Variable |
Overall, N = 483 |
2008–2013, n = 89 |
2014–2019, n = 394 |
---|---|---|---|
Sex | |||
F | 228 (47.2) | 48 (53.9) | 180 (45.7) |
M | 255 (52.8) | 41 (46.1) | 214 (54.3) |
Age, y, median (interquartile range) | 62 (41–75) | 60 (37–75) | 64 (41–75) |
Age group, y | |||
<5 | 24 (5.0) | 4 (4.5) | 20 (5.1) |
5–17 | 43 (4.8) | 5 (5.6) | 18 (4.6) |
18–34 | 45 (9.3) | 12 (13.5) | 33 (8.4) |
35–49 | 58 (12.0) | 10 (11.2) | 48 (12.2) |
50–64 | 104 (21.5) | 20 (22.5) | 84 (21.3) |
65–79 | 147 (30.4) | 21 (23.6) | 126 (32.0) |
≥80 | 92 (17.0) | 17 (19.1) | 65 (16.5) |
Race/ethnicity | n = 444† | n = 83† | n = 361† |
Hispanic | 22 (5.0) | 2 (2.4) | 20 (5.5) |
Non-Hispanic | |||
White | 390 (87.8) | 74 (89.2) | 316 (87.5) |
Black | 4 (0.9) | 1 (1.2) | 3 (0.8) |
American Indian/Alaska Native | 18 (4.1) | 5 (6.0) | 13 (3.6) |
Asian | 5 (1.1) | 1 (1.2) | 4 (1.1) |
Native Hawaiian/Pacific Islander | 5 (1.1) | 0 (0.0) | 5 (1.4) |
Residence type | n = 428* | n = 71* | n = 357* |
Private residence | 349 (81.5) | 56 (78.9) | 293 (82.1) |
Long-term care or nursing facility | 63 (14.7) | 13 (18.3) | 50 (14.1) |
Homeless | 9 (2.1) | 1 (1.4) | 8 (2.2) |
Correctional facility | 7 (1.6) | 1 (1.4) | 6 (1.7) |
Table 1. Demographics of patients with invasive group A Streptococcus disease, overall and by 6-year periods, Idaho, USA, 2008–2019*
*Values are no. (%) patients except as indicated. †Excludes cases with missing data.
Variable |
Unadjusted odds ratio* (95% CI) |
p value |
Adjusted odds ratio† (95% CI) |
p value |
---|---|---|---|---|
Sex | ||||
F | Referent | |||
M | 1.4 (0.9–2.2) | 0.16 | ||
Age group, y | ||||
0–17 | 1.2 (0.5–2.8) | 0.71 | 1.3 (0.5–3.3) | 0.63 |
18–49 | Referent | Referent | ||
50–64 | 1.2 (0.6–2.3) | 0.65 | 1.6 (0.7–3.8) | 0.29 |
65–79 | 1.7 (0.9–3.2) | 0.13 | 1.7 (0.8–3.8) | 0.16 |
≥80 | 1.1 (0.5–2.1) | 0.90 | 1.1 (0.5–2.6) | 0.84 |
Ethnicity | ||||
Non-Hispanic | Referent | |||
Hispanic | 2.4 (0.5–10.4) | 0.25 | ||
Residence type | ||||
Private | Referent | Referent | ||
Long-term care or nursing facility | 0.7 (0.4–1.4) | 0.37 | 0.7 (0.3–1.5) | 0.33 |
Correctional facility | 1.2 (0.1–9.7) | 0.90 | 1.9 (0.1–36.7) | 0.67 |
Homeless | 1.5 (0.2–12.5) | 0.69 | 0.7 (0.1–4.8) | 0.74 |
Underlying conditions | ||||
Diabetes | 0.9 (0.5–1.5) | 0.68 | ||
Heart disease: congestive heart failure or coronary artery disease | 1.3 (0.7–2.3) | 0.46 | ||
Obesity | 1.3 (0.7–2.4) | 0.49 | 1.2 (0.6–2.5) | 0.58 |
Chronic kidney disease or failure | 1.6 (0.7–3.6) | 0.30 | ||
