Abstract：
BACKGROUND: Aminopenicillins are recommended agents for non-invasive Haemophilus influenzae infections. One of the mechanisms of resistance to β-lactams is the alteration of the transpeptidase region of penicillin binding protein 3 (PBP3) which is caused by mutations in the ftsI gene. It was shown that exposure to beta-lactams has a stimulating effect on increase of prevalence of H. influenzae strains with the non-enzymatic mechanism of resistance.
OBJECTIVE: The aim of our study was to compare the mutational potential of ampicillin and cefuroxime in H. influenzae strains, determination of minimum inhibitory concentration and the evolution of mutations over time, focusing on amino acid substitutions in PBP3.
METHODS: 30 days of serial passaging of strains in liquid broth containing increasing concentrations of ampicillin or cefuroxime was followed by whole-genome sequencing.
RESULTS: On average, cefuroxime increased the minimum inhibitory concentration more than ampicillin. The minimum inhibitory concentration was increased by a maximum of 32 fold. Substitutions in the PBP3 started to appear after 15 days of passaging. In PBP3, cefuroxime caused different substitutions than ampicillin.
CONCLUSIONS: Our experiment observed differences in mutation selection by ampicillin and cefuroxime. Selection pressure of antibiotics in vitro generated substitutions that do not occur in clinical strains in the Czech Republic.
OBJECTIVE: The aim of our study was to compare the mutational potential of ampicillin and cefuroxime in H. influenzae strains, determination of minimum inhibitory concentration and the evolution of mutations over time, focusing on amino acid substitutions in PBP3.
METHODS: 30 days of serial passaging of strains in liquid broth containing increasing concentrations of ampicillin or cefuroxime was followed by whole-genome sequencing.
RESULTS: On average, cefuroxime increased the minimum inhibitory concentration more than ampicillin. The minimum inhibitory concentration was increased by a maximum of 32 fold. Substitutions in the PBP3 started to appear after 15 days of passaging. In PBP3, cefuroxime caused different substitutions than ampicillin.
CONCLUSIONS: Our experiment observed differences in mutation selection by ampicillin and cefuroxime. Selection pressure of antibiotics in vitro generated substitutions that do not occur in clinical strains in the Czech Republic.
摘要：
背景：氨基青霉素类是非侵袭性流感嗜血杆菌感染的推荐药物。对β-内酰胺的抗性机制之一是青霉素结合蛋白3（PBP3）的转肽酶区的改变，这是由ftsI基因突变引起的。研究表明，暴露于β-内酰胺对具有非酶抗性机制的流感嗜血杆菌菌株的患病率增加具有刺激作用。
目的：我们的研究目的是比较流感嗜血杆菌菌株中氨苄西林和头孢呋辛的突变潜力，最小抑制浓度的测定和突变随时间的演变，关注PBP3中的氨基酸取代。
方法：在含有递增浓度的氨苄青霉素或头孢呋辛的液体肉汤中连续传代30天，然后进行全基因组测序。
结果：平均而言，头孢呋辛的最低抑制浓度比氨苄西林的增加更多。最小抑制浓度增加了最大32倍。PBP3中的取代在传代15天后开始出现。在PBP3中，头孢呋辛引起的取代与氨苄青霉素不同。
结论：我们的实验观察到氨苄青霉素和头孢呋辛在突变选择方面的差异。抗生素的选择压力在体外产生的取代在捷克共和国的临床菌株中不发生。
目的：我们的研究目的是比较流感嗜血杆菌菌株中氨苄西林和头孢呋辛的突变潜力，最小抑制浓度的测定和突变随时间的演变，关注PBP3中的氨基酸取代。
方法：在含有递增浓度的氨苄青霉素或头孢呋辛的液体肉汤中连续传代30天，然后进行全基因组测序。
结果：平均而言，头孢呋辛的最低抑制浓度比氨苄西林的增加更多。最小抑制浓度增加了最大32倍。PBP3中的取代在传代15天后开始出现。在PBP3中，头孢呋辛引起的取代与氨苄青霉素不同。
结论：我们的实验观察到氨苄青霉素和头孢呋辛在突变选择方面的差异。抗生素的选择压力在体外产生的取代在捷克共和国的临床菌株中不发生。
