耐亚胺培南革兰阴性杆菌产碳青霉烯酶研究

目的 了解细菌产碳青霉烯酶及其对亚胺培南、美罗培南等碳青霉烯类抗生素耐药性之间的关系。方法 应用改良Hodge Test和乙二胺四乙酸（EDTA）协同试验法对2003．6～2004．5收集自复旦大学华山医院的耐亚胺培南革兰阴性杆菌进行碳青霉烯酶筛选。blaVIM-1、blaVIM-2、blaIMP-2、blaIMP-2、blaSPM、blaOXA-23为引物进行PCR扩增，并对PCR扩增阳性产物进行DNA测序分析。结果 在75株耐亚胺培南的铜绿假单胞菌中，共检出产VIM-2型金属13内酰胺酶菌株2株（2／75），在10株耐亚胺培南的假单胞菌属细菌中检出2株产VIM-2型金属13内酰胺酶（2／10），均为恶臭假单胞菌；耐亚胺培南的8株弗劳地柠檬酸杆菌和6株不动杆菌中全部分别检出IMP金属酶新亚型和OXA-23型碳青霉烯酶。结论 细菌产碳青霉烯酶是不动杆菌和弗劳地柠檬酸杆菌对亚胺培南和美罗培南等碳青霉烯类抗生素耐药的主要原因之一，但对铜绿假单胞菌而言，产碳青霉烯酶不是导致其对亚胺培南耐药的主要原因。     

耐亚胺培南鲍曼不动杆菌的耐药性分析

目的探讨我院耐亚胺培南鲍曼不动杆菌的耐药特性。方法对2009年1月至2011年12月我院临床标本采用常规方法进行蓠株分离,采用Vitek-32全自动细茼鉴定药敏系统及绒片扩散法（K—B法）测定鲍曼不动杆菌对16种抗菌药物的敏感性。结果．共检测到91株鲍曼不动杆菌,其中耐亚胺墙南的鲍曼不动杆菌为23株（占25．3％）,标本来源大部分为痰液（占94．9％）。耐亚胺培南鲍曼不动杆菌对常用16种抗蕾药物耐药率〉50％的有15种,耐药率〉90％有3种,分剐为氨苄西林（98．O％）、头孢唑林（99．O％）和呋喃妥因（99．0％）,对抗菌药物耐药率最低仅为头孢哌嗣／舒巳坦（10．2％）,另外检测到对所用抗菌素泛耐为4株（8．O％）;而对亚胺培南敏感的鲍曼不动杆菌对常用16种抗菌药物耐药率〉50％的仅为4种,耐药率〉90％同样为氨苄西林（100％）、头孢唑林（97．9％）和呋喃妥因（97．9％）,耐药率比较低的为美罗培南（10．4％）、妥布霉素（16．7％）和环丙沙星（16．7％）,耐药率最低也为头孢哌酮／舒巴坦（6．3％）。结论我院耐亚胺培南鲍曼不动杆茼多重耐药性严重,出现了泛耐菌株;临床可根据药敏试验选用抗茼药物,一般条件下耐亚胺培南鲍曼不动杆菌建议选用头孢哌嗣／舒巴坦。     

亚胺培南耐药鲍曼不动杆菌碳青霉烯酶基因型研究

目的 对临床分离亚胺培南耐药鲍曼不动杆菌耐药性及碳青霉烯酶基因型进行研究,以指导临床合理应用抗生素.方法 用琼脂稀释法检测最低抑菌浓度(MIC),聚合酶链反应(PCR)检测OXA-23、OXA-24、OXA-58、IMP和VIM碳青霉烯酶基因,并对PCR产物进行测序.结果 鲍曼不动杆菌对亚胺培南耐药率为36.9%,且亚胺培南耐药组菌株对12种抗菌药物耐药率与敏感组比较,差异有统计学意义(P<0.05);在24株亚胺培南耐药鲍曼不动杆菌中21株PCR扩增出OXA-23基因,2株扩增出VIM基因,检出率分别为87.5%和8.3%,OXA-24、OXA-58、IMP基因均未检出;PCR产物测序表明与Genbank相关基因同源性为100%.结论 该院亚胺培南耐药鲍不动杆菌耐药现象严重;OXA-23碳青霉烯酶基因的产生是鲍曼不动杆菌对碳青霉烯类药物耐药的重要机制之一.     

