广东地区家畜、家禽肠道大肠杆菌药物敏感性和O157:H7分离状况

The Drug Sensitivity of Escherichia coli and Isolation of Escherichia coli O157:H7 from the Livestock and Poultry in Guangdong

目的了解O157大肠杆菌在健康人、家畜和家禽中的存在情况和粪便中分离到的大肠杆菌的药物敏感性,为病原大肠杆菌耐药率增高寻找依据。方法2000～2001年选健康成人、小孩和健康家畜、禽粪便标本620份,一部分直接划种于选择培养基,37℃培养24h;另一部分用EC肉汤培养基,37℃培养18h,以进行增菌,然后转种于CT-SMAC平板,37℃培养24h。然后进行血清学鉴定以判断是否为O157大肠杆菌。用低片法测定分离到的620株大肠杆菌对氨苄西林(AMP)、氨苄西林/舒巴坦(AMS)、庆大霉素(GEN)、环丙沙星(CIP)和氧氟沙星(OFX)的药物敏感性;用琼脂平皿二倍稀释法测定不同来源标本分离的部分大肠杆菌对CIP和OFX的MIC值。结果在健康猪、牛和鸡的粪便中均找到了O157大肠杆菌,检出率在1.5%左右,健康成人和小孩粪便中均未找到O157大肠杆菌;健康成人、小孩、家畜和家禽粪便中分离的大肠杆菌,β-内酰胺酶产生率较低,在6%～12%之间;分离的大肠杆菌对氨苄西林、氨苄西林/舒巴坦和庆大霉素的耐药率较低,在10%以下,且人和家畜、禽粪便分离的大肠杆菌的耐药率差别不大;从人粪便分离的大肠杆菌对氟喹诺酮类药物的耐药率低,而从家畜、禽粪便分离的大肠杆菌的耐药率高。结论在广东,O157大肠杆菌亦存在于部分家畜、禽肠道中,有造成食物污染的危险;

Objective To investigate the occurance of Escherichia coli O157 in the health human,livestock and poultry and the drug resistancy of the E.coli isolated from the stool of the healthy human, livestock and poultry. Methods 620 stool samples were collected from healthy adults, children, livestock and poultry. Some were grown at 37℃for 24h in the selective medium,others were grown at 37℃for 18h in the EC broth medium and then transferred to the CT SMAC culture at 37℃for 24h. The cultured samples were idientified by serological method. 620 E.coli isolates were examined for the sensitivity of ampicillin, ampicillin/sulbactam, gentamicin, ciprofloxacin and ofloxacin with disk diffusion method. Minimum inhibitory concentration(MIC) of CIP and OFX against E.coli isolates were examined with dilution method. Results E.coli O157 was found in the stool of healthy pig, cattle and fowl and the detection ratio was about 1.5%. It was not found in the stool of the healthy adults and children. E.coli isolated from healthy adults, children, livestock and poultry has low β lactamases production ratio, about 6%～12%and the resistant ratio to ampicillin, ampicillin/sulbactam and gentamycin is low, less than 10%. The resistance to fluoroquinolone of the E.coli isolated from the stool of the human is low, while that from the livestock and poultry is high. Conclusions In Guangdong, E.coli O157 was found in the stool samples of the livestock and poultry. This may cause E.coli O157 contamination of food. The normal flora of E.coli in the intestinal tract of human and animals has lowβ lactamases production rate and has a low resistant ratio to the commonly used antibiotics. For fluoroquinolones, the resistant ratio is distinct greatly between the isolates of E.coli from the stool of human and one from livestock and poultry.