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Abstract：
The aim of this study was to evaluate the secondary resistance in Helicobacter pylori (Hp) infected patients who had failed a first-line therapy, and to compare the genotypic tests performed directly on gastric samples with phenotypic tests performed on culture media. The eradication rate of patients treated with bismuth quadruple therapy (BQT) is also evaluated. A total of 80 positive specimens were retrospectively examined. Antibiotic susceptibility testing of Hp strains was performed by E-test, whereas a molecular commercially available method was used for detecting the mutations involved in clarithromycin and levofloxacin resistance. High resistance levels to metronidazole and clarithromycin (61.6% and 35%, respectively) and worrying resistance levels to levofloxacin (15%) were found phenotypically. Multiple resistance to two or three antibiotics was observed as well. The polymorphism A2143G on clarithromycin 23S rRNA gene was found in 34/80 (42.5%) isolates including 10 mixed infections (29%), whereas 28/80 (35%) strains were resistant phenotypically. Levofloxacin resistance corresponded to 30% by PCR and 15% by E-test (statistically significant, p < 0.05). The knowledge of clarithromycin and levofloxacin resistance is crucial to establish an appropriate therapy in different geographical areas. The genetic methods were superior to phenotypic techniques in the absence of live bacteria or for identifying mixed infections that may lead to a resistance underestimation. The BQT eradication rate was effective (90%).
摘要：
这项研究的目的是评估一线治疗失败的幽门螺杆菌（Hp）感染患者的继发性耐药性。并将直接在胃样本上进行的基因型测试与在培养基上进行的表型测试进行比较。还评估了用铋四联疗法（BQT）治疗的患者的根除率。回顾性检查了总共80个阳性标本。通过E-test进行Hp菌株的抗生素敏感性测试，而分子市售方法用于检测与克拉霉素和左氧氟沙星耐药有关的突变。对甲硝唑和克拉霉素的高耐药水平（61.6％和35％，分别）和令人担忧的对左氧氟沙星（15％）的耐药水平。还观察到对两种或三种抗生素的多重抗性。克拉霉素23SrRNA基因的A2143G多态性在34/80（42.5％）中发现，包括10个混合感染（29％），而28/80（35％）菌株在表型上具有抗性。通过PCR，左氧氟沙星耐药性为30％，通过E检验为15％（具有统计学意义，p<0.05)。克拉霉素和左氧氟沙星耐药性的知识对于在不同地理区域建立适当的治疗至关重要。在没有活细菌或识别可能导致耐药性低估的混合感染的情况下，遗传方法优于表型技术。BQT根除率有效(90%)。
