江津地区幽门螺杆菌耐药情况分析

目的分析江津地区幽门螺杆菌(H.pylori)的耐药情况,探讨对H.pylori耐药菌株合理使用抗生素的方法。方法对首次做胃镜检查H.pylori尿素酶试验阳性的患者,检查前2周内未服用过抗菌、铋剂等药物,用琼脂稀释法和E-test法检测H.pylori对阿莫西林、克拉霉素和甲硝唑的耐药情况,同时行药敏试验检测H.pylori的药物敏感情况。结果江津地区H.pylori菌株对阿莫西林、克拉霉素、甲硝唑和克拉霉素双重耐药分别为1.8%(1/57)、15.8%(9/57)和54.4%(31/57);H.pylori菌株对呋喃唑酮高度敏感,对左氧氟沙星、青霉素敏感。不同性别和病种对甲硝唑和克拉霉素的耐药率无显著性差异(P>0.05)。结论重庆市江津地区H.pylori对甲硝唑和克拉霉素耐药现象已经相当普遍,对阿莫西林的耐药情况也不容忽视。医生应选择敏感药物使用,必要时适当延长抗H.pylori用药时间以增强疗效。     

上海市青浦区幽门螺杆菌抗生素耐药情况的研究

背景：幽门螺杆菌（H．pylori）对抗生素的耐药率在世界范围内呈上升趋势,但存在地域差异。目的：调查上海市青浦区H．pylori对5种根除治疗方案中常用抗生素的耐药情况。方法：选取青浦区两所医院因上消化道症状行胃镜检查、快速尿素酶试验阳性并符合纳入和排除标准的患者,取胃窦黏膜分离培养H．pylori．采用Kirby-Bauer纸片扩散法行药敏试验。结果：成功分离培养出120株H．pylori临床菌株,对甲硝唑、阿莫西林、克拉霉素、左氧氟沙星和呋喃唑酮的耐药率分别为82．5％、22．5％、36．7％、41．7％和0．8％。耐药率与患者性别无关;慢性胃炎菌株对左氧氟沙星的耐药率显著高于十二指肠溃疡菌株（P〈0．05）。60．8％的菌株对两种以及两种以上抗生素联合耐药。结论：青浦区H．pylori对甲硝唑、阿莫西林、克拉霉素、左氧氟沙星的耐药情况相当严重且多重耐药率高。初次根除治疗失败后．再次治疗时可在药敏试验指导下选择有效抗生素。呋喃唑酮可作为当地根除治疗方案的一线用药．     

幽门螺杆菌耐药性及三种耐药检测方法的比较

目的分析浙江地区幽门螺杆菌(Helicobacter pylori,H.pylori)耐药情况,并比较不同耐药检测方法的一致性.方法选择2017-06/2017-09进行胃镜检查的305例患者,取胃黏膜组织进行H.pylori菌株分离鉴定,对分离的127个菌株进行6种抗生素的药敏实验,提取菌株的DNA,以荧光定量PCR法和测序法对克拉霉素耐药相关基因23S rRNA和左氧氟沙星耐药相关基因gyrA进行扩增和测序.结果在305份胃黏膜活检标本中,分离出H.pylori 127株.127株H.pylori中124株为耐药菌株,3株为敏感菌株.阿莫西林、盐酸四环素、呋喃唑酮无耐药菌株;克拉霉素、左氧氟沙星、甲硝唑耐药率分别为33.86%(43/127)、44.88%(57/127)、91.34%(116/127)、三重耐药率为18.90%(24/127);克拉霉素和左氧氟沙星相关的主要耐药基因及其突变位点分别为23S rRNA(A2143G)、gyrA(C261A/G),突变频率分别为42.5%(54/127)和15.0%(19/127).不同耐药检测方法的一致性比较:荧光定量PCR法与测序法检测耐药突变一致性较高,与药敏培养法一致性相对较差.结论浙江地区对克拉霉素、左氧氟沙星耐药率均达到很高,在临床应用这些抗生素需结合耐药性,选择敏感的抗生素个体化地用药,提高根除效率.     

