Active Bacterial Core surveillance (ABCs)

ABCs (Group A Streptococcus)

Group A Streptococcus Bacteria on Human Neutrophil. Photo courtesy NIAID (


CEIP conducts surveillance for invasive bacterial diseases due to pathogens of public health importance in Alameda, Contra Costa, and San Francisco counties. For each case of invasive disease in the study population, CEIP generates a case report with basic demographic information and sends bacterial isolates from normally sterile sites to CDC for laboratory testing.


Main Components

The main components of ABCs are active laboratory-based surveillance and special studies.

Case Definition

A case of invasive bacterial disease is defined as isolation of H. influenzae, N. meningitidis, Group A Streptococcus, Group B Streptococcus, L. monocytogenes, S. pneumoniae, or MRSA from a normally sterile site in a resident of the catchment area. Normally sterile sites include: blood, cerebrospinal fluid, pleural fluid, peritoneal fluid, pericardial fluid, surgical aspirate, bone, joint fluid, or internal body site (e.g., lymph node, brain).

Under special circumstances, exceptions to the sterile site rule apply for Group A Streptococcus and Group B Streptococcus case definitions.

  • Group B Streptococcus isolated from the placenta and/or amniotic fluid accompanied by fetal demise
  • Group A Streptococcus isolated from a wound culture and accompanied by necrotizing fasciitis or streptococcal toxic shock syndrome (STSS)

Data Overview

Yearly surveillance reports from all ten EIP sites for pathogens under surveillance are available in PDF format at CDC’s ABCs Surveillance Reports site.

Current Projects

1. Active surveillance for invasive disease caused by Groups A and B Streptococcus, H. influenzae, N. meningitidis, S. pneumoniae, and MRSA.

2. Isolate collection and testing of all isolates of Group A Streptococcus, H. influenzae, N. meningitidis, and S. pneumoniae, and a subset of MRSA isolates.

3. Enhanced Surveillance for Invasive Early-Onset and Late-Onset Group B Streptococcal (EOGBS) and (LOGBS) Disease—Missed Opportunities for Prevention

Since January 1, 1998 for all cases of invasive EOGBS (cases <7 days of age) and January 1, 2003 for LOGBS (cases 7- 89 days old) prenatal screening and other EOGBS/LOGBS risk factor information has been collected from both infant and maternal (labor and delivery) charts. The goal of this study is to assess implementation of interventions to prevent perinatal transmission and risk factors for neonatal sepsis.

4. Active Surveillance for Pathogens Causing Neonatal Sepsis

Expanded surveillance for all culture-confirmed cases of bacterial sepsis and/or meningitis (excluding coagulase-negative Staphylococcal and contaminants) in infants less than 30 days of age began March 1, 1998. For cases occurring on or after January 1, 2000, the case definition was modified to include only infants less than seven days of age born in a three-county catchment area hospital. Data collected include labor and delivery, maternal risk factor information, and newborn clinical information abstracted from infant and maternal delivery charts.

5. Expanded Case Report Form for Invasive Pneumococcal Disease in Children

Since January 1, 2000, demographic information and vaccination history has been collected from primary health care providers for all invasive pneumococcal infections in children three months to less than five years of age. In 2010, CEIP expanded the age range to children ≥3 months to <18 years old in all three catchment area counties. Results from this expanded surveillance will enable the detection of pneumococcal conjugate vaccine failures or failures to vaccinate in this vulnerable population.

6. Assessing the Effectiveness of Tetravalent Meningococcal Conjugate Vaccine (MCV4) among Persons Aged 11-27 Years

The purpose of this study is to conduct a case-control, retrospective study to evaluate the effectiveness of the tetravalent (A, C, Y, W-135) meningococcal conjugate vaccine against invasive meningococcal disease in persons aged ≥ 11 years old and born on or after January 1, 1986. MCV4 was licensed based on safety and immunogenicity data, without data on clinical efficacy. In February 2005, MCV4 was recommended by the Advisory Committee on Immunization Practices of the CDC for routine use among young adolescents aged 11-12 years, for those adolescents who have not previously received MCV4 before high school entry, college freshmen living in dormitories, and other populations at increased risk. Study enrollment began January 1, 2006 and will continue through August 31, 2013.

