Active Bacterial Core surveillance (ABCs) is a core component of CDC’s Emerging Infections Programs (EIP) network. EIP is 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 in the surveillance population, ABC surveillance personnel complete a case report form [2 pages] with basic demographic and other information. Additionally, personnel send bacterial isolates to CDC and other reference laboratories for further laboratory evaluation.

ABCs also provides an infrastructure for further public health research, including:

  • Special studies to identify risk factors for disease
  • Post-licensure vaccine efficacy evaluations
  • Analyses to monitor the effectiveness of prevention policies

History and Current Scope

CDC initially established ABCs in four states in 1995. It currently operates among 10 EIP sites across the United States, representing a population of approximately 44 million people. At this time, ABCs conducts surveillance for five pathogens:

Enhanced pertussis surveillance started in 2011 through the ABCs/EIP network. ABCs surveillance for methicillin-resistant Staphylococcus aureus (MRSA) began in 2004 and in 2015, these activities transitioned to the Hospital Acquired Community Interface (HAIC) network, which is also under EIP. ABCs conducted active surveillance for legionellosis from 2011 through 2015.


CDC uses ABCs data and infrastructure to track disease trends. For example, ABCs data documented the decline in pneumococcal disease following introduction of the pediatric pneumococcal conjugate vaccine. ABCs also documented the emergence of serogroup Y meningococcal disease.

Additionally, CDC uses ABCs data to evaluate vaccine effectiveness. Past evaluations looked at the effectiveness of meningococcal conjugate vaccine in adolescents and pneumococcal conjugate vaccine in children and adults.

ABCs also provides critical information to inform public health policy. For example, ABCs data formed the basis of revised CDC guidelines recommending the use of universal screening of pregnant women to prevent early-onset GBS infections. ABCs data also formed the basis for the prevention of GAS infections among household contacts of people with invasive disease, as well as among postpartum and post-surgical patients. CDC developed a program to assist state and local health departments with surveillance for MRSA and drug-resistant S. pneumoniae, based primarily on lessons learned from ABCs.