Virulence factors and biofilm production among Escherichia coli strains causing bacteraemia of urinary tract origin

Molecular Characterization, Antibiotic Resistance, and Biofilm Formation of Escherichia coli Isolated from Commercial Broilers from Four Chinese Provinces

Escherichia coli (E. coli) represents a significant etiological agent of colibacillosis in poultry, resulting in considerable economic losses for the global poultry sector. The present study aimed to determine molecular characterization, antibiotic resistance, and biofilm formation of E. coli strains isolated from diseased broilers from four provinces of China. A total of 200 tissue samples were collected from the intestine, liver, crop, heart, and spleen and processed for microbiological examination. Molecular detection of E. coli strains, virulence genes, and serotypes was performed using polymerase chain reaction (PCR). Antibiotic susceptibility testing and biofilm formation were assessed using disk diffusion and 96-well microtiter plate assays. The study retrieved 68% (136/200) of E. coli strains from collected samples. Most of the E. coli strains were resistant to enrofloxacin (56%), followed by cefepime (54%), amoxicillin/clavulanate (52%), streptomycin (50%), ampicillin (48%), clindamycin (47%), kanamycin (41%), polymyxin B (37%), tetracycline (35%), sulfamethoxazole/trimethoprim (33%), ceftazidime (31%), meropenem (4.7%), and florfenicol (2.9%). Similarly, the E. coli strains tested positive for at least one virulence gene and specific serotypes. Among these, O145 was the most prevalent serotype, identified in 22 isolates (16.2%), followed by O8 (12.5%), O102 (11.8%), and O9 (11.0%). The tsh gene (10.2%) was the most prevalent virulence gene. This study found that 47.1% of E. coli strains were biofilm-producing, with 62.5% exhibiting weak biofilm production, 29.7% mild biofilm production, and 7.8% strong biofilm production. Similarly, 24.2% of the E. coli strains were avian pathogenic E. coli strains due to the presence of five or more virulence genes, specifically tsh, ompA, fimC, iss, fyuA, and astA, in a single strain by multiplex PCR. The present study recommends continuous surveillance and effective control measures to reduce the burden of avian pathogenic E. coli-related infections in poultry.

Bloodstream infections: mechanisms of pathogenesis and opportunities for intervention

Bloodstream infections (BSIs) are common in hospitals, often life-threatening and increasing in prevalence. Microorganisms in the blood are usually rapidly cleared by the immune system and filtering organs but, in some cases, they can cause an acute infection and trigger sepsis, a systemic response to infection that leads to circulatory collapse, multiorgan dysfunction and death. Most BSIs are caused by bacteria, although fungi also contribute to a substantial portion of cases. Escherichia coli, Staphylococcus aureus, coagulase-negative Staphylococcus, Klebsiella pneumoniae and Candida albicans are leading causes of BSIs, although their prevalence depends on patient demographics and geographical region. Each species is equipped with unique factors that aid in the colonization of initial sites and dissemination and survival in the blood, and these factors represent potential opportunities for interventions. As many pathogens become increasingly resistant to antimicrobials, new approaches to diagnose and treat BSIs at all stages of infection are urgently needed. In this Review, we explore the prevalence of major BSI pathogens, prominent mechanisms of BSI pathogenesis, opportunities for prevention and diagnosis, and treatment options.

Investigation of virulence factor genes and biofilm formation of antibiotic resistant clinical E.coli isolates

PURPOSE

The aim of this study is to investigate the antibiotic sensitivity, presence of virulence genes and biofilm formation capacity of 90 clinical E. coli isolates.

METHODS

The presence of virulence genes in E.coli isolates were investigated by PCR. Ninety clinical isolates of E.coli were subjected to biofilm quantitative analysis using the semi-quantitative crystal violet staining method.

RESULTS

it was observed that the isolates were resistant to quinolone, cephalosporin, aminoglycoside, carbapenem and penicillin group antibiotics. The presence of virulence factor genes were observed in a total of 86/90 E. coli. The highest rate of fim (92.2 %) virulence factor gene was detected in the strains. Afa, pap, cnf, sfa, hly were detected in 30 %, 13 %, 13 %, 3.3 %, 2.2 % respectively. Also, 13 different virulence factor gene patterns were determined in 90 E. coli isolates. Of the 90 E. coli isolates whose biofilm-forming capacities were evaluated, 42 were found to have biofilm-forming capacity. Of these 26 (28.8 %) the weak, 12 (13.3 %) moderate and 4 (4.4 %) strong biofilm-forming. Also, statistical analysis was performed to investigate the relationship between virulence factor genes and biofilm formation, and none of the 7 genes analyzed showed a significant relationship with biofilm formation.

CONCLUSION

since pathogenic E. coli is an important public health problem, investigating antibiotic resistance, virulence factor genes and biofilm formation in bacterial pathogens is important for better treatment options.

River waters in Greece: A reservoir for clinically relevant extended-spectrum-β-lactamases-producing Escherichia coli

In the current study, the genotypic characteristics such as antimicrobial resistance and virulence genes, and plasmid replicons and phenotypic characteristics such as biofilm formation and antimicrobial resistance of 87 extended-spectrum beta-lactamase (ESBL)-producing E. coli (ESBL-Ec) isolated from 7 water bodies in northern Greece were investigated. Our data show a high prevalence (60.0 %) of ESBL-Ec in surface waters that exhibit high genetic diversity, suggesting multiple sources of their transmission into the aquatic environment. When evaluating the antimicrobial resistance of isolates, wide variation in their resistance profiles has been detected, with all isolates being multi-drug resistant (MDR). Regarding biofilm formation capacity and phylogenetic groups, the majority (54.0 %, 47/87) of ESBL-Ec were classified as no biofilm producers mainly assigned to phylogroup A (35.6 %; 31/87), followed by B2 (26.5 %; 23/87). PCR screening showed that a high proportion of the isolates tested positive for the blaCTX-M-1 group genes (69 %, 60/87), followed by blaTEM (55.2 %, 48/87), blaOXA (25.3 %, 22/87) and blaCTX-M-9 (17.2 %, 15/87). A subset of 28 ESBL-Ec strains was further investigated by applying whole genome sequencing (WGS), and among them, certain clinically significant sequence types were identified, such as ST131 and ST10. The corresponding in silico analysis predicted all these isolates as human pathogens, while a significant proportion of WGS-ESBL-Ec were assigned to extraintestinal pathogenic E. coli (ExPEC; 32.1 %), and urinary pathogenic E. coli (UPEC; 28.6 %) pathotypes. Comparative phylogenetic analysis, showed that the genomes of the ST131-O25:H4-H30 isolates are genetically linked to the human clinical strains. Here, we report for the first time the detection of a plasmid-mediated mobile colistin resistance gene in ESBL-Ec in Greece isolated from an environmental source. Overall, this study underlines the role of surface waters as a reservoir for antibiotic resistance genes and for presumptive pathogenic ESBL-Ec.

Phylogenetic Diversity, Antibiotic Resistance, and Virulence of Escherichia coli Strains from Urinary Tract Infections in Algeria

Urinary tract infections (UTIs) caused by Escherichia coli represent a significant public health concern due to the high virulence and antimicrobial resistance exhibited by these pathogens. This study aimed to analyze the phylogenetic diversity and antibiotic resistance profiles of Uropathogenic E. coli (UPEC) strains isolated from UTI patients in Algeria, focusing on virulence factors such as extended β-lactamase (ESBL) production, biofilm formation, and hemolytic activity. Phylogenetic grouping of 86 clinical imipenem resistant E. coli isolates showed the prevalence of group B2 (48.9%), followed by groups E (22.1%), unknown (12.8%), A (8.1%), and B1 (4.7%), and Clade I, D, Clade I, or Clade II (1.2%). The highest resistance rates were observed towards amoxicillin (86.04%), ticarcillin (82.55%), piperacillin (73.25%), nitrofurantoin (84.88%), and trimethoprim-sulfamethoxazole (51.16%). Notably, 69.8% of UPEC strains were multidrug-resistant (MDR) and 23.2% were extensively drug-resistant (XDR). Additionally, 48.9%, 42%, and 71% of strains demonstrated ESBL production, hemolytic activity, and weak biofilm production, respectively. Continuous monitoring and characterization of UPEC strains are essential to track the spread of the most resistant and virulent phylogenetic groups over time, facilitating rapid therapeutic decisions to treat infections and prevent the emergence of new resistant organisms, helping choose the most effective antibiotics and reducing treatment failure.