耐亚胺培南鲍曼不动杆菌碳青霉烯酶及整合子分布

目的 了解耐亚胺培南鲍曼不动杆菌碳青霉烯酶及整合子分布情况.方法 收集天津医科大学总医院2008年1月至2010年3月期间,103株亚胺培南耐药鲍曼不动杆菌临床标本.用Vitek-2系统鉴定细菌,并进行药敏试验,通过改良Hodge试验、改良三维试验和2-巯基丙酸协同试验初筛碳青霉烯酶,多重PCR同时检测4种OXA型碳青霉烯酶基因、2种金属酶基因及整合酶基因,对整合子可变区进行PCR检测及序列分析.结果 103株鲍曼不动杆菌中,改良Hodge试验检出碳青霉烯酶阳性75株(72.8%),改良三维试验检出产碳青霉烯酶菌株80株(77.7%),未检出产金属酶菌株.PCR检出blaOXA-51-like+bsaOXA-23-like+int11基因84株,blaOxA-51-like+blaOXA-23-like阳性5株,blaOXA-51-like+intll阳性8株,blaOXA-51-like+blaOXA-24-like阳性2株,仅blaOXA-51-like阳性4株,blaOXA-58-like、金属酶基因(IMP-1、VIM-2)及Ⅱ类整合酶基因(intI2)均阴性.89株(96.7%)Ⅰ类整合酶阳性株均扩增出可变区,检出2种耐药基因盒组合形式:aacA4-catB8-aadAl(2 300 bp)81株,aacCl-orfX-orfX-orfX'-aadAla(3 000 bp)8株.结论 鲍曼不动杆菌对碳青霉烯类耐药及多重耐药主要与其携带的OXA-23型碳青霉烯酶和Ⅰ类整合子有关.

Abstract：

Objective To investigate the carbapenemases and integrons in imipenem-resistant Acinetobacter baumannii. Methods One hundred and three Acinetobacter baumannii were collected from Janurary 2008 to March 2010 in Tianjin Medical University General Hospital. The identification of strains and antimicrobial susceptibility test were performed by using Vitek-2 compact automatic system. Isolates of imipenem-resistant A. baumannii were screened for carbapenemases by modified Hodge test, improved threedimensional test and 2-mercaptopropionic acid synergy test. Isolates were then subjected to the multiplex PCR targeting genes encoding for OXA type carbapenemases, metallo-β-lactamases (MBLs) and integrases. The variable regions of integrons were amplificated and sequenced. Results Among the 103 isolates, 75 (72. 8% ) demonstrated positive in the modified Hodge test, 80 (77.7%)were positive in the improved three-dimensional test. No MBLs was found in the 2-mercaptopropionic acid synergy test. Eightyfour isolates were positive for blaOXA-51-like, blaOXA-23-like, and intI1; five were positive for blaOXA-51-like and blaOXA-23-like ;eight were positive for blaOXA-51-like and int11 ;two were positive for blaOXA-51-like and blaOXA-24-like ;four were only found positive for blaOXA-51-like. The blaOXA-58-like, IMP-1, VIM-2 and intI2 genes were all negative. Eighty-nine(96. 7% )of the intI1 positive strains owned the variable region. Two different cassettes arrangements were identified within class 1 integrons:81 isolates harbored aacA4-catB8-aadAI (2 300 bp) and 8 harbored aacCl-orX-orfX-orX'-aadAla (3 000 bp ) . Conclusion The presence of OXA-23 carbapenermase and class Ⅰ integrons are correlated with Acinetobacter baumannii resistant to carbapenems and multi-drug resistance.     