Chronic obstructive pulmonary disease | 0.8 (0.4–1.8) | 0.62 | ||
Cancer | 2.4 (0.7–7.9) | 0.17 | ||
Immunosuppression | 2.0 (0.5–8.6) | 0.37 | ||
Hepatitis C or chronic liver disease | 1.5 (0.4–6.9) | 0.57 | ||
Other‡ | 2.3 (0.3–18.2) | 0.42 | ||
Any underlying condition | 0.9 (0.5–1.7) | 0.75 | ||
Other risk factors | ||||
Skin injury | 1.0 (0.6–1.7) | 0.97 | ||
Cigarette smoking | 0.9 (0.5–1.9) | 0.82 | ||
Alcohol abuse | 0.9 (0.3–2.3) | 0.75 | ||
Injection drug use | 3.4 (0.2–60.0) | 0.40 | 3.2 (0.2–63.0) | 0.45 |
Table 2. Individual risk factor and multivariable analysis of risk factors comparing invasive group A Streptococcus cases during 2014–2019 with cases from the 2008–2013 baseline period, Idaho, USA
*Standard logistic regression analysis performed unless otherwise noted. An odds ratio >1 indicates higher odds of being in the 2014–2019 period. †Firth logistic regression used to account for separation attributable to limited sample size and highly predictive risk factors. For multivariable analysis, results for residence type and injection drug use represent total effect and results for age group and obesity represent direct effect. ‡Other underlying conditions include paralysis, neurologic conditions, and developmental delay.
Type of infection or clinical syndrome |
No. (%) patients |
p value‡ |
||
---|---|---|---|---|
Overall, N = 476† |
2008–2013, n = 82† |
2014–2019, n = 394 |
||
Bacteremia without focus§ | 163 (34.2) | 34 (41.5) | 129 (32.7) | 0.13 |
Cellulitis | 197 (41.4) | 30 (36.6) | 167 (42.4) | 0.33 |
Pneumonia | 80 (16.8) | 15 (18.3) | 65 (16.5) | 0.69 |
Streptococcal toxic shock syndrome | 25 (5.3) | 0 (0.0) | 25 (6.4) | 0.02 |
Septic arthritis | 24 (5.0) | 6 (7.3) | 18 (4.6) | 0.30 |
Empyema | 19 (4.0) | 4 (4.9) | 15 (3.8) | 0.65 |
Necrotizing fasciitis | 12 (2.5) | 4 (4.9) | 8 (2.0) | 0.14 |
Osteomyelitis | 6 (1.3) | 0 (0.0) | 6 (1.5) | 0.26 |
Meningitis | 4 (0.8) | 0 (0.0) | 4 (1.0) | 0.36 |
Other¶ | 3 (0.6) | 1 (1.2) | 2 (0.5) | 0.46 |
Table 3. Clinical syndromes of invasive group A Streptococcus disease, overall and by 6-year periods, Idaho, USA, 2008–2019*
*Cases can have >1 type of infection or clinical syndrome. †Excludes 7 cases with missing data on type of infection or clinical syndrome, all during 2008–2013. ‡By χ2 test. §Group A Streptococcus isolated from blood, with no other clinical syndrome identified. ¶Other includes abscess, epiglottitis, and pelvic inflammatory disease.
