The incidence of peripartum invasive group A streptococcal infections and association with illicit drug use

Abstract

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Objective

Group A streptococcal (GAS) infection ranges from mild infections to severe conditions like pneumonia, sepsis, and necrotizing fasciitis.1 Pregnancy increases the risk of adverse outcomes, including an 89-fold higher risk of puerperal sepsis.2 The incidence of invasive GAS (iGAS) appears to be rising, particularly in the pediatric population in the U.S. following the COVID-19 pandemic, though the impact on pregnant individuals is unclear.2^,^3 iGAS in pregnancy remains underexplored, with studies largely conducted before the pandemic.1 We aimed to determine the incidence of peripartum iGAS in a major Philadelphia health system and to identify associated risk factors, particularly injection drug use (IDU), timing, and outcomes.

Study design

We performed a retrospective chart review of all iGAS case in the Thomas Jefferson University Health System Pathology records between April 1, 2017 (date the electronic medical record system was implemented), and June 30, 2023. Peripartum iGAS incidence was calculated by dividing cases in pregnant persons by total deliveries (n = 17,277). The study was approved by the Thomas Jefferson University IRB. Descriptive statistics were performed using Excel.

Results

In our study period, 17 cases of peripartum iGAS were reported, with an incidence of 0.98 cases per 1,000 births. Of these, 12 (70.6%) were antepartum, 3 (17.6%) intrapartum, and 2 (11.8%) postpartum. One 17w5d miscarriage secondary to placental abruption associated with IDU occurred (Table 1, case 9). No other maternal, fetal, or neonatal mortality was reported. One patient (Table 1, case 14) had children at home, and 13 (76.5%) reported IDU (polysubstance use). Infections were often polymicrobial (n = 11, 64.7%), typically involving methicillin-resistant Staphylococcus aureus (n = 7, 41.2%). One patient (Table 1, case 13) had iGAS endometritis. Six (35.3%) patients needed surgical wound treatment. Of the patients who had follow-up care within three weeks of infection, no nonsuppurative complications of iGAS were recorded. The highest iGAS incidence was in 2018 (Supplemental Figure 1). Rates did not increase above baseline following the pandemic.Table 1. Patient demographics, clinical features, risk factors, and surgical management of peripartum iGAS cases in a major health system in Philadelphia from April 1, 2017, to June 30, 2023Table 1Case numberYearPatient ageGravidity and parityGestational age at iGAS diagnosisaiGAS infection collection sitePolymicrobial infectionIV antibiotic use (days)Surgical managementICU admission for management of iGASPregnancy outcomeRisk factors noted in EMR1201831G7P2042UnknownSputumNoNoneNoneNoLost to follow-upSick contact, IDU2201832G3P011136w2dbArm cellulitisYesNoneNoneNoSVD at homeIDU3201823G2P101136w5dElbow abscessYes29Abscess I&D, wound debridementNoCSIDU4201827G3P210319w1dArm abscessYesNoneAbscess I&D, wound debridementNoLost to follow-upIDU5201829G3P00206w1dArm abscessYes1NoneNoSVDIDU6201933G13P705734w3dNeck abscessYes1NoneNoLost to follow-upIDU7201940G4P3013PPD #1Urine, sputumNo1NoneNoSVDNone8201924G2P0010UnknownTonsillar abscessNo3Abscess I&D at bedsideNoLost to follow-upNone9201931G1P017w5dbUrineNoNoneNoneNoSpontaneous abortionIDU10202035G2P200219w3dLeg cellulitisYesNoneNoneNoC-sectionNone11202131G2P110233w4dMultiple abscessesYes8Abscess I&D, wound debridementYesC-sectionIDU12202130G6P104116w3dNeck abscessYes17Abscess I&D, wound debridementNoSVDIDU13202136G4P3104PPD #0Endometritis, bacteremiaNo9NoneYesSVDIDU14202228G4P211336w5dbBlood - BacteremiaNo4NoneNoCSChildren at home15202230G3P111234w4dMultiple abscessesYes5NoneNoCSIDU16202227G3P011021w0dPeriorbital abscessYes3Abscess I&D, wound debridementNoLost to follow-upIDU17202330G3P00105w6dBurnYes9Skin graft over full-thickness burnNoMedication abortionIDUCS, cesarean section; EMR, electronic medical record; I&D, incision and drainage; ICU, intensive care unit; IDU, illicit drug use; iGAS, invasive group A streptococcus; IV, intravenous; PPD#, post-partum day number; SVD, spontaneous vaginal delivery.aFor postpartum patients, postpartum day number (PPD#) is noted for presentation of iGAS infection.bIndicates intrapartum iGAS infection timing.Wagman. The incidence of peripartum invasive group A streptococcal infections and association with illicit drug use. AJOG Glob Rep 2025.

Conclusion

We observed an 8-fold higher incidence of peripartum iGAS infection in our population compared to the global incidence of 0.12 cases per 1000 births.1 This may be partially due to high rates of IDU in Philadelphia. Elevated IDU rates among iGAS patients align with trends in non-pregnant populations locally and nationally.4 We observed the highest rates in 2018, a year when hospitalizations for IDU-related endocarditis peaked in Philadelphia.5

Young children at home is a known risk factor for iGAS in pregnancy.2 One patient in our study had this risk factor, although records typically did not comment on it, so this was not systematically queried. Unlike trends observed in pediatrics, we did not see higher rates of iGAS infections following the pandemic, suggesting that children may not be the primary risk factor for iGAS in our population.3

Study strengths include detailed case examination and post-COVID-19 pandemic data. Limitations include a small sample size, loss to follow-up, and inability to assess IDU type, including the potential role of xylazine, an iGAS risk factor.5 National studies on peripartum iGAS are warranted, including investigating GAS screening in high-risk populations and evaluation of additional risk factors, such as immunosuppression in pregnancy. In the meantime, physicians should maintain a high index of suspicion for iGAS in pregnant patients with IDU, even in those without signs of GAS endometritis, as they may present atypically in the clinical setting. Future research is essential to better understand and prevent peripartum iGAS.

CRediT authorship contribution statement

Elizabeth Wagman: Writing – original draft. Matthew Pettengill: Writing – review & editing. Rupsa C. Boelig: Writing – review & editing. Sarah Boudova: Writing – review & editing.