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.


  • Determine the incidence and epidemiologic characteristics of invasive disease due to Group A Streptococcus, Group B Streptococcus, Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae, in several large populations.
  • Determine molecular epidemiologic patterns and microbiologic characteristics of public health relevance for isolates causing invasive infections for select pathogens.
  • Provide an infrastructure for further research, such as special studies aimed at identifying risk factors for disease, post-licensure evaluation of vaccine effectiveness, and monitoring effectiveness of prevention policies.

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, and S. pneumoniae 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, and S. pneumoniae.

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

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. On January 1, 2015, the age requirement for completion of the form switched from children less than 18 years to children < 5 years old. Results from this expanded surveillance will enable the detection of pneumococcal conjugate vaccine failures or failures to vaccinate in this vulnerable population.

6. Enhanced Surveillance for Severe Invasive Group A Streptococcus (GAS) Infections

To enhance detection and further refine the case definitions of necrotizing fasciitis (NF) and streptococcal toxic shock syndrome (STSS), CEIP began collecting GAS supplemental data using a standardized form on January 1, 2014. This form is completed for all GAS positive cases.

7. ABCs Surveillance of Culture-Independent Diagnostics

In 2012, CEIP staff began to monitor laboratories for transition to culture-independent diagnostic testing (CIDT). One hospital laboratory in the CEIP catchment area performs CIDT testing for GAS, GBS, H. influenzae, N. meningitidis and S. pneumoniae. Three other hospital laboratories plan to add CIDT testing in 2017. Starting in 2017, ABCs staff will conduct biannual surveys instead of annual surveys.

8. Surveillance for non-bacteremic pneumococcal pneumonia (SNIPP)

Since 2015, CEIP has conducted population-based surveillance of non-bacteremic pneumococcal pneumonia. Retrospective surveillance was conducted for 2013 and 2014. Eight tertiary care hospitals within the CEIP catchment area utilize the pneumococcal urine antigen test (UAT). All pneumococcal UAT positive cases identified will have a SNIPP case report form completed.

9. H. influenzae Neonatal Sepsis Expanded Surveillance (HINSES)

Beginning January 1, 2016, CEIP staff began completing an extended case report form for all cases with invasive H. influenzae if they are infants 0-30 days old, pregnant women, or women who delivered (including stillbirth or abortion) within 30 days before the specimen was obtained. Isolates from placenta or amniotic fluid associated with fetal death are also considered as maternal cases. Expanded surveillance will continue through the end of 2020.

10. Disseminated Gonococcal Infections (DGI)

Beginning January 1, 2017, CEIP started surveillance for Neisseria gonorrhoeae from sterile sites to identify disseminated gonococcal infections (DGI).  Cases will be identified through the current ABCs surveillance methods and a standardized case report form will be completed. Prospective surveillance will include any positive sterile site cultures of N. gonorrhoeae with a culture date on or after January 1, 2017. Retrospective case ascertainment will be performed for 2015-2016.

Special Studies

 Pneumococcal Conjugate Vaccine Effectiveness Evaluation on Adults 65 years or older

In December 2011, the 13-valent pneumococcal conjugate vaccine (PCV13) was licensed for use among adults age 50 years and older.  In August 2014, the Advisory Committee on Immunization Practices (ACIP) recommended that all adults ≥65 years of age receive a single dose of PCV13 followed by a dose of 23-valent pneumococcal polysaccharide vaccine (PPSV23). In light of these new recommendations, the purpose of this study is to evaluate the effectiveness of PCV13 in adults ≥65 years of age against Invasive Pneumococcal Disease (IPD) caused by PCV13 serotypes. The study will use a case-control design. Eligible cases will be identified through routine ABCs surveillance, beginning on October 1, 2015. Controls will be matched to cases by age and zip code. Participants will be interviewed about their vaccination status, medical history, functional status, household characteristics, and demographics. Study staff will contact participants’ medical providers to obtain vaccination and medical histories. Streptococcus pneumoniae isolates from case patients will be sent to the Centers for Disease Control and Prevention (CDC), and will undergo serotyping and whole genome sequencing (WGS). Study enrollment is expected to continue through 2018. Study data from CEIP will be de-identified and sent to CDC for analysis, along with data from the 9 other participating EIP sites throughout the country. CDC expects to have preliminary data analyses completed prior to the 2018 ACIP meeting to re-evaluate the adult pneumococcal vaccine recommendations.

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. The study results were published in the Obstetrics & Gynecology journal in 2014.

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.

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

The purpose of this study was 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 ended on August 31, 2013. Data analysis has been completed at CDC and a manuscript has been accepted for publication. Publication details are pending.

5. 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 was 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 ended in 2015. Primary data analysis was completed at CDC, and the study results were published in Lancet Respiratory Medicine in May 2016. Secondary analysis on the utility of using zip code to estimate socioeconomic status (SES) confounders was completed and published in SSM Population Health in December 2016.

Moore MR, Link-Gelles R, Schaffner W, Lynfield R, Holtzman C, Harrison LH, Zansky SM, Rosen JB, Reingold A, Scherzinger K, Thomas A, Guevara RE, Motala T, Eason J, Barnes M, Petit S, Farley MM, McGee L, Jorgensen JH, Whitney CG. Effectiveness of 13-valent pneumococcal conjugate vaccine for prevention of invasive pneumococcal disease in children in the USA: a matched case-control study. Lancet Respir Med. 2016 May;4(5):399-406. doi: 10.1016/S2213-2600(16)00052-7. Epub 2016 Mar 14.

