Microevolution in fimH gene of mucosa-associated Escherichia coli strains isolated from pediatric patients with inflammatory bowel disease

Several studies reported increased numbers of mucosa-associated Escherichia coli strains in patients with inflammatory bowel disease (IBD), encompassing Crohn''s disease (CD) and ulcerative colitis (UC). The majority of E. coli strains possess type 1 fimbriae, whose tip fibrillum protein, FimH, naturally undergoes amino acid replacements, an important process in the adaptation of commensal E. coli strains to environmental changes, like those observed in IBD and urinary tract infections. In this study, we analyzed mutational patterns in the fimH gene of 52 mucosa-associated E. coli strains isolated from IBD and non-IBD pediatric patients, in order to investigate microevolution of this genetic trait. FimH-positive strains were also phylogenetically typed and tested for their adhesive ability on Caco-2 cells. Specific FimH alleles for each grouping feature were found. Mutations G66S and V27A were related to CD, while mutations A242V, V163A, and T74I were attributed to UC. Otherwise, the G66S, N70S, and S78N mutations were specifically attributed to B2/D phylogroups. The N70S and A119V mutations were related to adhesive E. coli strains. Phylogroup B2, adhesive, and IBD E. coli strains showed a higher site substitution rate (SSR) in the fimH gene, together with a higher number of mutations. The degree of naïve mucosal inflammation was related to specific FimH alleles. Moreover, we could suggest that the V27A mutation is pathoadaptive for the CD intestinal habitat, while we could also suggest that both the N70S and S78N mutations are related to the more virulent E. coli B2 phylogroup. In conclusion, we found some FimH variants that seem to be more involved than others in the evolution of IBD pathogenesis.     

Escherichia coli strains with the capacity for long-term persistence in the bowel microbiota carry the potentially genotoxic pks island

The pks genomic island found in Escherichia coli strains of phylogenetic group B2 encodes colibactin, a polyketide-peptide genotoxin that causes DNA double-strand breaks. We investigated the relationship between carriage of the pks island and the capacity of E.?coli strains to persist in the gut microbiota of 130 Swedish infants, who were followed from birth to 18 months of age. Long-term colonizers were significantly more likely to have the pks island than either intermediate-term colonizers or transient strains, which suggests that the pks island contributes to the pronounced gut-colonizing capacity of group B2 strains. Long-term persistence in the colon of pks island-containing E.?coli strains may be associated with the induction of genomic mutations in the host intestine.     

Met-enkephalins in patients with inflammatory bowel diseases

PurposeOpioid peptides provide a link between the neuroendocrine and immune systems. They modify the inflammatory process through their effect on the synthesis and secretion of cytokines and on the proliferation of leukocytes to the inflammatory lesion. The evaluation analyzed changes in free met-enkephalin concentration values in the serum and colon mucosal biopsy specimens of patients with inflammatory bowel disease (IBD).Material and MethodsIn serum and colon mucosal biopsy specimens, free met-enkephalin levels were determined in 43 patients with ulcerative colitis (UC) and 38 individuals with Crohn's disease (CD). The evaluation analyzed the effect of disease activity, inflammatory lesions of the colon and laboratory parameters, on the level of the investigated marker. The control group consisted of 45 healthy volunteers.ResultsSerum free met-enkephalin levels were depressed in patients with CD (85.4pg/ml) and UC (101.5pg/ml) as compared to the controls (119.4pg/ml). Met-enkephalin levels in colonic biopsies collected from inflammatory lesions in IBD patients were significantly higher as compared to sections without inflammatory lesions (6.59pg/mg vs. 2.89pg/mg, p < 0.01 in the CD group and 6.12pg/mg vs. 3.47pg/mg, p < 0.05 in the UC group) and their level correlated with disease activity.ConclusionsThe present investigation is the first study that demonstrates changes in free met-enkephalin levels in IBD that may play a role in the pathogenesis and course of the disease. Further studies are necessary to assess the anti-inflammatory effect of opioid peptides.     

