STI Unit, Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Antwerp, 2000, Belgium.
Laboratory of Medical Microbiology, University of Antwerp, Wilrijk, 2610, Belgium.
F1000Res. 2022 Dec 9;11:1464. doi: 10.12688/f1000research.126078.2. eCollection 2022.
The effect of sequential exposure to different antibiotics is an underexplored topic. Azithromycin can be detected in humans for up to 28 days post-ingestion and may prime bacterial responses to subsequently ingested antibiotics. In this study, we assessed if preexposure to azithromycin could accelerate the acquisition of resistance to ciprofloxacin in reference strain, WHO-F. In a morbidostat, we set two conditions in 3 vials each: mono-exposure (preexposure to Gonococcal Broth followed by exposure to ciprofloxacin) and dual sequential exposure (preexposure to azithromycin followed by exposure to ciprofloxacin).The growth of the cultures was measured by a software (MATLAB). The program decided if gonococcal broth or antibiotics were added to the vials in order to keep the evolution of the cultures. Samples were taken twice a week until the end of the experiment i.e. until resistance was achieved or cellular death. Additionally, six replicates of WHO-F WT and WHO-F with mutation, caused by azithromycin, were exposed to increasing concentrations of ciprofloxacin in plates to assess if there were differences in the rate of resistance emergence. We found that after 12 hours of pre-exposure to azithromycin, resilience to ciprofloxacin exposure increased. Pre-exposure to azithromycin did not, however, accelerate the speed to acquisition of ciprofloxacin resistance. We found that azithromycin does not accelerate the emergence of ciprofloxacin resistance, but there were differences in the molecular pathways to the acquisition of ciprofloxacin resistance: the strains preexpossed to azithromycin followed a different route (GyrA: S91F pathway) than the ones without antibiotic preexposure (GyrA:D95N pathway). However, the number of isolates is too small to draw such strong conclusions.
序贯暴露于不同抗生素的效果是一个研究不足的课题。阿奇霉素在人类体内的检测时间最长可达摄入后 28 天，并且可能会使细菌对随后摄入的抗生素产生反应。在这项研究中，我们评估了预先暴露于阿奇霉素是否可以加速参考菌株 WHO-F 对环丙沙星的耐药性获得。在一个恒化器中，我们在 3 个小瓶中设置了两种条件：单一暴露（预先暴露于淋球菌肉汤，然后暴露于环丙沙星）和双重序贯暴露（预先暴露于阿奇霉素，然后暴露于环丙沙星）。通过软件（MATLAB）测量培养物的生长。该程序决定是否向小瓶中添加淋球菌肉汤或抗生素，以保持培养物的进化。每周取样两次，直到实验结束，即直到获得耐药性或细胞死亡。此外，还将携带由阿奇霉素引起的突变的 WHO-F WT 和 WHO-F 的 6 个重复暴露于平板中增加的环丙沙星浓度下，以评估在耐药性出现率方面是否存在差异。我们发现，在预先暴露于阿奇霉素 12 小时后，对环丙沙星暴露的抵抗力增加。然而，预先暴露于阿奇霉素并没有加速获得环丙沙星耐药性的速度。我们发现阿奇霉素不会加速环丙沙星耐药性的出现，但在获得环丙沙星耐药性的分子途径上存在差异：预先暴露于阿奇霉素的菌株遵循不同的途径（GyrA：S91F 途径），而未暴露于抗生素的菌株则遵循不同的途径（GyrA：D95N 途径）。然而，分离株的数量太少，无法得出如此强有力的结论。