贵阳地区儿童感染幽门螺杆菌的分离培养及耐药性检测

目的:了解贵阳地区儿童感染幽门螺杆菌(Helicobacter pylori,H.pylori)临床分离株对常用抗H.pylori抗生素甲硝唑、克拉霉素、阿莫西林等的体外敏感性,以指导临床用药根除H.pylori感染.方法:收集2011-10/2014-06贵阳市儿童医院行胃镜检查的患儿胃黏膜标本进行H.pylori分离培养,对分离鉴定后的菌株采用界值法进行甲硝唑、克拉霉素、阿莫西林、左氧氟沙星的敏感性试验.结果:从434例患儿胃黏膜中培养出H.pylori63株(14.5%),63例H.pylori菌株中3株为敏感菌株,60株为耐药菌株,其对甲硝唑、克拉霉素、阿莫西林、左氧氟沙星的耐药率分别为57.1%、85.7%、38.1%、90.5%.二重、三重、四重耐药率分别为90.5%(57/63)、57.1%(36/63)、38.1%(24/63).结论:贵阳地区儿童感染H.pylori对阿莫西林敏感性高于对其他常用药物的敏感性;对左氧氟沙星和克拉霉素的耐药率较高,并且多重耐药率较高.     

河南省幽门螺杆菌对利福昔明的药物敏感性及常用抗菌素耐药情况研究

目的了解河南省~(13)C呼气试验结果阳性的患者中分离的幽门螺杆菌(H.pylori)对利福昔明的药物敏感性及其他6种常用抗菌素(克拉霉素、左氧氟沙星、呋喃唑酮、四环素、甲硝唑、阿莫西林)的耐药情况,以掌握河南省H.pylori对上述抗菌素的药敏谱,指导临床用药。方法选取2019年4月至2019年12月在我院行~(13)C-快速尿素酶呼气试验检查(~(13)C-UBT)且结果为H.pylori阳性的河南省患者为本次研究对象。常规胃镜操作下取胃黏膜组织样本,送我院H.pylori实验室培养鉴定,获得H.pylori菌株,针对上述7种抗生素进行药敏试验。结果在248例送检胃黏膜组织标本中成功分离H.pylori菌株共154例,体外药敏试验分析,H.pylori对克拉霉素、左氧氟沙星、呋喃唑酮、阿莫西林、甲硝唑、利福昔明耐药率分别为29.22%、27.92%、11.04%、5.84%、83.77%、7.79%。未能发现对四环素耐药的H.pylori菌株。对上述所有抗生素均敏感的菌株共9例,占总菌株的5.84%;58例菌株对单种抗生素耐药,占总菌株的37.66%;87例H.pylori菌株对多种抗生素耐药,占总菌株的56.49%。结论河南省H.pylori对利福昔明的药物敏感性较高,可作为抗H.pylori的药物选择;对甲硝唑、克拉霉素、左氧氟沙星的耐药率较高,且存在交叉耐药,不宜作为河南省临床抗H.pylori的首要选择;对呋喃唑酮、阿莫西林、四环素耐药率较低,亦可选择上述药物用于临床常规治疗。     