Heterogeneity among strains of diffusely adherent Escherichia coli isolated in Brazil

One hundred twelve diffusely adherent Escherichia coli strains isolated from children in a case control study were evaluated for virulence-associated characteristics, serotyping, antibiotic resistance, and plasmid profiles. Half of the strains hybridized with the probes for icuA (aerobactin) and fimH (type 1 pili); daaE (F1845 fimbriae), afa (afimbrial Dr adhesin), agg-3A (aggregative adhesion fimbria type III fimbriae), pap (P fimbriae), astA (EAST1 toxin), and shET1 (Shigella enterotoxin 1) sequences were present in <20% of the strains. The shET1 gene was noted most frequently in strains isolated from patients. A minority (7%) of the strains produced hemolysin or colicin or showed cytotoxic effects on Vero cells. Forty-five different serotypes were found. The majority (70%) of the strains presented multiple antibiotic resistance. Antibiotic resistance and diffuse adherence were located on the same conjugative plasmids. These results suggest that the transfer of these potential virulence markers could be important in the epidemiology of diffusely adherent E. coli.     

Frequency of pathogenic and enteroadherent Escherichia coli in patients with inflammatory bowel disease and controls.

AIMS: To determine whether inflammatory bowel disease (IBD) is associated with pathogenic or enteroadherent Escherichia coli. METHODS: A least two stool specimens and one rectal biopsy were taken from 30 patients with IBD and from 20 controls. A large number of E coli-like colonies cultured from each stool sample and biopsy was tested, using DNA probes, for the presence of genes encoding shiga-like toxins, invasiveness, attachment-effacement and the ability to adhere to HEp-2 cells. Similarity among isolates from stool samples and rectal biopsies was determined by random amplified polymorphic DNA (RAPD) analysis. RESULTS: Enterohaemorrhagic and enteroinvasive E coli were not found in samples from either patients or controls. No significant difference in the detection rate of enteroadherent E coli between patients and controls was found. Rectal biopsies from 11 of 28 patients with IBD and 4 of 18 controls contained E coli, which hybridised with probes for detection of genes encoding diffuse adherence to HEp-2 cells, or encoding P-pili (p = 0.2). Enteroadherent E coli isolated from two or three stool specimens from the same patient or control appeared to be identical by RAPD analysis, and are considered to be residents in the colon. Probe positive isolates obtained from stool specimens and corresponding rectal biopsies were always identical on RAPD analysis. CONCLUSIONS: E coli strains possessing adherence factors reside in the large intestine and adhere to the rectal mucosa, irrespective of the presence of colitis.     

Escherichia coli O125ac:H6 encompasses atypical enteropathogenic E. coli strains that display the aggregative adherence pattern

O125 is an enteropathogenic Escherichia coli (EPEC) serogroup, which includes the O125ac:H6 serotype, defined as atypical EPEC. Strains of this serotype displayed the aggregative adherence (AA) pattern with HEp-2, Caco-2, T84, and HT-29 cells, possessed all the LEE region genes, and expressed intimin, Tir, and EspABD, although the attaching-effacing lesion was not detected in vitro. These results confirm that E. coli O125ac:H6 is atypical EPEC that displays the AA pattern and indicate the necessity of testing for EPEC genes combined with the determination of the adherence pattern for atypical EPEC identification.     

Revised prevalence of afa+ Escherichia coli strains in acute pyelonephritis of children

Two hundred E. coli strains isolated from children with pyelonephritis were investigated for the presence of six virulence factors. The used primers amplified adhesin pap and sfa, toxin haemolysin (hly) and cytotoxic necrotizing factor 1 (cnf1) and aerobactin (aer). For afimbrial adhesin, the previously used set of primers could not allow to detect the newly reported afa operons (Le Bouguenec et al., 2001). With a new set of primers specific for the afa operon family the prevalence of afa+ strains increased from 3.5% to 13.5%. Combinations of three or more factors in a same strain were found in 48.5%. Thirty two different urovirulent genotypes were observed; two strains contained the six studied factors.     

