Program Schedule

Resistance among Invasive Group A Streptococcal Infections, United States, 1999-2012

Session: Poster Abstract Session: Public Health
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Macrolide resistance among group A Streptococcus (GAS) is common in many countries. We analyzed prevalence of resistance to erythromycin (EryR) and other antibiotics among GAS isolates obtained from CDC’s Active Bacterial Core surveillance (ABCs) over a 14-year period.

Methods: ABCs is active, laboratory- and population-based surveillance for select bacterial infections in 10 geographically diverse U.S. sites. Isolates from invasive GAS infections were collected in participating ABCs sites from 1999-2012. Susceptibility was assessed using broth microdilution and D-zone testing for inducible clindamycin resistance (CliR); emm typing was performed using DNA sequencing.

Results: We tested 9175 (85%) isolates from 10,794 invasive GAS cases; 10.5% were EryR. Both EryR and CliR increased over the 14 years (test for trend: P<0.001). Marked yearly shifts in EryR prevalence occurred among several ABCs sites: CA (2001: 8.5%; 2006: 23.6%; 2010: 4.0%), MD (1999: 3.4%; 2008: 34.2%; 2012: 8.0%) and OR (2007: 4.4%; 2012: 28.3%). No penicillin or cephalosporin resistance was found. Among >85 emm types, 10 (emm 12, 49, 58, 73, 75, 76, 83, 92, 94, 114) accounted for 21% of all isolates but 65% of EryR isolates. Site-specific variability in EryR prevalence was primarily due to fluctuations of these emm types. Among 105 EryR isolates from 2012, 62 (59%) were inducibly CliR and 35 (41%) constitutively CliR; 72 of CliR (74.2%) were also tetracycline-resistant.  Data from 2001-2010 indicated that a genetic element that contains both ermTR and tetM accounted for most CliR. The patient case fatality ratio did not differ by EryR (10.7% EryR vs 12.2% erythromycin susceptible; P=0.18). EryR infections were more common (P<0.05) among men than women (11.7% vs. 9.3%) and among persons age 18-34 (13.2%) and 50-64 years (13.1%) than other age groups. EryR was lowest among children age <5 years (7.5%). 

Conclusion: Macrolide resistance among invasive GAS infections in the U.S. gradually increased over 14 years. However, local frequency of macrolide-resistant GAS infections fluctuated markedly, depending on circulating strains. Community-specific susceptibility testing is important for clinical management. Penicillin remains a good choice for therapy of invasive GAS infections.

Chris Van Beneden, MD, MPH1, Lesley Mcgee, PhD1, Yusra Ahmad2, Bernard Beall, PhD1, Lee Harrison, MD MPH3, Monica M. Farley, MD4, Megin Nichols, DVM, MPH, DACVPM5, Ann Thomas, MD, MPH6, Susan Petit, MPH7, Mary Lou Lindegren, MD, MPH8, Mirasol M. Apostol, MPH9, Jillian Karr, BS, MPH10, Lisa Miller, MD, MSPH11 and Ruth Lynfield, MD12, (1)Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, (2)Centers for Disease Control and Prevention, Atlanta, GA, (3)Emerging Infections Program, Pittsburgh, PA, (4)Georgia Emerging Infections Program, Decatur, GA, (5)New Mexico Department of Public Health, Santa Fe, NM, (6)Emerging Infections Program, Portland, OR, (7)Connecticut Emerging Infections Program, New Haven, CT, (8)Vanderbilt University School of Medicine, Nashville, TN, (9)California Emerging Infections Program, Oakland, CA, (10)New York State Dept of Health, Emerging Infections Program, Rochester, NY, (11)Colorado Department of Public Health and Environment, Denver, CO, (12)Minnesota Department of Health, St. Paul, MN


C. Van Beneden, None

L. Mcgee, None

Y. Ahmad, None

B. Beall, None

L. Harrison, None

M. M. Farley, None

M. Nichols, None

A. Thomas, None

S. Petit, None

M. L. Lindegren, None

M. M. Apostol, None

J. Karr, None

L. Miller, None

R. Lynfield, None

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