Virulence characteristics of Escherichia coli strains causing acute cystitis in young adults in Iran

Distribution of Iron Uptake Systems Encoding Genes Among the Clinical Isolates of Escherichia coli Compared to Foodstuffs Isolates

INTRODUCTION

Bacteria require iron ions to grow and infect the host, which, by using iron uptake systems, acquire free iron from their host cell. Escherichia coli is one of the most important pathogens to cause food poisoning and clinical infections. The aim of this study was to assess the distribution of iron uptake systems encoding genes in clinical isolates of E.coli compared to food samples isolates.

MATERIALS AND METHODS

This investigation was conducted to determine the prevalence of E. coli isolated from various sources of food and clinical specimens. The E. coli isolates confirmed by the standard microbiological methods. The isolates were examined for the presence of iut A and iuc A genes by specific primers using the polymerase chain reaction technique.

RESULTS

A total of 100 and 50 isolates of E. coli were collected from clinical samples and foodstuffs, respectively. The prevalence of E. coli in the food and clinical samples was 33.33% and 64.10%, respectively. The frequency of iut A and iuc A genes in the food and clinical isolates were 76%-84% and 86% - 83%, respectively.

CONCLUSION

Our results showed that the prevalence of E. coli isolates with iut A and iuc A genes was relatively higher compared to many previous studies. The existence of these genes in E. coli strains is likely to be related to pathogenicity in those strains, which requires further studies in the future.

Network Analysis Reveals Sex- and Antibiotic Resistance-Associated Antivirulence Targets in Clinical Uropathogens

Increasing antibiotic resistance among uropathogenic Escherichia coli (UPEC) is driving interest in therapeutic targeting of nonconserved virulence factor (VF) genes. The ability to formulate efficacious combinations of antivirulence agents requires an improved understanding of how UPEC deploy these genes. To identify clinically relevant VF combinations, we applied contemporary network analysis and biclustering algorithms to VF profiles from a large, previously characterized inpatient clinical cohort. These mathematical approaches identified four stereotypical VF combinations with distinctive relationships to antibiotic resistance and patient sex that are independent of traditional phylogenetic grouping. Targeting resistance- or sex-associated VFs based upon these contemporary mathematical approaches may facilitate individualized anti-infective therapies and identify synergistic VF combinations in bacterial pathogens.

Association of some virulence genes with antibiotic resistance among uropathogenic Escherichia coli isolated from urinary tract infection patients in Alexandria, Egypt: A hospital-based study

Uropathogenic Escherichia coli (UPEC) is the infecting agent most frequently involved in urinary tract infections (UTIs) worldwide. UPEC resistance to commonly used antibiotics represents a major health problem all over the world. Several factors have been associated with UPEC resistance to antibiotics. The present study deployed a molecular approach to explore the association between some UPEC virulence genes and antibiotic resistance among patients with UTI in Alexandria, Egypt. The study revealed a significant association between presence of the pap gene and resistance to gentamicin; however, it was not significantly associated with resistance to β-lactam antibiotics, quinolones, aminoglycosides, nitrofurantoin and trimethoprim/sulfamethoxazole. The genes sfa, aer and cnf1 were not significantly associated with UPEC resistance to any of the tested antibiotics. In conclusion, resistance of UPEC isolates in the present study could be attributed to other virulence factors.

Molecular Characterization of Uropathogenic Escherichia coli: Nalidixic Acid and Ciprofloxacin Resistance, Virulent Factors and Phylogenetic Background

BACKGROUND AND OBJECTIVE

A proficient pathogen should be virulent, resistant to antibiotics, and epidemic. However, the interplay between resistance and virulence is poorly understood. Perhaps, the most commonly accepted view is that resistance to quinolones is linked to a loss of virulence factors. However, the low virulent phylogenetic groups may be more prone to acquire resistance to quinolones. The aim of this study was to identify and characterise the Nalidixic Acid (NA) and ciprofloxacin (CIP) resistant uropathogenic Escherichia coli (UPEC) isolates with respect to virulence and phylogenetic background, from hospital settings in Kolkata, an eastern region in India. Research based on these bacterial populations will help in understanding the molecular mechanisms underlying the association between resistance and virulence, that in turn, may help in managing the future disseminations of UTIs in their entirety.

MATERIAL AND METHODS

One hundred and ten E. coli isolates were screened against NA and CIP using Kirby-Bauer disk diffusion technique, following CLSI guidelines. Prevalence of virulent factor genes and distribution of phylogenetic groups amongst the isolates was determined by PCR, using gene specific primers against the different virulent factors and DNA markers (chuA, yjaA and DNA fragment, TSPE4.C2) respectively. Statistical analysis of the data was performed using SPSS software.

