Antibiotic Resistance Threats in the United States, 2013 report

Technical Appendix
Clindamycin-Resistant Group B Streptococcus
Methods
Estimates of the proportion of GBS isolates resistant to erythromycin
and clindamycin are from isolates collected through Active Bacterial
Core surveillance (ABCs), which is part of CDC’s Emerging Infections
Program (EIP) network. 1 ABCs conducts surveillance for invasive
bacterial infections, including GBS, at 10 sites located throughout
the United States representing a population of approximately 32 million persons. Isolates
are collected currently from 7 of these states, from ~85% of the cases in these states
(approximately ~1500 isolates per year) and sent to reference laboratories for susceptibility
testing to twelve different antibiotics using Clinical and Laboratory Standards Institute
(CLSI) methods. Estimates of severe disease are also from ABCs. 2
Cases and deaths were estimated by applying the 2010 overall resistant rate to clindamycin
(28%) from the ABCs antimicrobial susceptibilities report 3 to total cases (27,000) and total
deaths (1,575) reported in the 2011 ABCs GBS surveillance report. 2
References
1 CDC. Active Bacterial Core Surveillance Methodology (2012). http://www.cdc.gov/abcs/
index.html [Accessed 5/23/2013].
2 CDC. Active Bacterial Core Surveillance (ABCs) Report, Emerging Infections Program
network, Group B Streptococcus (2011). http://www.cdc.gov/abcs/reports-findings/
survreports/gbs11.pdf [Accessed 7/23/2013].
3 CDC. Antimicrobial Susceptibilities Among Group B Streptococcus Isolates, Active
Bacterial Core Surveillance (ABCs) (2010). http://www.cdc.gov/abcs/reports-findings/
survreports/gbs10-suscept.html [Accessed 7/23/2013].
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