Mengeloğlu Fırat Zafer, Copur Çiçek Ayşegül, Koçoğlu Esra, Sandallı Cemal, Budak Emine Esra, Ozgümüş Osman Birol
Recep Tayyip Erdogan University Faculty of Medicine, Department of Medical Microbiology, Rize, Turkey.
Mikrobiyol Bul. 2014 Jan;48(1):48-58.
The dissemination of antibiotic resistance genes between bacteria leads to serious problems in the treatment of infectious diseases. It has been shown that resistance genes can also be carried by the integrons. There are limited studies regarding the carriage of class 1 and 2 integrons in Acinetobacter baumannii and Pseudomonas aeruginosa clinical strains in Turkey. The aims of this study were to investigate the carriage rates of class 1 and class 2 integrons in A.baumannii and P.aeruginosa strains isolated from clinical samples in Abant Izzet Baysal University Hospital, and to characterize the antibiotic resistance gene cassettes in these integrons by sequence analyses. A total of 137 strains (77 A.baumannii and 60 P.aeruginosa) isolated from various clinical specimens (56% were sputum, 19% wound, 11% urine, 11% blood, 3% catheter), between March 2010-December 2012, were included in the study. The identification and antibiotic susceptibility tests of the isolates were performed by Vitek 2 Compact (bioMérieux, France) and BD Phoenix 100 (Becton Dickinson, USA) systems. The presence of integrons were screened by PCR method using specific primer pairs targeting class 1 (intI1) and 2 (intI2) integrase regions. All the samples that revealed integron amplification were subjected to DNA sequence analysis, both in the forms of cloned products and PCR amplicons. In the study, the highest susceptibility rates were found against colistin (96%) and tigecycline (78%) in A.baumannii, and against piperacillin/tazobactam (97%) and piperacillin (93%) in P.aeruginosa isolates. The highest resistance rate was determined for piperacillin/tazobactam (95%) in A.baumannii strains. The presence of intI1 gene was detected in 33% (26/77) of A.baumannii and 10% (6/60) of P.aeruginosa isolates. When variable regions in intI1 positive strains were amplified by PCR, eight (8/77, 10%) A.baumannii and three (3/60, 5%) P.aeruginosa strains were found to harbor antibiotic resistance gene cassettes. IntI2 gene was not detected in any of the isolates. Resistance to piperacillin/tazobactam, ceftazidime, cefepime, ceftriaxone and ampicillin/sulbactam was detected as the common resistance pattern in all integron-positive A.baumannii strains, whereas resistance to ceftazidime, gentamicin and ciprofloxacin was the common pattern in all integron-positive P.aeruginosa strains. DNA sequence analysis of variable regions of integrons indicated that two separate gene cassette arrays (aacC1-aadA1 and aac(3)-1) were carried by A.baumannii strains, and two types of gene cassette arrays (blaOXA-30-aadA1 and blaOXA-11-cmlA7) were carried by P.aeruginosa strains. To our best knowledge, this is the first report of the gene sequence of blaOXA-11-cmlA7 defined in an integron gene cassette of P.aeruginosa.
细菌之间抗生素抗性基因的传播给传染病治疗带来了严重问题。已有研究表明，抗性基因也可由整合子携带。关于土耳其鲍曼不动杆菌和铜绿假单胞菌临床菌株中1类和2类整合子携带情况的研究有限。本研究的目的是调查从阿班特伊泽特贝萨尔大学医院临床样本中分离出的鲍曼不动杆菌和铜绿假单胞菌菌株中1类和2类整合子的携带率，并通过序列分析对这些整合子中的抗生素抗性基因盒进行特征分析。2010年3月至2012年12月期间，从各种临床标本（56%为痰液，19%为伤口，11%为尿液，11%为血液，3%为导管）中分离出的137株菌株（77株鲍曼不动杆菌和60株铜绿假单胞菌）纳入本研究。分离株的鉴定和抗生素敏感性试验通过Vitek 2 Compact（法国生物梅里埃公司）和BD Phoenix 100（美国贝克顿·迪金森公司）系统进行。使用针对1类（intI1）和2类（intI2）整合酶区域的特异性引物对，通过PCR方法筛选整合子的存在。所有显示整合子扩增的样本均以克隆产物和PCR扩增子的形式进行DNA序列分析。在本研究中，鲍曼不动杆菌对黏菌素（96%）和替加环素（78%）的敏感性最高，铜绿假单胞菌分离株对哌拉西林/他唑巴坦（97%）和哌拉西林（93%）的敏感性最高。鲍曼不动杆菌菌株中哌拉西林/他唑巴坦（95%）的耐药率最高。在33%（26/77）的鲍曼不动杆菌和10%（6/60）的铜绿假单胞菌分离株中检测到intI1基因。当通过PCR扩增intI1阳性菌株中的可变区时，发现8株（8/77，10%）鲍曼不动杆菌和3株（3/60，5%）铜绿假单胞菌菌株携带抗生素抗性基因盒。在任何分离株中均未检测到IntI2基因。在所有整合子阳性的鲍曼不动杆菌菌株中，对哌拉西林/他唑巴坦、头孢他啶、头孢吡肟、头孢曲松和氨苄西林/舒巴坦的耐药被检测为常见耐药模式，而在所有整合子阳性的铜绿假单胞菌菌株中，对头孢他啶、庆大霉素和环丙沙星的耐药是常见模式。整合子可变区的DNA序列分析表明，鲍曼不动杆菌菌株携带两种不同的基因盒阵列（aacC1-aadA1和aac(3)-1），铜绿假单胞菌菌株携带两种类型的基因盒阵列（blaOXA-30-aadA1和blaOXA-11-cmlA7）。据我们所知，这是在铜绿假单胞菌整合子基因盒中定义的blaOXA-11-cmlA7基因序列的首次报道。
