Prevalence of Macrolide Resistance Mechanisms in Streptococcus pneumoniae Isolates from a Multicenter Antibiotic Resistance Surveillance Study Conducted in the United States in 1994–1995

Two main mechanisms of macrolide resistance have been described in erythromycin-resistant Streptococcus pneumoniae (ERSP): a ribosomal methylase, ErmAM, and a macrolide efflux pump, MefE. In this study, we examined the prevalence of these mechanisms in 114 clinical isolates of ERSP from a 30-center...

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Bibliographic Details
Published in:Clinical infectious diseases 1999-11, Vol.29 (5), p.1186-1188
Main Authors: Shortridge, Virginia D., Doern, Gary V., Brueggemann, Angela B., Beyer, Jill M., Flamm, Robert K.
Format: Article
Language:English
Subjects:
Anti-Bacterial Agents - pharmacology
Antibacterial agents
Antibiotic resistance
Antibiotics. Antiinfectious agents. Antiparasitic agents
Biological and medical sciences
Clinical Articles
DNA-Binding Proteins - genetics
Drug Resistance, Microbial
ermAM gene
Erythromycin - pharmacology
Humans
Infectious diseases
Labor standards
Lincosamides
Macrolides
Medical sciences
mefE gene
Methylase
Microbial Sensitivity Tests
Pharmacology. Drug treatments
Phenotypes
Resistance mechanisms
Streptococcus pneumoniae
Streptococcus pneumoniae - drug effects
Streptococcus pneumoniae - genetics
Surveillance
Time Factors
Transcription Factors - genetics
United States
USA
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Summary:Two main mechanisms of macrolide resistance have been described in erythromycin-resistant Streptococcus pneumoniae (ERSP): a ribosomal methylase, ErmAM, and a macrolide efflux pump, MefE. In this study, we examined the prevalence of these mechanisms in 114 clinical isolates of ERSP from a 30-center study conducted in the United States between November 1994 and April 1995. The isolates were screened by polymerase chain reaction for the presence of known macrolide resistance genes. Seventy (61%) ERSP contained the macrolide efflux gene (mefE), whereas 36 isolates (32%) contained the biosomal methylase gene (ermAM). Isolates that were ermAM-positive had constitutive macrolide resistance. The minimum inhibitory concentrations (for which 90% of isolates were susceptible) of clarithromycin for the efflux-positive strains were much lower than those for the ermAM-positive strains (4 μg/mL vs. >128 μg/mL, respectively). The efflux mechanism is the predominant form of macrolide resistance in the United States.
ISSN:1058-4838
1537-6591
DOI:10.1086/313452