耐亚胺培南鲍曼不动杆菌碳青霉烯酶及整合子分布

Objective To investigate the carbapenemases and integrons in imipenem-resistant Acinetobacter baumannii. Methods One hundred and three Acinetobacter baumannii were collected from Janurary 2008 to March 2010 in Tianjin Medical University General Hospital. The identification of strains and antimicrobial susceptibility test were performed by using Vitek-2 compact automatic system. Isolates of imipenem-resistant A. baumannii were screened for carbapenemases by modified Hodge test, improved threedimensional test and 2-mercaptopropionic acid synergy test. Isolates were then subjected to the multiplex PCR targeting genes encoding for OXA type carbapenemases, metallo-β-lactamases (MBLs) and integrases. The variable regions of integrons were amplificated and sequenced. Results Among the 103 isolates, 75 (72. 8% ) demonstrated positive in the modified Hodge test, 80 (77.7%)were positive in the improved three-dimensional test. No MBLs was found in the 2-mercaptopropionic acid synergy test. Eightyfour isolates were positive for blaOXA-51-like, blaOXA-23-like, and intI1; five were positive for blaOXA-51-like and blaOXA-23-like ;eight were positive for blaOXA-51-like and int11 ;two were positive for blaOXA-51-like and blaOXA-24-like ;four were only found positive for blaOXA-51-like. The blaOXA-58-like, IMP-1, VIM-2 and intI2 genes were all negative. Eighty-nine(96. 7% )of the intI1 positive strains owned the variable region. Two different cassettes arrangements were identified within class 1 integrons:81 isolates harbored aacA4-catB8-aadAI (2 300 bp) and 8 harbored aacCl-orX-orfX-orX'-aadAla (3 000 bp ) . Conclusion The presence of OXA-23 carbapenermase and class Ⅰ integrons are correlated with Acinetobacter baumannii resistant to carbapenems and multi-drug resistance.     

耐亚胺培南鲍曼不动杆菌碳青霉烯酶及整合子分布

Objective To investigate the carbapenemases and integrons in imipenem-resistant Acinetobacter baumannii. Methods One hundred and three Acinetobacter baumannii were collected from Janurary 2008 to March 2010 in Tianjin Medical University General Hospital. The identification of strains and antimicrobial susceptibility test were performed by using Vitek-2 compact automatic system. Isolates of imipenem-resistant A. baumannii were screened for carbapenemases by modified Hodge test, improved threedimensional test and 2-mercaptopropionic acid synergy test. Isolates were then subjected to the multiplex PCR targeting genes encoding for OXA type carbapenemases, metallo-β-lactamases (MBLs) and integrases. The variable regions of integrons were amplificated and sequenced. Results Among the 103 isolates, 75 (72. 8% ) demonstrated positive in the modified Hodge test, 80 (77.7%)were positive in the improved three-dimensional test. No MBLs was found in the 2-mercaptopropionic acid synergy test. Eightyfour isolates were positive for blaOXA-51-like, blaOXA-23-like, and intI1; five were positive for blaOXA-51-like and blaOXA-23-like ;eight were positive for blaOXA-51-like and int11 ;two were positive for blaOXA-51-like and blaOXA-24-like ;four were only found positive for blaOXA-51-like. The blaOXA-58-like, IMP-1, VIM-2 and intI2 genes were all negative. Eighty-nine(96. 7% )of the intI1 positive strains owned the variable region. Two different cassettes arrangements were identified within class 1 integrons:81 isolates harbored aacA4-catB8-aadAI (2 300 bp) and 8 harbored aacCl-orX-orfX-orX'-aadAla (3 000 bp ) . Conclusion The presence of OXA-23 carbapenermase and class Ⅰ integrons are correlated with Acinetobacter baumannii resistant to carbapenems and multi-drug resistance.     

鲍曼不动杆菌OXA-51样碳青霉烯酶基因分型与耐药性研究

目的 研究鲍曼不动杆菌中OXA-51样碳青霉烯酶基因分型及与抗菌药物耐药的相关性.方法 纸片扩散法检测174株鲍曼不动杆菌对头孢他啶、头孢曲松、阿米卡星、环丙沙星的耐药性,琼脂稀释法检测亚胺培南和美罗培南的最低抑菌浓度(MIC值);PCR扩增碳青霉烯酶VIM、IMP、OXA-23、OXA-24、OXA-51和OXA-58相关基因;对ONA-51阳性菌株进行测序和基因分型.结果 所有菌株均未检出OXA-24、OXA-58、IMP及VIM基因;15.5%(27/174)的菌株OXA-23阳性,72.4%(126/174)的菌株OXA-51阳性,其中15.5%(27/174)菌株同时产OXA-51样酶和OXA-23酶,126株OXA-51样酶阳性菌株中,82.5%(104/126)为OXA-66型,非OXA-66基因型占17.5%(22/126),本次研究发现的8个新基因型;OXA-66型的耐药性明显高于其他基因型.结论 OXA-66为本地区分离鲍曼不动杆菌产生的OXA-51样碳青霉烯酶的主要基因型;OXA-66与碳青霉烯抗生素的低水平耐药有关,且可能与其他抗菌药物的耐药性相关,临床分离鲍曼不动杆菌中发现新的OXA-51样碳青霉烯酶基因.     

