Virulence factors and O groups of Escherichia coli isolates from patients with acute pyelonephritis, cystitis and asymptomatic bacteriuria (original) (raw)
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Low Virulence of Escherichia coli Strains Causing Urinary Tract Infection in Renal Disease Patients
European Journal of Clinical Microbiology & Infectious Diseases, 2000
∑ Escherichia (E.) coli, which causes over 80% of uncomplicated urinary tract infections, may simultaneously express a number of virulence factors of relevance for urinary tract infections. Some of the recognized E. coli virulence factors are adherence to uroepithelial cells, certain O and K serotypes, hemolysin production, and aerobactin production. One of E. coli adhesins, P-fimbriae, are known as a major virulence factor in the development of acute uncomplicated pyelonephritis. The aim of this study was to determine the virulence properties of E. coli strains isolated from the urine of patients with chronic pyelonephritis, and to compare them to the properties of strains isolated from patients with acute pyelonephritis, acute cystitis, and asymptomatic bacteriuria. For each strain, O-serogroup, adhesin type, motility, production of hemolysin, and the amount of capsular polysaccharide were examined. The strains isolated from patients with acute pyelonephritis were found to mostly express all five or four virulence markers tested, while the less virulent strains were detected in the group of patients with chronic pyelonephritis, where most strains expressed up to three virulence markers. The lowest virulence was observed among the strains isolated in the group of patients with asymptomatic bacteriuria. Expression of P-fimbriae and production of hemolysin were found to be the most important virulence factors with the highest power for discrimination between chronic and acute upper urinary tract infection (p<0.01).
International Journal of Infectious Diseases, 2013
Background: Escherichia coli is the predominant pathogen causing urinary tract infection (UTI), the most common bacterial infectious disease encountered in clinical practice, accounting for significant morbidity and high medical costs. The severity of UTI produced by E. coli is due to the expression of a wide spectrum of virulence factors. In this study we evaluated the role of E. coli virulence determinants in the pathogenesis of UTI. Methods: A total of 90 uropathogenic E. coli strains were screened by PCR for the prevalence of seven virulence genes encoding type 1 fimbriae (fimH), pili associated with pyelonephritis (pap), S and F1C fimbriae (sfa and foc), afimbrial adhesins (afa), cytotoxic necrotizing factor (cnf), hemolysin (hly), and aerobactin (aer). Results: The prevalence of genes coding for fimbrial adhesive systems was 68% for fimH, 41% for pap, and 34% for sfa/foc. The operons coding for afa afimbrial adhesins were identified in 20% of strains. The hly and cnf genes coding for toxins were amplified in 19% and 3% of strains, respectively. A prevalence of 52% was found for the aer gene. The various combinations of detected genes were designated as virulence patterns. The strains isolated from hospitalized patients displayed a great diversity of gene associations compared to those isolated from ambulatory patients. Conclusions: Our study showed that investigation of the bacterial pathogenicity associated with UTI may contribute to a better medical intervention.
International Journal of Advances in Medicine, 2014
The Urinary Tract Infections (UTIs) are one of the most prevalent bacterial infections. 1 E. coli accounts for 50%-90% of all the uncomplicated urinary tract infections. 2 These E. coli are primarily derived from the faecal flora, which can colonize the periurethral area, overcome the local host defences and enter and multiply within the urinary tract. These E. coli strains are designed as Uropathogenic E. Coli (UPEC) which possess distinctive traits that confer an enhanced extraintestinal virulence potential. 4-6 UTI is predominantly a disease of the females, because of the anatomy of the female urethra. The incidence of bacteriuria increases during pregnancy, due to the anatomical and the hormonal changes. In most of the hospitalized patients, nearly all the UTIs are preceded by the instrumentation of the urinary tract, mainly urinary catheterization and it is a frequent cause of significant morbidity, sepsis and death. 4 Most of the strains of E. coli which cause UTIs belong to a restricted range of serotypes which are different from the distribution in the faecal isolates. However, the serotypes alone cannot explain the uropathogenicity of E.
