Department of Biochemistry, University of Otago, Dunedin, New Zealand.
Microbiol Spectr. 2024 Oct 3;12(10):e0069424. doi: 10.1128/spectrum.00694-24. Epub 2024 Sep 9.
is a highly problematic opportunistic pathogen that causes a range of different infections. Infections are commonly treated with β-lactam antibiotics, including cephalosporins, monobactams, penicillins, and carbapenems, with carbapenems regarded as antibiotics of last resort. Isolates of can contain horizontally acquired genes encoding β-lactamase enzymes, but the extent to which these contribute to β-lactam resistance in this species has not been systematically quantified. The overall aim of this research was to address this knowledge gap by quantifying the frequency of β-lactamase-encoding genes in and by determining the effects of β-lactamases on susceptibility of to β-lactams. Genome analysis showed that β-lactamase-encoding genes are present in 3% of but are enriched in carbapenem-resistant isolates (35%). To determine the substrate antibiotics, 10 β-lactamases were expressed from an integrative plasmid in the chromosome of reference strain PAO1. The β-lactamases reduced susceptibility to a variety of clinically used antibiotics, including carbapenems (meropenem, imipenem), penicillins (ticarcillin, piperacillin), cephalosporins (ceftazidime, cefepime), and a monobactam (aztreonam). Different enzymes acted on different β-lactams. β-lactamases encoded by the genomes of clinical isolates had similar effects to the enzymes expressed in strain PAO1. Genome engineering was used to delete β-lactamase-encoding genes from three carbapenem-resistant clinical isolates and increased susceptibility to substrate β-lactams. Our findings demonstrate that acquired β-lactamases play an important role in β-lactam resistance in , identifying substrate antibiotics for a range of enzymes and quantifying their contributions to resistance.IMPORTANCE is an extremely problematic pathogen, with isolates that are resistant to the carbapenem class of β-lactam antibiotics being in critical need of new therapies. Genes encoding β-lactamase enzymes that degrade β-lactam antibiotics can be present in , including carbapenem-resistant isolates. Here, we show that β-lactamase genes are over-represented in carbapenem-resistant isolates, indicating their key role in resistance. We also show that different β-lactamases alter susceptibility of to different β-lactam antibiotics and quantify the effects of selected enzymes on β-lactam susceptibility. This research significantly advances the understanding of the contributions of acquired β-lactamases to antibiotic resistance, including carbapenem resistance, in and by implication in other species. It has potential to expedite development of methods that use whole genome sequencing of infecting bacteria to inform antibiotic treatment, allowing more effective use of antibiotics, and facilitate the development of new antibiotics.
是一种高度有问题的机会性病原体，可引起多种不同的感染。感染通常用β-内酰胺类抗生素治疗，包括头孢菌素、单环β-内酰胺类、青霉素和碳青霉烯类，碳青霉烯类被认为是抗生素的最后手段。可以包含水平获得的β-内酰胺酶基因，这些基因编码β-内酰胺酶，但这些基因在该物种中对β-内酰胺耐药性的贡献程度尚未系统量化。这项研究的总体目标是通过量化β-内酰胺酶编码基因在中的频率，并确定β-内酰胺酶对β-内酰胺类药物敏感性的影响来填补这一知识空白。基因组分析表明，β-内酰胺酶编码基因存在于 3%的中，但在耐碳青霉烯的分离株中富集（35%）。为了确定底物抗生素，将 10 种β-内酰胺酶从整合质粒中表达在 参考菌株 PAO1 的染色体中。β-内酰胺酶降低了对各种临床使用的抗生素的敏感性，包括碳青霉烯类（美罗培南、亚胺培南）、青霉素类（替卡西林、哌拉西林）、头孢菌素类（头孢他啶、头孢吡肟）和单环β-内酰胺类（氨曲南）。不同的酶作用于不同的β-内酰胺类药物。临床分离株基因组编码的β-内酰胺酶对 PAO1 中表达的酶具有相似的作用。基因组工程用于从三种耐碳青霉烯的临床分离株中删除β-内酰胺酶编码基因，并增加对底物β-内酰胺类药物的敏感性。我们的研究结果表明，获得性β-内酰胺酶在中β-内酰胺耐药性中起着重要作用，确定了一系列酶的底物抗生素，并量化了它们对耐药性的贡献。
是一种极其成问题的病原体，对碳青霉烯类β-内酰胺类抗生素耐药的分离株急需新的治疗方法。可存在编码β-内酰胺酶的基因，这些酶可降解β-内酰胺类抗生素，包括耐碳青霉烯的分离株。在这里，我们表明β-内酰胺酶基因在耐碳青霉烯的分离株中过度表达，表明它们在耐药性中的关键作用。我们还表明，不同的β-内酰胺酶改变了对不同β-内酰胺类抗生素的敏感性，并量化了选定酶对β-内酰胺类抗生素敏感性的影响。这项研究大大提高了对获得性β-内酰胺酶对包括碳青霉烯耐药在内的抗生素耐药性的认识，以及对其他物种的认识。它有可能加速利用感染细菌的全基因组测序来指导抗生素治疗的方法的发展，从而更有效地使用抗生素，并促进新抗生素的开发。
