Effect Of Escherichia Coli Biofilm On The Efficacy Of Antibiotics And Disinfectants

Dairy cow mastitis is the most common disease in dairy cows worldwide.Among them,environmental pathogenic bacteria mainly caused by Escherichia coli is the main pathogenic factor.In recent years,multi-drug resistant strains have become popular worldwide with the use of drugs such as antibiotics and disinfectants.The study found that bacterial biofilm is an important factor leading to bacterial resistance.Because biofilm is easy to adhere to the surface of organisms or non-living organisms,it has strong adaptability to the environment and can prevent the contact of drugs with bacteria.Bacterial resistance to antibiotics and disinfectants.In this paper,we screened the biofilm-positive strains of Escherichia coli and determined its formation ability,and studied the influence of culture conditions on biofilm formation ability,in order to select suitable film formation conditions,and explore the resistance of bacteria to biofilm formation.Changes to provide information for the prevention of Escherichia coli infection.The results of the study are as follows:1.In 35 strains of Escherichia coli,19 biofilms were positive(54.29%),and 16 biofilms were negative(45.71%).Among the positive strains,6 were strong film forming ability(31.58%),10 were medium film forming ability(52.63%),and 3 were weak film forming ability(15.79%),which produced both curly pili and extracellular cellulose(rdar).There are 12 strains(63.16%),only one strain(5.26%)is produced,and only 2 strains(10.53%)of extracellular cellulose(pdar)are produced,no curly pili and extracellular are produced.There are 4 strains(21.05%)of cellulose(saw).The greater the biofilm formation ability,the greater the ability of E.coli to migrate,as measured by the migration medium.2.When LB broth with a glucose content of 2%,a NaCl content of 0.5% and a pH of 7 was cultured at 37? for 48 h,the biofilm formation was the largest.3.After the formation of biofilm,the minimum inhibitory concentration and minimum bactericidal concentration of streptomycin,ceftiofur,tetracycline,gentamicin,penicillin and ciprofloxacin were increased by 4-16 times and 8-64 times,respectively.With the increase of drug concentration,the inhibition of biofilm formation and the elimination of mature biofilms were enhanced.Among them,ciprofloxacin had the best effect and penicillin had the worst effect.4.After the biofilm is formed,the sterilization rate of “84” disinfectant,benzalkonium bromide,iodophor,2% glutaraldehyde,75% ethanol is reduced,among which 1000 mg/L benzalkonium bromide,2% glutaraldehyde and 75% ethanol had the best bactericidal effect on planktonic bacteria.2% glutaraldehyde had the best bactericidal effect on biofilm,and the bactericidal rate reached 100% at 1 min.