What question did this study set out to answer?

Standardize the phenotypic differentiation of macrolide, lincosamide, and streptogramin B resistance mechanisms among erythromycin-resistant Streptococcus pneumoniae isolates.

April 1, 2001Journal of Clinical MicrobiologyOpen Access

Differentiation of Resistance Phenotypes among Erythromycin-Resistant Pneumococci

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Standardize the phenotypic differentiation of macrolide, lincosamide, and streptogramin B resistance mechanisms among erythromycin-resistant Streptococcus pneumoniae isolates.
Evaluated 85 erythromycin-resistant clinical isolates of S. pneumoniae (MIC ≥ 1 µg/ml) using an erythromycin-clindamycin double-disk diffusion test.
Conducted MIC induction testing by measuring antibiotic susceptibility before and after pre-exposure to 0.05 µg/ml erythromycin.
Developed a triple-disk diffusion test by adding a rokitamycin disk to simultaneously distinguish constitutive and inducible phenotypes.
The double-disk test identified 20 mef(E)-positive strains with the M phenotype and 65 erm(AM)-positive strains with the constitutive MLS (cMLS) phenotype, with zero strains displaying inducible clindamycin resistance.
Rokitamycin induction testing separated the 65 erm(AM) isolates into 10 true cMLS strains (constitutive rokitamycin resistance) and 55 inducible iMcLS strains that exhibited a greater than three-dilution MIC increase after induction.
The triple-disk assay accurately differentiated the M phenotype, true cMLS phenotype, and the newly designated iMcLS phenotype in a single test.

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Implication

Laboratory study demonstrates distinct inducible macrolide resistance patterns in Streptococcus pneumoniae, indicating that rokitamycin triple-disk testing refines phenotypic classification.

Cite This Study

Montanari et al. (2001) studied this question.

synapsesocial.com/papers/6a8bd867c12eaf65c8b21f21 https://doi.org/10.1128/jcm.39.4.1311-1315.2001

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Implication

Laboratory study demonstrates distinct inducible macrolide resistance patterns in Streptococcus pneumoniae, indicating that rokitamycin triple-disk testing refines phenotypic classification.

Differentiation of Resistance Phenotypes among Erythromycin-Resistant Pneumococci

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Discussion

Implication

Cite This Study

Differentiation of Resistance Phenotypes among Erythromycin-Resistant Pneumococci

Key Points

Discussion

Implication

Cite This Study

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