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Published on: December 27, 2016
In vitro effects of penicillin and telithromycin on the expression of Streptococcus pneumoniae capsule
Itzhak Brook1, Jeffrey N Hausfeld
1Department of Pediatrics and Medicine, Georgetown University and George Washington University, Schools of Medicine, Washington, DC, USA. ib6@georgetown.edu
Objective:
To evaluate the effects of subinhibitory concentrations of penicillin and telithromycin on capsular formation by Streptococcus pneumoniae.
Methods:
A total of 60 isolates of S. pneumoniae, 20 susceptible, 20 intermediately resistant and 20 resistant to penicillin, were studied. All isolates were susceptible to telithromycin.
Results:
All isolates were capsulate when grown without antibiotics. Encapsulation was lower after incubation with telithromycin as compared with penicillin in isolates susceptible to penicillin (20% versus 75%), in those intermediately resistant to penicillin (25% versus 95%) and in isolates fully resistant to penicillin (15% versus 100%) (P < 0.01).
Conclusions:
Telithromycin appears to be superior to penicillin in reducing the expression of the capsule by S. pneumoniae.
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