Group A Streptococcal Infections Research Articles

Group A Streptococcus induces lysosomal dysfunction in THP-1 macrophages

ABSTRACT The human-specific bacterial pathogen group A Streptococcus (GAS) is a significant cause of morbidity and mortality. Macrophages are important to control GAS infection, but previous data indicate that GAS can persist in macrophages. In this study, we detail the molecular mechanisms by which GAS survives in THP-1 macrophages. Our fluorescence microscopy studies demonstrate that GAS is readily phagocytosed by macrophages, but persists within phagolysosomes. These phagolysosomes are not acidified, which is in agreement with our findings that GAS cannot survive in low pH environments. We find that the secreted pore-forming toxin Streptolysin O (SLO) perforates the phagolysosomal membrane, allowing leakage of not only protons but also large proteins including the lysosomal protease cathepsin B. Additionally, GAS recruits CD63/LAMP-3, which may contribute to lysosomal permeabilization, especially in the absence of SLO. Thus, although GAS does not inhibit fusion of the lysosome with the phagosome, it has multiple mechanisms to prevent proper phagolysosome function, allowing for persistence of the bacteria within the macrophage. This has important implications for not only the initial response but also the overall functionality of the macrophages, which may lead to the resulting pathologies in GAS infection. Our data suggest that therapies aimed at improving macrophage function may positively impact patient outcomes in GAS infection.

Immune Responses in Children Infected with Streptoccocus A during the Spring 2023 Epidemic in Bulgaria

Streptococcus pyogenes, Group A Streptococcus (GAS), is the most common cause of bacterial tonsillitis, scarlet fever, impetigo, etc. in children and adults. Innate and adaptive host immune responses are fundamental for human defence against GAS, but are also important to the clinical manifestations of the infection. Our aim was to study the humoral and cellular immune responses in children infected with GAS and diagnosed with tonsillitis in the Clinic of Pediatrics in University Hospital “Lozenets”. The study included 22 infected children and 20 healthy controls. The following immune parameters were investigated: i) Humoral immune response – total serum IgG, IgM, IgA; C3, C4 – complement components, as well as the serum cytokines IFNγ, IL-6, IL-1β, TNFα, IL-17A, IL-10. ii) Cellular immune subsets were tested by immunophenotyping of total T cells, B cells, NK cells, T helper and T cytotoxic subsets. In this cross-sectional study we found a significant increase in the complement components C3 and C4, increased production of serum IFNγ, IL-6 and IL-10 and decreased levels of IL-17A in infected children with tonsillitis, compared to healthy controls. The cellular immune parameters in infected children showed lymphopenia, reduced total T lymphocytes and T-helper subpopulation, compared to healthy controls. We assumed that these imbalanced immune responses, found in infected children, are connected with GAS infection and deserved more detailed investigation.

Antibiotic susceptibility of Streptococcus species that cause pharyngitis in children

Background: Group A Streptococcus (GAS) significantly impacts global health, especially among children aged 5–14 years, causing approximately 288 million episodes of sore throat annually and resulting in around 100,000 disability-adjusted life years (DALYs) each year. GAS infections are particularly prevalent in developing countries. Objective: To assess the patterns of antibiotic resistance of Streptococcus spp. that cause pharyngitis in children. Patients and Methods: It was collected 100 pediatric patients. It was taken throat swabs for Streptococcus species culture and antibiotic sensitivity test. In addition, it was recorded the data of patient’s age and gender. Results: It was shown in this study that an average age of 4.4 ± 3.7 years for pharyngitis in children. In this study was diagnosed that Streptococcus agalactiae (24%) and Streptococcus pyogenes (18%) as the common causes Streptococcus species causes pharyngitis in children. It was noted that the differences in bacterial species according to the patient’s ages. Antibiotic sensitivity testing determined that there are high sensitivity of S. pneumoniae and S. parasanguinis to multiple antibiotics. In addition, it was showed resistance of S. pyogenes to Metronidazole and Azithromycin. Conclusion: In this study, it was found that the risk age for pharyngitis in children is four years old. Streptococcus agalactiae and Streptococcus pyogenes are the common bacterial causes for this infection. In addition, it was shown that S. pneumoniae appeared a high sensitivity to Ceftriaxone, Ciprofloxacin, and Meropenem, and S. parasanguinis was sensitive to Azithromycin, Cefixime, and Cefotaxime, and S. pyogenes showed a high sensitivity to Meropenem and Imipenem.

