Han Lei, Lei Jine, Xu Jiru, Han Shaoshan
Department of Microbiology and Immunology, School of Basic Medical Science, Xi'an Jiaotong University Health Science Center Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education Department of Laboratory Medicine Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
Medicine (Baltimore). 2017 Dec;96(48):e8965. doi: 10.1097/MD.0000000000008965.
Acinetobacter baumannii is one of the major threats in clinical infections due to its antibiotic resistance ability. It shows increasing resistance to carbapenems, mainly due to β-lactamase mediated mechanisms. The aim of this study was to investigate carbapenem resistance (CR) profiles and analyze β-lactamases genes composition of clinical A. baumannii strains from a teaching hospital in Xi'an. The resistance patterns to imipenem and meropenem were checked for 51 clinical A. baumannii strains. The existence of 15 β-lactamases genes was detected by polymerase chain reaction (PCR), and the positive genes were sequenced. The correlation between PCR-positive genes and CR phenotype was analyzed using Chi-square test and contingency coefficient. The expressions of PCR-positive genes were investigated. Forty-five out of 51 strains were resistant to imipenem and meropenem. blaTEM, blaOXA-23-like, and blaOXA-51-like were positive among 15 β-lactamases genes, and TEM-1, OXA-23, and OXA-66/69 were their subtypes. TEM and OXA-23-like only showed up in CR isolates, with the occurrence rate of 91.1% and 97.8%, respectively, whereas OXA-51-like appeared in all strains. ISAba1 was present in the upstream of OXA-23-like, but absent from that of OXA-51-like in our strains. OXA-23-like had highest relationship with CR, followed by TEM, but OXA-51-like had no correlation. This was verified by RT-qPCR that the expression was positive for OXA-23 and TEM-1, but negative for OXA-66/-69. A high rate of CR A. baumannii was detected in this study. Coexistence of TEM, OXA-23-like, and OXA-51-like was the primary resistance profile. The expressions of OXA-23-like and TEM genes were closely related with CR, while OXA-51-like had no contribution to the CR phenotype.
鲍曼不动杆菌因其抗生素耐药能力而成为临床感染中的主要威胁之一。它对碳青霉烯类药物的耐药性不断增加，主要是由于β-内酰胺酶介导的机制。本研究的目的是调查西安一家教学医院临床分离的鲍曼不动杆菌菌株的碳青霉烯耐药（CR）谱，并分析β-内酰胺酶基因组成。检测了51株临床鲍曼不动杆菌菌株对亚胺培南和美罗培南的耐药模式。通过聚合酶链反应（PCR）检测15种β-内酰胺酶基因的存在情况，并对阳性基因进行测序。使用卡方检验和列联系数分析PCR阳性基因与CR表型之间的相关性。研究了PCR阳性基因的表达情况。51株菌株中有45株对亚胺培南和美罗培南耐药。在15种β-内酰胺酶基因中，blaTEM、blaOXA-23-like和blaOXA-51-like呈阳性，TEM-1、OXA-23和OXA-66/69是它们的亚型。TEM和OXA-23-like仅在CR分离株中出现，发生率分别为91.1%和97.8%，而OXA-51-like在所有菌株中均有出现。在我们的菌株中，ISAba1存在于OXA-23-like的上游，但不存在于OXA-51-like的上游。OXA-23-like与CR的相关性最高，其次是TEM，但OXA-51-like与CR无相关性。RT-qPCR证实OXA-23和TEM-1的表达为阳性，但OXA-66/-69的表达为阴性。本研究中检测到高比例的CR鲍曼不动杆菌。TEM、OXA-23-like和OXA-51-like共存是主要的耐药谱。OXA-23-like和TEM基因的表达与CR密切相关，而OXA-51-like对CR表型无影响。