Progress toward a vaccine for extraintestinal pathogenic E. coli (ExPEC) II: efficacy of a toxin-autotransporter dual antigen approach

Extraintestinal pathogenic Escherichia coli (ExPEC) is a leading cause of worldwide morbidity and mortality, the top cause of antimicrobial-resistant (AMR) infections, and the most frequent cause of life-threatening sepsis and urinary tract infections (UTI) in adults. The development of an effective and universal vaccine is complicated by this pathogen's pan-genome, its ability to mix and match virulence factors and AMR genes via horizontal gene transfer, an inability to decipher commensal from pathogens, and its intimate association and co-evolution with mammals. Using a pan virulome analysis of >20,000 sequenced E. coli strains, we identified the secreted cytolysin α-hemolysin (HlyA) as a high priority target for vaccine exploration studies. We demonstrate that a catalytically inactive pure form of HlyA, expressed in an autologous host using its own secretion system, is highly immunogenic in a murine host, protects against several forms of ExPEC infection (including lethal bacteremia), and significantly lowers bacterial burdens in multiple organ systems. Interestingly, the combination of a previously reported autotransporter (SinH) with HlyA was notably effective, inducing near complete protection against lethal challenge, including commonly used infection strains ST73 (CFT073) and ST95 (UTI89), as well as a mixture of 10 of the most highly virulent sequence types and strains from our clinical collection. Both HlyA and HlyA-SinH combinations also afforded some protection against UTI89 colonization in a murine UTI model. These findings suggest recombinant, inactive hemolysin and/or its combination with SinH warrant investigation in the development of an E. coli vaccine against invasive disease.

Biofilm-forming ability, antibiotic resistance and phylogeny of Escherichia coli isolated from extra intestinal infections of humans, dogs, and chickens

Escherichia coli (E. coli) causes various infections in humans and animals. The biofilm-forming ability of E. coli has increased antimicrobial resistance and capacity to cause recurrent and chronic infections. This study determined the biofilm-forming ability of E. coli isolated from extraintestinal infections of humans, chickens, and dogs in relation to the phylogroup, type of infection, and antibiotic resistance. Isolates from chickens showed significantly higher biofilm-forming ability compared to those causing urinary tract infections in humans (p = 0.0001). Further, isolates belonging to phylogroup B1 displayed a higher likelihood to form biofilms. Resistance to ciprofloxacin and trimethoprim-sulfamethoxazole was positively correlated with biofilm-forming ability. Harbouring plasmid-mediated quinolone resistance gene, qnrS was also positively correlated with biofilm formation. This study provides insight into factors such as phylogroup and the type of infections that could enhance biofilm formation, as well as genotypic and phenotypic antibiotic resistance that could correlate with the ability to form biofilms.

Correlation of biofilm formation, virulence factors, and phylogenetic groups among Escherichia coli strains causing urinary tract infection: A global systematic review and meta-analysis

Background

Different virulence factors are involved in the pathogenesis of urinary tract infection (UTI) caused by Uropathogenic Escherichia coli (UPEC); hence, this study aimed to study the prevalence of biofilm formation, virulence factors, and phylogenetic groups and their correlation with biofilm formation among UPEC isolates through a systematic review and meta-analysis.

Materials and Methods

A literature search was conducted from 1, 2000, to the end of 2021 in different databases for studies that reported biofilm together with virulence genes or phylogenetic groups in UPEC isolates from patients with UTI according to PRISMA protocol. Data were analyzed by Comprehensive meta-analysis software.

Results

The pooled prevalence of biofilm formers was 74.7%. The combined prevalence of phylogenetic Groups A, B1, B2, and D (s) were reported at 19.6%, 11%, 50.7%, and 20.5%, respectively. The most common virulence genes reported worldwide were fimA, ecpA, and fimH, with a combined prevalence of 90.3%, 86.6%, and 64.9%, respectively. The pooled prevalence of biofilm formation in UPEC isolates with phylogenetic Groups A, B1, B2, D, C, and F were 12.4%, 8.7%, 33.7%, 12.4%, 2.6%, and 2.65%, respectively. Several studies showed a correlation between biofilm production and virulence genes, or phylogenetic groups.

Conclusion

Regarding data obtained, the high level of combined biofilm formation (74.7%) and the presence of a positive correlation between biofilm production and virulence genes, or phylogenetic groups as reported by the most studies included in the present review, indicates an important role of biofilm in the persistence of UPEC in the UTI.

Escherichia coli from biopsies differ in virulence genes between patients with colorectal neoplasia and healthy controls

Introduction

Pathogenic strains of Escherichia coli have been clearly identified as the causative agents of extraintestinal and diarrheal infections; however, the etiopathogenic role of E. coli in other conditions, including colorectal cancer, remains unclear.

Methods

This study aimed to characterize mucosal E. coli isolates (n = 246) from 61 neoplasia patients and 20 healthy controls for the presence of 35 genetic determinants encoding known virulence factors.

Results

Virulence determinants encoding invasin (ibeA), siderophore receptor (iroN), S-fimbriae (sfa), and genotoxin (usp) were more prevalent among E. coli isolated from patients with neoplasia compared to the control group (p < 0.05). In addition, the prevalence of these virulence determinants was increased in more advanced neoplasia stages (p _adj < 0.0125). Compared to patients with advanced colorectal adenoma and carcinoma, the ibeA gene was rarely found in the control group and among patients with non-advanced adenoma (p < 0.05), indicating its potential as the advanced-neoplasia biomarker. Patients with neoplasia frequently had E. coli strains with at least one of the abovementioned virulence factors, whereby specific combinations of these virulence factors were found.

Discussion

These findings suggest that E. coli strains isolated from patients with colorectal neoplasia possess several virulence factors, which could contribute to the development of neoplastic processes in the large intestine.

A Biomimetic Porcine Urothelial Model for Assessing Escherichia coli Pathogenicity

Urinary tract infections can be severe, sometimes fatal, diseases whose etiological pathogens are predominantly uropathogenic strains of E. coli (UPEC). To investigate the UPEC pathogenesis, several models have already been established with minor or major disadvantages. The aim was to develop a simple, fast, and inexpensive biomimetic in vitro model based on normal porcine urothelial (NPU) cells that are genetically and physiologically similar to human bladder urothelium and to perform basic studies of E. coli pathogenicity. Initially, the model was tested using a set of control E. coli strains and, subsequently, with human E. coli strains isolated either from patients with urinary infections or from the feces of healthy individuals. A drop in viability of NPU cells was used as a measure of the pathogenicity of the individual strain tested. To visualize the subcellular events, transmission and scanning electron microscopy was performed. The strains were tested for the presence of different virulence-associated genes, phylogroup, type of core lipid, O-serotype, and type of lipopolysaccharide and a statistical analysis of possible correlations between strains’ characteristics and the effect on the model was performed. Results showed that our model has the discriminatory power to distinguish pathogenic from non-pathogenic E. coli strains, and to identify new, potentially pathogenic strains.

A global systematic review and meta-analysis on correlation between Biofilm producers and Non-biofilm producers with antibiotic resistance in Uropathogenic Escherichiacoli

Escherichia coli accounts for nearly 80% of community-acquired and 50% of hospital-acquired urinary tract infections (UTI). This study aimed to evaluate the correlation between biofilm producers and Non-biofilm producers with antibiotic resistance in Uropathogenic Escherichia coli (UPEC) isolated from patients with UTI globally. The search was conducted between 1st 2000 to 30^th October 2021 in various databases (PubMed, Scopus, Web of sciences, and Google Scholar) with suitable MeSH terms, and text words. Then, after applying the appropriate inclusion and exclusion criteria on the studies for their selection, the data were analyzed by CMA software. Thirty-seven studies met the eligibility criteria to include. The pooled prevalence of ESBL and MDR isolates were reported 37.9%, and 65.8%, respectively. Biofilm formation varied between 13.3% and 99% all over the world. A total of 74.4% of all isolates were biofilm producers, out of which 28.6%, 35.2%, and 38.6% showed strong, moderate, and weak biofilm. The highest and lowest resistance was against Amoxicillin and Meropenem with the prevalence of 80.8%, and 13%, respectively. Fourteen out of 17(82.35%) studies reported a positive correlation between biofilm and antibiotic resistance. Findings showed high numbers of isolates were able to form biofilm, which is one of the factors of antibiotic resistance, and this has been confirmed by the positive significant correlation between biofilm formation and antibiotic resistance that has been reported by studies included. Therefore, due to the importance of biofilm in the etiology of UTI caused by UPEC, it should be prevented; consequently, bacterial resistance can be reduced and controlled.

