Download Primary Investigation of the Virulence Factors of

Primary Investigation of the Virulence
Factors
of
vancomycin-resistant
Enterococcus faecium in a tertiary-care
hospital of Sichuan, China hospital
Yao Deng, Zhenhui Li, Yanchun Huang, Yulin Xiao, Chao He,Xie
Yi, Mei Kang, Hong Fan
Division of Clinical Microbiology, Department of Laboratory
Medicine, West china Hospital SiChuan University. ChengDu
SiChuan 610041
Keywords:
vancomycin-resistance
Enterococcus
faecium;
virulence gene; Antibiotic resistance
Corresponding author: Mei kang, Hong Fan
Abstract
Objective
Objective
To analyze the phenotypic and molecular characterization of vancomycin-
resistant Enterococcus faecium(VREFm) isolates, and figure out the potential
association of the three virulence factors: enterococcal surface protein (esp);
hyaluronidase (hyl); adhesin of collagen from E. faecium(acm) with the colonization
or infection of E.faecium.
Methods
VREFm isolates(n=45) from intestinal colonization of patients in
Intensive Care Unit(ICU) had been screened by VRE chromogenic agar and identified
by multiplex polymerase chain reaction(PCR) for the D-Ala-D-Ala ligase gene(ddl
gene). Infective ampocillin-resistant vancomycin-susceptible E.faecium (VSEFm)
isolates(n=60) and infective VREFm isolates (n=8) had been identified by Vitek II
compact. Use E-test to detect the minimum inhibitory concentrations (MICs)of VREFm.
The vancomycin-resistant genes and the virulence factors(hyl、esp、acm) were detected
by PCR.
Results
53 VREFm strains(8 infective strains and 45 intestinal colonization
strains) and 60 VSEFm strains over 1 year period were collected. 34 VSEFm strains
from blood, other 26 VSEFm strains from pleural fluid and CSF. All the 53 VREFm
isolates harbored the vanA gene and exhibited the VanA phenotype. 37 of 45(82.22%)
intestinal colonization VREFm strains, all the 8 clinical infective VREFm strains
and 32 of 60(53.33%) clinical infective VSEFm strains carried the esp gene. 21 of
45(46.67%) intestinal colonization VREFm strains, 3 of 8(37.5%) clinical infective
VREFm strains and 17 of 60(28.3%) clinical infective VSEFm strains carried the hyl
gene. 41 of 45(91.11%) intestinal colonization VREFm strains, 6 of 8(75%)clinical
infective VREFm strains carried the acm gene, compared with 55% acm-positive in
clinical infective VSEFm strains .In VREFm group, 21of 24(87.5%) hyl-positive
strains carried the esp gene, however, in VSE group, only 5 of 17(29.41%)
hyl-positive strains carried the esp gene. In addition, the positive rate of acm
gene in VSEFm strains from blood(32.35%) is much lower than that from the pleural
fluid and CSF (84.62%).
Conclusion
Esp、hyl and acm are highly related to the infection of E.faecium.
Especially for VREFm, the esp and acm gene are more related to its infection or
colonization than hyl gene. A further research will be carry out to confirm whether
esp can help the E.faecium resistant to antibiotic in hyl-positive strains and
whether acm can help the E.faecium invading the serous cavity.