Preliminary Study Of Escherichia Coli Disinfectant And Antimicrobial Cross-resistance Mechanisms

As the drug resistant strain continuously emerging, the effects of antibiotics decease or even no curative effect due to the abuse of drug in clinical. However, it’s not just to the antibiotics, but to the disinfectant, there was found resistant bacteria. The same as bacteria resistance to antibiotics, the emergence of bacteria resistance to disinfectant is due to the abusing of disinfectant in animal husbandry, food production enterprises, medical and health institution and other area. In breeding factory, the disinfectant is wildly used. When medium or inefficient disinfectant used below the minimal bactericidal concentration for a long time, the bacteria may have different in ecology and appear drug resistance. It’s called Selective Pressure, the main reason for the bacteria resistance to disinfectant. Although it not serious as drug resistance to antibiotics, it’s still worth notice. This study was found on Escherichia coli separated from clinical and artificial induction to explore the mechanism of cross resistance of bacteria between antibiotics and disinfectant and provide theory for disinfectant using in clinical.1. Analysis the cross resistance of Escherichia coli separated from clinical between antibiotics and disinfectantThe K-B test paper was used to detect the drug resistance of104strains Escherichia coli to ofloxacin, ciprofloxacin, gentamicin, sulfadiazine and other12kinds of antibiotics. The bacteriostatic test in vitro was used to test the sensitivity of Escherichia coli to disinfectant (benzalkonium bromide and chlorhexidine acetate). It showed Escherichia coli separated from clinical had drug resistance to disinfectant.The results:The drug-resistant rates of104strains Escherichia coli to antibiotics were87.5%in ampicillin,26.8%in ofloxacin,29.6%in levofloxacin,75%in ciprofloxacin,67.3%in gentamicin,29.6%in norfloxacin,24.3%in enoxacin,11.5%in lomefloxacin,,16.4%in fleroxacin,19.7%in gatifloxacin,95.2%in sulfadiazine and20%in enrofloxacin. The minimal inhibitory concentration of disinfectant to Escherichia coli separated from clinical was higher than quality-control strains.Conclusion:Escherichia coli separated from clinical had drug resistance to both antibiotics and disinfectant, and the expression of drug-resistant gene was higher in disinfectant. It suggested we should pay attention to the fair use of disinfectant to explore the mechanism of drug resistance.2. Detect the qacEΔ1-sul Ⅰ in cross resistance of Escherichia coli between disinfectant and sulfadiazineThe DNA kits was used to extract DNA from104strains bacteria, and it was detected the expression of qacEA1-sulⅠ in cross resistance of Escherichia coli between disinfectant and sulfadiazine by PCR.Result:the detection rate of qacEΔ1-sul Ⅰ was95.19%.Conclusion:In clinical, there were Escherichia coli with drug-resistant gene to disinfectant and high detection rate. This showed we should use disinfectant reasonably in clinical. In the test, we found this gene could analysis the drug-resistant both to antibiotics and disinfectant. It meant there was relationship between the drug resistant to disinfectant and antibiotics. qacEΔ1-sul Ⅰ could analysis the efflux pump provided the theory to explore the mechanism of cross drug resistance.3. Analysis the cross drug resistance in artificial induction bacteria to disinfectant and antibioticsATCC25922quality-control strains were selected. The1/2MIC of disinfectant and antibiotics were chosen to induce the stable drug-resistant bacteria in vitro. The change of MIC of disinfectant and antibiotics during induction was detected by bacteriostatic test in vitro.Results:before and after induced by benzalkonium bromide and chlorhexidine acetate, MIC of oxytetracycline increased greatest for500times, and other antibiotics’ MIC also increased; before and after induced by antibiotics, MIC of benzalkonium bromide increased64times, but to chlorhexidine acetate, there was no significant different. MIC of other antibiotics was changed a lot.Conclusion:single drug could induce multiple resistance in Escherichia coli, and the artificial induction bacteria had drug-resistant to disinfectant, the same to several antibiotics. It showed there was relationship between drug-resistant to disinfectant and antibiotics.4. Expression of acrA、mdfA in efflux pump before and after inductionThe kits were used to extract RNA from bacteria, transformed to cDNA. The expression of acrA、mdfA in efflux pump was detected by real-time PCR, and it tried to explore the relationship between acrA、mdfA in efflux pump and cross drug-resistant in disinfectant and antibiotics.Results:compared with ATCC25922, the expression of acrA in bacteria induced by benzalkonium bromide increased3.6times, and mdfA increased1.9times; there was little change to chlorhexidine acetate. The expression of acrA in bacteria induced by ciprofloxacin increased9.5times, and mdfA increased6times, and there was little change to other antibiotics.Conclusion:The expression of crA、mdfA in efflux pump increased before and after induction, that meant these genes could analysis increasing of efflux pump. In another words, there was relationship between drug-resistant and efflux pump, and the cross drug-resistant in Escherichia coli to disinfectant and antibiotics may caused by efflux pump.