【作者】 曹孟淑；

【导师】 胡杰贵； 徐元宏；

【作者基本信息】 安徽医科大学 ， 内科学， 2003， 硕士

【摘要】 目的：研究下呼吸道铜绿假单胞菌β-内酰酶，主要是超广谱β-内酰酶(ESBLs)、AmpC酶的表达情况，以及产酶菌和非产酶菌的耐药性，探索铜绿假单胞菌的耐药机制并指导临床合理使用抗生素。方法：收集来源下呼吸道的铜绿假单胞菌114株，首先采用纸片扩散法(即K-B法)，用亚胺培南(IMP)、头孢噻肟(CTX)、头孢他啶(CAZ)、头孢噻肟/克拉维酸(CD03)、头孢他啶/克拉维酸(CD02)、头孢西丁(FOX)、头孢吡肟(FEP)、氯唑西林(OB5)8种药敏纸片检测铜绿假单胞菌的ESBLs、AmpC酶以及3种不同表型的AmpC酶产生情况；然后使用微量肉汤稀释法检测上述菌株对常用的20种抗生素的MIC值，依据NCCLS推荐的标准分析产酶菌株与不产酶菌株耐药性。结果：1．使用K-B法，在114株铜绿假单胞菌中检出产ESBLs菌10株(8.8％)，检出产AmpC酶菌79株(69.5％)，检出同时产ESBLs和AmpC酶菌4株(3.5％)。产AmpC酶的菌株表现为3种表型，高产高表达型61株(53.5％)、低产高表达型33株(27.5％)、低产低表达型43株(37.7％)。高产高表达Ampc酶菌株明显多于低产高表达型和低产低表达型，其差异具有显著性。2．铜绿假单胞菌对氨苄西林/舒巴坦(A/S)、氨苄西林(AM)、头孢噻吩(CF)、头孢唑林(CFZ)、头孢西丁(FOX)、头孢呋新(CRM)、复方新诺明(T/S)、头孢泊肟(CPD)的耐药率都在90％以上；对头孢曲松(CRO)、头孢噻肟(CTX)耐药率分别为74.6％、85.1％。对β-内酰胺类抗生素复合剂哌拉西林胞唑巴坦(P/T)、氨苄西林/舒巴坦(A/S)敏感率分别为75.8％和3.5％；对头孢他啶(CAZ)、亚胺培南(IMP)的敏感率分别为86.8％、75.8％。3．产ESBLs的菌株对IMP、头孢吡肟(FEP)、CAZ敏感率在60％以上；对其它抗生素的敏感率均在30％以下。产AmpC酶的菌株对阿米卡星(AK)、CAZ均耐药率6.3％，均敏感率60.8％；对AK、IMP均耐药率15.2％，均敏感率58.2％。三安徽医科大学硕士学位论文种不同AmpC酶表型的菌株，低产低表达型对呱拉西和他哇巴坦(P汀)、呱拉西林(PI)、氨曲南(ATM)、CAZ、FEP、IN[P的敏感率均明显高于低产高表达型和高产高表达型，其差别具有显著性。结论:1.采用玲B法，联合CTX、CD03和CAZ、CD02可以提高铜绿假单胞菌ESBLs的检出率。临床实验室通过使用CTX、CD03、CAZ、CD02、IN于5种药片可以快速检测AmPC酶及其不同的表型。2.下呼吸道铜绿假单胞菌ESBLs产生率低，Am解酶产生率高。3.铜绿假单胞菌对多种抗生素耐药，对产ESBLs的铜绿假单胞菌治疗上可选用INIP、CAZ、FEP;对产AmpC的菌株联合AK和协任、AK和CAz。4.下呼吸道铜绿假单胞菌高产AmpC酶产生可能是对p一内酞胺类抗生素耐药的主要机制。更多还原

【Abstract】 Objective: To study on the incidence of beta-lactamses, mainly including ESBLs and AmpC beta-lactamases of Pseudomonas aeruginosa in lower respiratory tracts, and drug-resistance of those beta-lactamse positive and negative strains, and to investigate drug-resistant mechanism of Pseudomonas aeruginosa and to instruct clinical application of antibiotics reasonably. Methods: We collected 114 strains of Pseudomonas aeruginosa coming from lower respiratory tracts, firstly K-B method was adopted to detect ESBLs, AmpC enzymes and three different phenotypes of AmpC beta-lactamase with eight discs including IMP, CTX, CAZ, CD03, CD02, FOX, FEP, OB5. Then Trace Broth Dilution Method was adopted to detect MICs of 20 different antibiotics used frequently, and we analysed drug-resistance of those beta-lactamase positive and negative strains according to NCCLS standards. Results: 1. We detected 114 isolates of Pseudomonas aeruginosa, 10(8.8%) isolates of 114 were considered as ESBLs positive strains, 79(69.5%) isolates were considered as producing AmpC beta- lactamases, and 4(3.5%) isolates were considered as both ESBLs and AmpC beta- lactamases positive strains. The isolates of producing AmpC enzymes were grouped into three phenotypes: high producing and high expressing beta-lactamase production, low producing and high expressing beta-lactamase production and low producing and low expressing beta-lactamase production. The strains of producing high producing and high expressing beta-lactamases were more than the other. There is a significant difference between them. 2. The resistant rate of A/S, AM, CF, CFZ, FOX, CRM, T/S, CPD to Pseudomonas aeruginosa was above 90%; the rate of CRO, CTX was 74.6%> 85.1%, respectively. The sensitive rate of -lactam comparator P/T, A/S was 75.8%, 3.5%, respectively.The sensitive rate of CAZ, IMP was 86.8%, 75.8% respectively. 3. The sensitive rate of IMP, FEP, CAZ to ESBL positive strains was morethan 60%, but the rates of the others were below 30%. The resistant rate of AK and CAZ to AmpC beta-lactamase positive strains was 6.3%, while the sensitive rate was 60.8%. The resistant rate of AK and IMP to AmpC enzyme positive strains was 15.2%, and the sensitive rate 58.2%. Among three different AmpC phenotypic strains, the sensitive rate of P,T, PI, ATM, CAZ, FEP, IMP to low producing and low expressing AmpC beta-lactamase positive strains was higher than high producing and high expressing AmpC beta-lactamase positive strains and low producing and high expressing AmpC beta-lactamase positive strains. The difference between them was significant. Conclusions: 1. The detective rate of ESBLs of Pseudomonas aeruginosa may be IMProved by using CTX, CD03 and CAZ, CD02 in K-B method. In clinical laboratory, AmpC beta-lactamases and their different phenotypes may be detected rapidly by using 5 discs of CTX, CD03, CAZ, CD02, IMP. 2. The incidence of ESBLs of Pseudomonas aeruginosa in lower respiratory tracts was low, but the incidence of AmpC beta-lactamases was very high. 3. Pseudomonas aeruginosa was resistant to many antibiotics. IMP, CAZ and FEP may be selected in treating ESBLs positive Pseudomonas aeruginosa infections. AK, IMP and AK, CAZ may be selected unitedly in treating AmpC enzymes positive strains infections. 4. High producing AmpC beta-lactamase may be beta-lactams main resistance mechanism of Pseudomonas aeruginosa in lower respiratory tracts.更多还原