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Multicenter Study
. 2019 Apr 1;179(4):479-488.
doi: 10.1001/jamainternmed.2018.7269.

Epidemiology of Invasive Group B Streptococcal Infections Among Nonpregnant Adults in the United States, 2008-2016

Louise K Francois Watkins  1   2   3 , Lesley McGee  2 , Stephanie J Schrag  2 , Bernard Beall  2 , Jennifer Hudson Jain  2 , Tracy Pondo  2 , Monica M Farley  4 , Lee H Harrison  5 , Shelley M Zansky  6 , Joan Baumbach  7 , Ruth Lynfield  8 , Paula Snippes Vagnone  8 , Lisa A Miller  9   10 , William Schaffner  11 , Ann R Thomas  12 , James P Watt  13 , Susan Petit  14 , Gayle E Langley  2   15
Affiliations
Multicenter Study

Epidemiology of Invasive Group B Streptococcal Infections Among Nonpregnant Adults in the United States, 2008-2016

Louise K Francois Watkins et al. JAMA Intern Med. .

Abstract

Importance: Group B Streptococcus (GBS) is an important cause of invasive bacterial disease. Previous studies have shown a substantial and increasing burden of GBS infections among nonpregnant adults, particularly older adults and those with underlying medical conditions.

Objective: To update trends of invasive GBS disease among US adults using population-based surveillance data.

Design, setting, and participants: In this population-based surveillance study, a case was defined as isolation of GBS from a sterile site between January 1, 2008, and December 31, 2016. Demographic and clinical data were abstracted from medical records. Rates were calculated using US Census data. Antimicrobial susceptibility testing and serotyping were performed on a subset of isolates. Case patients were residents of 1 of 10 catchment areas of the Active Bacterial Core surveillance (ABCs) network, representing approximately 11.5% of the US adult population. Patients were included in the study if they were nonpregnant, were 18 years or older, were residents of an ABCs catchment site, and had a positive GBS culture from a normally sterile body site.

Main outcomes and measures: Trends in GBS cases overall and by demographic characteristics (sex, age, and race), underlying clinical conditions of patients, and isolate characteristics are described.

Results: The ABCs network detected 21 250 patients with invasive GBS among nonpregnant adults from 2008 through 2016. The GBS incidence in this population increased from 8.1 cases per 100 000 population in 2008 to 10.9 in 2016 (P = .002 for trend). There were 3146 cases reported in 2016 (59% male; median age, 64 years; age range, 18-103 years). The GBS incidence was higher among men than women and among blacks than whites and increased with age. Projected to the US population, an estimated 27 729 cases of invasive disease and 1541 deaths occurred in the United States in 2016. Ninety-five percent of cases in 2016 occurred in someone with at least 1 underlying condition, most commonly obesity (53.9%) and diabetes (53.4%). Resistance to clindamycin increased from 37.0% of isolates in 2011 to 43.2% in 2016 (P = .02). Serotypes Ia, Ib, II, III, and V accounted for 86.4% of isolates in 2016; serotype IV increased from 4.7% in 2008 to 11.3% in 2016 (P < .001 for trend).

Conclusions and relevance: The public health burden of invasive GBS disease among nonpregnant adults is substantial and continues to increase. Chronic diseases, such as obesity and diabetes, may contribute.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Harrison reported receiving travel support from Sanofi Pasteur to attend a meeting on meningococcal disease and vaccines, reported receiving consulting fees from Merck to make a presentation on pneumococcal epidemiology and vaccines, and reported serving on a GlaxoSmithKline scientific advisory board on meningococcal vaccines. Dr Schaffner reported being a member of data safety monitoring boards for Merck and Pfizer and reported consulting with Dynavax, Seqirus, SutroVax, and Shionogi Inc. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Incidence of Invasive Group B Streptococcal Infections Among Nonpregnant Adults
Data are shown for Active Bacterial Core surveillance sites, 2008-2016.
Figure 2.
Figure 2.. Incidence of Invasive Group B Streptococcal Infections Among Nonpregnant Adults by Race and Sex
A and B, Data are shown for Active Bacterial Core surveillance sites, 2008-2016.
Figure 3.
Figure 3.. Incidence of Invasive Group B Streptococcal Infections Among Nonpregnant Adults by Serotype
Data are shown for Active Bacterial Core surveillance (ABCs) sites, 2008-2016. Other serotypes include Ic, VI, VII, VIII, IX, and nontypeable isolates.
Figure 4.
Figure 4.. Resistance of Invasive Group B Streptococcal Isolates to Erythromycin and Clindamycin Over Time
Data are shown for Active Bacterial Core surveillance sites, 2008-2016. In 2008 to 2010, conventional antimicrobial susceptibility testing without clindamycin inducible-resistance testing was performed. In 2011 to 2015, both conventional antimicrobial susceptibility testing and clindamycin inducible-resistance testing were performed; inducible clindamycin resistance accounted for 6.8% to 7.2% of the total. In 2016, resistance was determined based on the presence of resistance genes in sequenced isolates (the presence of a resistance gene predicts total clindamycin resistance).
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