ABSTRACT
ABSTRACT Objective: To evaluate the influence of sub-minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) on biofilm formation and virulence factors of Escherichia coli clinical isolates. Methods: Sub-MICs of CIP were determined using growth curve experiments. The biofilm-forming capacity of E. coli clinical isolates and E. coli ATCC 25922 treated or untreated with sub-MICs of CIP was assessed using a crystal violet staining assay. The biofilm structure of E. coli isolate was assessed with scanning electron microscopy (SEM). The expression levels of the virulence genes fim, usp, and iron and the biofilm formation genes of the pgaABCD locus were measured using quantification RT-PCR (qRT-PCR) in E. coli isolates and E. coli ATCC 25922. Results: Based on our results, the sub-MICs of CIP were 1/4 MICs. Sub-MICs of CIP significantly inhibited biofilm formation of E. coli clinical isolates and E. coli ATCC 25922 (p < 0.01). SEM analyses indicated that the biofilm structure of the E. coli changed significantly after treatment with sub-MICs of CIP. Expression levels of the virulence genes fim, usp, and iron and the biofilm formation genes of the pgaABCD locus were also suppressed. Conclusions: The results revealed that treatment with sub-MICs of CIP for 24 h inhibited biofilm formation and reduced the expression of virulence genes and biofilm formation genes in E. coli.
Subject(s)
Ciprofloxacin/pharmacology , Biofilms/drug effects , Virulence Factors , Escherichia coli/drug effects , Escherichia coli/genetics , Anti-Bacterial Agents/pharmacology , Reference Values , Time Factors , Microscopy, Electron, Scanning , Microbial Sensitivity Tests , Gene Expression/drug effects , Reverse Transcriptase Polymerase Chain Reaction , Gentian VioletABSTRACT
Dynamic changes in mRNA expressions of liver tissue apoptosis-promoting genes Fas and Bax and apoptosis-inhibiting gene Bcl-2 of vibrio vulnificus sepsis rats were detected and the effects of antibacterial agents were examined.The rat model with Vibrio vulnificus sepsis (VV group) was established and some of the Vibrio vulnificus sepsis rats were treated with antibacterial agents (AA group).The mRNA expressions of Fas,Bax and Bcl-2 were measured by reverse transcription polymerase chain reaction (RT-PCR).As compared with normal control group (NC group),the expressions of Fas and Bax mRNA in liver tissue at all different time points in VV group were increased significantly (P<0.05),and the highest levels of Fas and Bax mRNA expressions were 6 and 12 h after the infection,respectively.At the same time,the expression of Bcl-2 mRNA in liver tissue at all different time points in VV group were decreased significantly (P<0.05),and the lowest level of Bcl-2 mRNA expression appeared 2 h after the infection.The mRNA expressions of Bcl-2 in liver tissue 9 and 12 h after the infection in AA group were increased significantly (P<0.05) compared with NC group,while the expressions of Fas and Bax mRNA were not significantly different from those of NC group.Compared with VV group,the expression of Fas mRNA in AA group was decreased (P<0.05) and Bax mRNA was decreased significantly 12 and 16 h after the infection (P<0.05),while the expressions of Bcl-2 mRNA were increased significantly 9,12 and 16 h after the infection (P<0.05).It is concluded that the mRNA expressions of liver tissue apoptosis-promoting genes Fas and Bax were increased remarkably in vibrio vulnificus sepsis rats,whereas the expression of apoptosis-inhibiting gene Bcl-2 mRNA was decreased obviously in sepsis rats in early stage.The treatment with cefoperazone sodium and levofloxacin lactate could inhibit the expression of Fas mR.NA and Bax mRNA and enhance the expression of Bcl-2 mRNA at the same time.
ABSTRACT
A stable and reliable infected necrotizing pancreatitis (INP) model in rats was established in order to study the pathophysiological mechanism and pathological development rule of INP and explore the new therapeutic methods for the diseases. Forty-six SD rats were randomly divided into 5 groups. The animals in group A received the injection of 5% sodium taurocholate into the pancreatic duct and those in group B underwent that of E. Coli into the pancreatic duct. The rats in groups C, D and E were subjected to the injection of 5% sodium tanrocholate in combination with different con-centrations of E. Coli (103, 104, 105/mL, respectively) into the pancreatic duct. The dose of injection was 0.1 mL/100 g and the velocity of injection was 0.2 mL/min in all the 5 groups. Eight h after the injection, the survival rate of animals was recorded and the surviving rats were killed to determine the serum content of amylase and perform pathological examination and germ cultivation of the pancre-atic tissue. The results showed that acute necrotizing panereatitis model was induced by injection of 5% sodium taurocholate into the pancreatic duct. The positive rate of germ cultivation in group A was 12.5%. The acute necrotizing pancreatitis model was not induced by injection of E. Coli into the pan-creatic duct and the positive rate of germ cultivation in group B was 0. The INP model was estab-lished in groups C to E. The positive rate of germ cultivation was 60%, 100% and 100% and 8-h sur-vival rate 100%, 100% and 70% in groups C, D and E, respectively. It was concluded that a stable and reliable model of INP was established by injection of 5% sodium taurocholate in combination with 104/mL E. Coli into the pancreatic duct with a dose of 0.1 mL/100 g and a velocity of 0.2 mL/min. The pathogenesis of INP might he that the hemorrhage and necrosis of pancreatic tissue in-duced by sodium taurocholate results in weakness of pancreatic tissue in fighting against the germs.Meanwhile, the necrotic pancreatic tissue provides a good proliferative environment for the germs.