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Active Bacterial Core surveillance (ABCs) is a core component of CDC’s Emerging Infections Programs (EIP) network, a collaboration between CDC, state health departments, and universities. ABCs is an active laboratory- and population-based surveillance system for invasive bacterial pathogens of public health importance. For each case of invasive disease in the surveillance population, a case report form with basic demographic and other information is completed and bacterial isolates are sent to CDC and other reference laboratories for additional laboratory evaluation. ABCs also provides an infrastructure for further public health research, including special studies to identify risk factors for disease, evaluate vaccine efficacy after licensure, and monitor the effectiveness of prevention policies.

ABCs was initially established in four states in 1995. It currently operates among 10 EIP sites across the United States, representing a population of approximately 43 million people. At this time, ABCs conducts surveillance for five pathogens: group A and group B Streptococcus (GAS, GBS), Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae. Additionally, active surveillance for legionellosis was conducted from 2011 through 2015 and enhanced surveillance for pertussis started in 2011 through the ABCs/EIP network. Surveillance for methicillin-resistant Staphylococcus aureus (MRSA) is ongoing since 2009. However, activities have transitioned and are now part of the Hospital Acquired Community Interface (HAIC) network, also under EIP.

ABCs data and infrastructure have been used to track disease trends, including the decline in pneumococcal disease following the introduction of the pediatric pneumococcal conjugate vaccine and the emergence of serogroup Y meningococcal disease. Additionally, these data have been used to evaluate vaccine effectiveness for several vaccines, including meningococcal conjugate vaccine in adolescents and pneumococcal conjugate vaccine in children and adults. ABCs has also contributed to public health policy by providing information that formed the basis of revised CDC guidelines recommending the use of universal screening of pregnant women to prevent early-onset GBS infections and the prevention of GAS infections among household contacts of people with invasive disease, as well as among postpartum and post-surgical patients. A program to assist state and local health departments with surveillance for MRSA and drug-resistant S. pneumoniae has been developed, based primarily on lessons learned from ABCs.