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Comparative effects of clindamycin and ampicillin on superantigenic activity of Streptococcus pyogenes
S Sriskandan1, A McKee, L Hall
1Department of Infectious Diseases, Royal Postgraduate Medical School, London, UK.
Abstract:
We have tested the ability of Streptococcus pyogenes to produce streptococcal pyrogenic exotoxin A (SPEA) and superantigenic activity in the presence of sub-inhibitory concentrations of ampicillin and clindamycin. After 6 h of culture, SPEA production by S. pyogenes was higher in broths containing ampicillin (715.7 +/- 296.4 pg/10(6) cfu) than in broths containing clindamycin (167.1 +/- 31.9 pg/10(6) cfu), a difference that was not significant (P = 0.25). Promitogenic activity of bacterial supernatants was also greater in ampicillin-treated cultures (467.5 +/- 17.2 ccpm/10(6) cfu) than in clindamycin-treated cultures (169.2 +/- 8.9 ccpm/10(6) cfu), a difference that was highly significant (P = 0.0001). The data support the use of clindamycin in the treatment of streptococcal toxic shock-like syndrome, in order to inhibit superantigen synthesis.
Insights
Sub-inhibitory ampicillin increased Streptococcus pyogenes toxin production more than clindamycin. Clindamycin is recommended for treating streptococcal toxic shock-like syndrome to reduce superantigen synthesis.
Area of Science:
- Microbiology
- Toxicology
- Pharmacology
Background:
- Streptococcus pyogenes can cause severe infections like streptococcal toxic shock-like syndrome (STSS).
- Superantigens, such as streptococcal pyrogenic exotoxin A (SPEA), play a key role in STSS pathogenesis.
- Sub-inhibitory antibiotic concentrations may affect bacterial toxin production.
Purpose of the Study:
- To investigate the effect of sub-inhibitory ampicillin and clindamycin on SPEA production and superantigenic activity in Streptococcus pyogenes.
- To determine the optimal antibiotic choice for managing STSS by assessing their impact on superantigen synthesis.
Main Methods:
- Streptococcus pyogenes cultures were treated with sub-inhibitory concentrations of ampicillin and clindamycin.
- Streptococcal pyrogenic exotoxin A (SPEA) production was quantified after 6 hours of incubation.
- Superantigenic (promitogenic) activity of bacterial supernatants was measured.
Main Results:
- SPEA production was higher in ampicillin-treated cultures compared to clindamycin-treated cultures, though not statistically significant (P=0.25).
- Superantigenic activity was significantly higher in ampicillin-treated cultures (P=0.0001) than in clindamycin-treated cultures.
- Clindamycin significantly inhibited both SPEA production and superantigenic activity.
Conclusions:
- Clindamycin demonstrates a greater inhibitory effect on Streptococcus pyogenes superantigen synthesis compared to ampicillin at sub-inhibitory concentrations.
- These findings support the use of clindamycin as a preferred therapeutic agent for streptococcal toxic shock-like syndrome to mitigate toxin-mediated pathology.