Correlation of two-component signaling system ComD/ComE and β-lactam antibiotics resistance of Streptococcus pneumoniae
10.3760/cma.j.issn.0254-5101.2010.11.014
- VernacularTitle:二元信号系统ComD/ComE与肺炎链球菌对β-内酰胺类抗生素耐药的相关性
- Author:
Huan FAN
;
Jie YAN
;
Aihua SUN
- Publication Type:Journal Article
- Keywords:
Streptococcus pneumoniae;
Two-component signaling system ComD/ComE;
β-lactam antibiotics;
Drug resistance;
Closantel;
Expression regulation
- From:
Chinese Journal of Microbiology and Immunology
2010;30(11):1038-1043
- CountryChina
- Language:Chinese
-
Abstract:
Objective To generate a comD gene knock-out mutant of Streptococcus pneumoniae,and determine the correlation of comD gene and the bacterial resistance against β-lactam antibiotics and understand the effect of closantel down-regulating comD, comE and comC mRNA levels. Methods A suicide plasmid pEVP3comD was constructed for comD gene knock-out and a comD gene knock-out mutant (comD-)was generated through homologous recombination and insertion inactivation. PCR and immunofluorescence method were used to identify the comD- mutant and real-time fluorescence quantitative PCR was applied to detect the changes of comD, comE and comC mRNA levels before and after closantel treatment in comD-mutant and wild-type strain. Double agar dilution method was performed to determine the sensitivity of comD- mutant and wild-type strain to penicillin G and cefotaxime. Results The comD gene in genome DNA of the generated comD- mutant was inactivated by sequencing and immunofluorescence detection. 50 μ mol/L or 100 μmol/L closantel had a function to down-regulate the comD, comE and comC mRNA levels ( P ＜ 0. 05) whereas 25 μmol/L closantel did not. Both the MIC values of penicillin G and cefotaxime inhibiting comD- mutant were 32 μg/ml which was significantly higher than that of wild-type strain (0.06 μg/ml and 1 μg/ml). Conclusion In this study a comD gene knock-out mutant of S. pneumoniae was successfully generated. There is a close correlation between comD gene and β-lactam antibiotics resistance of S. pneumoniae. Closantel has a function to inhibit the competence formation of S. pneumoniae through down-regulating the transcription levels of comD, comE and comC genes.
