Salman Emrah, Levent Belkıs, Karahan Zeynep Ceren
Ankara University Faculty of Medicine, Department of Medical Microbiology, Ankara, Turkey. Cukurova University Faculty of Medicine, Department of Medical Microbiology, Discipline of Medical Immunology, Adana, Turkey.
Mikrobiyol Bul. 2017 Jul;51(3):236-246. doi: 10.5578/mb.57467.
Clostridium difficile infection is one of the most important hospital-acquired infections. Infections caused by hypervirulent C.difficile strains which produce toxins at high levels, have higher morbidity and mortality rates, more complications and relapses. They are characterized by higher sporulation ratios and resistance rates for fluoroquinolones. In order to prevent serious morbidities, mortalities and remarkable increase in health costs, highly pathogenic C.difficile strains must be identified before causing severe outbreaks. The aim of this study was to determine the antimicrobial susceptibilities and molecular characteristics of 61 C.difficile strains isolated by culture from toxin-positive fecal samples of patients who were admitted to three different laboratories in Ankara, between September 2012 and November 2014. Antimicrobial susceptibilities were determined by using gradient test strips and results were interpreted according to the current CLSI and EUCAST criteria. The presence of toxin genes was investigated by polymerase chain reaction (PCR), and mutations in the tcdC gene were determined by sequence analysis following PCR amplification. Genetic characterization of one hypervirulent strain was performed by Public Health Institution of Turkey using the GenoType CDiff (Hain Lifescience, Germany) test. All strains were susceptible to vancomycin and metronidazole. Three (4.9%) isolates were resistant to moxifloxacin with a minimum inhibitory concentration (MIC) of > 8 µg/ml. The MIC50 and MIC90 values for erythromycin and clindamycin were 1.5-3 µg/ml, and 2-4 µg/ml, respectively. All strains carried the tcdA and tcdB genes, and 1 (1.6%) was positive for the binary-toxin (cdtA and cdtB) genes. The binary-toxin positive strain carried a 54 bp deletion as well as a single nucleotide change in the tcdC gene. Various single nucleotide changes were found in the tcdC gene of 12 strains (19.6%). Our results have shown that, hypervirulent strains exist in our country, but we have no evidence for the presence of ribotype 027 yet. On the other hand, when the increasing incidence of these strains through out the world is taken into consideration, it would be of great importance to perform surveillance studies and characterize the isolated strains.
艰难梭菌感染是最重要的医院获得性感染之一。由产生高毒素水平的高毒力艰难梭菌菌株引起的感染，发病率和死亡率更高，并发症和复发更多。它们的特点是孢子形成率更高，对氟喹诺酮类药物的耐药率更高。为了预防严重的发病、死亡以及医疗费用的显著增加，必须在高致病性艰难梭菌菌株引发严重疫情之前对其进行鉴定。本研究的目的是确定2012年9月至2014年11月期间从安卡拉三个不同实验室收治的患者毒素阳性粪便样本中通过培养分离出的61株艰难梭菌菌株的抗菌药敏性和分子特征。使用梯度测试条确定抗菌药敏性，并根据当前的CLSI和EUCAST标准解释结果。通过聚合酶链反应（PCR）研究毒素基因的存在，并在PCR扩增后通过序列分析确定tcdC基因中的突变。土耳其公共卫生机构使用GenoType CDiff（德国海因生命科学公司）检测对一株高毒力菌株进行了基因特征分析。所有菌株对万古霉素和甲硝唑敏感。三株（4.9%）分离株对莫西沙星耐药，最低抑菌浓度（MIC）>8μg/ml。红霉素和克林霉素的MIC50和MIC90值分别为1.5 - 3μg/ml和2 - 4μg/ml。所有菌株均携带tcdA和tcdB基因，1株（1.6%）二元毒素（cdtA和cdtB）基因呈阳性。二元毒素阳性菌株在tcdC基因中存在54bp缺失以及一个单核苷酸变化。在12株菌株（19.6%）的tcdC基因中发现了各种单核苷酸变化。我们的结果表明，我国存在高毒力菌株，但尚无证据表明存在核糖体分型027。另一方面，考虑到这些菌株在全球范围内的发病率不断上升，开展监测研究并对分离菌株进行特征分析将非常重要。