Prevalence of Escherichia coli strains with localized, diffuse, and aggregative adherence to HeLa cells in infants with diarrhea and matched controls

To determine the possible role of Escherichia coli strains with three different patterns of adherence to HeLa cells in causing diarrhea in infants in S?o Paulo, Brazil, we studied stool specimens from 100 infants up to 1 year of age with acute diarrheal illnesses and 100 age-matched control infants without recent diarrhea. E. coli with localized adherence to HeLa cells was much more common in patients (23%) than in controls (2%) (P less than 0.0001) and was detected more frequently than rotavirus (19%) was in patients, even though the study was conducted during the coldest months of the year. Most (80%) of the E. coli colonies with localized adherence were of traditional enteropathogenic E. coli serotypes. Little difference was found between patients and controls in the rate of isolation of E. coli with diffuse adherence (31 and 32%, respectively) or aggregative adherence (10 and 8%, respectively). A genetic probe used to detect a plasmid-mediated adhesin which confers expression of localized adherence proved to be 100% sensitive and 99.9% specific in detecting E. coli with localized adherence to HeLa cells. Although E. coli strains with localized adherence have now been shown to be enteric pathogens in several parts of the world, the role of strains showing diffuse adherence and aggregative adherence is still uncertain.     

Complex effects of pulsed infrared laser and asparaginase on Escherichia coli strains isolated from patients with urinary diseases

Treatment with L-asparaginase and low-frequency laser decreased adhesion of uropathogenic Escherichia coli to human erythrocytes. The maximum effect was observed after combined treatment (laser exposure followed by enzyme treatment).     

High prevalence iron receptor genes of avian pathogenic Escherichia coli.

Avian pathogenic Escherichia coli are known to cause significant losses in the poultry industry worldwide. Although prophylactic measures based on vaccination are advisable, until now no full heterologous protection against colibacillosis has been achieved. Since iron is an essential nutrient to these bacteria, the aim of this study was to investigate the prevalence of 12 outer-membrane iron receptor genes in 239 pathogenic strains isolated from clinical cases of colibacillosis in chickens. Five multiplex polymerase chain reactions were developed as a tool for efficient screening. Among the 239 avian E. coli isolates, 100% were positive for fhuE and fepA, 96.2% for fiu, 92.9% for cir, 92.5% for iroN, 87.4% for iutA, 63.2% for fecA, 53.1% for fyuA, 46.9% for fhuA, 45.6% for ireA, 41.8% for chuA and 4.6% for iha.     

Phylogenetic group B2 Escherichia coli strains from the bowel microbiota of Pakistani infants carry few virulence genes and lack the capacity for long-term persistence

Escherichia coli strains of phylogenetic group B2 obtained from Western human hosts are enriched in virulence-associated genes and have a superior capacity to persist in the colonic microbiota. Here, E . coli strains from 22 infants born in Pakistan whose rectal flora was sampled regularly over the first 6 months of life were examined. B2 strains did not carry the virulence-associated genes sfaD/E , papC , neuB or hlyA more often than strains of other phylogenetic groups . B2 origin was not associated with persistence in the bowel microbiota. As compared with B2 strains from Swedish infants, Pakistani B2 strains carried significantly less often the virulence genes fimH (p 0.04), papC (p 0.02), papG class III (p 0.01), sfaD / E (p ≤0.0001), neuB (p ≤0.0001), and hlyA (p 0.005), and also the high-pathogenicity island (p ≤0.0001). A minority of Pakistani B2 strains belonged to recognized uropathogenic O-groups, which are common among 'Western' B2 strains. Thus, extra-intestinal pathogenicity may be the foremost characteristic of B2 strains colonizing Western populations.     

Phylogenetic analysis and prevalence of urosepsis strains of Escherichia coli bearing pathogenicity island-like domains

