Muhammad Ibrahim, Golparian Daniel, Dillon Jo-Anne R, Johansson Asa, Ohnishi Makoto, Sethi Sunil, Chen Shao-chun, Nakayama Shu-ichi, Sundqvist Martin, Bala Manju, Unemo Magnus
Department of Laboratory Medicine, WHO Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, National Reference Laboratory for Pathogenic Neisseria, Microbiology, Örebro University Hospital, SE-701 85, Örebro, Sweden.
BMC Infect Dis. 2014 Aug 22;14:454. doi: 10.1186/1471-2334-14-454.
Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern worldwide. It has been recently feared that the blaTEM-1 gene is, via blaTEM-135, evolving into an extended-spectrum β-lactamase (ESBL), which could degrade all cephalosporins including ceftriaxone. The aims of the present study were to characterize the blaTEM genes, types of β-lactamase plasmids, the degradation of ampicillin by TEM-135 compared to TEM-1, and to perform molecular epidemiological typing of β-lactamase-producing N. gonorrhoeae strains internationally.
β-lactamase producing N. gonorrhoeae isolates (n = 139) cultured from 2000 to 2011 in 15 countries were examined using antibiograms, blaTEM gene sequencing, β-lactamase plasmid typing, and N. gonorrhoeae multiantigen sequence typing (NG-MAST). Furthermore, the blaTEM gene was sequenced in the first described Toronto plasmid (pJD7), one of the first Asian plasmids (pJD4) and African plasmids (pJD5) isolated in Canada. The degradation of ampicillin by TEM-135 compared to TEM-1 was examined using a MALDI-TOF MS hydrolysis assay.
Six different blaTEM sequences were identified (among isolates with 125 different NG-MAST STs), i.e. blaTEM-1 (in 104 isolates), blaTEM-135 (in 30 isolates), and four novel blaTEM sequences (in 5 isolates). The blaTEM-1 allele was only found in the African and Asian plasmids, while all Rio/Toronto plasmids possessed the blaTEM-135 allele. Most interesting, the first described gonococcal Toronto plasmid (pJD7), identified in 1984, also possessed the highly conserved blaTEM-135 allele. The degradation of ampicillin by TEM-135 compared to TEM-1 was indistinguishable in the MALDI-TOF MS hydrolysis assay.
blaTEM-135, encoding TEM-135, is predominantly and originally associated with the Rio/Toronto plasmid and prevalent among the β-lactamase producing gonococcal strains circulating globally. blaTEM-135 does not appear, as previously hypothesized, to have recently evolved due to some evolutionary selective pressure, for example, by the extensive use of extended-spectrum cephalosporins worldwide. On the contrary, the present study shows that blaTEM-135 existed in the Toronto plasmid from its discovery and that blaTEM-135 is highly conserved (not further evolved in the past >30 years). Nevertheless, international studies for monitoring the presence of different blaTEM alleles, the possible evolution of the blaTEM-135 allele, and the types of β-lactamase producing plasmids, remain imperative.
淋病奈瑟菌的抗菌药物耐药性（AMR）是全球主要关注的问题。最近有人担心blaTEM-1基因正通过blaTEM-135演变成超广谱β-内酰胺酶（ESBL），这可能会使包括头孢曲松在内的所有头孢菌素降解。本研究的目的是对blaTEM基因进行特征分析、β-内酰胺酶质粒的类型分析、与TEM-1相比TEM-135对氨苄西林的降解情况分析，并对国际上产β-内酰胺酶的淋病奈瑟菌菌株进行分子流行病学分型。
对2000年至2011年期间在15个国家培养的产β-内酰胺酶的淋病奈瑟菌分离株（n = 139）进行了抗菌谱分析、blaTEM基因测序、β-内酰胺酶质粒分型以及淋病奈瑟菌多抗原序列分型（NG-MAST）。此外，对在加拿大分离出的首个描述的多伦多质粒（pJD7）、首个亚洲质粒（pJD4）和非洲质粒（pJD5）中的blaTEM基因进行了测序。使用基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）水解试验检测了与TEM-1相比TEM-135对氨苄西林的降解情况。
鉴定出六种不同的blaTEM序列（在具有125种不同NG-MAST STs的分离株中），即blaTEM-1（104株分离株中）、blaTEM-135（30株分离株中）和四种新的blaTEM序列（5株分离株中）。blaTEM-1等位基因仅在非洲和亚洲质粒中发现，而所有里约热内卢/多伦多质粒都具有blaTEM-135等位基因。最有趣的是，1984年鉴定出的首个描述的淋球菌多伦多质粒（pJD7）也具有高度保守的blaTEM-135等位基因。在MALDI-TOF MS水解试验中，与TEM-1相比，TEM-135对氨苄西林的降解情况无法区分。
编码TEM-135的blaTEM-135主要且最初与里约热内卢/多伦多质粒相关，并在全球传播的产β-内酰胺酶的淋球菌菌株中普遍存在。如先前假设的那样，blaTEM-135似乎并没有因某些进化选择压力（例如全球范围内广泛使用超广谱头孢菌素）而在近期发生进化。相反，本研究表明blaTEM-135自发现以来一直存在于多伦多质粒中，并且blaTEM-135高度保守（在过去30多年中没有进一步进化）。尽管如此，监测不同blaTEM等位基因的存在、blaTEM-135等位基因可能的进化以及产β-内酰胺酶质粒的类型的国际研究仍然势在必行。
