Community-based surveillance in the united states of macrolide-resistant pediatric pharyngeal group A streptococci during 3 respiratory disease seasons.
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.
Tanz
Robert R
RR
Division of General Academic Pediatrics, Children's Memorial Hospital, Chicago, IL 60614, USA. rtanz@northwestern.edu
Shulman
Stanford T
ST
Shortridge
Virginia D
VD
Kabat
William
W
Kabat
Kathy
K
Cederlund
Emily
E
Rippe
Jason
J
Beyer
Jill
J
Doktor
Stella
S
Beall
Bernard W
BW
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
D018942:Macrolides