中国幽门螺杆菌耐药状况以及耐药对治疗的影响—— 全国多中心临床研究

随着幽门螺杆菌（H．pylori）根除治疗的广泛开展，H．pylori对抗生素的耐药率逐年上升，并成为含质子泵抑制剂（PPI）三联疗法根除率下降的主要原因。了解我国H．pylori对抗生素的总体耐药情况，对指导我国临床医师开展H．pylori根除治疗有重要参考价值。目前这方面的资料尚少。目的：了解我国H．pylori对抗生素（甲硝唑、克拉霉素和阿莫西林）的耐药情况以及耐药对三联7d疗法根除H．pylori治疗的影响。方法：采用全国多中心随机对照临床研究。共纳入910例因上消化道症状而接受胃镜检查的H．pylori感染者．所有患者随机分为两个治疗组：LCA组，兰索拉唑30mg bid，克拉霉素500mg bid，阿莫西林1000mg bid；LCM组，兰索拉唑30mg bid，克拉霉素500mg bid，甲硝唑400mg bid。疗程均为7d，均行H．pylori培养。H．pylori分离菌株采用E-test法行甲硝唑、克拉霉素和阿莫西林药敏实验，甲硝唑最低抑菌浓度（MIC）≥8mg／L、克拉霉素MIC≥2mg／L、阿莫西林MIC≥1mg／L判断为耐药。结果：910例患者中，LCA组和LCM组的H．pylori按方案（PP）分析根除率分别为82．7％和68．6％（P〈0．001）。340例H．pylori菌株培养阳性。H．pylori对甲硝唑、克拉霉素和阿莫西林的耐药率分别为75．6％、27．6％和2．7％。LCM组对甲硝唑和克拉霉素均敏感和均耐药菌株的PP根除率分别为84．4％和42．1％（P〈0．001）。LCA组对克拉霉素敏感和耐药菌株的PP根除率分别为91．6％和58．1％（P〈0．001）。结论：中国H．pylori菌株对甲硝唑和克拉霉素的耐药率均较高．对阿莫西林的耐药率较低。H．pylori对抗生素耐药是导致根除治疗失败的主要原因。     

1134例幽门螺旋杆菌培养及药敏分析

目的 了解嘉兴地区H.pylori感染、耐药情况及依据药敏试验行抗H.pylori治疗后,H.pylori根除的情况.方法 选取1134例上消化道疾病患者胃黏膜组织,于微需氧环境的分离培养基上培养.采用抗生素药敏试验纸片琼脂扩散法(简称K-B法),对分离到的H.pylori菌株进行药物敏感试验,抗生素选用甲硝唑、阿莫西林、克拉霉素、呋喃唑酮、庆大霉素及左氧氟沙星.所有H.pylori培养阳性患者,均依据药敏试验结果进行抗H.pylori治疗,4周后复查.结果 1134例患者中,H.pylori分离培养阳性者341例,阳性率30.07%.病理组织学检测阳性者477例,阳性率42.06%,明显高于分离培养阳性者(P<0.001).对341例分离培养的H.pylori菌株进行药敏试验.甲硝唑耐药率最高,左氧氟沙星最低,依次为甲硝唑(99.12%)、阿莫西林(46.04%)、克拉霉素(34.02%)、呋喃唑酮(16.42%)、庆大霉素(6.45%)、左氧氟沙星(0.59%).细菌对抗生素的敏感度左氧氟沙星最高.甲硝唑最低,依次为左氧氟沙星(20.51%)、庆大霉素(18.43%)、阿莫西林(17.04%)、呋喃唑酮(16.92%)、克拉霉素(15.54%)、甲硝唑(10.33%).结论 依据药敏试验进行抗H.pylori治疗,是抗H.pylori治疗的最佳选择.     

闽浙边界地区上消化道症状者幽门螺杆菌耐药性及相关基因突变研究

目的 调查闽浙边界地区上消化道症状者幽门螺杆菌（Hp）耐药情况及其与临床特征的关系,探讨克拉霉素耐药菌株23S rRNA基因及左氧氟沙星耐药菌株gyrA基因的突变特性。方法 选择2019年10月至2020年1月闽浙边界地区417例因上消化道症状于福建中医药大学附属福鼎医院消化内镜中心行胃镜检查及胃黏膜活体组织检查者,行Hp菌株分离、培养和鉴定。使用6种抗菌药物对Hp菌株进行药物敏感度体外实验,分析单药、双重及三重耐药情况,并探讨Hp耐药情况与患者年龄的关系。随机选取50株克拉霉素耐药菌株和50株左氧氟沙星耐药菌株,采用PCR法和Sanger测序法分析耐药相关基因23S rRNA和gyrA的突变情况。结果 247株Hp菌株的总体耐药率为98.8%,其中甲硝唑的耐药率（96.4%）最高,其次为左氧氟沙星（45.7%）,克拉霉素的耐药率达40.9%,未发现阿莫西林、呋喃唑酮和四环素耐药菌株。Hp菌株对左氧氟沙星的耐药率、对甲硝唑和左氧氟沙星的双重耐药率,以及对甲硝唑、左氧氟沙星和克拉霉素的三重耐药率均随年龄增长呈升高趋势（P均<0.05）。50株克拉霉素耐药菌株均发生23S rRNA基...     

