compared with QseC, thereby explaining the increased levels of active QseB in the qseC mutant. In addition to PmrB activating QseB on the protein level, we found that the PmrA response regulator contributes to qseB transcription in the absence of QseC and PmrA specifically binds the qseBC promoter, indicative of a direct regulation of qseBC gene transcription by PmrAB under physiological conditions. Addition of ferric iron in the growth medium of wild-type uropathogenic E. coli induced the expression of qseBC in a PmrB-dependent manner. Taken together, our findings suggest that (i) robust cross-talk between noncognate partners is possible and (ii) this interaction can be manipulated for the development of antivirulence strategies aimed at targeting uropathogenic Escherichia coli and potentially other QseBC-PmrAB-bearing pathogens.

Shigella takes the temperature

For bacteria, temperature is a fairly reliable cue for entry into a vertebrate host. Many pathogenic bacteria sense elevated temperatures (37°C) and turn on virulence and metabolic genes appropriate for survival and growth within the host. A recent study demonstrated that the expression of a heme uptake protein in Shigella dysenteriae and pathogenic Escherichia coli was dependent on an RNA thermometer.

Detection of intracellular bacterial communities in a child with Escherichia coli recurrent urinary tract infections

The formation of intracellular bacterial communities (IBC) has been proposed as a new pathogenic model for urinary tract infections. Scarce reports describe this phenomenon in humans. We describe the presence of IBC in uroepithelial cells of a child with recurrent urinary infections. Urine specimen was collected from a child with Escherichia coli UTI and analyzed by light and confocal laser scanning microscopy (CLSM). The capability of this strain to produce intracellular infection in bladder tissue was confirmed in mice models. Escherichia coli phylogenetic group, presence of virulence factors genes, and its multiple locus sequence type were determined. CLSM showed large collections of morphologically coccoid and rod bacteria in eukaryotic cells cytoplasm, even seemingly protruding from the cells. Escherichia coli EC7U, ST3626, harbored type 1, P, and S/F1C fimbriae and K1 capsule genes. In this report, we confirm the presence of IBC in children with UTI, as it has been described before in women.

The antibiotic susceptibility patterns of uropathogenic Escherichia coli, with special reference to the fluoroquinolones

CONTEXT

The emergence of drug resistance to trimethoprim-sulfamethoxazole, the penicillins, cephalosporins, and fluoroquinolones by Uropathogenic Escherichia coli (UPEC) has limited the options for selecting the appropriate antibiotic for the treatment of urinary tract infections.

AIMS

The The E. coli isolates, which were obtained from the culture of urine samples,were studied for their antibiotic resistance patterns, with special reference to the antimicrobial activity of the fluoroquinolones and the production of the extended spectrum β-lactamases. (ESBL), Settings and Design: This was a hospital based, prospective study which was done for a period of eighteen months.

MATERIAL AND METHODS

This study was done by using the standard culture techniques for urine samples, the modified Kirby-Bauer disk diffusion method for the antibiotic susceptibility testing and the disk diffusion method to confirm the ESBL production by the clinical isolates of E. coli in urine. The sensitivity pattern was correlated with the clinical condition and the presence of the risk factors. The statistical analysis which was used: The statistical analysis was done by using the proportions of sensitive, resistant and intermediates. Descriptive statistics like the total, mean and percentage were done by using the Statistical Package for the Social Sciences (SPSS), version 15.0.

RESULTS

The hospital isolates showed high degrees of resistance to the penicillins, cephalosporins, nalidixic acid and the fluoroquinolones, with 59% of the isolates being ESBL producers.

CONCLUSIONS

The incidence of the multidrug resistant strains of Escherichia coli has been steadily increasing over the past few years. The knowledge on the resistance pattern of the bacterial strains in a geographical area will help in guiding the appropriate and the judicious use of antibiotics. Also, the formulation of an appropriate hospital antibiotic policy will go a long way in controlling these infections.

Urinary tract infections: current and emerging management strategies

Acute cystitis is one of the most commonly encountered bacterial infections and is responsible for substantial morbidity and high medical costs in the United States and across the globe. Though generally considered to be self-limiting and easily treated with antibiotics, urinary tract infections (UTIs) are often incompletely resolved by antibiotic therapy and frequently recur. This is in part due to the ability of uropathogenic bacteria to invade, replicate, and persist within host epithelial cells. The biological complexity of these infections combined with a dramatic rise in antibiotic-resistant pathogens highlight the need for alternative therapies. In this review we examine current management strategies for UTIs, as well as emerging treatments, including novel compounds that block bacterial interactions with the urothelium and vaccines focused on preventing both acute and recurrent infections.