鲍曼不动杆菌对亚胺培南耐药机制研究

目的了解鲍曼不动杆菌对亚胺培南的耐药性及耐药机制。方法琼脂稀释法对62株鲍曼不动杆菌进行药敏检测,对其中20株亚胺培南耐药的鲍曼不动杆菌进行耐药机制研究。酶三维试验检测ESBLs和AmpC酶,PCR扩增和测序分析检测碳青霉烯酶VIM、IMP、OXA-23和OXA-24,SDS-PAGE方法研究外膜蛋白表达情况,利血平协同抑制试验检测膜外排机制。结果62株鲍曼不动杆菌中,亚胺培南耐药25株,占41%;20株亚胺培南耐药菌中,ESBLs和AmpC酶阳性株分别为10株(50%)和20株(100%),PCR扩增VIM、IMP和OXA-24均阴性;OXA-23基因扩增显示19株(95%)阳性,PCR产物并经序列分析证实为OXA-23;与敏感株相比,部分菌株存在22、29、33kD的外膜蛋白缺失;利血平不能降低亚胺培南对鲍曼不动杆菌的MIC值。结论产OXA-23型β-内酰胺酶是本院鲍曼不动杆菌对亚胺培南耐药的重要原因,产AmpC酶合并外膜蛋白缺失与鲍曼不动杆菌对亚胺培南耐药有密切关系。     

亚胺培南耐药鲍曼不动杆菌小鼠肺部感染模型建立

目的 建立亚胺培南耐药鲍曼不动杆菌小鼠肺部模型,为泛耐药鲍曼不动杆菌抗感染研究提供实验动物模型.方法 随机选取120只约4周大雄性BALB/C小鼠,平均分成3组:微量气管注射法组、超声雾化法组和滴鼻法组.每组小鼠用甲氨蝶呤化疗降低BALB/C小鼠的免疫力,然后将亚胺培南耐药鲍曼不动杆菌分别用微量气管注射法、超声雾化法、滴鼻法感染免疫力低下和正常的BALB/C小鼠,检测微量气管注射法、超声雾化法、滴鼻法感染的小鼠感染率、死亡率、细菌清除率、肺部病理变化.结果 微量气管注射法、超声雾化法感染免疫力低下的BALB/C小鼠的肺部感染率均为100%(30/30),死亡率分别为100%(10/10),33%(3/10),2组小鼠肺部细菌感染12～24 h后支气管周及肺泡间质内见中性粒细胞、淋巴细胞、巨噬细胞为主的炎症细胞浸润,微量气管注射法感染的小鼠部分肺泡组织结构崩解,肺泡腔内可见脓肿形成及较多细菌集落,超声雾化法感染的小鼠24 h见肺部部分区域存在细胞变性,但支气管及肺泡组织结构基本正常,肺泡壁血管轻度扩张伴淤血,24～48 h后可见支气管和支气管周围变性,部分肺组织血管高度扩张,伴有水肿,48 h后炎症逐渐恢复.滴鼻法感染免疫力低下的BALB/C小鼠的肺部感染不明显,未见小鼠死亡(0/10),肺部无明显病理变化.结论 免疫力低下BALB/C小鼠可以通过微量气管注射法和超声雾化法建立亚胺培南耐药鲍曼不动杆菌肺部感染模型,超声雾化法可以大批量同时操作,简单经济快速,实用性强.亚胺培南耐药鲍曼不动杆菌难以感染免疫力正常小鼠.     

