title: Community-based surveillance in the united states of macrolide-resistant pediatric pharyngeal group A streptococci during 3 respiratory disease seasons.
abstract: BACKGROUND
  In 2001, a total of 48% of pharyngeal group A streptococci (GAS) from Pittsburgh children were macrolide resistant. We assessed macrolide resistance, resistance genes, and emm types among GAS in the United States.
  
  
  METHODS
  In prospective, multicenter, community-based surveillance of pharyngeal GAS recovered from children 3-18 years old during 3 respiratory seasons (the 2000-2001 season, the 2001-2002 season, and the 2002-2003 season), GAS were tested for macrolide resistance and underwent emm gene sequencing. Macrolide-resistant GAS were tested for resistance to clindamycin, and resistance genes were determined.
  
  
  RESULTS
  Erythromycin resistance was observed in 4.4% of isolates from the 2000-2001 season, 4.3% from the 2001-2002 season, and 3.8% from the 2002-2003 season (P=.80). Clindamycin resistance was found in 1.04% of isolates; annual rates of clindamycin resistance were stable (P=.75). The predominant resistance genotype each year was mef A (65%-76.9%; overall, 70.3%). Resistant isolates included strains representing 8-11 different emm types each year. Heterogeneity of emm subtypes, resistance genes, and clindamycin resistance was evident among resistant isolates within some emm types. Geographic variability in resistance rates was present each year.
  
  
  CONCLUSIONS
  The macrolide resistance rate among pharyngeal GAS was <5% and was stable over the 3 seasons. However, rates varied among sites each year. There was no evidence of spread of a specific resistant clone, increasing clindamycin resistance, or escalation in median erythromycin MICs.
authors.affiliation: Division of General Academic Pediatrics, Children's Memorial Hospital, Chicago, IL 60614, USA. rtanz@northwestern.edu
authors.forename: Robert R
authors.initials: RR
authors.lastname: Tanz
authors.forename: Stanford T
authors.initials: ST
authors.lastname: Shulman
authors.forename: Virginia D
authors.initials: VD
authors.lastname: Shortridge
authors.forename: William
authors.initials: W
authors.lastname: Kabat
authors.forename: Kathy
authors.initials: K
authors.lastname: Kabat
authors.forename: Emily
authors.initials: E
authors.lastname: Cederlund
authors.forename: Jason
authors.initials: J
authors.lastname: Rippe
authors.forename: Jill
authors.initials: J
authors.lastname: Beyer
authors.forename: Stella
authors.initials: S
authors.lastname: Doktor
authors.forename: Bernard W
authors.initials: BW
authors.lastname: Beall
mesh_terms: D002648:Child; D004351:Drug Resistance; D005260:Female; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008297:Male; D008826:Microbial Sensitivity Tests; D010372:Pediatrics; D010612:Pharyngitis / Q000382:microbiology*; D011159:Population Surveillance; D012111:Residence Characteristics; D012140:Respiratory Tract Diseases / Q000453:epidemiology / Q000382:microbiology*; D012621:Seasons; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000187:drug effects*; D014481:United States
chemical_list: D018942:Macrolides