Gostev Vladimir, Kalinogorskaya Olga, Ivanova Ksenia, Kalisnikova Ekaterina, Lazareva Irina, Starkova Polina, Sidorenko Sergey
Department of Medical Microbiology and Molecular Epidemiology, Pediatric Research and Clinical Center for Infectious Diseases, 194017 Saint Petersburg, Russia.
Department of Medical Microbiology, North-Western State Medical University named after I.I Mechnikov, 195067 Saint Petersburg, Russia.
Antibiotics (Basel). 2021 May 26;10(6):637. doi: 10.3390/antibiotics10060637.
Selective pressure of beta-lactams is thought to be responsible for mutation selection in methicillin-susceptible (MSSA). We used next-generation sequencing to compare the genomes of beta-lactamase-positive (SA0707) and -negative (SA0937) MSSA isolates with their derivatives obtained after selection with oxacillin, ceftaroline, or meropenem. Selection with oxacillin and ceftaroline caused a rapid and significant (6-8 times) increase in the minimum inhibitory concentration (MICs) of oxacillin, penicillin, amoxicillin/clavulanate, and ceftaroline against the derivatives of both isolates, associated with growth impairment. Selection with meropenem caused a limited increase in the MICs of all beta-lactams against both isolates. During the initial stages of selection (after 5-15 passages), mutations were detected only in some reads, which indicated the heterogeneity of the population; however, during the later stages, either the population reversed to the wild type or fixation of the mutation was observed in the entire population. Selection with different beta-lactams caused diverse mutational events, but common mutations were detected in all penicillin-binding proteins, cell wall regulators (), and deletions in the promoter region of . Therefore, the disk diffusion test with cefoxitin does not reveal resistance associated with these mechanisms in some cases, which can lead to the failure of beta-lactam therapy.
β-内酰胺类抗生素的选择压力被认为是导致甲氧西林敏感金黄色葡萄球菌（MSSA）发生突变选择的原因。我们使用下一代测序技术，比较了β-内酰胺酶阳性（SA0707）和阴性（SA0937）的MSSA分离株及其在用苯唑西林、头孢洛林或美罗培南选择后获得的衍生物的基因组。用苯唑西林和头孢洛林进行选择导致苯唑西林、青霉素、阿莫西林/克拉维酸和头孢洛林对两种分离株衍生物的最低抑菌浓度（MICs）迅速且显著（6-8倍）增加，并伴有生长抑制。用美罗培南进行选择导致所有β-内酰胺类抗生素对两种分离株的MICs仅有限增加。在选择的初始阶段（5-15代后），仅在一些读数中检测到突变，这表明群体的异质性；然而，在后期阶段，群体要么恢复为野生型，要么在整个群体中观察到突变的固定。用不同的β-内酰胺类抗生素进行选择导致了不同的突变事件，但在所有青霉素结合蛋白、细胞壁调节因子（）以及的启动子区域缺失中都检测到了常见突变。因此，在某些情况下，头孢西丁纸片扩散试验无法揭示与这些机制相关的耐药性，这可能导致β-内酰胺类治疗失败。
