沙门氏菌耐药质粒及其耐药基因的筛查

发布时间：2018-03-09 05:11

本文选题：沙门氏菌　切入点：耐药性　出处：《上海交通大学》2013年硕士论文　论文类型：学位论文

【摘要】：沙门氏菌是一种重要的食源性致病菌，每年都导致大量的疾病，引起全球范围内的广泛关注。抗生素对致病菌是非常有效的治疗手段，但近年来抗生素的广泛应用使沙门氏菌产生了耐药性。随着时间的推移，耐药性不断增强，并且耐药谱不断扩增，从而增加了对沙门氏菌感染治疗的难度。因此，沙门氏菌的耐药性受到广泛的关注。近年来发现，除了基因突变，基因的水平转移也成为病原菌耐药性传播重要途径，例如质粒作为独立于染色体之外的可移动遗传元件，在耐药基因的传播中就起到了不可忽视的作用。因此，分析不同来源沙门氏菌耐药性及其可移动遗传元件上耐药基因携带情况，从而揭示可移动遗传元件上耐药基因与菌株耐药性的对应关系具有很重要的意义。本论文的主要研究内容及结果如下： 1.食源性及医源性的沙门氏菌分离株的耐药性初筛。共选用226株沙门氏菌用试卡法测试其耐药性，按2012年美国实验室标准委员会(CLSI)指导原则的标准计算细菌对抗菌药物的耐药率(R)，中介率(I)，和敏感率(S)。结果表明，针对青霉素类抗生素中，耐氨苄青霉素的菌株达到15.9%(36/226)，耐舒巴坦/氨苄青霉素达到12.8%(29/226)；针对氨基糖苷类抗生素中，耐妥布霉素的菌株达到6.2%(14/226)、耐庆大霉素5.8%(13/226)；针对喹诺酮类抗生素中，耐环丙沙星的菌株达到4.0%(9/226)，耐左氧氟沙星1.8%(4/226)；针对头孢菌素类抗生素中，耐头孢唑啉4.4%(10/226)，耐头孢他啶和头孢曲松分别为2.2%(5/226)，，耐头孢替坦0.9%(2/226)。针对碳青霉烯类和除青霉素类、头孢菌素类以外的β-内酰胺酶类，所有分离株的筛查结果均为敏感。 2.VITEK药敏实验结果中耐药菌用K-B纸片扩散法进行复筛。非敏感表型分离株共59株，亚胺培南、阿米卡星、头孢吡啶准符合率(CA)都达到100%，头孢他啶标准符合率达到98.3%，左氧氟沙星为96.6%，头孢曲松为94.9%，氨曲南准为93.2%，氨苄青霉素、妥布霉素、环丙沙星标准符合率达到91.5%，甲氧胺嘧啶/磺胺甲恶唑为86.4%，庆大霉素为84.7%。 3.VITEK试卡法检测出来的非敏感表型的分离株进行耐药基因的筛查。非敏感表型的分离株共84株，分别进行了β-内酰胺酶类抗生素耐药基因、喹诺酮类抗生素耐药基因及氨基糖苷类抗生素耐药基因的筛查。结果表明，β-内酰胺酶类抗生素非敏感菌株中，β-内酰胺酶类耐药基因携带率为59.5%(50/84)，其中CMY基因携带率为10.7%(9/84)；OXA基因携带率为27.3%(23/84)；TEM基因携带率为39.2%(33/84)；PSE基因携带率为1.2%(1/84)。对喹诺酮类抗生素非敏感菌株中，喹诺酮类耐药基因携带率为14.7%(5/34)，其中qnrA基因携带率为11.8%(4/34)；qnrS基因携带率为2.9%(1/34)。对喹诺酮类和氨基糖苷类抗生素非敏感菌株中，acc(6’)-Ib-cr基因的携带率为17.1%(7/41)。仅CMY基因在食源性和医源性分离株中的分布具有统计学差异(χ~2=5.480，P0.05)。 4.VITEK试卡法检测出来的非敏感表型的分离株进行毒性质粒的筛查。对非敏感表型的分离株共84株进行了spv基因的筛查，结果表明其携带率为6.0%(5/84)。这5株沙门氏菌分离株携带spv基因全部来自于医源，所以其医源性携带率为14.7%(5/34)，食源性与医源性分离株的携带率无统计学差异(χ~2=2.05，P0.05)。利用本研究获得的食源性和医源性沙门氏菌耐药表型及耐药基因型信息，可为食品安全风险评估提供依据，同时为临床治疗用药选择提供参考数据。
[Abstract]:Salmonella is an important foodborne pathogen, has led to a large number of diseases each year, causing widespread concern worldwide. Antibiotics are very effective treatment of pathogens, but the extensive application of antibiotics in recent years that Salmonella produced resistance. With the passage of time, resistance increased, and drug resistance continuous spectrum amplification, thus increasing the difficulty of treatment in Salmonella infection. Therefore, the drug resistance of Salmonella has been widely concerned. In recent years, in addition to gene mutation, gene horizontal transfer of antibiotic resistance of pathogens has become an important means of communication, such as a plasmid as an independent chromosome outside of mobile genetic elements, not played an essential role in the spread of resistance genes. Therefore, analysis of drug resistance of Salmonella from different sources and mobile genetic elements on resistance gene carrying case, It is of great significance to reveal the relationship between the resistance genes of the mobile genetic elements and the resistance of the strains.
The main contents and results of this paper are as follows:
1. foodborne and iatrogenic Salmonella isolates resistance screening. A total of 226 strains of Salmonella by test method to test the resistance of the United States in 2012, according to the Laboratory Standards Committee (CLSI) the guiding principles of the standard to calculate the antibiotic resistance rate (R), intermediate rate (I), and sensitive rate (S). The results show that for penicillin, ampicillin resistant strains reached 15.9% (36/226), resistance to ampicillin / sulbactam reached 12.8% (29/226); for aminoglycosides, tobramycin resistant strains reached 6.2% (14/226), 5.8% (13/226); gentamicin resistance to quinolones antibiotics, ciprofloxacin resistant strains reached 4% (9/226), levofloxacin resistant (4/226); according to the 1.8% cephalosporin antibiotics, resistant to cefazolin (4.4% 10/226), resistant to ceftazidime and ceftriaxone were 2.2% (5/226), resistance to cefotetan (0.9% 2/226). The screening results of all the isolates were sensitive to the beta lactamases other than cephalosporins for carbapenems and penicillins.
The experimental results of 2.VITEK drug sensitivity in drug resistant bacteria by K-B disk diffusion method for multiple screen. Non sensitive phenotype isolates there were 59 strains of imipenem, Amikacin, ceftazidime pyridine (CA) quasi coincidence rate reached 100%, ceftazidime standard rate of 98.3%, levofloxacin 96.6%, head of ceftriaxone was 94.9%, ammonia aztreonam quasi 93.2%, ampicillin, ciprofloxacin and tobramycin, the standard rate of 91.5%, methoxamine pyrimidine / sulfamethoxazole gentamicin was 86.4%, 84.7%.
3.VITEK test method to detect non sensitive isolates were screened for resistance genes. Non sensitive isolates of 84 strains were beta lactam antibiotic resistance genes, screening of quinolone antibiotic resistance genes and aminoglycoside antibiotic resistance genes. The results showed that beta lactam non sensitive isolates, beta lactamase resistant gene carrying rate was 59.5% (50/84), the CMY gene carrying rate was 10.7% (9/84); OXA gene carrying rate was 27.3% (23/84); TEM gene carrying rate was 39.2% (33/84); PSE gene carrying rate was 1.2% (1/84) of quinolone antibiotics non sensitive isolates, quinolone resistance gene carrying rate was 14.7% (5/34), the qnrA gene carrying rate was 11.8% (4/34); qnrS gene carrying rate was 2.9% (1/34). To quinolones and aminoglycosides (non sensitive strains, ACC The carrying rate of the 6 '-Ib-cr gene was 17.1% (7/41). The distribution of only CMY gene in food borne and iatrogenic isolates was statistically different (x ~2=5.480, P0.05).
4.VITEK test method to detect non sensitive isolates were screened for virulence plasmid. The non sensitive isolates were screened 84 strains of SPV gene, the results showed that the positive rate is 6% (5/84). The 5 strains of Salmonella strains carrying SPV gene from all medical sources, so the iatrogenic carrying rate was 14.7% (5/34), and the medical source of foodborne isolates carrying rate showed no significant difference (~2=2.05, P0.05).
Using the information obtained from this study on drug resistance phenotype and resistance genotype of Salmonella, we can provide a basis for food safety risk assessment, and provide reference data for clinical treatment.

【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R3416

【参考文献】