Group A Streptococcal Infections in Pediatric Age: Updates about a Re-Emerging Pathogen.

Group A Streptococcus (GAS) presents a significant global health burden due to its diverse clinical manifestations ranging from mild infections to life-threatening invasive diseases. While historically stable, the incidence of GAS infections declined during the COVID-19 pandemic but resurged following the relaxation of preventive measures. Despite general responsiveness to β-lactam antibiotics, there remains an urgent need for a GAS vaccine due to its substantial global disease burden, particularly in low-resource settings. Vaccine development faces numerous challenges, including the extensive strain diversity, the lack of suitable animal models for testing, potential autoimmune complications, and the need for global distribution, while addressing socioeconomic disparities in vaccine access. Several vaccine candidates are in various stages of development, offering hope for effective prevention strategies in the future.

Recombinational exchange of M-fibril and T-pilus genes generates extensive cell surface diversity in the global group A Streptococcus population.

Among genes present in all group A streptococci (GAS), those encoding M-fibril and T-pilus proteins display the highest levels of sequence diversity, giving rise to the two primary serological typing schemes historically used to define strain. A new genotyping scheme for the pilin adhesin and backbone genes is developed and, when combined with emm typing, provides an account of the global GAS strain population. Cluster analysis based on nucleotide sequence similarity assigns most T-serotypes to discrete pilin backbone sequence clusters, yet the established T-types correspond to only half the clusters. The major pilin adhesin and backbone sequence clusters yield 98 unique combinations, defined as "pilin types." Numerous horizontal transfer events that involve pilin or emm genes generate extensive antigenic and functional diversity on the bacterial cell surface and lead to the emergence of new strains. Inferred pilin genotypes applied to a meta-analysis of global population-based collections of pharyngitis and impetigo isolates reveal highly significant associations between pilin genotypes and GAS infection at distinct ecological niches, consistent with a role for pilin gene products in adaptive evolution. Integration of emm and pilin typing into open-access online tools (pubmlst.org) ensures broad utility for end-users wanting to determine the architecture of M-fibril and T-pilus genes from genome assemblies.IMPORTANCEPrecision in defining the variant forms of infectious agents is critical to understanding their population biology and the epidemiology of associated diseases. Group A Streptococcus (GAS) is a global pathogen that causes a wide range of diseases and displays a highly diverse cell surface due to the antigenic heterogeneity of M-fibril and T-pilus proteins which also act as virulence factors of varied functions. emm genotyping is well-established and highly utilized, but there is no counterpart for pilin genes. A global GAS collection provides the basis for a comprehensive pilin typing scheme, and online tools for determining emm and pilin genotypes are developed. Application of these tools reveals the expansion of structural-functional diversity among GAS via horizontal gene transfer, as evidenced by unique combinations of surface protein genes. Pilin and emm genotype correlations with superficial throat vs skin infection provide new insights on the molecular determinants underlying key ecological and epidemiological trends.

Epidemiological changes of acute respiratory infections in children: A single-center experience after COVID-19 lockdown.

Since the start of the COVID-19 pandemic, the epidemiology of acute respiratory infections (ARIs) has continually changed, making it difficult to predict. Our study aimed to evaluate epidemiological changes and clinical outcomes of ARIs in pediatric patients in the post-lockdown period. A single-center retrospective cross-sectional study was performed in one of the largest pediatric emergency departments in Lithuania during two cold seasons-from October 1, 2021, to April 30, 2022 (Season I) and in the same period in 2022-2023 (Season II). Patients under 18 years of age who had been tested for COVID-19 were enrolled in the study. Additional data about other respiratory pathogens in the study group (specifically influenza A/B, respiratory syncytial virus (RSV) and group A Streptococcus (GAS)), were included. During both seasons of our study, 19,366 children were screened for COVID-19. Positive tests for COVID-19 decreased from 14.5% in Season I to 5.9% in Season II, while at the same time, the rates of other infections increased significantly: influenza from 17.5% to 27.1%, RSV from 8.8% to 27.6%, and GAS from 8.4% to 44%, respectively. In Season II, COVID-19 infection presented in fewer admissions to pediatric intensive care (0.8% vs. 3.7%, p<0.01) and there were no deaths, while influenza presented in a higher proportion of hospitalizations (10.5% vs. 6.1%, p<0.01) and there was one death. The proportion of RSV hospitalizations also increased in Season II (34.6% vs. 44.0%, p<0.01). The early post-lockdown period saw a decline of COVID-19 and re-emergence of influenza, RSV and GAS infections in children. In Season II, COVID-19 cases became milder contrary to influenza. RSV infection contributed significantly to hospitalizations for respiratory infections in children in both seasons, particularly in Season II. Coinfections were not associated with a more severe course of the disease.