Link-Gelles R, Westreich D, Aiello AE, Shang N, Weber DJ, Holtzman C, Scherzinger K, Reingold A, Schaffner W, Harrison LH, Rosen JB, Petit S, Farley M, Thomas A, Eason J, Wigen C, Barnes M, Thomas O, Zansky S, Beall B, Whitney CG, Moore MR. Bias with respect to socioeconomic status: A closer look at zip code matching in a pneumococcal vaccine effectiveness study. SSM Popul Health. 2016 Dec;2:587-594.

6. Legionellosis Surveillance

From January 1, 2011 through December 31, 2015, CEIP conducted 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 collected 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. An analysis of the data is pending.


Muhammad RD, Oza-Frank R, Zell E, Link-Gelles R, Narayan KM, Schaffner W, Thomas A, Lexau C, Bennett NM, Farley MM, Harrison LH, Reingold A, Hadler J, Beall B, Klugman KP, Moore MR. Epidemiology of invasive pneumococcal disease among high-risk adults since the introduction of pneumococcal conjugate vaccine for children. Clin Infect Dis. 2013 Mar;56(5):e59-67. doi: 10.1093/cid/cis971. Epub 2012 Nov 15.

Wortham JM, Zell ER, Pondo T, Harrison LH, Schaffner W, Lynfield R, Thomas A, Reingold A, Bennett NM, Petit S, Aragon D, Bareta J, Juni BA, Farley MM, Beall B, Moore MR. Racial disparities in invasive Streptococcus pneumoniae infections, 1998-2009. Clin Infect Dis. 2014 May;58(9):1250-7. doi: 10.1093/cid/ciu108. Epub 2014 Feb 27.

Blain A, MacNeil J, Wang X, Bennett N, Farley MM, Harrison LH, Lexau C, Miller L, Nichols M, Petit S, Reingold A, Schaffner W, Thomas A, Clark T, Cohn A, Briere E. Invasive Haemophilus influenzae Disease in Adults ≥65 Years, United States, 2011.Open Forum Infect Dis. 2014 Jul 3;1(2):ofu044. doi: 10.1093/ofid/ofu044. eCollection 2014 Sep.

MacNeil JR, Bennett N, Farley MM, Harrison LH, Lynfield R, Nichols M, Petit S, Reingold A, Schaffner W, Thomas A, Pondo T, Mayer LW, Clark TA, Cohn AC. Epidemiology of infant meningococcal disease in the United States, 2006-2012. Pediatrics. 2015 Feb;135(2):e305-11. doi: 10.1542/peds.2014-2035. Epub 2015 Jan 12.

Langley G, Hao Y, Pondo T, Miller L, Petit S, Thomas A, Lindegren ML, Farley MM, Dumyati G, Como-Sabetti K, Harrison LH, Baumbach J, Watt J, Van Beneden C. The Impact of Obesity and Diabetes on the Risk of Disease and Death due to Invasive Group A Streptococcus Infections in Adults. Clin Infect Dis. 2016 Apr 1;62(7):845-52. doi: 10.1093/cid/civ1032. Epub 2015 Dec 23.

Nelson GE, Pondo T, Toews KA, Farley MM, Lindegren ML, Lynfield R, Aragon D, Zansky SM, Watt JP, Cieslak PR, Angeles K, Harrison LH, Petit S, Beall B, Van Beneden CA. Epidemiology of Invasive Group A Streptococcal Infections in the United States, 2005-2012.Clin Infect Dis. 2016 Aug 15;63(4):478-86. doi: 10.1093/cid/ciw248. Epub 2016 Apr 22.

Blain AE, Mandal S, Wu H, MacNeil JR, Harrison LH, Farley MM, Lynfield R, Miller L, Nichols M, Petit S, Reingold A, Schaffner W, Thomas A, Zansky SM, Anderson R, Harcourt BH, Mayer LW, Clark TA, Cohn AC. Penicillin Use in Meningococcal Disease Management: Active Bacterial Core Surveillance Sites, 2009. Open Forum Infect Dis. 2016 Jul 13;3(3):ofw152. eCollection 2016 Sep.

Harris CM, Wu HM, Li J, Hall HI, Lee A, Zell E, Harrison LH, Petit S, Farley MM, Lynfield R, Miller L, Nichols M, Reingold A, Schaffner W, Thomas A, MacNeil JR, Clark TA, Cohn AC. Meningococcal Disease in Patients With Human Immunodeficiency Virus Infection: A Review of Cases Reported Through Active Surveillance in the United States, 2000-2008. Open Forum Infect Dis. 2016 Dec 20;3(4):ofw226. doi: 10.1093/ofid/ofw226. eCollection 2016 Oct.

Schrag SJ, Farley MM, Petit S, Reingold A, Weston EJ, Pondo T, Hudson Jain J, Lynfield R. Epidemiology of Invasive Early-Onset Neonatal Sepsis, 2005 to 2014.Pediatrics. 2016 Dec;138(6). pii: e20162013.

Cohn AC, MacNeil JR, Harrison LH, Lynfield R, Reingold A, Schaffner W, Zell ER, Plikaytis B, Wang X, Messonnier NE; Active Bacterial Core Surveillance (ABCs) Team and MeningNet Surveillance Partners. Effectiveness and Duration of Protection of One Dose of a Meningococcal Conjugate Vaccine.Pediatrics. 2017 Feb;139(2). pii: e20162193. doi: 10.1542/peds.2016-2193.


For questions about ABCs surveillance and projects, please contact:

Mirasol Apostol, MPH
Project Coordinator, ABCs