RESULTS

Resistance to both NA and CIP was reported in 75.5 % of the isolates which were analysed. The virulent determinants, papC, pap GII, papEF, afa, cnf1, hlyA and iroN were significantly predominant in the drug susceptible than the resistant isolates. A significant reduction of phylogroup B2 in NA (85.7% versus 64.6%, χ(2)P<0.001) and CIP (85.2 % versus 61.4%, χ(2)P<0.001) resistant UPEC isolates, followed by increase in predominance of non-B2 phylotypes (group D and group B1), were observed.

CONCLUSION

This is the first report from India that has indicated possible evidence on horizontal gene transfer from pathogenic to commensal strains and selection of the latter, on extensive usage of this group of antimicrobials in hospital settings, where these drugs were routinely prescribed for treating urinary tract infection. Therefore, this information necessitates surveillance programs and administration of effective strategies, to put an end to random prescription policies involving this group of antimicrobials.

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.

Virulence characteristics and phylogenetic background of ciprofloxacin resistant Escherichia coli in the urine samples from Korean women with acute uncomplicated cystitis

To clarify the characteristics of the virulence factors (VFs) of ciprofloxacin resistant Escherichia coli (CFRE) with acute uncomplicated cystitis (AUC), we determined the VFs and the phylogenetic background of all 54 CFRE strains and the 55 randomly selected ciprofloxacin sensitive E. coli strains (CFSE) from patients with AUC in 22 Korean hospitals. The prevalence of the VFs was as follows: fimA, papEF, papGIII, sfaI, dafaBC, cnf1, and hlyA were presented in 96%, 54%, 68%, 91%, 49%, 72%, and 29% of the samples, respectively. The expressions of papEF, cnf1, and hlyA were significantly more prevalent in the CFSE. Moreover, the expressions of cnf, and papEF significantly reduced the risk of ciprofloxacin resistance. The CFSE was also marginally associated with the group B2 (P=0.05). Although the presence of pyuria and a previous cystitis history were not related with the phylotyping and the expressions of VFs, group B2, and fimA and papEF were more expressed in the younger age patients (P<0.05). In conclusion, the CFRE exhibits a selective loss of VFs and the non-B2 phylotype in Korean AUC patients. The group B2 and the presence of fimA and papEF are associated with a younger age of AUC patients.

Genetic relatedness and virulence gene profiles of Escherichia coli strains isolated from septicaemic and uroseptic patients

We investigated the relationship between clonality and virulence factors (VFs) of a collection of Escherichia coli strains isolated from septicaemic and uroseptic patients with respect to their origin of translocation. Forty septicaemic and 30 uroseptic strains of E. coli were tested for their phylogenetic groupings, genetic relatedness using randomly amplified polymorphic DNA (RAPD), biochemical fingerprinting method (biochemical phenotypes [BPTs]), adherence to HT-29 cells and the presence of 56 E. coli VF genes. Strains belonging to phylogenetic groups B2 and D constituted 93% of all strains. Fifty-four (77%) strains belonged to two major BPT/RAPD clusters (A and B), with cluster A carrying significantly (P = 0.0099) more uroseptic strains. The degree of adhesion to HT-29 cells of uroseptic strains was significantly (P = 0.0012) greater than that of septicaemic strains. Of the 56 VF genes tested, pap genes was the only group that were found significantly (P < 0.0001) more often among uroseptic isolates. Phylogenetic group B2 contained a significantly higher number of strains carrying pap genes than those in group D. We conclude that uroseptic E. coli are clonally different from septicaemic strains, carry more pap genes and predominantly adhere more to the HT-29 cell model of the gut.

Extraintestinal pathogenic Escherichia coli

Extraintestinal pathogenic Escherichia coli (ExPEC) possesses virulence traits that allow it to invade, colonize, and induce disease in bodily sites outside of the gastrointestinal tract. Human diseases caused by ExPEC include urinary tract infections, neonatal meningitis, sepsis, pneumonia, surgical site infections, as well as infections in other extraintestinal locations. ExPEC-induced diseases represent a large burden in terms of medical costs and productivity losses. In addition to human illnesses, ExPEC strains also cause extraintestinal infections in domestic animals and pets. A commonality of virulence factors has been demonstrated between human and animal ExPEC, suggesting that the organisms are zoonotic pathogens. ExPEC strains have been isolated from food products, in particular from raw meats and poultry, indicating that these organisms potentially represent a new class of foodborne pathogens. This review discusses various aspects of ExPEC, including its presence in food products, in animals used for food or as companion pets; the diseases ExPEC can cause; and the virulence factors and virulence mechanisms that cause disease.