Incidence of invasive infections with Group B streptococcus in adults in Norway 1996-2019: a nationwide registry-based case-control study.

Group B streptococcus (GBS) colonizes the gastrointestinal and vaginal mucosa in healthy adults, but has also become an increasing cause of invasive infection. The aims of this study were to describe the incidence and factors associated with the occurrence of invasive GBS disease in adults in Norway. We performed a nationwide retrospective case-control study of invasive GBS infections during 1996-2019, with two control groups; invasive Group A streptococcal disease (GAS) to control for changes in surveillance and diagnostics, and a second representing the general population. A total of 3710 GBS episodes were identified. The age-standardized incidence rate increased steadily from 1.10 (95% CI 0.80-1.50) in 1996 to 6.70 (95% CI 5.90-7.50) per 100,000 person-years in 2019. The incidence rate had an average annual increase of 6.44% (95% CI 5.12-7.78). Incidence rates of GAS varied considerably, and there was no evidence of a consistent change over the study period. GBS incidence was highest among adults > 60years of age. Cardiovascular disease, cancer, and diabetes were the most common comorbid conditions. There was a shift in the distribution of capsular serotypes from three dominant types to more equal distribution among the six most common serotypes. The incidence of invasive GBS disease in adults increased significantly from 1996 to 2019. The increasing age of the population with accompanying underlying comorbid conditions might contribute to the increasing burden of invasive GBS disease. Interestingly, type 1 diabetes was also associated with the occurrence of invasive GBS disease.

Recent Scientific Advancements towards a Vaccine against Group A Streptococcus.

Group A Streptococcus (GAS), or Streptococcus pyogenes, is a gram-positive bacterium that extensively colonises within the human host. GAS is responsible for causing a range of human infections, such as pharyngitis, impetigo, scarlet fever, septicemia, and necrotising fasciitis. GAS pathogens have the potential to elicit fatal autoimmune sequelae diseases (including rheumatic fever and rheumatic heart diseases) due to recurrent GAS infections, leading to high morbidity and mortality of young children and the elderly worldwide. Antibiotic drugs are the primary method of controlling and treating the early stages of GAS infection; however, the recent identification of clinical GAS isolates with reduced sensitivity to penicillin-adjunctive antibiotics and increasing macrolide resistance is an increasing threat. Vaccination is credited as the most successful medical intervention against infectious diseases since it was discovered by Edward Jenner in 1796. Immunisation with an inactive/live-attenuated whole pathogen or selective pathogen-derived antigens induces a potent adaptive immunity and protection against infectious diseases. Although no GAS vaccines have been approved for the market following more than 100 years of GAS vaccine development, the understanding of GAS pathogenesis and transmission has significantly increased, providing detailed insight into the primary pathogenic proteins, and enhancing GAS vaccine design. This review highlights recent advances in GAS vaccine development, providing detailed data from preclinical and clinical studies across the globe for potential GAS vaccine candidates. Furthermore, the challenges and future perspectives on the development of GAS vaccines are also described.

Clinical, microbiological, and molecular characterization of pediatric invasive infections by Streptococcus pyogenes in Spain in a context of global outbreak.

Group A Streptococcus (GAS) is a common bacterial pathogen in the pediatric population. In the last months of 2022, an unusual increase in GAS infections was detected in various countries. Certain strains were overrepresented, although the cause of this raise is not clear. In Spain, a significant increase in mild and severe cases was also observed; this study evaluates the clinical characteristics and the strains involved in both scenarios. Our study showed that the increase in incidence did not correlate with an increase in resistance or with an emm types shift. However, there seemed to be a rise in severity, partly related to a greater rate of pneumonia cases. These findings suggest a general increase in iGAS that highlights the need for surveillance. The introduction of whole genome sequencing in the diagnosis and surveillance of iGAS may improve the understanding of antibiotic resistance, virulence, and clones, facilitating its control and personalized treatment.

Preadmission course and management of severe pediatric group A streptococcal infections during the 2022-2023 outbreak: a single-center experience.