Background: Urinary tract infections are significant health problem, with E. coli as a primary pathogen in approximately 80% of cases. The pathogenesis of E. coli in urinary tract infections is attributed to the production of virulence factors and phylogenetic background groups. Objectives: The aim of this study was to determine differences in prevalence of virulence factors of E. coli isolates belonged to phylogenetic group B2 and D collected from patient with urinary tract infection. Material and methods: A total of 100 E. coli isolates were identified by conventional biochemical tests from patients with urinary tracts infection (UTIs) in teaching hospitals of Zabol, Iran. DNA was extracted using boiling method. The analysis of phylogenetic groups, along with detection of virulence factor genes was performed by Multiplex-PCR method. Associations were assessed between type 1 fimberia- encoding gene, sidrophore receptor encoding genes and hemolysin encoding gene among 55 B2 group E. coli isolates and 22 D group E. coli isolates. Statistical analysis was performed by using the Fisher exact test. Results: Phylogenetic analysis showed that 55 and 22 of 100 isolates belonged to the B2 and D phylogenetic groups, respectively. hlyA, iroN, iucD and fimH genes were present in 29(52.72%), 22(40%), 46(83.63%) and 55(100%) of isolates belonged to phylogenetic group B2, whereas in 2(9.09%), 2(9.09%), 10(45.45%) and 22(100%) of isolates belonged to phylogenetic group D, respectively. The comparison shows that there was significant difference between the presence of hlyA and iroN genes in isolates belonged to phylogenetic group B2 and D (P ≤ 0.05). Conclusion: This study determined that strains belonging to B2 group are the most important and abundant phylogenetic groups among E. coli strains causing urinary tract infection. Keyword: Uropathogenic E. coli (UPEC), Urinary tract infections (UTIs), Virulence factors, Phylogenetic analysis. Comparison of the Virulence Factors distribution in Uropathogenic E. coli isolates belonged to phylogenetic group B2 and D - ResearchGate. Available from: http://www.researchgate.net/publication/264551427\_Comparison\_of\_the\_Virulence\_Factors\_distribution\_in\_Uropathogenic\_E.\_coli\_isolates\_belonged\_to\_phylogenetic\_group\_B2\_and\_D [accessed Aug 3, 2015].
Infection and immunity, 1981
The purpose of this investigation was to study potential virulence factors associated with Escherichia coli urinary pathogens isolated from patients with urinary tract infection. These factors were compared with characteristics of normal-flora E. coli isolated from stool specimens of healthy individuals without a history of urinary tract infection. The potential virulence factor focused on in this study was hemagglutination (HA) of human type O erythrocytes by E. coli urinary pathogens. A total of 265 strains of E. coli isolated from patients with urinary tract infections were tested for their ability to hemagglutinate human type O erythrocytes; of these, 148 (56%) were HA positive. Only 6 of 36 fecal E. coli strains (17%) isolated from healthy controls were HA positive. This significant association of the presence of hemagglutinin on E. coli that causes urinary tract infections indicates the likelihood that HA is a marker of virulence. Only 12% (5 of 43) of Proteus mirabilis and 3%...
Iranian journal of kidney diseases, 2011
Escherichia coli are the most frequent pathogens in acute urinary infections. They are classified based on various types of O antigen. Escherichia coli strains that cause urinary tract infections possess several genes encoding urovirulent factors. To assay the relation of virulent factors of E coli in acute urinary infections, the serotypes and virulence factor genotypes were determined. We studied 96 E coli isolates from children with acute urinary infections. Four urovirulence determinants were analyzed by DNA colony hybridization, including the genes for type 1 fimbriae (pil), P fimbriae (pap), S fimbriae (sfa), hemolysin (hly), and cytotoxic necrotizing factor 1 (cnf1). O serotypes were also determined. The most frequently found virulence factor-encoding gene in the E coli strains studied was the gene for type 1 fimbriae (27.4%). The prevalence of pap, sfa, hly, and cnf1 were higher in serotypes causing pyelonephritis than cystitis. The most common type of O antigen was O1 (12.2...