Genetic Diversity, Carbapenem Resistance Genes, and Biofilm Formation in UPEC Isolated from Patients with Catheter-Associated Urinary Tract Infection in North of Iran

BACKGROUND

Infections due to carbapenem-resistant Enterobacteriaceae (CRE) are associated in patients with urinary catheters alarming rate of emergency status. The aim of this study is to investigate the molecular causes of carbapenem resistance among UPEC as well as antimicrobial resistance trends. Additionally, the potential of isolates to produce biofilms, in addition to their clonal and genetic diversity, was investigated. Material and Methods. A cross-sectional study was accomplished on a collection of 76 non-duplicate UPEC isolates obtained from CAUTIs from May 2021 to September 2021. The modified carbapenem inactivation method (mCIM) and EDTA-modified carbapenem inactivation method (eCIM) test was performed for the detection of carbapenemase and metallo-beta-lactamase activity. Also, the presence of carbapenemase genes was determined using PCR assays. In 96-well microtiter plates, biofilm development was evaluated. ERIC-PCR was used to investigate the clonal and genetic variety of isolates.

RESULTS

A total of 76 confirmed UPEC isolates were obtained from patients mentioned to teaching hospitals in Babol, Iran. The results of antibiotic susceptibility testing revealed a high rate of antibiotic resistance against nalidixic acid (81.6%) and trimethoprim-sulfamethoxazole (80.3%). Among UPEC isolates, 63.2% and 13.2% of UPEC isolates were positive for MBL production. The frequencies of the studied genes are in order of bla _NDM (14.5%), bla _OXA-23 (2.6%), and bla _OXA-48 (2.6%). Forty-two isolates (55.3%) were positive for biofilm formation. ERIC-PCR revealed that UPEC isolates could be categorized into nine clusters A-I and five isolates were categorized as a singleton.

CONCLUSION

The high prevalence of MDR and carbapenemase-producing isolates among the UPEC strain in this investigation is concerning. Moreover, the bla _NDM was the most frequent cause of producing metallo-beta-lactamase and carbapenemase. Also, analysis revealed a partial genetic similarity among the studied isolates, indicating that the same UPEC clones may have spread to other hospital units.

Biofilm formation by uropathogenic Escherichia coli: a complicating factor for treatment and recurrence of urinary tract infections

BACKGROUND

Uropathogenic Escherichia coli (UPEC) are the principal cause of urinary tract infections (UTIs) which can be either hospital- or community-acquired. The most crucial factor in the persistence and recurrence of UTIs is the biofilm formation ability of UPEC, which protects them against antimicrobial treatment.

AIM

To investigate the genetic relatedness, biofilm formation ability, and biofilm-related genes in UPEC isolated from hospital- and community-acquired UTI patients.

METHODS

In vitro biofilm formation ability of 100 UPEC isolates, collected from the urine samples of 49 inpatients and 51 outpatients with UTIs, was assessed by the microtitre plate method. The association between the presence of fimH, papC, sfa/focDE, csgA, crl, afa, flu, and bcsA genes and biofilm formation ability of UPEC was statistically analysed. The genetic relatedness of UPEC isolates was evaluated by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR).

FINDINGS

Overall, 99% of the UPEC isolates showed in vitro biofilm formation ability, and 27% of the isolates were moderate to strong biofilm producers. Only the presence of sfa/focDE gene was significantly associated with moderate and strong biofilm formation by the UPEC isolates. Analysis of dendrograms revealed higher genetic similarities among UPEC isolates of inpatients compared with outpatients.

CONCLUSION

Based on the results, selection of effective therapeutic approaches, which can affect both biofilm formation and enclosed UPEC, is important for preventing recurrent UTIs. The common UPEC clones among inpatients in different hospital units emphasize the need for more rigid control measures to prevent the spread of UPEC in hospitalized patients and to reduce the occurrence of hospital-acquired UTIs.

Antimicrobial Resistance Profile and ExPEC Virulence Potential in Commensal Escherichia coli of Multiple Sources

We recently described the genetic antimicrobial resistance and virulence profile of a collection of 279 commensal E. coli of food-producing animal (FPA), pet, wildlife and human origin. Phenotypic antimicrobial resistance (AMR) and the role of commensal E. coli as reservoir of extra-intestinal pathogenic Escherichia coli (ExPEC) virulence-associated genes (VAGs) or as potential ExPEC pathogens were evaluated. The most common phenotypic resistance was to tetracycline (76/279, 27.24%), sulfamethoxazole/trimethoprim (73/279, 26.16%), streptomycin and sulfisoxazole (71/279, 25.45% both) among the overall collection. Poultry and rabbit were the sources mostly associated to AMR, with a significant resistance rate (p > 0.01) to quinolones, streptomycin, sulphonamides, tetracycline and, only for poultry, to ampicillin and chloramphenicol. Finally, rabbit was the source mostly associated to colistin resistance. Different pandemic (ST69/69*, ST95, ST131) and emerging (ST10/ST10*, ST23, ST58, ST117, ST405, ST648) ExPEC sequence types (STs) were identified among the collection, especially in poultry source. Both ST groups carried high number of ExPEC VAGs (pandemic ExPEC STs, mean = 8.92; emerging ExPEC STs, mean = 6.43) and showed phenotypic resistance to different antimicrobials (pandemic ExPEC STs, mean = 2.23; emerging ExPEC STs, mean = 2.43), suggesting their role as potential ExPEC pathogens. Variable phenotypic resistance and ExPEC VAG distribution was also observed in uncommon ExPEC lineages, suggesting commensal flora as a potential reservoir of virulence (mean = 3.80) and antimicrobial resistance (mean = 1.69) determinants.

In Vitro and In Vivo Biological Activity of Berberine Chloride against Uropathogenic E. coli Strains Using Galleria mellonella as a Host Model

Berberine is an alkaloid of the protoberberine type used in traditional oriental medicine. Its biological activities include documented antibacterial properties against a wide variety of microorganisms; nonetheless, its use against Escherichia coli strains isolated from urinary infections has not yet been widely investigated in vivo. The emergence of antimicrobial resistance requires new therapeutic approaches to ensure the continued effectiveness of antibiotics for the treatment and prevention of urinary infections. Moreover, uropathogenic Escherichia coli (UPEC) has developed several virulence factors and resistance to routine antibiotic therapy. To this end, several in vitro and in vivo tests were conducted to assess the activity of berberine on uropathogenic E. coli strains. Galleria mellonella as an infection model was employed to confirm the in vivo translatability of in vitro data on berberine activity and its influence on adhesion and invasion proprieties of E. coli on human bladder cells. In vitro pre-treatment with berberine was able to decrease the adhesive and invasive UPEC ability. In vivo treatment increased the larvae survival infected with UPEC strains and reduced the number of circulating pathogens in larvae hemolymph. These preliminary findings demonstrated the efficacy and reliability of G. mellonella as in vivo model for pre-clinical studies of natural substances.

Phylogenetic Analysis and Antimicrobial Resistance Profiles of Escherichia coli Strains Isolated from UTI-Suspected Patients

Background:

Escherichia coli as one of the most predominant pathogens is the major cause of urinary tract infections (UTI) worldwide. E. coli strains could be classified into distinct phylo-groups based on PCR method. Additionally, studying the antimicrobial resistance profiles of these strains is essential for finding the effective selection of treatment and evaluating the differences among resistance patterns of particular phylogenetic groups. This study aimed to determine the phylogroups of E. coli isolated from patients with UTI in Tehran, Iran.

