AI-2/LuxS Is Involved in Increased Biofilm Formation by Streptococcus intermedius in the Presence of Antibiotics
AI-2/LuxS Is Involved in Increased Biofilm Formation by Streptococcus intermedius in the Presence of Antibiotics
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DOI：
10.1128/aac.00546-09
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发表时间：
2009-10-01
影响因子：
4.9
通讯作者：
Scheie, Anne A.
中科院分区：
文献类型：
--
作者：
Ahmed, Nibras A.;Petersen, Fernanda C.;Scheie, Anne A.
细菌利用群体感应通信来组织它们的行为，通过监测细菌信号的浓度，称为自诱导物（AI）。AI-2信号及其酶合酶（LuxS）在细菌中的广泛检测表明，AI-2是种间和种内的通信信号。我们以前已经表明，抗生素敏感性是受AI-2信号在链球菌咽峡炎。由于慢性感染涉及对抗生素治疗有弹性的持久生物膜，因此我们探索了当生物体暴露于氨苄青霉素、环丙沙星或四环素的亚MIC时AI-2/LuxS在中间链球菌生物膜形成和细胞活力中的作用。色葡萄将中间型野生型（WT）及其同基因luxS突变株（SI 006）暴露于亚MIC氨苄青霉素、环丙沙星或四环素。在微量滴定板中的聚苯乙烯盘上形成生物膜。为了评估增殖细胞活力，进行ATP微生物活力测定并测定CFU数。对于互补测定，使用AI-2前体二羟基戊二酮（DPD）作为SI 006的补充物。通过实时PCR定量相对luxS表达。所有三种抗生素的亚MIC均增加了S.中间型野生型然而，SI 006的生物膜形成不受影响或减少（P < 0.05）。生物膜和增殖细胞培养物的细菌活力测试表明，SI 006比WT对抗生素更敏感。DPD补充了luxS突变体表型。实时PCR显示，在增加生物膜形成的抗生素浓度存在下，luxS表达发生了适度但显著的变化。总之，在S.在中间型中，AI-2/LuxS参与抗生素敏感性并在抗生素的亚MIC下增加生物膜形成。
Bacteria utilize quorum-sensing communication to organize their behavior by monitoring the concentration of bacterial signals, referred to as autoinducers (AIs). The widespread detection of AI-2 signals and its enzymatic synthase (LuxS) in bacteria suggests that AI-2 is an inter-and intraspecies communication signal. We have previously shown that antibiotic susceptibility is affected by AI-2 signaling in Streptococcus anginosus. Since chronic infections involve persistent biofilms resilient to antibiotic treatment, we explored the role of AI-2/LuxS in Streptococcus intermedius biofilm formation and cell viability when the organism was exposed to sub-MICs of ampicillin, ciprofloxacin, or tetracycline. The S. intermedius wild type (WT) and its isogenic luxS mutant, strain SI006, were exposed to sub-MICs of ampicillin, ciprofloxacin, or tetracycline. Biofilms were formed on polystyrene discs in microtiter plates. To assess planktonic cell viability, the ATP microbial viability assay was performed and the numbers of CFU were determined. For complementation assays, the AI-2 precursor dihydroxy pentanedione (DPD) was used as a supplement for SI006. Relative luxS expression was quantified by real-time PCR. The sub-MICs of all three antibiotics increased biofilm formation in S. intermedius WT. However, biofilm formation by SI006 was either unaffected or reduced (P < 0.05). Bacterial viability tests of biofilm and planktonic cell cultures indicated that SI006 was more susceptible to antibiotics than the WT. DPD complemented the luxS mutant phenotype. Real-time PCR revealed modest yet significant changes in luxS expression in the presence of antibiotic concentrations that increased biofilm formation. In conclusion, in S. intermedius, AI-2/LuxS was involved in antibiotic susceptibility and increased biofilm formation at sub-MICs of antibiotic.