title: Identification of a mutation associated with erythromycin resistance in Bordetella pertussis: implications for surveillance of antimicrobial resistance.
abstract: Erythromycin treatment failures and in vitro resistance of Bordetella pertussis have been reported on several occasions in the past few years, but the mechanism of resistance has not been described. One potential mechanism, genetic modification of the erythromycin-binding site on the 23S rRNA of the 50S ribosomal subunit, has been observed in other bacteria. To explore this possibility, we amplified the portion of the 23S rRNA gene encoding the central loop of domain V. DNA sequencing and restriction fragment length polymorphism of the PCR products showed that each of the four erythromycin-resistant B. pertussis strains tested contained an A-to-G transition mutation at position 2058 (Escherichia coli numbering) of the 23S rRNA gene. The mutation was not found in seven erythromycin-susceptible isolates tested. Two of the resistant isolates were heterozygous, containing at least one mutant copy and one wild-type copy of the 23S rRNA gene. These results indicate that erythromycin resistance in these strains is likely due to a mutation of the erythromycin-binding site in the 23S rRNA gene. Identification of the resistance mechanism will facilitate development of molecular susceptibility testing methods that can be used directly on clinical specimens in the absence of an isolate.
authors.affiliation: Minnesota Department of Health, Minneapolis. Crossroads Medical Center, Chaska, Minnesota, USA. joanne.bartkus@health.state.mn.us
authors.forename: J M
authors.initials: JM
authors.lastname: Bartkus
authors.forename: B A
authors.initials: BA
authors.lastname: Juni
authors.forename: K
authors.initials: K
authors.lastname: Ehresmann
authors.forename: C A
authors.initials: CA
authors.lastname: Miller
authors.forename: G N
authors.initials: GN
authors.lastname: Sanden
authors.forename: P K
authors.initials: PK
authors.lastname: Cassiday
authors.forename: M
authors.initials: M
authors.lastname: Saubolle
authors.forename: B
authors.initials: B
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Long
authors.forename: A R
authors.initials: AR
authors.lastname: Harrison
authors.forename: J M
authors.initials: JM
authors.lastname: Besser
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001886:Bordetella pertussis / Q000187:drug effects* / Q000235:genetics; D002648:Child; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology*; D005260:Female; D006579:Heterozygote; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004917:Erythromycin