7. Evaluating the Effectiveness of a 13-Valent Pneumococcal Conjugate Vaccine (PCV13) among Children

S. pneumoniae (pneumococcus) is a significant cause of meningitis, pneumonia, and bacteremia in children. Since 2000, the use of the 7-valent pneumococcal conjugate vaccine (PCV7), has significantly reduced the incidence of invasive pneumococcal disease (IPD) in children less than five years-old. There is less IPD overall since the introduction of the vaccine, but the proportion of disease caused by pneumococcal strains other than the seven represented in the PCV7 vaccine has increased. In 2010, the FDA licensed a new vaccine, the 13-valent pneumococcal conjugate vaccine, that protects against an additional six serotypes, including 19-A, which is the serotype that now causes the greatest proportion of disease. Vaccination with PCV13 is now recommended for all children between 2 to 59 months old.

The PCV13 Vaccine Effectiveness Study is a case-control study to evaluate the effectiveness of one or more doses of PCV13 vaccine against IPD caused by PCV13 serotypes (as a group) among children between 2 and 59 months old. Study enrollment began in August 2010 and will continue into 2014.

8. Legionellosis Surveillance

Beginning January 1, 2011, CEIP began conducting active surveillance for legionellosis. Legionellosis is a term used to describe any disease caused by Legionella bacteria, which usually manifests as one of two distinct diseases: 1) Legionnaires’ disease (LD), a serious, sometimes lethal, form of pneumonia, and 2) Pontiac fever (PF), a flu-like, self-limited illness. CEIP staff have been collecting risk factor information for all suspect and confirmed cases of legionellosis in an effort to better describe the incidence and epidemiologic characteristics of the disease.

For more details on ABCs projects, please visit the following links:

Completed Projects

1. Enhanced Collection of Vaccination History For All Invasive Haemophilus influenzae Type b (Hib) or of Unknown Type in Children Less Than 15 years of Age

For cases occurring between January 1, 1998 and December 31, 2006, CEIP collected additional information on cases of H. influenzae infection in persons less than 15 years of age in which the serotype is either type b (Hib) or unknown. Information collected included household risk factors, underlying humoral immune deficiencies, and vaccination history.

2. Active Surveillance for Non A, Non B beta-hemolytic Streptococcal Invasive Disease

Active surveillance was conducted for all cases occurring in 2003, 2004, and 2005. Cases under surveillance were defined as: sterile site isolates of groups C, F, L, E, P, U, or V ß-hemolytic Streptococci, including the following (only if ß-hemolytic): S. dysgalactiae, S. equi, S. iniae, S. constellatus, S. phocae, S. canis, S. anginosus (or S. milleri group), S. porcinus, S. intermedius, S. didelphis. Isolates were collected whenever possible and forwarded to the CDC Streptococcus Laboratory for testing.

3. Early Onset GBS Traceback Study

Beginning in May 2010, CEIP staff reviewed labor, delivery, and prenatal records of mothers of infants with early-onset GBS disease (aged < 7 days with GBS isolated from a normally sterile site) retrospectively identified from 2008-2009 cases. The medical record review gathered relevant prenatal and intrapartum information. Prenatal care providers were interviewed to determine if the mothers underwent screening prenatal for GBS. Relevant prenatal specimen laboratory records and standard operating procedure information for GBS specimens were obtained from the laboratory where the screening test was processed. CDC is analyzing these data and a draft manuscript has been submitted for review.


Verani JR, Spina NL, Lynfield R, Schaffner W, Harrison L, Holst A, Thomas S, Garcia JM, Scherzinger K, Aragon D, Petit S, Thompson J, Pasutti L, Carey R, McGee L, Weston E, Schrag S. Early-onset Group B Streptococcal Disease in the United States: Potential for Further Reduction. Obstet Gynecol 2014; 123 4:828-837.


For questions about ABCs surveillance and projects, please contact:

Mirasol Apostol, MPH
Project Coordinator, ABCs