亚胺培南耐药鲍曼不动杆菌外排泵机制研究

目的研究亚胺培南耐药鲍曼不动杆菌(IRAB)耐药性与主动外排泵之间的关系,从而指导临床合理用药及控制院内感染。方法收集临床分离的IRAB 50株,亚胺培南敏感鲍曼不动杆菌(ISAB)30株。采用琼脂稀释法检测上述细菌对13种抗菌药物的最低抑菌浓度(MIC),加入外排泵抑制剂Phe-Arg-beta-Naphthylamide(PAβN)观察对亚胺培南MIC变化;脉冲场凝胶电泳(PFGE)分析菌株同源性;聚合酶链反应(PCR)检测adeB、adeR、adeS、adeJ、abeM基因。结果 50株IRAB中MIC50>128μg/mL的抗菌药物有阿米卡星、环丙沙星、哌拉西林-他唑巴坦、头孢哌酮、头孢西丁、四环素和复方磺胺甲口恶唑,MIC50在32～128μg/mL的抗菌药物有美罗培南、头孢哌酮-舒巴坦、头孢吡肟、头孢他啶、头孢曲松、头孢噻肟,MIC50<8μg/mL的抗菌药物有左氧氟沙星和多黏菌素B。对30株ISAB,MIC50<8μg/mL的药物有美罗培南、阿米卡星、头孢哌酮-舒巴坦、头孢他啶、头孢吡肟、多黏菌素B。加入抑制剂,33株IRAB(66%)对亚胺培南的MIC有4～32倍的降低,ISAB无明显变化。根据PFGE图谱可分为7型,A型为主要流行株。PCR扩增,IRAB的adeB、adeR、adeS、adeJ、abeM基因检出率均>80%,与ISAB相比,差异有统计学意义(P<0.01)。结论仁济医院IRAB存在播散流行,且有AdeABC、AdeIJK、AbeM等外排泵广泛存在。     

鲍曼不动杆菌对碳青霉烯类抗生素的耐药机制

鲍曼不动杆菌（Acinetobacter baumannii）是医院感染的重要条件致病菌。鲍曼不动杆菌感染常发生在具有基础疾病的患者,如皮肤黏膜或呼吸道保护屏障受损的重症患者,正在接受侵袭性诊疗措施以及使用免疫抑制剂和广谱抗生素的患者。鲍曼不动杆菌常引起呼吸机相关肺炎、尿路感染、菌血症、皮肤软组织感染、腹腔和中枢神经系统感染,鲍曼不动杆菌也是战争相关伤口主要病原体之一。     

25株耐碳青霉烯类抗生素鲍曼不动杆菌的耐药机制研究

目的:了解临床分离的耐碳青霉烯类抗生素鲍曼不动杆菌的耐药谱特征、同源性及碳青霉烯酶的产生状况。方法:采用PHOENIX100自动化细菌鉴定药敏系统及纸片扩散法进行药敏试验;基因外重复回文序列PCR(REP-PCR)法分析其基因同源性;聚合酶链反应(PCR)检测β内酰胺酶基因,并对扩增出的碳青霉烯酶基因进行序列分析;对整合子基因进行PCR检测。等电聚焦电泳测定β内酰胺酶的等电点。碱裂解法提取质粒。结果:2003年1月～2005年12月我院共分离到30株碳青霉烯类中介或耐药的鲍曼不动杆菌,其中儿科ICU病房9株,外科ICU病房12株。菌株表现为多重耐药,但儿科ICU与其他病房分离株的耐药谱有差异。对存活的非重复的25株菌进行检测,REP-PCR图谱分为A、B、C、D4个基因型,A型7株集中在儿科ICU,16株属于B型,C型和D型各1株。PCR检出10株菌携带OXA-23基因,其中包括7株儿科ICU的碳青霉烯类耐药菌,而外科ICU分离的耐药菌株不具有OXA-23基因。所有菌株均未能检出OXA-24、IMP及VIM基因。有20株携带PER-1型酶基因。22株细菌检测出Ⅰ型整合子基因结构(大小约180～3500bp)。结论:本院碳青霉烯类耐药鲍曼不动杆菌流行主要为医院感染所致,儿科ICU分离的菌株对碳青霉烯类耐药的主要机制为产生OXA-23型酶,外科ICU分离的菌株对碳青霉烯类耐药的主要机制则可能为膜通透性降低的原因。     

