title: Comparison of extended spectrum β-lactamases-producing Escherichia coli with non-ESBLs-producing E.coli: drug-resistance and virulence.
abstract: BACKGROUND
  The virulent factors of Escherichia coli (E.coli) play an important role in the process of pathopoiesis. The study aimed to compare drug-resistant genes and virulence genes between extended spectrum β-lactamases (ESBLs)-producing E.coli and non-ESBLs-producing E.coli to provide a reference for physicians in management of hospital infection.
  
  
  METHODS
  From October 2010 to August 2011, 96 drug-resistant strains of E.coli isolated were collected from the specimens in Qingdao Municipal Hospital, Qingdao, China. These bacteria strains were divided into a ESBLs-producing group and a non-ESBLs-producing group. Drug sensitivity tests were performed using the Kirby-Bauer (K-B) method. Disinfectant gene, qacEΔ1-sull and 8 virulence genes (CNF2, hlyA, eaeA, VT1, est, bfpA, elt, and CNF1) were tested by polymerase chain reaction (PCR).
  
  
  RESULTS
  Among the 96 E.coli isolates, the ESBLs-producing E.coli comprised 46 (47.9%) strains and the non-ESBLs-producing E.coli consisted of 50 (52.1%) strains. The detection rates of multiple drug-resistant strain, qacEΔ1-sull, CNF2, hlyA, eaeA,VT1, est, bfpA, elt, and CNF1 in 46 ESBLs-producing E.coli isolates were 89.1%, 76.1%, 6.5%, 69.6%, 69.6%, 89.1%, 10.9%, 26.1%, 8.7%, and 19.6%, respectively. In the non-ESBLs-producing E.coli strains, the positive rates of multiple drug-resistant strain, qacEΔ1-sull, CNF2, hlyA, eaeA, VT1, est, bfpA, elt, and CNF1 were 62.0%, 80.0%, 16.0%, 28.0%, 64.0%, 38.0%, 6.0%, 34.0%, 10.0%, and 24.0%, respectively. The difference in the detection rates of multiple drug-resistant strain, hlyA and VT1 between the ESBLs-producing E.coli strains and the non-ESBLs-producing E.coli strains was statistically significant (P<0.05).
  
  
  CONCLUSIONS
  The positive rate of multiple drug-resistant strains is higher in the ESBLs-producing strains than in the non-ESBLs-producing strains. The expression of some virulence genes hlyA and VT1 varies between the ESBLs-producing strains and the non-ESBLs-producing strains. Increased awareness of clinicians and enhanced testing by laboratories are required to reduce treatment failures and prevent the spread of multiple drug-resistant strains.
authors.affiliation: Department of Nursing, Qingdao University Medical College, Qingdao 266021, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Li
authors.affiliation: ICU, Qingdao Municipal Hospital, Qingdao 266071, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Qu
authors.affiliation: ICU, Qingdao Municipal Hospital, Qingdao 266071, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Hu
authors.affiliation: Department of Clinical Laboratory, Qingdao Municipal Hospital, Qingdao 266071, China.
authors.forename: Yong-Xin
authors.initials: YX
authors.lastname: Shi
keywords: Drug-resistant genes; ESBLs-producing Escherichia coli; Multiple drug-resistant; Non-ESBLs-producing E.coli; Virulence genes