In vitro activity of tigecycline against contemporary clinical isolates of Streptococcus pneumoniae
Abstract number: P604
Blondeau J., Borsos S.
Objectives:Streptococcus pneumoniae (SP) remains amongst the most prevalent causes of community-acquired respiratory tract infections. Both penicillin and multidrug resistant strains may compromise drug use and ongoing interest in newer antimicrobial agents necessitates ongoing testing of clinical strains. We determined the in vitro activity of tigecycline against blood and respiratory SP isolates.
Methods: Minimum inhibitory concentration (MIC) testing was based on current Clinical and Laboratory Standards Institute procedure by microbroth dilution using 105 cfu/ml tested against doubling drug dilutions in appropriate media. Following incubation, the lowest drug concentration preventing growth was the MIC. For mutant prevention concentration (MPC) testing, 109 CFUs were applied to solidified Todd-Hewitt broth containing doubling drug dilution and following incubation, the lowest concentration preventing growth was the MPC.
Results: A total of 174 isolates (47 blood, 127 respiratory) were tested. MIC values were not different for blood versus respiratory isolates. The MIC50/90/100 (mg/L) values were 0.031/0.063/0.063. The MIC range values were 0.0080.063 mg/L. Against penicillin intermediate and resistant strains, tigecycline MIC values ranged from 0.0080.063 mg/L. MPC values ranged from 0.0630.5 mg/L.
Conclusions: Tigecycline was highly active in vitro against contemporary blood and respiratory SP isolates. No isolate had an MIC above 0.063 mg/L and MIC results were not different against penicillin susceptible or resistant strains. MPC values were 0.0630.5 mg/L. This data suggests tigecycline to be highly active against SP isolates and also demonstrates a low propensity to select for resistance.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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