Contribution of PBP3 Substitutions and TEM-1, TEM-15, and ROB-1 Beta-Lactamases to Cefotaxime Resistance in Haemophilus influenzae and Haemophilus parainfluenzae
Contribution of PBP3 Substitutions and TEM-1, TEM-15, and ROB-1 Beta-Lactamases to Cefotaxime Resistance in Haemophilus influenzae and Haemophilus parainfluenzae
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DOI：
10.1089/mdr.2015.0189
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发表时间：
2016-06-01
影响因子：
2.6
通讯作者：
Norskov-Lauritsen, Niels
中科院分区：
文献类型：
--
作者：
Sondergaard, Annette;Norskov-Lauritsen, Niels
目的：研究天然存在的青霉素结合蛋白 3 (PBP3) 取代以及 TEM-1、TEM-15 和 ROB-1 β-内酰胺酶对流感嗜血杆菌和副流感嗜血杆菌对第三代头孢菌素耐药性的相对贡献。结果：用 PCR 扩增的表达改变的 PBP3 的 ftsI 基因和/或编码 β-内酰胺酶的小质粒转化到流感嗜血杆菌和副流感嗜血杆菌的同基因环境中后，评估了头孢噻肟 (CTX) 的最低抑制浓度 (MIC)。 III组PBP3包含取代N526K、S385T和L389F，根据EUCAST解释标准赋予CTX对流感嗜血杆菌的抗性。 III 类 PBP3（包含 N526H 和 S385T 取代）使副流感嗜血杆菌的 CTX MIC 增加了九倍，但该水平并未超过耐药断点。 TEM-15 β-内酰胺酶的产生赋予流感嗜血杆菌和副流感嗜血杆菌以 CTX 抗性。头孢硝酯水解测定表明，与 TEM-1 相比，TEM-15 是效率较低的酶。结论：TEM-15 和 PBP3 替代对流感嗜血杆菌和副流感嗜血杆菌对第三代头孢菌素的耐药性产生累加效应。 PBP3 取代对副流感嗜血杆菌 β-内酰胺抗性的影响可以通过体外转移 ftsI 基因来解决。
Aims: To investigate the relative contributions of naturally occurring penicillin-binding protein 3 (PBP3) substitutions, and TEM-1, TEM-15, and ROB-1 beta-lactamases on resistance to a third-generation cephalosporin in Haemophilus influenzae and Haemophilus parainfluenzae. Results: The minimum inhibitory concentration (MIC) of cefotaxime (CTX) was assessed after transformation with PCR-amplified ftsI genes expressing altered PBP3 and/or small plasmids encoding beta-lactamases into an isogenic environment of H. influenzae and H. parainfluenzae. Group III PBP3, comprising substitutions N526K, S385T, and L389F, conferred CTX resistance to H. influenzae according to EUCAST interpretative criteria. Group III-like PBP3, comprising substitutions N526H and S385T, increased the CTX MIC of H. parainfluenzae ninefold, but the level did not transgress the resistance breakpoint. Production of TEM-15 beta-lactamase conferred CTX resistance on both H. influenzae and H. parainfluenzae. A nitrocefin hydrolysis assay showed TEM-15 to be a less efficient enzyme compared to TEM-1. Conclusions: TEM-15 and PBP3 substitutions impose an additive effect on resistance to third-generation cephalosporins in both H. influenzae and H. parainfluenzae. The effect of PBP3 substitutions on beta-lactam resistance in H. parainfluenzae can be addressed by transfer of ftsI genes in vitro.