Abstract：
The tellurite toxicity in Haemophilus influenzae and H. parainfluenzae remains unclear. To understand the potential of tellurite as a therapeutic option for these bacteria, we investigated the antimicrobial efficacy of AS101, a tellurium compound, against H. influenzae and H. parainfluenzae and the molecular basis of their differences in AS101 susceptibility. Through broth microdilution, we examined the minimum inhibitory concentration (MIC) of AS101 in 51 H. influenzae and 28 H. parainfluenzae isolates. Whole-genome sequencing was performed on the H. influenzae isolates to identify genetic variations associated with AS101 susceptibility. The MICs of AS101 were ≦ 4, 16-32, and ≧ 64 μg/mL in 9 (17.6%), 12 (23.5%), and 30 (58.8%) H. influenzae isolates, respectively, whereas ≦ 0.5 μg/mL in all H. parainfluenzae isolates, including multidrug-resistant isolates. Time-killing kinetic assay and scanning electron microscopy revealed the in vitro bactericidal activity of AS101 against H. parainfluenzae. Forty variations in nine tellurite resistance-related genes were associated with AS101 susceptibility. Logistic regression, receiver operator characteristic curve analysis, Venn diagram, and protein sequence alignment indicated that Val195Ile substitution in TerC, Ser93Gly in Gor (glutathione reductase), Pro44Ala/Ala50Pro in NapB (nitrate reductase), Val307Leu in TehA (tellurite resistance protein), Cys105Arg in CysK (cysteine synthase), and Thr364Ser in Csd (Cysteine desulfurase) were strongly associated with reduced AS101 susceptibility, whereas Ser155Pro in TehA with increased AS101 susceptibility. In conclusions, the antimicrobial efficacy of AS101 is high against H. parainfluenzae but low against H. influenzae. Genetic variations and corresponding protein changes relevant to AS101 non-susceptibility in H. influenzae were identified.
摘要：
碲酸盐对流感嗜血杆菌和副流感嗜血杆菌的毒性尚不清楚。为了了解亚碲酸盐作为这些细菌的治疗选择的潜力，我们研究了碲化合物AS101的抗菌功效，针对流感嗜血杆菌和副流感嗜血杆菌及其AS101易感性差异的分子基础。通过肉汤微量稀释，我们检测了AS101在51株流感嗜血杆菌和28株副流感嗜血杆菌中的最低抑菌浓度（MIC）。对流感嗜血杆菌分离株进行全基因组测序以鉴定与AS101易感性相关的遗传变异。AS101的MIC≤4，16-32，在9(17.6%)中≥64μg/mL，12（23.5%），和30（58.8%）流感嗜血杆菌分离株，分别,而在所有副流感嗜血杆菌分离物中≤0.5μg/mL，包括多重耐药的分离株。时间杀伤动力学测定和扫描电子显微镜显示了AS101对副流感嗜血杆菌的体外杀菌活性。9个碲酸盐抗性相关基因的40个变异与AS101易感性相关。Logistic回归，接收机操作员特性曲线分析，维恩图,和蛋白质序列比对表明TerC中的Val195Ile取代，Gor中的Ser93Gly（谷胱甘肽还原酶），Pro44Ala/Ala50Pro在NapB（硝酸还原酶），Val307Leu在TehA（碲酸盐抗性蛋白）中，CysK（半胱氨酸合酶）中的Cys105Arg，Csd（半胱氨酸脱硫酶）中的Thr364Ser与AS101易感性降低密切相关，而Ser155Pro在TehA中具有增加的AS101易感性。在结论中，AS101对副流感嗜血杆菌的抗菌效力较高，但对流感嗜血杆菌的抗菌效力较低。确定了与流感嗜血杆菌中AS101非易感性相关的遗传变异和相应的蛋白质变化。