The massive increase of infections with Group A Streptococcus (GAS) in 2022-2023 coincided in Switzerland with a change of the recommendations for the management of GAS pharyngitis. Therefore, the objective of the present study was to investigate whether the clinical manifestations and management before hospitalization for GAS infection differed in 2022-2023 compared with 2013-2022. Retrospective study of GAS infections requiring hospitalization in patients below 16years. Preadmission illness (modified McIsaac score), oral antibiotic use, and outcome in 2022-2023 were compared with 2013-2022. Time series were compared with surveillance data for respiratory viruses. In 2022-2023, the median modified McIsaac score was lower (2 [IQR 2-3] vs. 3 [IQR 2-4], p = < 0.0001) and the duration of preadmission illness was longer (4days [3-7] vs. 3 [2-6], p = 0.004) than in 2013-2022. In both periods, withholding of preadmission oral antibiotics despite a modified McIsaac score ≥ 3 (12% vs. 18%, n.s.) or ≥ 4 (2.4% vs. 10.0%, p = 0.027) was rare. Respiratory disease, skeletal/muscle infection, and invasive GAS disease were significantly more frequent in 2022-2023, but there were no differences in clinical outcome. The time course of GAS cases in 2022-2023 coincided with the activity of influenza A/B. We found no evidence supporting the hypothesis that the 2022-2023 GAS outbreak was associated with a change in preadmission management possibly induced by the new recommendation for GAS pharyngitis. However, clinical manifestations before admission and comparative examination of time-series strongly suggest that viral co-circulation played an important role in this outbreak.

Conserved molecular chaperone PrsA stimulates protective immunity against group A Streptococcus

Group A Streptococcus (GAS) is a significant human pathogen that poses a global health concern. However, the development of a GAS vaccine has been challenging due to the multitude of diverse M-types and the risk of triggering cross-reactive immune responses. Our previous research has identified a critical role of PrsA1 and PrsA2, surface post-translational molecular chaperone proteins, in maintaining GAS proteome homeostasis and virulence traits. In this study, we aimed to further explore the potential of PrsA1 and PrsA2 as vaccine candidates for preventing GAS infection. We found that PrsA1 and PrsA2 are highly conserved among GAS isolates, demonstrating minimal amino acid variation. Antibodies specifically targeting PrsA1/A2 showed no cross-reactivity with human heart proteins and effectively enhanced neutrophil opsonophagocytic killing of various GAS serotypes. Additionally, passive transfer of PrsA1/A2-specific antibodies conferred protective immunity in infected mice. Compared to alum, immunization with CFA-adjuvanted PrsA1/A2 induced higher levels of Th1-associated IgG isotypes and complement activation and provided approximately 70% protection against invasive GAS challenge. These findings highlight the potential of PrsA1 and PrsA2 as universal vaccine candidates for the development of an effective GAS vaccine.

Streptococcal infection and autoimmune diseases.

Excessive activation of immune cells by environmental factors, such as infection or individual genetic risk, causes various autoimmune diseases. Streptococcus species are gram-positive bacteria that colonize the nasopharynx, respiratory tract, gastrointestinal tract, genitourinary tract, and skin. Group A Streptococcus (GAS) species cause various symptoms, ranging from mild infections, such as tonsillitis and pharyngitis, to serious infections, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The contribution of GAS infections to several autoimmune diseases, including acute rheumatic fever, vasculitis, and neuropsychiatric disorders, has been studied. In this review, we focus on the association between streptococcal infections and autoimmune diseases, and discuss current research on the mechanisms underlying the initiation and progression of autoimmune diseases.

Unveiling the Group A Streptococcus Vaccine-Based L-Rhamnose from Backbone of Group A Carbohydrate: Current Insight Against Acute Rheumatic Fever to Reduce the Global Burden of Rheumatic Heart Disease