幽门螺杆菌对左氧氟沙星耐药的研究

背景：耐药菌株的出现是近年来药物根除幽门螺杆菌（H．pflori）成功率下降的主要原因，尤其是对常用抗生素克拉霉素和甲硝唑耐药。左氧氟沙星是一个新近用于根除H．pylori的抗生素，含左氧氟沙星的方案是有效的补救方案，但关于左氧氟沙星的耐药率以及耐药机制目前知之甚少。目的：监测H．pylori对左氧氟沙星的耐药率，观察耐药倾向．探讨可能的耐药机制。方法：对2003年在仁济医院内镜中心行胃镜检查的连续26株临床菌株行左氧氟沙星、克拉霉素和甲硝唑敏感性试验；选取8株敏感株（2株标准菌株）行左氧氟沙星体外选择耐药试验；以修饰内切酶位点的指定引物人工将Hinf Ⅰ酶切位点引入左氧氟沙星耐药菌株（体外人工选择分离株和临床株）的聚合酶链反应（PCR）产物．然后以Hinf Ⅰ行酶切以鉴别gyrA基因91位密码子是否存在突变。结果：左氧氟沙星的耐药率为3．8％（1/26），2株对克拉霉素耐药的菌株均对左氧氟沙星敏感。体外选择耐药试验的8株菌株中有5株选择分离出耐药菌株，但均为低度耐药菌株。4株体外人工选择分离耐药菌株均为gyrA基因喹诺酮耐药决定区域（QRDR）中编码Asp91的密码子突变，5株临床耐药株中有4株为91位密码子突变。结论：目前Mpylori对左氧氟沙星的耐药率低．左氧氟沙星是较好的根除H．pylori方案的可选药物之一。由于体外试验较易选择出耐药，因此需监测左氧氟沙星的耐药率。gvrA基因0RDR中编码91位Asp的密码子突变在左氧氟沙星的耐药机制中占主导地位。     

克拉霉素耐药幽门螺杆菌株的基因型分布

背景：根除幽门螺杆菌（H.pylori）治疗在临床上的应用日益普遍。耐药菌株的出现是近年H.pylori根除率下降的主要原因,尤其是目前根除治疗作用最强的抗生素之一——克拉霉素。目的：研究克拉霉素耐药H.pylori菌株的基因型分布,为快速检出抗生素耐药提供基础。方法：以琼脂稀释法筛选出2002年9月～2003年2月13株原发性、22株获得性克拉霉素耐药H.pylori菌株,提取基因组DNA。聚合酶链反应（PCR）-反向斑点杂交法检测克拉霉素耐药H.pylori菌株23SrRNA基因中7种不同的点突变（A2115G、G2141A、A2142G、A2142C、A2143G、A2143C和A2142T）。结果：34株（97.1%）克拉霉素耐药H.pylori菌株发生A2143G突变,其中13株为原发性,21株为获得性;1株（2.9%）获得性耐药菌株发生A2142G突变。结论：我国克拉霉素耐药H.pylori菌株基因型以23SrRNA基因A2143G突变占主导地位,与欧美国家报道的A2142G和A2143G突变率相近不同。     

Resistance of Helicobacter pylori to antibiotics from 2000 to 2009 in Shanghai

AIM: To investigate the resistance of Helicobacter pylori (H. pylori ) to 6 commonly used antibiotics from 2000 to 2009 in Shanghai. METHODS: A total of 293 H. pylori strains were collected from 2000 to 2009 in Shanghai and tested for their susceptibility to metronidazole, clarithromycin, amoxicillin, furazolidone, levofloxacin and tetracycline using agar dilution. RESULTS: The resistant rates of H. pylori to clarithromycin (8.6%, 9.0% and 20.7%) and levofloxacin (10.3%, 24.0% and 32.5%) increased from 2000...     