Methods:

The urine samples were collected from patients suspected to UTI from four hospitals in Tehran, Iran; Mofid, Vali-Asr, Bu-Ali and Tehran Heart Center (THC) Hospitals during 2014–2016. Assessing the antimicrobial resistance profile of the identified strains was accomplished using ampicillin, ceftriaxone, cefotaxime, and ceftazidime among β-lactam group; gentamicin, and streptomycin among aminoglycosides; nalidixic acid and norfloxacin from quinolones; and chloramphenicol disks. The phylogenetic characterization of 60 E. coli isolates obtained from patients with UTI was done by triplex PCR method.

Results:

E. coli strains showed high resistance toward streptomycin (93.33%), ampicillin (86.6%) and nalidixic acid (73.33%) while resistance against chloramphenicol showed the lowest (10%). The prevalent groups were B2 (n=50/60, 83%), followed by D (n=6/60, 10%), B1 (n=3/60, 5%), and A (n=1, 1.6%).

Conclusion:

The most predominant phylogenetic group was B2 with the major frequent detected with the major drug resistant (48%) compared to other Phylogenetic groups.

Comprehensive phenotypic and genotypic characterization and comparison of virulence, biofilm, and antimicrobial resistance in urinary Escherichia coli isolated from canines

Urinary tract infections (UTIs) affect nearly half of women and an estimated 14 % of the canine companion animal population at least once in their lifetime. As with humans, Escherichia coli is the most commonly isolated bacteria from canine UTIs and infections are dominated by specific phylogenetic groups with notable virulence attributes. In this study, we evaluated uropathogenic E. coli (UPEC) (n = 69) isolated from canine UTIs phenotypically and genotypically for virulence factors, biofilm formation and antimicrobial resistance profiles. Biofilm formation in UPEC strains was positively associated with common virulence factors including papG (p = 0.006), fimH (p < 0.0001), sfaS (p = 0.004), focA (p = 0.004), cnf-1 (p = 0.009) and hlyA (p = 0.006). There was a negative association between biofilm formation and phenotypic antimicrobial resistance for ampicillin (p < 0.0004), ciprofloxacin (p < 0.0001), and trimethoprim-sulfamethoxazole (p < 0.02), as well as multidrug resistance (isolates resistant to ≥ 3 classes of antimicrobials) (p < 0.0002), and the presence of extended spectrum beta-lactamase (ESBL)-producing genes (p < 0.05). In conclusion, UPECs isolated from clinical cases of canine UTIs show a broad negative association between antimicrobial resistance and biofilm formation, and this observation is supported both by phenotypic and genotypic endpoints. As the biofilm formation may result in antimicrobial tolerance, this could be a secondary evasive tactic of UPEC lacking traditional antimicrobial resistance traits. This observation is important for veterinary practitioners to consider when treating puzzling chronic intractable and/or recurrent cases of UTI that appear to be susceptible to antimicrobial therapy via traditional antimicrobial susceptibility testing (AST) methods.

Development of three multiplex-PCR assays for virulence profiling of different iron acquisition systems in Escherichia coli

BACKGROUND AND OBJECTIVES

Escherichia coli is responsible for various enteric and extraintestinal infections in animals and humans. Iron as an essential nutrient, has a proven role in pathogenicity of E. coli. Pathogenic E. coli benefits of having complicated systems for iron acquisition but our current knowledge is limited because of complexity of these systems. In the present study, three multiplex-PCR assays were developed to screen nine different virulence genes related to diverse iron acquisition systems in E. coli.

MATERIALS AND METHODS

The multiplex-PCR systems were designed and optimized in three panels. Each panel includes a triplex-PCR cocktail. The panels are as follow: panel 1: iroN, iutA and fecA; panel 2: fyuA, sitA and irp2; and panel 3: iucD, chuA and tonB. A total of 39 pathogenic E. coli was screened according to the designed multiplex-PCR.

RESULTS

In total, the top three frequent genes were tonB (100%), fecA (66.6%) and sitA (58.9%). With the exception of fecA and tonB, comparing the prevalence of genes among different origin of isolates (human, cattle, poultry and pigeon) showed significant associations (P < 0.05). Moreover, the iroN, sitA and iucD genes were significantly prevalent (P < 0.05) among members of extraintestinal pathogenic E. coli in comparison with the group of diarrheagenic E. coli.

CONCLUSION

The current multiplex-PCR assays could be a valuable, rapid and economic tool to investigate diverse iron acquisition systems in E. coli for more precise virulence typing of pathogenic or commensal strains.

Distribution of Pathogenicity Island Markers and H-Antigen Types of Escherichia coli O25b/ST131 Isolates from Patients with Urinary Tract Infection in Iran

Escherichia coli serogroup O25b-sequence type 131 (E. coli O25b/ST131) is known as a multidrug-resistant organism with high virulence potential and has received attention internationally. We aim to investigate the prevalence of O25b/ST131 and the distribution of bla_CTX-M-15, pathogenicity island (PAI) markers, phylogenetic groups, and H-antigen typing in the E. coli O25b/ST131 isolated from patients with urinary tract infection (UTI) in Tehran, the capital of Iran. Seventy (26.9%) E. coli isolates were identified as O25b/ST131. There was also a significant difference in the prevalence of virulence genes, including papA, sfa, sat, cnf1, iutA, kpMII, traT, and usp, in the O25b/ST131 isolates rather than non-O25b/ST131 ones (p ≤ 0.05). Furthermore, 78% of the O25b/ST131 isolates carried four to seven PAIs, while 71% of non-O25b/ST131 isolates carried two to four PAI markers (p ≤ 0.05). Our study showed that in addition to H4, other H-antigens may play a role in the O25b/ST131 virulence potential. Besides, a significant association was found between the history of previous UTIs and infection among the O25b/ST131 clone isolates. Pulsed-field gel electrophoresis revealed circulating of O25b:H4-ST131/PST43 clone in both hospital and community. Approximately one in every three uropathogenic E. coli isolates was the O25b/ST131 clone, representing a significant public health threat. Practical investigation on O25b/ST131 can be helpful in better understanding of ST131 evolution and controlling UTI in hospitals.

Characterization of fosfomycin heteroresistance among multidrug-resistant Escherichia coli isolates from hospitalized patients in Rio de Janeiro, Brazil

OBJECTIVES

Urinary tract infections (UTIs) caused by multidrug-resistant Escherichia coli have become a major medical concern. Old antibiotics such as fosfomycin have become an alternative therapeutic option due to their effectiveness and, as a result, fosfomycin is now used as a first-line drug for the treatment of UTIs in many countries. Despite low resistance rates, fosfomycin heteroresistance, defined as a phenomenon where subpopulations of bacteria are resistant to high antibiotic concentrations whereas most of the bacteria are susceptible, is an underestimated problem.

METHODS

The frequency of heteroresistance in E. coli isolated from hospitalized patients in Brazil and its effect on susceptibility of E. coli in biofilms was studied and the isolates were molecularly characterized to reveal the mechanisms behind their fosfomycin heteroresistance using whole-genome sequencing.

RESULTS

A higher frequency of fosfomycin heteroresistance compared with other studies was found. In biofilms, most heteroresistant isolates were less sensitive to fosfomycin than control isolates and showed overexpression of metabolic genes thereby increasing their survival rate. Molecular characterization showed that some resistant subpopulations derived from heteroresistant isolates had a defect in their fosfomycin uptake system caused by mutations in transporter and regulatory genes, whereas others overexpressed the murA gene. None to minor effects on bacterial fitness were observed. Oxidative stress protection, virulence and metabolic genes were differentially expressed in resistant subpopulations and heteroresistant isolates.

CONCLUSION

Frequent detection of heteroresistance in UTIs may play a role in the failure of antibiotic treatments and should therefore be more carefully diagnosed.

Characterization of antibiotic resistance and virulence factors of Escherichia coli strains isolated from Iranian inpatients with urinary tract infections

Background

Urinary tract infections (UTIs) are one of the most frequent human infectious diseases causing considerable amount of morbidity and mortality. The present study aimed to investigate the occurrence of antibiotics resistance and virulence genes among Escherichia coli strains isolated from UTIs in the north of Iran.

Methods

This cross-sectional study was performed at 5 teaching hospitals in Rasht in the north of Iran. Totally, 129 E. coli isolates were identified by standard microbiologic tests. Antimicrobial susceptibility pattern was determined using disk diffusion method. The presence of virulence genes was detected by PCR method.