Group A Streptococcus (GAS) is a widely distributed bacterium that is Gram-positive and serves as the primary cause of acute rheumatic fever (ARF) episodes. Rheumatic heart disease (RHD) is a sequela resulting from repeated ARF attacks which are also caused by repeated GAS infections. ARF/RHD morbidity and mortality rates are incredibly high in low- and middle-income countries. This is closely related to poor levels of sanitation which causes the enhanced incidence of GAS infections. Management of carditis in RHD cases is quite challenging, particularly in developing countries, considering that medical treatment is only palliative, while definitive treatment often requires more invasive procedures with the high costs. Preventive action through vaccination against GAS infection is one of the most effective steps as a solution in reducing RHD morbidity and mortality due to curative treatments are expensive. Various developments of M-protein-based GAS vaccines have been carried out over the last few decades and have recently begun to enter the clinical stage. Nevertheless, this vaccination generates cross-reactive antibodies that might trigger ARF assaults as a result of the resemblance between the M-protein structure and proteins found in many human tissues. Consequently, the development of a vaccine utilizing L-Rhamnose derived from the poly-rhamnose backbone of Group A Carbohydrate (GAC) commenced. The L-Rhamnose-based vaccine was chosen due to the absence of the Rhamnose biosynthesis pathway in mammalian cells including humans thus this molecule is not found in any body tissue. Recent pre-clinical studies reveal that L-Rhamnose-based vaccines provide a protective effect by increasing IgG antibody titers without causing cross-reactive antibodies in test animal tissue. These findings demonstrate that the L-Rhamnose-based vaccine possesses strong immunogenicity, which effectively protects against GAS infection while maintaining a significantly higher degree of safety.

Polymeric Nanoparticles as Oral and Intranasal Peptide Vaccine Delivery Systems: The Role of Shape and Conjugation.

Mucosal vaccines are highly attractive due to high patient compliance and their suitability for mass immunizations. However, all currently licensed mucosal vaccines are composed of attenuated/inactive whole microbes, which are associated with a variety of safety concerns. In contrast, modern subunit vaccines use minimal pathogenic components (antigens) that are safe but typically poorly immunogenic when delivered via mucosal administration. In this study, we demonstrated the utility of various functional polymer-based nanostructures as vaccine carriers. A Group A Streptococcus (GAS)-derived peptide antigen (PJ8) was selected in light of the recent global spread of invasive GAS infection. The vaccine candidates were prepared by either conjugation or physical mixing of PJ8 with rod-, sphere-, worm-, and tadpole-shaped polymeric nanoparticles. The roles of nanoparticle shape and antigen conjugation in vaccine immunogenicity were demonstrated through the comparison of three distinct immunization pathways (subcutaneous, intranasal, and oral). No additional adjuvant or carrier was required to induce bactericidal immune responses even upon oral vaccine administration.

Clinical and molecular epidemiological features of critically ill patients with invasive group A Streptococcus infections: a Belgian multicenter case-series

BackgroundRecent alerts have highlighted an increase in group A streptococcal (GAS) infections since 2022 in Europe and the United States. Streptococcus pyogenes can cause limited skin or mucosal disease, but can also present as severe invasive disease necessitating critical care. We performed a multicenter retrospective study of patients with GAS infections recently admitted to Belgian intensive care units (ICUs) since January 2022. We describe patient characteristics and investigate the molecular epidemiology of the S. pyogenes strains involved.ResultsBetween January 2022 and May 2023, a total of 86 cases (56 adults, 30 children) with GAS disease were admitted to critical care in the university hospitals of Leuven, Antwerp and Liège. We noted a strikingly high incidence of severe community-acquired pneumonia (sCAP) (45% of adults, 77% of children) complicated with empyema in 45% and 83% of adult and pediatric cases, respectively. Two-thirds of patients with S. pyogenes pneumonia had viral co-infection, with influenza (13 adults, 5 children) predominating. Other disease presentations included necrotizing fasciitis (23% of adults), other severe skin/soft tissue infections (16% of adults, 13% of children) and ear/nose/throat infections (13% of adults, 13% of children). Cardiogenic shock was frequent (36% of adults, 20% of children). Fifty-six patients (65%) had toxic shock syndrome. Organ support requirements were high and included invasive mechanical ventilation (77% of adults, 50% of children), renal replacement therapy (29% of adults, 3% of children) and extracorporeal membrane oxygenation (20% of adults, 7% of children). Mortality was 21% in adults and 3% in children. Genomic analysis of S. pyogenes strains from 55 out of 86 patients showed a predominance of emm1 strains (73%), with a replacement of the M1global lineage by the toxigenic M1UK lineage (83% of emm1 strains were M1UK).ConclusionsThe recent rise of severe GAS infections (2022–23) is associated with introduction of the M1UK lineage in Belgium, but other factors may be at play—including intense circulation of respiratory viruses and potentially an immune debt after the COVID pandemic. Importantly, critical care physicians should include S. pyogenes as causative pathogen in the differential diagnosis of sCAP.

Echocardiographic Screening of Rheumatic Heart Disease: Current Concepts and Challenges.