幽门螺杆菌耐药性检测

目的 体外观察北京地区人群幽门螺杆菌（Ｈｐ）菌株对临床常用４种抗菌药物的敏感性和耐药性。方法 ①菌株：Ｈｐ菌株２０株（２株国际标准菌株,１８株临床分离株）,同时以金黄色葡萄球菌ＡＴＣＣ２５９２３为质控菌株。②药物：羟氨苄青霉素,克拉霉素,甲硝唑,呋喃唑酮。③药敏试验：滤纸片琼脂扩散法。结果 甲硝唑耐药率９４．４％,克拉霉素、呋喃唑酮耐药率５．６％,羟氨苄青霉素耐药率０。结论 北京地区人群Ｈｐ菌株甲     

广东珠海地区慢性胃炎患者幽门螺杆菌的体外多重耐药性研究

目的分析广东珠海地区幽门螺杆菌（Hp）临床分离株体外多重耐药特点,为临床根除Hp治疗提供依据。方法对珠海地区312例经胃镜确诊、活检快速尿素酶试验阳性的慢性胃炎患者行Hp分离及菌株培养,采用折点敏感试验方法测定Hp对甲硝唑、呋喃唑酮、阿莫西林、克拉霉素的单药及多药耐药情况。结果共获得95株Hp菌株,其对4种抗生素耐药率由高到低依次为甲硝唑、呋喃唑酮、阿莫西林、克拉霉素,双重耐药率为30．53％-58．95％,多重耐药率26．32％～37．89％。结论广东珠海地区Hp多重耐药情况严重,行根除Hp治疗时应尽量避免应用甲硝哗：府进行药敏试验,寻求个体化治疗方案。     

幽门螺杆菌对克拉霉素的耐药性与23S rRNA基因突变相关性分析

[目的]研究本地区幽门螺杆菌（Helicobacter pylori,HP）的克拉霉素耐药与23S rRNA基因位点突变的关系,为临床根除HP治疗提供依据.[方法]入选消化性溃疡患者180例,在胃窦小弯侧距幽门2～3cm范围内取1块胃黏膜组织行常规病理检查,在胃窦小弯侧、十二指肠球部、胃体大弯侧各取1块黏膜行HP培养,对HP阳性分离菌株进行药敏实验.选取其中克拉霉素耐药菌株35例及敏感菌株30例,对23S rRNA基因PCR扩增后进行全基因测序对比分析.[结果] 180例中HP阳性率占76.11％,活检组织培养HP阳性率占73.89％.药敏检查结果克拉霉素耐药率为33.08％.HP23S rRNA测序结果显示存在多位点突变,耐药组及非耐药组中T2182C普遍存在,A2143G、A2142G和A2097G在耐药组中多见,A2097C、A2097T仅在敏感组中发现,差异有统计学意义.[结论]本地区HP对克拉霉素耐药率高,克拉霉素耐药菌株A2143G、A2142G和A2097G位点突变高于敏感组,建议根据药敏试验指导根除HP方案.     

Inhibitory effects of emodin,baicalin, schizandrin and berberine on hef A gene: Treatment of Helicobacter pylori-induced multidrug resistance

AIM: To investigate the inhibitory effects of emodin, baicalin, etc. on the hefA gene of multidrug resistance(MDR) in Helicobacter pylori(H. pylori).METHODS: The double dilution method was used to screen MDR H. pylori strains and determine the minimum inhibitory concentrations(MICs) of emodin, baicalin, schizandrin, berberine, clarithromycin, metronidazole, tetracycline, amoxicillin and levofloxacin against H. pylori strains. After the screened MDR stains were treated with emodin, baicalin, schizandrin or berberine at a 1/2 MIC concentration for 48 h, changes in MICs of amoxicillin, tetracycline, levofloxacin, metronidazole and clarithromycin were determined.MDR strains with reduced MICs of amoxicillin were selected to detect the hefA mR NA expression by realtime quantitative PCR.RESULTS: A total of four MDR H. pylori strains were screened. Treatment with emodin, baicalin, schizandrin and berberine significantly decreased the MICs of amoxicillin and tetracycline against some strains, decreased by 1 to 2 times, but did not significantly change the MICs of clarithromycin, levofloxacin, and metronidazole against MDR strains. In the majority of strains with reduced MICs of amoxicillin, hef A m RNA expression was decreased; one-way ANOVA(SPSS 12.0) used for comparative analysis, P < 0.05.CONCLUSION: Emodin, baicalin, schizandrin and berberine significantly decreased the MICs of amoxicillin and tetracycline against some H. pylori strains, possibly by mechanisms associated with decreasing hefA mR NA expression.     

