四川省副猪嗜血杆菌分离株β-内酰胺类药物药敏特性及质粒介导耐药基因检测研究

Detection of β-lactam drug susceptibility and plasmid mediated drug-resistance genes in Haemophilus parasuis isolates of Sichuan Province

为了给四川地区养猪场提供副猪嗜血杆菌(HPS)病的科学防控及合理的治疗用药方案,并研究HPS的β-内酰胺类药物的耐药机制,本实验于2014年8月～2016年9月,对四川省18个地区养猪场疑似感染HPS的病猪进行了解剖及病理变化观察,采集病料分离并鉴定得到97株HPS,分别采用纸片法检测5种β-内酰胺类药物耐药情况,PCR检测5种质粒介导的β-内酰胺类耐药基因携带情况。结果显示,分离株中耐药菌株比例高达86.6%(84/97);分离株对氨苄西林、阿莫西林、青霉素、头孢噻肟、头孢唑啉的耐药率分别为63.9%(62/97)、56.7%(55/97)、74.2%(72/97)、37.1%(36/97)、29.9%(29/97),且多重耐药情况比较严重;86.6%(84/97)分离株的质粒至少携带一种耐药基因,耐药基因TEM、SHV、CTX、OXA、DHA的检出率分别为57.7%(56/97)、33.0%(32/97)、17.5%(17/97)、19.6%(19/97)、2.1%(2/97),有32株分离株携带2～3种耐药基因;耐药基因和耐药表型的符合率为88.1%(74/84)。HPS四川分离株对β-内酰胺类抗生素严重耐药,其质粒介导的β-内酰胺类耐药基因携带率较高。耐药基因和表型符合率较高,表明通过检测耐药基因来初步确定菌株的耐药情况可行性高。本研究为临床防治HPS病奠定了一定的基础。

To provide scientific prevention measures and reasonable treatment schedule for Haemophilus parasuis （HPS） disease, and study the resistance mechanism to β-lactamase of HPS, from August 2014 to September 2016, pathological changes of diseased pigs suspected to be infected with HPS were observed in 18 pig farms in Sichuan province. Then 97 HPS strains were isolated and identified from the samples colected from the diseased pigs, and kirby-bauer test was processed to detect the resistance to β-1actam antibiotic while PCR was used to investigate the resistance gene to β-lactam antibiotic mediated by 5 kinds of plasmids. The results showed that drug-resistant isolates reached up to 86.6% （84/97） while the drug resistance rates of ampicillin, amoxicillin, penicillin, cefotaxime, cefazolin were 63.9% （62/97）, 56.7% （55/97）, 74.2% （72/97）, 37.1% （36/97）, 29.9% （29/97）, respectively and multi-resistance cases were severe. The plasmids from 86.6% （84/97） isolates carried one or more resistance genes and the positive rates of resistance genes TEM, SHV, CTX, OXA, DHA were 57.7% （56/97）, 33.0% （32/97）, 17.5% （17/97）, 19.6% （19/97）, 2.1% （2/97） respectively, and 32 isolates had 2 or 3 resistance genes. Moreover the coincidence rate of drug-resistant genes and drug-resistant phenotypes was 88.1%（74/84）. So HPS Sichuan isolates were highly resistant to β-lactam antibiotics and the carrying rate of β-lactam resistant genes mediated by plasmids was high. The result of high coincidence rate between resistance gene and resistance phenotype shows that it is feasible to determine the drug resistance of the isolates by detecting the resistant genes, and provides the basis for clinical prevention and cure the disease caused by HPS.