Contribution of acquired carbapenem-hydrolyzing oxacillinases to carbapenem resistance in Acinetobacter baumannii

Carbapenem-hydrolyzing oxacillinases are reported increasingly in Acinetobacter baumannii. Since they hydrolyze carbapenems at low levels, the roles of carbapenem-hydrolyzing oxacillinases OXA-23, OXA-40, and OXA-58 in A. baumannii were determined. The bla(OXA-23), bla(OXA-40), and bla(OXA-58) genes were inserted in broad-host-range plasmid pAT801 and transformed in Escherichia coli DH10B and in A. baumannii CIP 70.10 and its point mutant derivative A. baumannii BM4547, which overexpresses the efflux pump AdeABC. Natural plasmids harboring the bla(OXA-23) and bla(OXA-58) genes were also transformed in A. baumannii CIP 70.10. In addition, the bla(OXA-40) gene was inactivated at its chromosome location in A. baumannii CLA-1. Intermediate levels of resistance or reduced susceptibilities to carbapenems were observed for A. baumannii transformants expressing OXA-23, OXA-40, and OXA-58. The inactivation of bla(OXA-40) in A. baumannii CLA-1 yielded reduced susceptibilities to carbapenems. Carbapenem-hydrolyzing oxacillinases OXA-23, OXA-40, and to a lesser extent OXA-58 play a role in carbapenem resistance in A. baumannii, and overexpression of efflux pump AdeABC may also contribute to higher levels of resistance to beta-lactams, including carbapenems.     

耐碳青霉烯类鲍曼不动杆菌耐药机制研究

目的了解碳青霉烯类耐药鲍曼不动杆菌的耐药性、同源性及其耐药机制。方法收集碳青霉烯类耐药鲍曼不动杆菌20株,用E试验行药敏测定;脉冲场凝胶电泳(PFGE)行同源性分析;通过等电点聚热电泳(IEF)、三维试验及抑制试验、PCR、克隆测序、十二烷基硫酸钠-聚丙酰胺凝胶电泳(SDS-PAGE)等方法分析碳青霉烯酶型及外膜蛋白(OMP)。结果20株碳青霉烯类耐药鲍曼不动杆菌对多黏菌素B仍保持良好的敏感性(90%),莫西沙星对约40%菌株的MIC在0.125mg/L以下;根据PFGE图谱将其分为5型,A1型是主要流行株(9株),主要集中在我校附属二院ICU和附属一院呼吸科;所有菌株均产等电点6.7的碳青霉烯酶,PCR方法及测序证实为OXA-23型碳青霉烯酶,未发现金属酶,且都含有Ⅰ类整合子,但未发现质粒;OMP分析发现部分克隆有31ku的条带丢失。结论亚胺培南耐药不动杆菌存在医院间克隆传播,值得关注;我校鲍曼不动杆菌主要产生OXA-23型碳青霉烯酶;OMP31ku的条带丢失是耐药机制之一;我校耐碳青霉烯类鲍曼不动杆菌耐药机制可能是产酶和OMP丢失共同作用。     

西安地区耐亚胺培南鲍曼不动杆菌的碳青霉烯酶及同源性研究

目的 调查西安地区耐亚胺堵南鲍曼不动杆菌的耐药性,研究其同源性及分子耐药机制.方法 收集西安地区6所三级甲等医院1年间临床分离的非重复鲍曼不动杆菌株146株,采用K-B法进行药敏试验,E试验检测金属酶(MBL),PCR扩增OXA-23,-24,-58,-51 like型及IMP-1型和VIM-2型碳青霉烯酶基因,其阳性产物经测序分析,应用肠杆菌科基因组内重复序列(ERIC)-PCR对菌株进行DNA分型和同源性分析.结果 筛选出对亚胺培南耐药鲍曼不动杆菌(IRAB)非重复株1 5株,其中1株经E试验检测产金属酶,但扩增blaTMP-1,blaVIM-2均阴性,另外14株扩增blaOXA-66均阳性,11株blaUXA-23阳性,1株blaXA 58阳性;ERIC-PCR将15株IRAB分为A型和B型,其中部分菌株的亲缘关系很近,同源性达90%以上.结论 产OXA型碳青霉烯酶是西安地区该菌对亚胺培南耐药的主要原因.其中OXA-23型普遍存在,OXA-58型和OXA-66型基因在国内尚属新型碳青霉烯酶基因型;15株IRAB为2种克隆型,可能存在局部暴发流行.     