Results

The results of antibiotic susceptibility showed that the highest resistance rates were to ampicillin (78.3%) followed by nalidixic acid (74.4%) and trimethoprim/sulfamethoxazole (69.8%). On the other hand, the highest susceptibility was toward nitrofurantoin (96.1%) and imipenem (92.2%). Further analysis revealed that the rate of ESBL-producing and multiple-drug resistant isolates was 51.2% and 84.5%, respectively. Molecular analysis revealed that traaT (87.6%) gene was the most prevalent virulence factors followed by fyuA (86%) and kpsmt (76%) genes. Also, fimH gene was the most frequently detected adhesion-associated gene with 74.4%.

Conclusion

In summary, our results showed a remarkable rate of drug resistance and heterogeneity for virulence factors among E. coli strains isolated from UTIs in the north of Iran. The emergence of such strains can be a predictive marker for their persistence in the hospital and consequently a significant threat for hospitalized patients.

Virulence factors, prevalence and potential transmission of extraintestinal pathogenic Escherichia coli isolated from different sources: recent reports

Extraintestinal pathogenic E. coli (ExPEC) are facultative pathogens that are part of the normal human intestinal flora. The ExPEC group includes uropathogenic E. coli (UPEC), neonatal meningitis E. coli (NMEC), sepsis-associated E. coli (SEPEC), and avian pathogenic E. coli (APEC). Virulence factors (VF) related to the pathogenicity of ExPEC are numerous and have a wide range of activities, from those related to bacteria colonization to those related to virulence, including adhesins, toxins, iron acquisition factors, lipopolysaccharides, polysaccharide capsules, and invasins, which are usually encoded on pathogenicity islands (PAIs), plasmids and other mobile genetic elements. Mechanisms underlying the dynamics of ExPEC transmission and the selection of virulent clones are still poorly understood and require further research. The time shift between colonization of ExPEC and the development of infection remains problematic in the context of establishing the relation between consumption of contaminated food and the appearance of first disease symptoms. What appears to be most difficult is to prove that ExPEC strains cause disease symptoms and to examine the mechanism of transition from the asymptomatic colonization of the intestines to the spreading of the bacteria outside the digestive system. A significant problem for researchers who are trying to ascribe ExPEC transmission to food, people or the environment is to draw the distinction between colonization of ExPEC and infection. Food safety is an important challenge for public health both at the production stage and in the course of its processing and distribution. Examination of the genetic similarity of ExPEC strains will allow to determine their origin from different sources. Many levels of genotyping have been proposed in which the typing of strains, plasmids and genes is compared in order to obtain a more complete picture of this complex problem. The aim of our study was to characterize E. coli strains isolated from humans, animals and food for the presence of bacterial genes encoding virulence factors such as toxins, and iron acquisition systems (siderophores) in the context of an increasing spread of ExPEC infections.

Molecular Analysis of Uropathogenic E.coli Isolates from Urinary Tract Infections

INTRODUCTION

The aim of the current study was to investigate the prevalence of virulence genes in uropathogenic Escherichia coli (UPEC) isolates in Ilam.

MATERIALS AND METHODS

For this purpose, a total of 80 UPEC isolates were collected for patients with UTIs during a 6 months period. The multiplex polymerase chain reaction (multiplex PCR) was used to detect the papEF, fimH, iucD, hlyA, fyuA, and ompT genes.

RESULTS

The prevalence of fimH, papEF, iucD, fyuA, hlyA, hlyA, and ompT genes were 87.5%, 47.5%, 60%, 67.5%, 27.5%, 47.5% and 71.2%, respectively. Among all of the isolates, 27 profiles were obtained.

CONCLUSION

Our findings demonstrated that the most prevalence was found for fimH, and different distribution of virulence genes suggested different ability of pathogenicity.

Relationships between Virulence Factors and Antimicrobial Resistance among Escherichia coli Isolated from Urinary Tract Infections and Commensal Isolates in Tehran, Iran

Objectives

Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs). Here, we determined whether sensitivity to antibiotics was related to the prevalence of iron scavenging genes, or to biofilm and hemolysis formation.

Methods

A total of 110 UPEC and 30 E coli isolates were collected from the urine of UTI patients and feces of healthy individuals without UTI, respectively. The presence of iron receptor genes and phenotypic properties were evaluated by polymerase chain reaction and phenotypic methods, respectively. Susceptibility to routine antibiotics was evaluated using the disc diffusion method.

Results

The prevalence of iron scavenging genes ranged from 21.8% (ireA) to 84.5% (chuA) in the UPEC. Resistance to ceftazidime and cefotaxime was significantly correlated with the presence of fyuA and iutA iron genes. Biofilm production was significantly associated with the prevalence of fyuA and hma iron genes. A higher degree of antibiotic resistance was exhibited by isolates that produced biofilms than by their non-biofilm producing counterparts.

Conclusion

Our study clearly indicates that biofilm production is associated with antibiotic resistance, and that iron receptors and hemolysin production also contribute to reduced antibiotic sensitivity. These results further our understanding of the role that these virulence factors play during UPEC pathogenesis, which in turn may be valuable for the development of novel treatment strategies against UTIs.

Phylogenetic relationships, biofilm formation, motility, antibiotic resistance and extended virulence genotypes among Escherichia coli strains from women with community-onset primitive acute pyelonephritis

The present work set out to search for a virulence repertoire distinctive for Escherichia coli causing primitive acute pyelonephritis (APN). To this end, the virulence potential of 18 E. coli APN strains was genotypically and phenotypically assessed, comparatively with 19 strains causing recurrent cystitis (RC), and 16 clinically not significant (control, CO) strains. Most of the strains belong to phylogenetic group B1 (69.8%; p<0.01), and APN strains showed unique features, which are the presence of phylogroup A, and the absence of phylogroup B2 and non-typeable strains. Overall, the most dominant virulence factor genes (VFGs) were ecpA and fyuA (92.4 and 86.7%, respectively; p<0.05), and the mean number of VFGs was significantly higher in uropathogenic strains. Particularly, papAH and malX were exclusive for uropathogenic strains. APN and RC strains showed a significantly higher prevalence of fyuA, usp, and malX than of CO strains. Compared to RC strains, APN ones showed a higher prevalence of iha, but a lower prevalence of iroN, cnf1, and kpsMT-II. Hierarchical cluster analysis showed a higher proportion of two gene clusters (malX and usp, and fyuA and ecpA) were detected in the APN and RC groups than in CO, whereas iutA and iha clusters were detected more frequently in APN strains. The motility level did not differ among the study-groups and phylogroups considered, although a higher proportion of swarming strains was observed in APN strains. Antibiotic-resistance rates were generally low except for ampicillin (37.7%), and were not associated with specific study- or phylogenetic groups. APN and RC strains produced more biofilm than CO strains. In APN strains, iha was associated with higher biofilm biomass formation, whereas iroN and KpSMT-K1 were associated with a lower amount of biofilm biomass. Further work is needed to grasp the virulence and fitness mechanisms adopted by E. coli causing APN, and hence develop new therapeutic and prophylactic approaches.

Distribution of extended-spectrum β-lactam, quinolone and carbapenem resistance genes, and genetic diversity among uropathogenic Escherichia coli isolates in Tehran, Iran

OBJECTIVES

Antimicrobial resistance among uropathogenic Escherichia coli (UPEC) is increasing. The aim of this study was to evaluate antimicrobial resistance in UPEC isolates and its correlation with virulence factors.

METHODS

A total of 120 E. coli isolates were collected from patients with urinary tract infection in Tehran, Iran. Biofilm formation and antimicrobial susceptibility were determined by phenotypic tests. The combination disk diffusion test and modified Hodge test (MHT) were performed for phenotypic detection of extended-spectrum β-lactamases (ESBLs) and carbapenemases, respectively. PCR was used for the detection of virulence genes, ESBL-encoding genes, and quinolone (qnr) and carbapenem resistance genes. Pulsed-field gel electrophoresis (PFGE) was performed to explore the genetic relatedness among isolates.

RESULTS

Most isolates exhibited biofilm formation, and different frequencies of virulence genes were observed. There was a high rate of resistance, especially multidrug resistance, to most of the antimicrobial agents tested. Phenotypically, 67.5% of the isolates produced an ESBL and were resistant to different antimicrobial classes. In total, 83.3% of the isolates harboured ESBL genes, especially bla_TEM and bla_CTX-M, and 32.5% were positive for the quinolone resistance genes qnrS and qnrB. All isolates were negative for carbapenemases by the MHT and PCR. These results indicate the association between the presence of various virulence genes and antimicrobial susceptibility. PFGE analysis showed that there was great clonal diversity among the selected isolates, with 17 isolates divided into five clusters.

