title: Virulence versus fitness determinants in Escherichia coli isolated from asymptomatic bacteriuria in healthy nonpregnant women.
abstract: OBJECTIVE
  Escherichia coli isolated from asymptomatic bacteriuria (ABU) correlated genotypically and phenotypically with cystitis isolates may help in distinguishing urovirulence determinants from 'fitness factors', latter necessary only for survival of E. coli in urinary tract; for gaining insight into the pathogenesis of urinary tract infection.
  
  
  METHODS
  In this cross-sectional study, we compared genotypic (phylogroups and 15 putative virulence genes), and phenotypic profiles of ABU E. coli strains with our previously genotyped collection of cystitis isolates. Virulence score was calculated for each isolate as a number of virulence genes detected.
  
  
  RESULTS
  Significant differences were observed in the proportion of four phylogenetic groups (P=0.009) amongst cystitis and ABU isolates. Average virulence score was higher for ABU isolates (6.6) than cystitis strains (4.2); and hlyA (P=0.001), cytotoxic necrotising factor 1 (P=0.00), fyuA (P=0.00), ibeA (P=0.00), kpsMII (P=0.01), and malX/pathogenicity-associated island (P=0.01) were more frequently present in ABU strains.
  
  
  CONCLUSIONS
  The expression of adhesins, haemolysin, aerobactin, and capsule synthesis gene were similar in two groups suggesting their role as fitness factors. ABU isolates were better biofilm producers, reflecting its importance in silent persistence. Serum resistance gene which was more expressed in cystitis isolates may represent virulence determinant. Genetic makeup of E. coli does not change much rather genes helping in survival and colonisation are expressed equally in ABU and cystitis isolates as opposed to phenotypic attenuation of those that helps in invasion or inflammation in ABU isolates.
authors.forename: Sugandha
authors.initials: S
authors.lastname: Srivastava
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, Uttar Pradesh, India.
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Agarwal
authors.forename: Bharti
authors.initials: B
authors.lastname: Mishra
authors.forename: Richa
authors.initials: R
authors.lastname: Srivastava
mesh_terms: D000293:Adolescent; D000328:Adult; D001437:Bacteriuria / Q000382:microbiology*; D003430:Cross-Sectional Studies; D003556:Cystitis / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology*; D005260:Female; D005838:Genotype; D064368:Healthy Volunteers; D006801:Humans; D008875:Middle Aged; D010641:Phenotype; D037521:Virulence Factors / Q000235:genetics*; D055815:Young Adult
chemical_list: D037521:Virulence Factors