多重耐药鲍曼不动杆菌表型及耐药基因型的研究

目的对我院临床分离的31株多重耐药鲍曼不动杆菌表型和耐药基因进行分析。方法用纸片扩散法检测鲍曼不动杆菌的药敏结果,用三维试验检测超广谱β-内酰胺酶(ESBL)、头孢菌素酶(AmpC酶),用协同法检测金属β-内酰胺酶(MBL),用聚合酶链反应(PCR)检测耐药基因。结果31株多重耐药鲍曼不动杆菌中,90%对亚胺培南敏感;22%对头孢哌酮-舒巴坦耐药,74%中介;其他抗菌药物的敏感率均在6%以下。2株菌(6%)单产ESBL;93%菌株高产AmpC酶,其中19%菌株同时产ESBL。所有菌株b laTEM、aacA4和gyrA基因均为阳性;96%菌株ampC基因为阳性;2株菌同时携带b laPER和b laOXA-23型基因,另有1株菌b laOXA-23基因阳性。结论同时携带b laTEM、ampC、aacA4和gyrA突变以及b laPER、b laOXA-23等多种耐药基因是鲍曼不动杆菌多重耐药的主要原因。     

多重耐药鲍曼不动杆菌表型及耐药基因型的研究

目的 对我院临床分离的31株多重耐药鲍曼不动杆菌表型和耐药基因进行分析。方法 用纸片扩散法检测鲍曼不动杆菌的药敏结果,用三维试验检测超广谱β-内酰胺酶（ESBL）、头孢菌素酶（AmpC酶）,用协同法检测金属β-内酰胺酶（MBL）,用聚合酶链反应（PCR）检测耐药基因。结果 31株多重耐药鲍曼不动杆菌中,90％对亚胺培南敏感;22％对头孢哌酮-舒巴坦耐药,74％中介;其他抗菌药物的敏感率均在6％以下。2株菌（6％）单产ESBL;93％菌株高产AmpC酶,其中19％菌株同时产ESBL。所有菌株blaTEM、aacA4和gyrA基因均为阳性;96％菌株ampC基因为阳性;2株菌同时携带blaFER和blaOXA-23,型基因,另有1株菌blaOXA-23,基因阳性。结论 同时携带blaTEM、ampC、aacA4和gyrA突变以及blaFEM、blaOA-23等多种耐药基因是鲍曼不动杆菌多重耐药的主要原因。     

Rifampicin/imipenem combination in the treatment of carbapenem-resistant Acinetobacter baumannii infections

BACKGROUND: In the setting of a large endemic of Acinetobacter baumannii infections, treatment of those due to carbapenem-resistant strains, susceptible only to colistin, has become a major problem in our hospital during the past years. Successful results have been reported using colistin, but clinical experience with this antibiotic is limited. In our experimental studies using these strains in a mouse pneumonia model, the best results were observed with a combination of rifampicin and imipenem. METHODS: From July 2000 to September 2001, we performed a pilot study with patients suffering from serious infections due to carbapenem-resistant A. baumannii. Patients were treated with a rifampicin/imipenem combination and followed up prospectively. Cultures were repeated during and after treatment, and in vitro activity of rifampicin was monitored. Genotyping of these strains was performed by means of PFGE. RESULTS: Ten patients were selected: four with ventilator-associated pneumonia, and six with other infections (one catheter-related bacteraemia, five surgical infections). Three patients died, two of whom were considered therapeutic failures. In five of the seven patients who were cured, other procedures were also performed such as surgical drainage or catheter removal. In vitro development of high resistance to rifampicin was shown in seven (70%). PFGE demonstrated that initial isolates and high-resistant strains belonged to the same clones. CONCLUSIONS: The results of our study argue against the use of a rifampicin/imipenem combination for the treatment of carbapenem-resistant A. baumannii infections. However, combinations of rifampicin with other antibiotics merit further studies.