CONCLUSIONS

These results indicate that the high antimicrobial resistance among UPEC isolates is alarming and requires urgent attention.

Molecular characterisation of uropathogenic Escherichia coli isolates at a tertiary care hospital in South India

Uropathogenic Escherichia coli (UPEC) express a multitude of virulence factors (VFs) to break the inertia of the mucosal barrier of the urinary tract. The aim of the present study was undertaken to characterised the UPEC strains and to correlate carriage of specific virulence markers with different phylogroups and also to correlate these findings with clinical outcome of patients. A total of 156 non-repeated, clinically significant UPEC isolates were studied. Virulent genes were determined by two set of multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Antibiograms and patient's clinical outcomes were collected in a structured pro forma. Of the 156 patients infected by UPEC strains with significant bacterial counts the most common predisposing factors were diabetes (45.5%) followed by carcinoma (7%). On analysis of the VF genes of the isolates, a majority of strains (140; 90%) were possessing the fimH gene followed by iutA (98; 63%), papC (76; 49%), cnf1 (46; 29.5%), hlyA (45; 29%) and neuC (8; 5%), respectively. On phylogenetic analysis, 27 (17%) isolates were belong to phylogroup A, 16 (10%) strains to Group B1, 59 (38%) were from Group B2 and 54 (35%) were from Group D. High prevalence of antibiotic resistance was observed among the isolates. The incidence of papC, cnf1 and hlyA was significantly higher (P < 0.05) among the isolates from relapse patients. Our findings indicate that virulent as well as commensal strains are capable of causing urinary tract infection. Virulence genes as well as patients-related factors are equally responsible for the development of infections and also that virulence genes may help such isolates to persist even with appropriate chemotherapy and be responsible for recurrent infections.

Antibiotic resistance, virulence factors and biofilm formation ability in Escherichia coli strains isolated from chicken meat and wildlife in the Czech Republic

Attachment of pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent a serious threat for the food industry, since these bacteria are more resistant to antimicrobials or possess more virulence factors. The main aim of this study was to investigate the correlation between antibiotic resistance against 13 antibiotics, distribution of 10 virulence factors and biofilm formation in 105 Escherichia coli strains according to their origin. The high prevalence of antibiotic resistance that we have found in wildlife isolates could be acquired by horizontal transfer of resistance genes from human or domestic or farm animals. Consequently, these commensal bacteria might serve as indicator of antimicrobial usage for human and veterinary purposes in the Czech Republic. Further, 46 out of 66 resistant isolates (70%) were able to form biofilm and we found out statistically significant correlation between prevalence of antibiotic resistance and biofilm formation ability. The highest prevalence of antibiotic resistance was observed in weak biofilm producers. Biofilm formation was not statistically associated with any virulence determinant. However, we confirmed the correlation between prevalence of virulence factors and host origin. Chicken isolates possessed more virulence factors (66%), than isolates from wildlife (37%). We can conclude that the potential spread of antibiotic resistance pattern via the food chain is of high concern for public health. Even more, alarming is that E. coli isolates remain pathogenic potential with ability to form biofilm and these bacteria may persist during food processing and consequently lead to greater risks of food contamination.

Antibiotic Resistance and Virulence Phenotypes of Recent Bacterial Strains Isolated from Urinary Tract Infections in Elderly Patients with Prostatic Disease

Acute bacterial prostatitis is one of the frequent complications of urinary tract infection (UTI). From the approximately 10% of men having prostatitis, 7% experience a bacterial prostatitis. The purpose of this study was to investigate the prevalence of uropathogens associated with UTIs in older patients with benign prostatic hyperplasia and to assess their susceptibility to commonly prescribed antibiotics as well as the relationships between microbial virulence and resistance features. Uropathogenic Escherichia coli was found to be the most frequent bacterial strain isolated from patients with benign prostatic hyperplasia, followed by Enterococcus spp., Enterobacter spp., Klebsiella spp., Proteus spp., Pseudomonas aeruginosa, and Serratia marcescens. Increased resistance rates to tetracyclines, quinolones, and sulfonamides were registered. Besides their resistance profiles, the uropathogenic isolates produced various virulence factors with possible implications in the pathogenesis process. The great majority of the uropathogenic isolates revealed a high capacity to adhere to HEp-2 cell monolayer in vitro, mostly exhibiting a localized adherence pattern. Differences in the repertoire of soluble virulence factors that can affect bacterial growth and persistence within the urinary tract were detected. The Gram-negative strains produced pore-forming toxins-such as hemolysins, lecithinases, and lipases-proteases, siderophore-like molecules resulted from the esculin hydrolysis and amylases, while Enterococcus sp. strains were positive only for caseinase and esculin hydrolase. Our study demonstrates that necessity of investigating the etiology and local resistance patterns of uropathogenic organisms, which is crucial for determining appropriate empirical antibiotic treatment in elderly patients with UTI, while establishing correlations between resistance and virulence profiles could provide valuable input about the clinical evolution and recurrence rates of UTI.

Characterization and virulence clustering analysis of extraintestinal pathogenic Escherichia coli isolated from swine in China

BACKGROUND

Swine extraintestinal pathogenic Escherichia coli (ExPEC) is an important pathogen that leads to economic and welfare costs in the swine industry worldwide, and is occurring with increasing frequency in China. By far, various virulence factors have been recognized in ExPEC. Here, we investigated the virulence genotypes and clonal structure of collected strains to improve the knowledge of phylogenetic traits of porcine ExPECs in China.

RESULTS

We isolated 64 Chinese porcine ExPEC strains from 2013 to 14 in China. By multiplex PCR, the distribution of isolates belonging to phylogenetic groups B1, B2, A and D was 9.4%, 10.9%, 57.8% and 21.9%, respectively. Nineteen virulence-related genes were detected by PCR assay; ompA, fimH, vat, traT and iutA were highly prevalent. Virulence-related genes were remarkably more prevalent in group B2 than in groups A, B1 and D; notably, usp, cnf1, hlyD, papA and ibeA were only found in group B2 strains. Genotyping analysis was performed and four clusters of strains (named I to IV) were identified. Cluster IV contained all isolates from group B2 and Cluster IV isolates had the strongest pathogenicity in a mouse infection model. As phylogenetic group B2 and D ExPEC isolates are generally considered virulent, multilocus sequence typing (MLST) analysis was performed for these isolates to further investigate genetic relationships. Two novel sequence types, ST5170 and ST5171, were discovered. Among the nine clonal complexes identified among our group B2 and D isolates, CC12 and CC95 have been indicated to have high zoonotic pathogenicity. The distinction between group B2 and non-B2 isolates in virulence and genotype accorded with MLST analysis.

CONCLUSION

This study reveals significant genetic diversity among ExPEC isolates and helps us to better understand their pathogenesis. Importantly, our data suggest group B2 (Cluster IV) strains have the highest risk of causing animal disease and illustrate the correlation between genotype and virulence.

Urosepsis: Overview of the Diagnostic and Treatment Challenges

Urosepsis is defined as sepsis caused by an infection in the urogenital tract. In approximately 30% of all septic patients the infectious focus is localized in the urogenital tract, mainly due to obstructions at various levels, such as ureteral stones. Urosepsis may also occur after operations in the urogenital tract. In urosepsis, complete bacteria and components of the bacterial cell wall from the urogenital tract trigger the host inflammatory event and act as exogenous pyrogens on eukaryotic target cells of patients. A burst of second messenger molecules leads to several different stages of the septic process, from hyperactivity to immunosuppression. As pyelonephritis is the most frequent cause for urosepsis, the kidney function is therefore most important in terms of cause and as a target organ for dysfunction in the course of the sepsis.Since effective antimicrobial therapy must be initiated early during sepsis, the empiric intravenous therapy should be initiated immediately after microbiological sampling. For the selection of appropriate antimicrobials, it is important to know risk factors for resistant organisms and whether the sepsis is primary or secondary and community or nosocomially acquired. In addition, the preceding antimicrobial therapies should be recorded as precisely as possible. Resistance surveillance should, in any case, be performed locally to adjust for the best suitable empiric treatment. Treatment challenges arise from the rapid increase of antibiotic resistance in Gram-negative bacteria, especially extended-spectrum β-lactamase (ESBL)-producing bacteria. Treatment of urosepsis comprises four basic strategies I) supportive therapy (stabilizing and maintaining blood pressure), II) antimicrobial therapy, III) control or elimination of the complicating factor, and IV) specific sepsis therapy.