幽门螺杆菌体外诱导耐药试验和耐药率监测

目的 抗生素耐药越来越被公认为是根除幽门螺杆菌（Hp)治疗失败的主要原因。比较根除Hp常用抗生素耐药性发生倾向和监测耐药率。方法 选用7株敏感菌株（其中2株为标准菌株）进行阿莫西林，四环素，呋喃唑酮，甲硝唑和克拉霉素5种抗生素的体外诱导耐药试验。随机选取2000-2001年间保存的165株菌株，用琼脂稀释法测定最低抑菌浓度（MIC），对上述5种抗生素进行耐药监测。结果 体外诱导试验显示，7株Hp中5株诱导出甲硝唑耐药，且可诱导倍数最高。5株诱导出四环素耐药。虽未诱导出克拉霉素耐药，但有1株可诱导倍数较高。未诱导出阿莫西林或呋喃唑酮耐药，呋喃唑酮可诱导倍数最低。耐药监测甲硝唑耐药率为49.7%(82/165)，克拉霉素为7.3%(12/165)，阿莫西林为1.2%(2/165)，四环素为2.4%(4/165)，呋喃唑酮为1.2%(2/165)。结论 Hp对甲硝唑很容易产生耐药，对克拉霉素可产生耐药，对呋喃唑酮和阿莫西林不易产生耐药。除四环素外，Hp对其他4种抗生素发生耐药的难易程度与实际监测的耐药率高低相关，这有助于预测感染Hp后抗生素耐药率变迁的倾向。     

Primary Antibiotic Resistance of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> in China

Background and Aims

Antibiotic resistance is the most important factor leading to the failure of eradication regimens; thus, it is important to obtain regional antibiotic resistance information. This review focuses on the prevalence of Helicobacter pylori primary resistance to clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and furazolidone in China.

Methods

We searched the PubMed, EMBASE, the China National Knowledge Infrastructure, and Chinese Biomedical databases from the earliest date of each database to October 2016. The search terms included the following: H. pylori, antibiotic (including clarithromycin, metronidazole, amoxicillin, levofloxacin, tetracycline, and furazolidone) resistance with or without China or different regions of China. The data analysis was performed using MedCalc 15.2.2. Each article was weighted according to the number of isolated H. pylori strains. A pooled proportion analysis was performed.

Results

Twenty-three studies (14 studies in English and 9 in Chinese) were included in this review. A total of 6274, 6418, 3921, 5468, 2802, and 275 H. pylori strains were included in this review to evaluate the prevalence of H. pylori primary resistance to clarithromycin, metronidazole, levofloxacin, amoxicillin, tetracycline, and furazolidone, respectively. Overall, the primary resistance rates of clarithromycin, metronidazole, levofloxacin, amoxicillin, tetracycline, and furazolidone were 28.9, 63.8, 28.0, 3.1, 3.9, and 1.7%, respectively.

Conclusions

In China, the prevalence of H. pylori primary resistance to clarithromycin, metronidazole, and levofloxacin was high and increased over time, whereas the resistance rates to amoxicillin, tetracycline, and furazolidone were low and stable over time.