We characterized 100 Escherichia coli urosepsis isolates from adult patients according to host compromise status by means of ribotyping, PCR phylogenetic grouping, and PCR detection of papG alleles and the virulence-related genes sfa/foc, fyuA, irp-2, aer, hly, cnf-1 and hra. We also tested these strains for copies of pap and hly and their direct physical linkage with other virulence genes in an attempt to look for pathogenicity islands (PAIs) described for the archetypal uropathogenic strains J96, CFT073, and 536. Most of the isolates belonged to E. coli phylogenetic groups B2 and D and bore papG allele II, aer, and fyuA/irp-2. papG allele II-bearing strains were more common in noncompromised patients, while papG allele-negative strains were significantly more frequent in compromised patients. Fifteen ribotypes were identified. The three archetypal strains harbored different ribotypes, and only one-third of our urosepsis strains were genetically related to one of the archetypal strains. Three and 18 strains harbored three and two copies of pap, respectively, and 5 strains harbored two copies of hly. papGIII was physically linked to hly, cnf-1, and hra (reported to be PAI II(J96)-like genetic elements) in 14% of the strains. The PAI II(J96)-like domain was inserted within pheR tRNA in 11 strains and near leuX tRNA in 3 strains. Moreover, the colocalized genes cnf-1, hra, and hly were physically linked to papGII in four strains and to no pap gene in three strains. papGII and hly (reported to be PAI I(CFT073)-like genetic elements) were physically linked in 16 strains, pointing to a PAI I(CFT073)-like domain. Three strains contained both a PAI II(J96)-like domain and a PAI I(CFTO73)-like domain. Forty-two strains harbored papGII but not hly, in keeping with the presence of a PAI II(CFT073)-like domain. Only one strain harbored a PAI I(536)-like domain (hly only), and none harbored a PAI I(J96)-like domain (papGI plus hly) or a PAI II(536)-like domain (papGIII plus hly). This study provides new data on the prevalence and variability of physical genetic linkage between pap and certain virulence-associated genes that are consistent with their colocalization on archetypal PAIs.     

Escherichia coli isolates from patients with inflammatory bowel disease: ExPEC virulence- and colicin-determinants are more frequent compared to healthy controls

A set of 178 Escherichia coli isolates taken from patients with inflammatory bowel disease (IBD) was analyzed for bacteriocin production and tested for the prevalence of 30 bacteriocin and 22 virulence factor determinants. Additionally, E. coli phylogenetic groups were also determined. Pulsed-field gel electrophoresis (PFGE) was used for exclusion of clonal character of isolates. Results were compared to data from a previously published analysis of 1283 fecal commensal E. coli isolates.The frequency of bacteriocinogenic isolates (66.9%) was significantly higher in IBD E. coli compared to fecal commensal E. coli isolates (54.2%, p < 0.01). In the group of IBD E. coli isolates, a higher prevalence of determinants for group B colicins (i.e., colicins B, D, Ia, Ib, M, and 5/10) (p < 0.01), including a higher prevalence of the colicin B determinant (p < 0.01) was found. Virulence factor determinants encoding fimbriae (fimA, 91.0%; pap, 27.5%), cytotoxic necrotizing factor (cnf1, 11.2%), aerobactin synthesis (aer, 43.3%), and the locus associated with invasivity (ial, 9.0%) were more prevalent in IBD E. coli (p < 0.05 for all five determinants). E. coli isolates from IBD mucosal biopsies were more frequently bacteriocinogenic (84.6%, p < 0.01) compared to fecal IBD isolates and fecal commensal E. coli. PFGE analysis revealed clusters specific for IBD E. coli isolates (n = 11), for fecal isolates (n = 13), and clusters containing both IBD and fecal isolates (n = 10).ExPEC (Extraintestinal Pathogenic E. coli) virulence and colicin determinants appear to be important characteristics of IBD E. coli isolates, especially the E. coli isolates obtained directly from biopsy samples.     

Association of enteroaggregative Escherichia coli with irritable bowel syndrome

Increased numbers of faecal Enterobacteriaceae are observed among patients with irritable bowel syndrome. Escherichia coli strains are present in the lower intestine of humans, and may include several potentially pathogenic adhesive pathotypes. The aim of this study was to determine whether there were differences between the adhesive pathotypes of E. coli strains recovered from stool specimens of patients with irritable bowel syndrome and those recovered from healthy controls. The ability of E. coli isolates to adhere to cultured epithelial cells was assessed in an in-vitro adherence assay with HEp-2 cells. Enteroaggregative E. coli (EAEC) strains were isolated significantly more frequently (p <0.00001) from patients with irritable bowel syndrome (81.8%) than from healthy controls (32.3%). However, despite this association, the precise role of the EAEC pathotype in irritable bowel syndrome remains to be determined.     

