Role of Uropathogenic Escherichia coli. Virulence Factors in Development of Urinary Tract Infection and Kidney Damage

Witold Stefanski Institute of Parasitology of the Polish Academy of Sciences, 51/55 Twarda Street, 00818 Warsaw, Poland.
International journal of nephrology 03/2012; 2012:681473. DOI: 10.1155/2012/681473
Source: PubMed


Uropathogenic Escherichia coli (UPEC) is a causative agent in the vast majority of urinary tract infections (UTIs), including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs.

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Available from: Olga Sokolova, Mar 17, 2014
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    • "The cnf1 gene is produced by 1/3 of all pyelonephritis strains and may also be involved in kidney damages, bladder cell exfoliation and enhancement of bacterial access to underlying tissue (Mills et al., 2000). The hly gene is associated with upper UTIs such as pyelonephritis and also is able to lyses nucleated host cell, damage effectors' immune cells, induce the apoptosis of T lymphocytes, neutrophils and renal cells, and gain enhanced access to host nutrients and iron stores (Bien et al., 2012; Los et al., 2013). Clinical findings recommend that UPEC strains with afa adhesins have characters potentially favoring the occurrence of pyelonephritis, recurrent and chronic UTIs (Le Bouguénec 2005). "
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    ABSTRACT: From a clinical perspective, it is imperative to discern the differences in the distribution of virulence factors between imipenem resistant and imipenem susceptible strains of uropathogenic Escherichia coli isolated from hospitalized patients. The present study was carried out to find this purpose. One-hundred and sixty urine specimens of children and seniors were collected from the Educational Hospital of Tehran, Iran. The urine samples were cultured immediately and those that were E. coli-positive were analyzed for the antimicrobial susceptibility pattern against imipenem using disk diffusion method. Imipenem resistant and imipenem susceptible strains were analyzed for the presence of sfa, afa, pap, hly, cnf1 and fim virulence factors using the PCR technique. Fifty out of 70 (71.42%) children urines and 55 out of 90 (61.11%) seniors urine samples harbored E. coli. The incidence of resistance against imipenem in children and seniors were 6% and 9.09%, respectively. In the other hand, 99.39% of tested strains were susceptible to imipenem. Total prevalence of pap, cnf1, hly, sfa, afa and fim genes in the imipenem resistant strains were 12.5% 25%, 50%, 75%, 62.5% and 25%, respectively. Prevalence of the sfa, afa and hly genes was lower in the imipenem susceptible strains of E. coli, while the pap, cnf1 and fim genes was entirely higher in the imipenem susceptible strains. This finding suggests that imipenem resistance could be directly associated with decreased prevalence of pap, cnf1 and fim virulent genes. However, the findings of the present study are novel and valuable but more courtesy studies are necessary to authorize them.
    Biosciences Biotechnology Research Asia 09/2014; 11(2):469-477. DOI:10.13005/bbra/1297
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    • "The first step is colonisation of periurethral cells with uropathogenic bacteria, which is then followed by the passage of bacteria through the urethra. The second step is adherence of the bacteria biofilm to the bladder wall [5] . Therefore, the prevention of recurrent UTIs using a natural nonantimicrobial based approach is the most desirable. "
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    ABSTRACT: Objective To report the antimicrobial effect and biofilm forming capacity of the uropathogenic strains that have been isolated from recurrent urinary tract infections (UTIs) in the presence of Hibiscus sabdariffa (H. sabdariffa) extract. Methods Six Escherichia coli and two Klebsiella pneumoniae isolates were collected from patients with recurrent UTIs. The susceptibility of bacterial isolates to H. sabdariffa extracts were tested by determining their minimum inhibitory concentrations (MICs), and minimum bactericidal concentration (MBC) by using the broth microdilution method in accordance to Clinical and Laboratory Standards Institute guidelines. Time-kill curves were plotted against the eight isolates based on the MIC results. The biofilm forming capacity of the isolates were evaluated using the microtiter plate assay. Detection of biofilms was done using the crystal violet staining method. Results Various levels of the extracts MIC were observed against all the uropathogenic isolates. MIC values ranged from 0.5 to 4 mg/mL, and MBC values ranged from 8 to 64 mg/mL. Both the time-kill experiment and MBC-MIC ratio demonstrated that the extracts' effect was in general, bacteriostatic. The biofilm capacity inhibition assay results showed that extracts inhibited biofilm production of all the isolates. The level of biofilm inhibition however, had varied among the bacterial strains and ranged from 8%–60% reduction in optical density. Conclusions The results of the study support the effective potential of H. sabdariffa extract to prevent recurrent UTIs and to emphasize the significance of the plant extract, in order to approach it as a potential antimicrobial agent.
    Asian Pacific Journal of Tropical Disease 08/2014; 4(4):317–322. DOI:10.1016/S2222-1808(14)60581-8
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    • "The hlyA gene is frequently detected in ExPEC and it was the most prevalent gene in our strains of hemoculture (30%) [19, 20]. Escherichia coli hemolysin (hlyA) is a pore-forming bacterial exotoxin that may contribute to the virulence of bacteria during bloodstream infection and sepsis [20, 21]. The PAIs I536, II536, ICFT073, IJ96, and IIJ96 harbor a copy of hlyABCD system encoding α-hemolysin, and in our study, six strains harbor hlyA gene and three also had these PAIs (Table 3). "
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    ABSTRACT: Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the main etiological agents of bloodstream infections caused by Gram-negative bacilli. In the present study, 20 E. coli isolates from human hemocultures were characterized to identify genetic features associated with virulence (pathogenicity islands markers, phylogenetic group, virulence genes, plasmid profiles, and conjugative plasmids) and these results were compared with commensal isolates. The most prevalent pathogenicity island, in strains from hemoculture, were PAI IV536, described by many researchers as a stable island in enterobacteria. Among virulence genes, iutA gene was found more frequently and this gene enconding the aerobactin siderophore receptor. According to the phylogenetic classification, group B2 was the most commonly found. Additionally, through plasmid analysis, 14 isolates showed plasmids and 3 of these were shown to be conjugative. Although in stool samples of healthy people the presence of commensal strains is common, human intestinal tract may serve as a reservoir for ExPEC.
    04/2014; 2014:465054. DOI:10.1155/2014/465054
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