     

Antibiotic resistance of Helicobacter pylori isolated from Korean patients]

The distribution of minimal inhibitory concentrations (MIC) for amoxicillin, clarithromycin, metronidazole, tetracycline, azithromycin, and fluoroquinolone (ciprofloxacin, levofloxacin, and moxifloxacin) have shifted to higher concentrations from 1987 to 2003 in Helicobacter pylori (H. pylori) strains isolated from Korean patients. MIC values of secondary isolates were higher than those of primary isolates. Of treatment-failure patients, 16.4% showed mixed infections with both antibiotic-susceptible and -resistant H. pylori strains. A total of 89.6% of patients with treatment failure and 52.3% of patients without antibiotic treatment had H. pylori strains resistant to two or more antimicrobial agents (multi-drug resistance, MDR). The most common antibiotics showing MDR were clarithromycin, metronidazole, and azithromycin. The resistance rates to both amoxicillin and clarithromycin were 34.3% in secondary isolates and 6.2% in primary isolates. The resistance rates to both clarithromycin and metronidazole were 73.1% in secondary isolates and 7.7% in primary isolates. In addition, there was a significant difference in antibiotic resistance between two institutions located at Seoul and Gyeonggi provinces. To provide adequate informations about susceptible antibiotics to clinicians, continuous surveillance of antibiotic susceptibilities is needed in Korea.     

New mutation points in 23S rRNA gene associated with Helicobacter pylori resistance to clarithromycin in northeast China

AIM: To investigate the resistance rate of Helicobacter pylori (H pylori ) to clarithromycin, metronidazole, amoxicillin and tetracycline to guide clinical practice, and to study the mechanism of H pylori resistant to clarithromycin. METHODS: Thirty H pylori strains were isolated from the mucosa of peptic ulcer, gastric tumor and chronic gastritis patients, then the minimal inhibitory concentration (MIC) to clarithromycin, metronidazole, amoxicillin and tetracycline was evaluated by E-test method. The sequence analysis of PCR fragments was conducted in 23S rRNA gene of H pylori resistant to clarithromycin to get the resistance mechanism of the bacteria. RESULTS: Among 30 H pylori strains, 7 cases were resistant to clarithromycin, 12 to metronidazole, 2 to tetracycline and no strain was found to be resistant to amoxicillin. The resistance rates were 23.3%, 40%, 6.7% and 0%, respectively. Three new mutation points were found to be related to the clarithromycin resistance in H pylori isolates, which were G2224A, C2245T and T2289C. CONCLUSION: In northeast China, H pylori shows high resistance to metronidazole, while sensitive to amoxicillin. The mechanism of resistance to clarithromycin may be related to the mutation of G2224A, C2245T and T2289C in the 23S rRNA gene.     

Resistance to metronidazole, clarithromycin and levofloxacin of Helicobacter pylori before and after clarithromycin-based therapy in Taiwan

Background and Aim:  Clarithromycin-based triple therapy has been commonly applied as the first-line therapy for Helicobacter pylori eradication. Levofloxacin could serve as an alternative in either first-line or second-line regimens. This study surveyed the prevalence of levofloxacin resistance of H. pylori isolates in naive patients and in patients with a failed clarithromycin-based triple therapy.
Methods:  The study collected the H. pylori isolates from 180 naive patients and 47 patients with a failed clarithromycin-based triple therapy. Their in vitro antimicrobial resistance was determined by E -test.
Results:  The naive H. pylori isolates had resistance rates for amoxicillin, levofloxacin, clarithromycin and metronidazole of 0%, 9.4%, 10.6% and 26.7%, respectively. An evolutional increase of the primary levofloxacin resistance was observed in isolates collected after 2004, as compared to isolates collected before 2004 (16.3% vs 3.2%, P  = 0.003). There was no evolutional increment of the primary clarithromycin resistance. The clarithromycin resistance elevated significantly after a failed clarithromycin-based triple therapy (78.7% vs 10.6%, P  < 0.001). The post-treatment isolates remained to have a levofloxacin resistance rate of near 17%, but the levofloxacin-resistant isolates were correlated with a higher incidence of metronidazole resistance ( P  = 0.023). No strain was found to be resistant to amoxicillin even after eradication failure.
Conclusion:  The levofloxacin resistance of naive H. pylori remains less than 10% in Taiwan. With relatively lower resistance to levofloxacin than to metronidazole of the H. pylori isolates collected after a failed clarithromycin-based therapy, proton pump inhibitor–levofloxacin–amoxicillin may be an alternative choice to serve as the second-line therapy.