Risk factor |
No. (%) patients |
||
---|---|---|---|
Overall, N = 432* |
2008–2013, n = 69* |
2014–2019, n = 363* |
|
Any underlying condition | |||
No | 113 (26.2) | 17 (24.6) | 96 (26.5) |
Yes | 319 (73.8) | 52 (75.4) | 267 (73.6) |
Condition | |||
Diabetes | 178 (41.2) | 30 (43.5) | 148 (40.8) |
Heart disease: congestive heart failure or coronary artery disease | 116 (26.9) | 16 (23.2) | 100 (27.6) |
Obesity | 95 (22.0) | 13 (18.8) | 82 (22.6) |
Kidney disease: chronic kidney disease or chronic kidney failure | 61 (14.1) | 7 (10) | 54 (14.9) |
Chronic obstructive pulmonary disease or emphysema | 43 (10.0) | 8 (11.6) | 35 (9.6) |
Cancer | 38 (8.8) | 3 (4.3) | 35 (9.6) |
Immunosuppression | 22 (5.1) | 2 (2.9) | 20 (5.5) |
Hepatitis C or chronic liver disease | 18 (4.2) | 2 (2.9) | 16 (4.4) |
Other† | 13 (3.0) | 1 (1.4) | 12 (3.3) |
Total underlying conditions | |||
0 | 115 (26.6) | 17 (24.6) | 98 (27.0) |
1 | 113 (26.2) | 24 (34.8) | 89 (24.5) |
2 | 93 (21.5) | 10 (14.5) | 83 (22.9) |
≥3 | 111 (25.7) | 18 (26.1) | 93 (25.6) |
Skin injury | |||
Any skin injury | n = 412* | n = 70* | n = 342* |
No | 211 (51.2) | 36 (51.4) | 175 (51.2) |
Yes | 201 (47.8) | 34 (48.6) | 167 (48.8) |
Type of skin injury‡ | n = 201 | n = 34 | n = 167 |
Nonsurgical wound | 127 (63.2) | 22 (64.7) | 105 (62.9) |
Surgical wound | 17 (8.5) | 3 (8.8) | 14 (8.4) |
Trauma§ | 47 (23.4) | 8 (23.5) | 39 (23.4) |
Burn | 2 (1.0) | 0 | 2 (1.2) |
Skin breakdown | 3 (1.5) | 1 (2.9) | 2 (1.2) |
Other | 5 (2.5) | 0 | 5 (3.0) |
Behavioral risk factors | |||
Current cigarette smoking¶ | n = 375* | n = 60* | n = 315* |
No | 310 (82.7) | 49 (81.6) | 261 (82.9) |
Yes | 65 (17.3) | 11 (18.3) | 54 (17.1) |
Substance abuse | n = 386* | n = 63* | n = 323* |
Alcohol abuse | 27 (7.0) | 5 (7.9) | 22 (6.8) |
Methamphetamine use | 6 (1.6) | 0 | 6 (1.8) |
Injection drug use | 8 (2.1) | 0 | 8 (2.5) |
None of the above | 346 (89.6) | 58 (92.1) | 288 (89.2) |
Other risk factors | n = 389* | n = 66* | n = 323* |
GAS pharyngitis | 31 (8.0) | 7 (10.6) | 24 (7.4) |
Household member with GAS | 8 (2.1) | 2 (3.0) | 6 (1.9) |
Influenza | 12 (3.1) | 4 (6.1) | 8 (2.5) |
None of the above | 336 (86.4) | 54 (81.8) | 282 (87.3) |
Table 4. Underlying conditions and risk factors of patients with invasive group A Streptococcus disease, overall and by 6-year periods, Idaho, 2008–2019
*Excludes missing data. †Other underlying conditions include paralysis, neurologic conditions, and developmental delay. ‡Data from 201 cases with a skin injury reported. §Cut, laceration, or puncture wounds. ¶Does not include e-cigarette use or vaping.
This activity is intended for infectious disease clinicians, internists, critical care clinicians, diabetologists, dermatologists, and other clinicians caring for patients with invasive group A Streptococcus infection.
The goal of this activity is for learners to be better able to describe the epidemiology of invasive group A Streptococcus in Idaho (where invasive group A Streptococcus is a reportable disease) during 2008 to 2019, based on a retrospective analytical study using surveillance data, emm typing results, and medical record review.
Upon completion of this activity, participants will:
Medscape, LLC requires every individual in a position to control educational content to disclose all financial relationships with ineligible companies that have occurred within the past 24 months. Ineligible companies are organizations whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.
All relevant financial relationships for anyone with the ability to control the content of this educational activity are listed below and have been mitigated. Others involved in the planning of this activity have no relevant financial relationships.
Medscape, LLC designates this Journal-based CME activity for a maximum of 1.0
AMA PRA Category 1 Credit(s)™
. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.0 MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program. Participants will earn MOC points equivalent to the amount of CME credits claimed for the activity. It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.
For questions regarding the content of this activity, contact the accredited provider for this CME/CE activity noted above. For technical assistance, contact [email protected]
There are no fees for participating in or receiving credit for this online educational activity. For information on applicability
and acceptance of continuing education credit for this activity, please consult your professional licensing board.