Correlation between biofilm formation and resistance toward different commonly used antibiotics along with extended spectrum beta lactamase production in uropathogenic Escherichia coli isolated from the patients suspected of urinary tract infections visiting Shree Birendra Hospital, Chhauni, Kathmandu, Nepal

Background

Escherichia coli is the most predominant causative agent of urinary tract infection (UTI). Recently, increase in drug resistance among the uropathogenic bacteria has caused great problem in treatment of UTI. The main objective of this research is to determine the correlation between biofilm formation and resistance toward different commonly used antibiotics along with extended spectrum beta lactamase production in uropathogenic Escherichia coli.

Methods

The urine samples collected from the patients suspected of urinary tract infections (visiting Shree Birendra Hospital, Chhauni, Kathmandu, Nepal between July to December 2013) were cultured in cystine lactose electrolyte deficient (CLED) agar by using semi quantitative culture technique. Extended spectrum beta lactamase (ESBL) production was detected by combined disc diffusion technique and biofilm formation was detected by Congo red agar method. Chi-square test was applied and p-value < 0.05 was considered statistically significant.

Results

Out of 1480 urine samples, E. Coli was isolated from 208 (14.1 %) samples. Of total 69 (33.2 %) ESBL producing uropathogenic strains of E. coli, 20 (29 %) were strong biofilm producers, 22 (31.9 %) were moderate biofilm producers, 11 (15.9 %) were weak biofilm producers and 16 (23.2 %) were biofilm non producers. Whereas among 139 ESBL non producing E. coli, 22 (15.8 %) were strong biofilm producers, 20 (14.4 %) were moderate biofilm producers, 13 (9.4 %) were weak biofilm producers and 84 (60.4 %) were biofilm non producers. Among total 108 biofilm producing E. coli, maximum resistance was observed toward cephalexin followed by amoxicillin and highest susceptibility was seen toward amikacin.

Conclusion

The ability of biofilm formation was found to be significantly higher in ESBL producing strains of E. coli than that in ESBL non producing strains (p < 0.05). There was higher resistance rate to antimicrobial agents among biofilm producing strains of E. coli than that in biofilm non producing strains. According to our antimicrobial susceptibility pattern for E. coli, to start preliminary treatment for UTI in Nepal, we recommend to use amikacin or nitrofurantoin. Further, for the treatment of the UTI, the antibiotics should be selected on the basis of the urine culture and sensitivity report.

Distribution of virulence associated traits among urine Escherichia coli isolates from patients in onco-hematology

Escherchia coli is the most common etiological agent of urinary tract infections. In this study we had two goals: First of all, to find out if urine stains isolated from our patients--having the particularity of being immunocompromised--would have a virulence genes distribution different from the one observed in strains isolated from ordinary patients. Second, we wanted to identify a common virulence profile associated to these particular strains. The prevalence of virulence factors (VF)-encoding genes was analyzed by PCR. Of the tested VF-encoding genes, malX (80%), ompT (79%), fyuA (74%), usp (67%), chuA (66%), iroN (59%), iutA (56%), papC (36%), pap AH (30%), papEF (28%), hlyA (28%), papG allele II (25%), cnf1 (21%), focG (20%),cvaC (20%) and papG allele III (7%) were significantly associated to urinary strains. Virulence genes distribution of urinary strains isolated from onco-hematology patients and the one observed in strains isolated from ordinary patients are almost the same. The virulence profiles containing adhesins type 1, S and F1C fimbriae, siderophore genes and three individual genes ompT, usp and malX were present in half of the urinary strains and were significantly associated to them. Two virulence signatures occurred significantly in UTI-causing strains (12%). These findings provide first insight into the virulence of UTI-causing E. coli strains isolated in onco-hematology patients.

Multilocus Sequence Typing and Virulence Profiles in Uropathogenic Escherichia coli Isolated from Cats in the United States

The population structure, virulence, and antimicrobial resistance of uropathogenic E. coli (UPEC) from cats are rarely characterized. The aim of this study was to compare and characterize the UPEC isolated from cats in four geographic regions of USA in terms of their multilocus sequence typing (MLST), virulence profiles, clinical signs, antimicrobial resistance and phylogenetic grouping. The results showed that a total of 74 E. coli isolates were typed to 40 sequence types with 10 being novel. The most frequent phylogenetic group was B2 (n = 57). The most frequent sequence types were ST73 (n = 12) and ST83 (n = 6), ST73 was represented by four multidrug resistant (MDR) and eight non-multidrug resistant (SDR) isolates, and ST83 were significantly more likely to exhibit no drug resistant (NDR) isolates carrying the highest number of virulence genes. Additionally, MDR isolates were more diverse, and followed by SDR and NDR isolates in regards to the distribution of the STs. afa/draBC was the most prevalent among the 29 virulence-associated genes. Linking virulence profile and antimicrobial resistance, the majority of virulence-associated genes tested were more prevalent in NDR isolates, and followed by SDR and MDR isolates. Twenty (50%) MLST types in this study have previously been associated with human isolates, suggesting that these STs are potentially zoonotic. Our data enhanced the understanding of E. coli population structure and virulence association from cats. The diverse and various combinations of virulence-associated genes implied that the infection control may be challenging.

Bacterial Genotoxins: Merging the DNA Damage Response into Infection Biology

Bacterial genotoxins are unique among bacterial toxins as their molecular target is DNA. The consequence of intoxication or infection is induction of DNA breaks that, if not properly repaired, results in irreversible cell cycle arrest (senescence) or death of the target cells. At present, only three bacterial genotoxins have been identified. Two are protein toxins: the cytolethal distending toxin (CDT) family produced by a number of Gram-negative bacteria and the typhoid toxin produced by Salmonella enterica serovar Typhi. The third member, colibactin, is a peptide-polyketide genotoxin, produced by strains belonging to the phylogenetic group B2 of Escherichia coli. This review will present the cellular effects of acute and chronic intoxication or infection with the genotoxins-producing bacteria. The carcinogenic properties and the role of these effectors in the context of the host-microbe interaction will be discussed. We will further highlight the open questions that remain to be solved regarding the biology of this unusual family of bacterial toxins.

Characterization of Escherichia coli Phylogenetic Groups Associated with Extraintestinal Infections in South Indian Population

Background:

Escherichia coli strains mainly fall into four phylogenetic groups (A, B1, B2, and D) and that virulent extra-intestinal strains mainly belong to groups B2 and D.

Aim:

The aim was to determine the association between phylogenetic groups of E. coli causing extraintestinal infections (ExPEC) regarding the site of infection, expression of virulence factors, antimicrobial resistance patterns, and clinical outcome. This descriptive study was carried out in a multi-specialty Tertiary Care Hospital.

Materials and Methods:

A total of 300 E. coli causing ExPEC were studied. Triplex polymerase chain reaction was used to classify the phylogenetic groups; hemolysin production was assessed on sheep blood agar and biofilm production in a microtiter plate assay. Production of extended spectrum of beta-lactamase (ESBLs) was detected by combination disk method; AmpC was detected by AmpC disk test, Carbapenemase production was detected by modified Hodge test and metallo-β-lactamase by metallo-beta-lactamases (MBL) E-test.

Results:

Of 300 isolates, 61/300 (20%) belonged to phylogroup A, 27/300 (9%) to phylogroup B1, 104/300 (35%) were B2 and 108/300 (36%) belonged to group D, respectively. Phylogroups B2 and D were the most predominant groups in urinary tract infection and sepsis. Prognoses were better in infections with group A and B1 isolates, and relapses and death were common in infections with B2 and D. Expression of biofilm was greatest in B1 and hemolysin in group B2. Group A and B1 showed higher resistance to ciprofloxacin and were most frequent β-lactamase (ESBL, AmpC, Carbapenemase and MBL) producers.

