Characteristics of Escherichia coli biofilm production, genetic typing, drug resistance pattern and gene expression under aminoglycoside pressures.

Abstract In our studies, qualitative (scanning electron microscope) and semi-quantitative (modified crystal violet staining method) methods had been used to evaluate Escherichia coli biofilm-forming ability. Broth microdilution method and enterobacterial repetitive intergenic consensus-based PCR (ERIC-PCR) were performed to study E. coli drug resistance pattern and genetic typing. Based on the results above, we studied the correlation between biofilm-forming ability phenotype, drug resistance pattern and genetic typing in E. coli . Real-time qPCR (qRT-PCR) was used to reveal mRNA expression level of E. coli biofilm related multiple antibiotics resistance genes ( acrA , agn43 , csgA , csgD , ompF and pgaA ) under different concentrations of four aminoglycoside pressures. Our results showed that: (i) forty-nine out of 64 strains of E. coli (76.56%) showed significant production of biofilm and most of them performed weak biofilm-forming ability; (ii) ERIC-PCR showed that there was significant correlation between biofilm-forming ability and genotype; while there was weak correlation between biofilm-forming ability and drug resistance patterns based upon the results of semi-quantitative method and antibiotics susceptibility test; (iii) qRT-PCR revealed mRNA expression of acrA , agn43 , csgA , csgD , ompF and pgaA genes changed accordingly by stimulation of different concentrations of four aminoglycosides.