This activity is designed to be completed within the time designated on the title page; physicians should claim only those
credits that reflect the time actually spent in the activity. To successfully earn credit, participants must complete the
activity online during the valid credit period that is noted on the title page. To receive AMA PRA Category 1 Credit™, you must receive a minimum score of 70% on the post-test.
Follow these steps to earn CME/CE credit*:
You may now view or print the certificate from your CME/CE Tracker. You may print the certificate, but you cannot alter it.
Credits will be tallied in your CME/CE Tracker and archived for 6 years; at any point within this time period, you can print
out the tally as well as the certificates from the CME/CE Tracker.
*The credit that you receive is based on your user profile.
CME / ABIM MOC Released: 8/22/2022
Valid for credit through: 8/22/2023, 11:59 PM EST
processing....
We investigated invasive group A Streptococcus epidemiology in Idaho, USA, during 2008–2019 using surveillance data, medical record review, and emm (M protein gene) typing results. Incidence increased from 1.04 to 4.76 cases/100,000 persons during 2008–2019. emm 1, 12, 28, 11, and 4 were the most common types, and 2 outbreaks were identified. We examined changes in distribution of clinical syndrome, patient demographics, and risk factors by comparing 2008–2013 baseline with 2014–2019 data. Incidence was higher among all age groups during 2014–2019. Streptococcal toxic shock syndrome increased from 0% to 6.4% of cases (p = 0.02). We identified no differences in distribution of demographic or risk factors between periods. Results indicated that invasive group A Streptococcus is increasing among the general population of Idaho. Ongoing surveillance of state-level invasive group A Streptococcus cases could help identify outbreaks, track regional trends in incidence, and monitor circulating emm types.
Invasive group A Streptococcus (iGAS) disease is a severe bacterial infection caused by Streptococcus pyogenes, sometimes called strep A; ≈25,000 cases occurred in the United States in 2019[1]. iGAS disease is defined as illness associated with detection of group A Streptococcus in a normally sterile site, such as blood, pleural fluid, joint fluid, or deep tissue. iGAS has different clinical syndromes, including bacteremia without focus, pneumonia, and cellulitis, and severe manifestations, include necrotizing fasciitis and streptococcal toxic shock syndrome (STSS). The highly variable M protein, encoded by emm (M protein gene), is essential for virulence and serves as the primary target for epidemiologic typing of GAS[2]. Most patients with iGAS are hospitalized and the estimated case-fatality rate in the United States is 12%[3]. Numerous risk factors are associated with iGAS, including older age, diabetes, HIV infection, heart disease, cancer, obesity, injection drug use, long-term care facility (LTCF) residence, homelessness, preceding or concurrent influenza infection, and exposure to children with sore throats[4–9]. No licensed vaccines for GAS exist despite its substantial global disease burden: an estimated 1.78 million new cases of severe GAS (iGAS, acute rheumatic fever, rheumatic heart disease, and poststreptococcal glomerulonephritis) and 517,000 deaths occurring each year[10]. In 2019, the World Health Organization recognized GAS as a leading cause of infectious disease burden and proposed better characterization of GAS epidemiology as a priority activity for vaccine development[11].
During the past decade, iGAS incidence has increased in the United States, Canada, Ireland, Australia, and New Zealand[1,12–16]. Reasons for these increases are unclear but could include changing demographics (e.g., an aging population at higher risk for iGAS), rising prevalence of other risk factors associated with iGAS infection, or changes in circulating emm types. In some US states, iGAS outbreaks among specific populations (e.g., persons experiencing homelessness or who inject drugs) or the emergence of rarely occurring emm types were linked to increases in iGAS incidence[17–21]. In Idaho, a rural, western US state with a 2020 population of ≈1.8 million persons, iGAS is a reportable disease. We conducted a retrospective analytical study using surveillance data, emm typing results, and medical record review to describe the epidemiology of iGAS in Idaho during 2008–2019. In addition, we compared cases reported during 2014–2019 with cases from a lower-incidence 2008–2013 baseline period to determine whether clinical syndromes, patient demographics, and risk factors were associated with increased iGAS incidence.