Chapter 2 Virulence Factors of Uropathogenic E . coli
2019
In order for a successful infection and creating a satisfactory environment inside the host, strains of uropathogenic Escherichia coli (UPEC) need some special features that are achieved by expressing particular genes, called virulence factors. Two of the most important surface virulence factors of UPEC are type 1 fimbriae and P fimbriae that are crucial for the colonization process inside the urinary tract. Expression of these virulence factors converts a commensal strain into an uropathogen. Beside these factors, outer membrane proteins also contribute to virulence being involved in the secretory machinery; an example of such type is TolC protein that transfers α-hemolysin across the outer membrane of E. coli. However, α-hemolysin along with many other toxins serves various pathogenic roles during UTIs including adhesion, colonization, cytotoxic activity, etc. Moreover, virulence factors located on bacterial surface including capsule and lipopolysaccharides may also have the contr...
International Journal of Enteric Pathogens, 2014
Background: Urinary tract infections are a significant health problem, with Escherichia coli as a primary pathogen in approximately 80% of cases. The pathogenesis of E. coli in urinary tract infections is attributed to the production of virulence factors and phylogenetic background groups. Objectives: The aim of this study was to determine differences in prevalence of virulence factors of E. coli isolates from phylogenetic groups B2 and D, collected from patients with urinary tract infections. Materials and Methods: A total of 100 E. coli isolates were identified by conventional biochemical tests from patients with urinary tracts infections (UTIs) in teaching hospitals of Zabol, Iran. DNA was extracted using the boiling method. Analysis of phylogenetic groups, along with detection of virulence factor genes was performed by the multiplex-PCR method. Associations were assessed between type 1 fimberiaencoding gene, siderophore receptor encoding genes and hemolysin encoding gene among 55 B2 group E. coli isolates and 22 D group E. coli isolates. Statistical analysis was performed using the Fisher exact test. Results: Phylogenetic analysis showed that 55 and 22 of 100 isolates belonged to the B2 and D phylogenetic groups, respectively. The hlyA, iroN, iucD and fimH genes were present in 29 (52.72%), 22 (40%), 46 (83.63%) and 55 (100%) isolates belonging to the phylogenetic group B2, whereas in 2 (9.09%), 2 (9.09%), 10 (45.45%) and 22 (100%) isolates belonging to the phylogenetic group D, respectively. The comparison showed that there was a significant difference between the presence of hlyA and iroN genes in isolates belonging to the phylogenetic group B2 and D (P ≤ 0.05). Conclusions: This study determined that strains belonging to group B2 are the most important and abundant E. coli strains causing urinary tract infections.
Virulence Factors of Uropathogenic E. coli
IntechOpen, 2018
In order for a successful infection and creating a satisfactory environment inside the host, strains of uropathogenic Escherichia coli (UPEC) need some special features that are achieved by expressing particular genes, called virulence factors. Two of the most important surface virulence factors of UPEC are type 1 fimbriae and P fimbriae that are crucial for the colonization process inside the urinary tract. Expression of these virulence factors converts a commensal strain into an uropathogen. Beside these factors, outer membrane proteins also contribute to virulence being involved in the secretory machinery; an example of such type is TolC protein that transfers α-hemolysin across the outer membrane of E. coli. However, α-hemolysin along with many other toxins serves various pathogenic roles during UTIs including adhesion, colonization, cytotoxic activity, etc. Moreover, virulence factors located on bacterial surface including capsule and lipopolysaccharides may also have the contribution to UTIs providing antiphagocytosis and antibactericidal complement activity.