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[Antimicrobial activities of clindamycin against clinical isolated Streptococcus pneumoniae]
Y Suzuki1, R Ishihara, Y Ishii
1Section of Studies, Tokyo Clinical Research Center.
Abstract:
We investigated antimicrobial activity of clindamycin (CLDM) against clinically isolated Streptococcus pneumoniae in 1996. The results are summarized as follows; 1. The detection frequencies of macrolides (MLs)-resistance against penicillin (PC)-susceptible S. pneumoniae (PSSP) was 48.0% and those against PC-intermediate S. pneumoniae (PISP)/ PC-resistant S. pneumoniae (PRSP) was 92.0%. 2. It was found that the ratio of MLs-inducible resistant strains of PSSP was 24.6% and that of PISP/PRSP was 66.0%. MLs-constitutive resistant strains of PSSP accounted for 24.0% and that of PISP/PRSP for 26.0%. MLs-constitutive resistant strains was relatively frequent in PSSP and MLs-inducible resistant strains was frequent in PISP/PRSP. 3. CLDM showed strong antimicrobial activity against MLs-inducible resistant strains. The MIC70 of CLDM against PSSP was < or = 0.025 microgram/ml and that against PISP/PRSP was 0.1 microgram/ml. From these results, it was suggested that CLDM is effective against the infection of PISP/PRSP where the detection frequency of MLs-inducible strains was high. 4. Antimicrobial activity of CLDM was found to be strong against MLs-inducible resistant strains, but to be weak against MLs-constitutive resistant strains. When S. pneumoniae is detected, susceptibility of the strain to CLDM should be examined.
Insights
Clindamycin (CLDM) demonstrates potent activity against macrolide (MLs)-inducible resistant Streptococcus pneumoniae strains, particularly those resistant to penicillin. Susceptibility testing for CLDM is recommended when S. pneumoniae is detected.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Macrolide resistance in Streptococcus pneumoniae is a growing clinical concern.
- Penicillin-intermediate and resistant strains exhibit high rates of macrolide resistance.
- Understanding resistance mechanisms is crucial for effective antibiotic therapy.
Purpose of the Study:
- To evaluate the in vitro antimicrobial activity of clindamycin (CLDM) against clinical isolates of Streptococcus pneumoniae.
- To assess CLDM's efficacy against macrolide-resistant S. pneumoniae strains, considering different penicillin susceptibility profiles.
- To determine the prevalence of inducible and constitutive macrolide resistance mechanisms.
Main Methods:
- Antimicrobial susceptibility testing of S. pneumoniae isolates using clindamycin.
- Determination of minimum inhibitory concentration (MIC70) values for CLDM.
- Classification of isolates based on penicillin susceptibility (PSSP, PISP, PRSP) and macrolide resistance phenotype (inducible vs. constitutive).
Main Results:
- High frequencies of macrolide resistance were observed in penicillin-intermediate/resistant S. pneumoniae (92.0%) compared to susceptible strains (48.0%).
- MLs-inducible resistance was more prevalent in PISP/PRSP (66.0%) than PSSP (24.6%), while MLs-constitutive resistance was more frequent in PSSP (24.0%).
- Clindamycin exhibited strong activity against MLs-inducible resistant strains (MIC70 ≤ 0.025 µg/ml for PSSP, 0.1 µg/ml for PISP/PRSP), but weak activity against MLs-constitutive resistant strains.
Conclusions:
- Clindamycin is effective against macrolide-inducible resistant Streptococcus pneumoniae, especially penicillin-intermediate/resistant strains.
- The high prevalence of inducible resistance in PISP/PRSP suggests clindamycin as a potential therapeutic option.
- Antimicrobial susceptibility testing for clindamycin is recommended for all S. pneumoniae infections to guide treatment decisions.