Study On Antibiotic Resistance Of Lactic Acid Bacteria Separated From The Market Yogurt

30strains of lactic acid bacteria which were separated from27kinds of commercially available yogurt by using the streak plate method and the Gram staining method were investigated in the present study and biological characteristics were studied. Besides, resistance of6common antibiotics were also analyzed on the separated strains. Then plasmid extraction test were carried out on the drug resistant strains and plasmid metastatic trials on the extracted plasmids. The results showed that the lactic acid bacteria strains were generally sensitive to amoxicillin, ampicillin and erythromycin. The incidence of erythromycin resistance was0%since there are5strains showed moderately sensitive to erythromycin while the others showed sensitive. There was general resistance to norfloxacin with the rate of90%in light of only3strains showed moderately sensitive while the others resistant. As for ciprofloxacin, the rate was23.3%, for there were7strains showed resistant and21strains showed moderately sensitive.15strains of isolated lactic acid bacteria were moderately sensitive to ofloxacin, and the rest were sensitive with a rate of0%. Small kit method was used to extracted the plasmid of drug resistance strains.But we failed to extract the plasmid of27resistant strains.