Serum bactericidal activity of extended-release clarithromycin against macrolide-resistant strains of Streptococcus pneumoniae.
OBJECTIVE
To investigate the serum bactericidal activity (SBA) over time of extended-release clarithromycin against moderately resistant strains of Streptococcus pneumoniae.


METHODS
Prospective, single-dose pharmacodynamic study.


METHODS
University-affiliated research center.


METHODS
Eleven healthy male volunteers.


METHODS
All volunteers received a single dose of extended-release clarithromycin as two 500-mg tablets, and blood samples were obtained at 0, 2, 6, 12, and 24 hours after administration of the dose.


RESULTS
For each blood sample, a serum bactericidal titer (SBT) was determined against S. pneumoniae strains with minimum inhibitory concentrations (MICs) of 0.5, 1.0, 2.0, 4.0, and 8.0 microg/ml to clarithromycin. The median SBT was determined for each time period. The extended-release formulation of clarithromycin exhibited SBA for 24 hours against pneumococcal strains with MICs of 0.5, 1.0, and 2.0 microg/ml. No SBA was observed against isolates with MICs of 4.0 or 8.0 microg/ml.


CONCLUSIONS
The extended-release formulation of clarithromycin, taken once/day, will provide SBA for 24 hours against strains of S. pneumoniae with MICs of 2.0 microg/ml or less.
Stein
Gary E
GE
Department of Medicine, Michigan State University, East Lansing 48824, USA.
Schooley
Sharon
S
D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D017291:Clarithromycin / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D003692:Delayed-Action Preparations; D004351:Drug Resistance; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000382:microbiology; D015610:Serum Bactericidal Test; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics; D013997:Time Factors
D000900:Anti-Bacterial Agents; D003692:Delayed-Action Preparations; D017291:Clarithromycin