Intermedilysin release by Streptococcus intermedius: effects of various antibacterial drugs at sub-MIC levels |
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Authors: | Taylor Mark B Oh Janice H L Kang K L Chow Vincent T K |
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Institution: | Department of Microbiology, National University of Singapore, Blk MD4, 5 Science Drive 2, Singapore 117597, Singapore. micmbt@nus.edu.sg |
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Abstract: | Intermedilysin is a cytolytic toxin produced by Streptococcus intermedius, a pathogen of humans. In vitro studies showed that exposure of S. intermedius to sub-minimum inhibitory concentration (MIC) levels (1/2 MIC) of protein-inhibiting antibiotics and nucleic acid-inhibiting antibiotics decreased intermedilysin release by S. intermedius. The most potent antibiotic was clindamycin. On the other hand, exposure to cell wall-inhibiting antibiotics generally showed insignificant changes in intermedilysin release at sub-MIC concentrations. Investigations into possible mechanisms underlying this sub-MIC effect with clindamycin showed that there was selective decrease in biosynthesis and release of toxin after exposure to 1/2 MIC condition. However, no significant differences in the mRNA levels of the intermedilysin gene were observed. |
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Keywords: | Streptococcus intermedius Sub-minimum inhibitory concentration Intermedilysin |
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