Prevalence of diarrheagenic Escherichia coli strains detected by PCR in patients with travelers' diarrhea

Objective: To determine the prevalence of the different categories of diarrheagenic Escherichia coli , enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), verotoxin-producing E. coli (VTEC), enteroaggregative E. coli (EAggEC), diffusely adherent E. coli (DAEC), and enteropathogenic E. coli (EPEC), associated with travelers' diarrhea.
Methods: Stool specimens from 350 patients with travelers' diarrhea were collected between 1994 and 1996. The virulence factors of the diarrheagenic E. coli isolated were detected by PCR technique, in subcultures of single colonies of all morphotypes of E. coli observed in culture on MacConkey agar.
Results: ETEC (15.7%), EAggEC (13.4%) and DAEC (9.14%) are significantly more prevalent than EIEC (3.4%), EPEC (2.86%) and VTEC (0.86%) (p < 0.05; z -test). The prevalence of ETEC and EAggEC was similar in all geographic areas visited.
Conclusions: PCR is a rapid and specific technique to use in the identification of the different categories of diarrheagenic E. coli and greatly increases the yield of potential enteropathogens from cases of travelers' diarrhea. Not only ETEC but also EAggEC and DAEC strains play a major role in the etiology of travelers' diarrhea, whereas EIEC, EPEC, and VTEC strains play a minor role, leading to the question of whether it is necessary to search routinely for these three types of E. coli in diagnostic laboratories.     

Pathogenic strains of Escherichia coli in Taiwan

From July 1994 through June 1996, 28 strains of Escherichia coli were isolated from 1,260 patients with acute diarrhea. These strains were further differentiated with serotypes and virulence factors. Enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), and enteroinvasive E. coli (EIEC) were accounted for 53.6 (15 of 28 strains), 28.6 (8 of 28), 10.7 (3 of 28) and 7.1% (2 of 28), respectively. Therefore, ETEC and EPEC are playing an important role in food-borne illness in Taiwan. Escherichia coli O157:H7, a new emerging pathogen of food-borne disease, has not been isolated in this study.     

Combined effect of low-frequency laser and polyphenol oxidase on adhesive activity of Escherichia coli strains isolated from patients with urinary diseases

The effects of polyphenol oxidase and low-frequency laser irradiation on adhesion of pathogenic Escherichia coli to human erythrocytes and buccal epithelial cells were studied. The maximum decrease in adhesive activity of these strains was observed after complex exposure to laser and enzyme.     

Clinical management of rheumatologic conditions co-occurring with inflammatory bowel diseases

Introduction: Spondyloarthritis (SpA) is the most common extra-intestinal manifestation in patients with inflammatory bowel diseases (IBD). Articular disorders may also appear as ‘paradoxical’ effects during biologic therapy with anti-tumor necrosis factor (TNF).

Areas covered: In this narrative review, we report the current knowledge about the pathogenesis, the diagnosis and the therapeutic management of articular diseases occurring in patients with IBD.

Expert commentary: Evidence-based recommendations for the management of IBD-associated SpA and paradoxical arthritis are lacking. Then, collaboration between gastroenterologists and rheumatologists is mandatory to guarantee the best outcomes for these patients, from a prompt diagnosis to an appropriate therapeutic strategy. Among therapies currently available, steroids, sulfasalazine, methotrexate and anti-TNFs are recommended for both gastrointestinal and articular diseases, whereas non-steroidal anti-inflammatory drugs (NSAIDs) and etanercept are contraindicated in IBD. Thiopurines are not effective for the treatment of articular symptoms. Several agents have been recently introduced for the treatment of IBD, such as vedolizumab, a gut-selective anti-α4β7integrin, and ustekinumab, an anti-interleukin 12/23. Their effects on SpA still need to be clarified; however, the possible contemporary administration of biologics with different molecular targets is becoming an intriguing option to cover multiple inflammatory manifestations in the same patient and is worthy of further investigation.