Conclusions:

Phylogenetic group B2 and D were predominant in ExPEC and exhibited least antimicrobial resistance among the groups. Resistance to multiple antibiotics was most prevalent in group A and B1. Regular monitoring of antimicrobial susceptibility in commensal strains is essential as they might transfer the property of antimicrobial resistance to pathogenic strains.

Sub-Conjunctival Injection of Antibiotics vs. Povidone-Iodine Drop on Bacterial Colonies in Phacoemulsification Cataract Surgery

BACKGROUND

Postoperative endophthalmitis is one the most serious complications of cataract surgery. The majority of causative organisms in this destructive infection come from the patient's own periocular flora. Efforts have been made to reduce the virulence of organisms in the eyelid and conjunctiva with perioperative topical antibiotics, preparation of surgical field, covering eyelids and conjunctival surface with 5% povidone-iodine solution and intracameral antibiotics at the time of surgery to minimize the risk of endophthalmitis.

OBJECTIVES

We assessed the effect of subconjunctival injection of cefazolin and pouring povidone-iodine on the conjunctiva bacterial colony forming units (CFU) in phacoemulsification cataract surgery.

PATIENTS AND METHODS

In this prospective, randomized, double-blind clinical trial, 122 patients having phacoemulsification cataract surgery with clear corneal incision and topical anesthesia were randomized into two groups including group 1 (subconjunctival injection of cefazolin) and group 2 (recipients of a drop of povidone-iodine). Cultures were collected from the bulbar conjunctiva at the injection site and from the corresponding location in the patient's eye, three different times.

RESULTS

The mean of eyelid samples on blood and chocolate agars, on the day after compared to the day before the surgery in group 1 showed a 52% and 56% reduction. These values were 58% and 50% in group 2 (P < 0.05). The mean CFU of conjunctiva before and at the end of surgery on blood and chocolate agars showed 57% and 56% reduction in group one and 51% and 52% reduction in group 2 (P < 0.05). While comparing mean CFU of conjunctiva at the end and one day post-surgery (interval of 14 ± 2 hours) showed 27% and 27% increase in group 1 and 20% and 21% increase in group 2 (P < 0.05), which reflects conjunctival flora proliferation during the early postoperative period.

CONCLUSIONS

Due to the good tolerance of patients towards topical anesthesia, pouring a drop of povidone-iodine 10% seems to be a simple and acceptable method to reduce the growth of microorganisms of the conjunctiva.

Is biofilm formation related to the hypermutator phenotype in clinical Enterobacteriaceae isolates?

In bacteria, complex adaptive processes are involved during transition from the planktonic to the biofilm mode of growth, and mutator strains are more prone to producing biofilms. Enterobacteriaceae species were isolated from urinary tract infections (UTIs; 222 strains) and from bloodstream infections (BSIs; 213 strains). Relationship between the hypermutable phenotype and biofilm forming capacity was investigated in these clinical strains. Mutation frequencies were estimated by monitoring the capacity of each strain to generate mutations that conferred rifampicin resistance on supplemented medium. Initiation of biofilm formation was assayed by determining the ability of the cells to adhere to a 96-well polystyrene microtitre plate. UTI Enterobacteriaceae strains showed significantly higher biofilm-forming capacity: 63.1% (54.0% for E. coli strains) vs. 42.3% for BSI strains (47.7% for E. coli). Strains isolated from UTIs did not present higher mutation frequencies than those from BSIs: contrary to what has been widely described for P. aeruginosa strains, isolated from pulmonary samples in patients suffering from cystic fibrosis, no relationship was found between the hypermutator phenotype in Enterobacteriaceae and the ability to initiate a biofilm.

Escherichia coli sequence type 131 as a prominent cause of antibiotic resistance among urinary Escherichia coli isolates from reproductive-age women

The recent emergence of multidrug-resistant Escherichia coli sequence type 131 (ST131) has coincided with an increase in general antibiotic resistance of E. coli, suggesting that ST131 has a contributing role in resistance. However, there is little information about the contribution of ST131 to different clinical syndromes or the basis for its impressive emergence and epidemic spread. To investigate this, we studied 953 E. coli isolates from women of reproductive age in the central west region of New South Wales, Australia, including 623 urinary isolates from patients with cystitis (cystitis isolates) (n = 322) or pyelonephritis (pyelonephritis isolates) (n = 301) and 330 fecal isolates from healthy controls. The characteristics studied included ST131 clonal group status, resistance to different antibiotics, presence of virulence factor (VF) genes, and biofilm production. As expected, fecal isolates differed significantly from urinary (cystitis and pyelonephritis) isolates in most of the studied characteristics. Antibiotic resistance was significantly more common in ST131 than in non-ST131 isolates. Both antibiotic resistance and ST131 were more common in pyelonephritis than cystitis isolates and least so among fecal isolates. Within each source group, individual VF genes were more prevalent and VF scores were higher for ST131 than for non-ST131 isolates. For ST131 only, the prevalences of most individual VF genes and VF scores were the lowest in the fecal isolates, higher in the cystitis isolates, and highest in the pyelonephritis isolates. Biofilm production was strongly associated with ST131 status and antibiotic resistance. These results clarify the distribution of the ST131 clonal group and its epidemiological associations in our region and suggest that it exhibits both enhanced virulence and increased antibiotic resistance compared with those of other urinary tract infection (UTI) and fecal E. coli isolates from women of reproductive age.

Global transcriptional responses to the bacteriocin colicin M in Escherichia coli

Background

Bacteriocins are protein antimicrobial agents that are produced by all prokaryotic lineages. Escherichia coli strains frequently produce the bacteriocins known as colicins. One of the most prevalent colicins, colicin M, can kill susceptible cells by hydrolyzing the peptidoglycan lipid II intermediate, which arrests peptidoglycan polymerization steps and provokes cell lysis. Due to the alarming rise in antibiotic resistance and the lack of novel antimicrobial agents, colicin M has recently received renewed attention as a promising antimicrobial candidate. Here the effects of subinhibitory concentrations of colicin M on whole genome transcription in E. coli were investigated, to gain insight into its ecological role and for purposes related to antimicrobial therapy.

Results

Transcriptome analysis revealed that exposure to subinhibitory concentrations of colicin M altered expression of genes involved in envelope, osmotic and other stresses, including genes of the CreBC two-component system, exopolysaccharide production and cell motility. Nonetheless, there was no induction of biofilm formation or genes involved in mutagenesis.

Conclusion

At subinhibitory concentrations colicin M induces an adaptive response primarily to protect the bacterial cells against envelope stress provoked by peptidoglycan damage. Among the first induced were genes of the CreBC two-component system known to promote increased resistance against colicins M and E2, providing novel insight into the ecology of colicin M production in natural environments. While an adaptive response was induced nevertheless, colicin M application did not increase biofilm formation, nor induce SOS genes, adverse effects that can be provoked by a number of traditional antibiotics, providing support for colicin M as a promising antimicrobial agent.

Biofilm formation with mixed cultures of Pseudomonas aeruginosa/Escherichia coli on silicone using artificial urine to mimic urinary catheters

In this study, single and dual species biofilms of Pseudomonas aeruginosa and Escherichia coli, two common bacteria associated with urinary tract infections, were formed in silicon coupons immersed in artificial urine medium. In single species experiments, E. coli appeared to form biofilms more easily than P. aeruginosa. In mixed biofilms, both species apparently benefited from the presence of the other, as the average Log total cells cm(-2) of mixed biofilms (7.29 cells cm(-2)) was higher than obtained for single cultures (6.99 cells cm(-2)). However, the use of selective media seemed to indicate that P. aeruginosa was the only microorganism to benefit in mixed biofilms (Log 7 CFU of P. aeruginosa cm(-2), compared to Log 6 CFU cm(-2) obtained in pure cultures). Peptide nucleic acid-fluorescence in situ hybridization combined with confocal laser scanning microscopy confirmed that E. coli was indeed being outnumbered by P. aeruginosa at 48 h. Whereas E. coli is the main causative agent of catheter-associated urinary tract infections, the results from this study indicate that the reason for the higher prevalence of this microorganism is not related to an enhanced ability to form biofilm and outcompete other species that may also be present, but rather to a better ability to form single-species biofilms possibly due to a more frequent access to the catheter surface.