The incidence of acute rheumatic fever (ARF), which most commonly affects children aged 5-15 years after group A Streptococcus (GAS) infection, ranges from 8 to 51 per 100 000 people worldwide. Rheumatic heart disease (RHD), which occurs when patients with ARF are inappropriately treated or not given regular prophylaxis, is the most common cause of non-congenital heart disease in children and young adults in low-income countries. Timely treatment of GAS infection can prevent ARF, and penicillin prophylaxis can prevent recurrence of ARF. Secondary prophylaxis with benzathine penicillin G has been shown to decrease the incidence of RHD and is a key aspect of RHD control. The most important factor determining the prognosis of RHD is the severity of cardiac involvement. Although approximately 70% of patients with carditis in the acute phase of the disease recover without sequelae, carditis is important because it is the only complication of ARF that causes sequelae. One-third of patients with ARF are asymptomatic. Patients with mild symptoms of recurrent ARF and silent RHD will develop severe morbidities within 5-10 years if they do not receive secondary preventive treatments. A new screening program should be established to prevent cardiac morbidities of ARF in moderate- and highrisk populations. In the present study, we examined the applicability of echocardiographic screening programs for RHD. Cite this article as: Topçu S, Uçar T. Echocardiographic screening of rheumatic heart disease: Current concepts and challenges. Turk Arch Pediatr. 2024;59(1):3-12.

Group A streptococcal infection in the United Kingdom: an emerging threat

Within group A Streptococcus (GAS), only Streptococcus pyogenes exhibits clinical significance. GAS is typed serologically based on unique surface proteins and critical virulence factors, such as a hyaluronic acid capsule that shields GAS from phagocytosis. The burden of GAS was estimated in the last five years as 14,000 to 25,000 cases of the invasive group A streptococcal disease in the USA with an estimated death from 1,500 to 2,300 cases per year. Early in the summer of 2022 in England, there was more scarlet fever than was anticipated. Early in the current season, the number of notifications rose to unusual heights. The analysis of invasive GAS (iGAS) isolate typing data shows that this season has seen a wide variety of encoding mature M protein (emm) gene sequence types found. Therefore, public health authorities should think about initiatives to increase clinicians’ and the general public’s awareness of GAS infections and to promote their quick diagnosis, molecular testing and antibiotic susceptibility testing, and standard treatment.

Clinical manifestations, diagnosis, and antimicrobial resistance of group A streptococci infections

Group A streptococci (GAS) cause diverse diseases ranging from mild to severe illnesses, and the global burden of GAS infections is enormous. Serological typing has been replaced by emm genotyping for the epidemiological study of GAS. Acute bacterial pharyngitis is a common illness, which requires either throat culture or rapid Ag test for diagnosis. Moreover, molecular point-of-care tests have been introduced owing to their higher sensitivity. Optimal diagnosis of bacterial pharyngitis is necessary for the adequate use of antibiotics. Although antimicrobial resistance (AMR) to erythromycin or clindamycin does not seem serious in Korea, it is very high in China, being reported at over 90%. Antibiotic surveillance and relevant education are necessary for primary clinical physicians and pediatricians. It is necessary to monitor AMR and develop a system for reporting the appearance of highly virulent diseases, such as necrotizing fasciitis or streptococcal toxic-shock syndrome, to the government authority.

1681. Persistent Increased Invasive Pediatric Streptococcus pyogenes (Group A Streptococcus) Infections with Correlated Increase in Superficial Infection and Pharyngitis

Abstract Background Children's Hospital of Philadelphia (CHOP) clinicians observed an increase in invasive group A Streptococcus infections (iGAS) in November 2022. In December 2022, the Centers for Disease Control and Prevention published an investigation of increased iGAS. At CHOP iGAS remain increased, even after peak respiratory viral season. Our objective was to compare pre-pandemic and current case counts and to investigate if the increase in iGAS correlates with an increase in non-invasive GAS infections (nGAS). Methods Data for positive Streptococcus pyogenes results at CHOP from January 2018 to April 2023 was collected from the electronic medical record (n=466). Results were classified by source and specimen type as pharyngitis, superficial, and invasive, then further classified as non-invasive (pharyngitis and superficial) or invasive. For infection events with multiple results only one result was included, giving preference to the most aggressive classification (invasive &amp;gt;pharyngitis &amp;gt;superficial). Fisher's exact test was used to assess association between the increase in nGAS and iGAS prior to and after the start of the COVID-19 pandemic (2018-2019 vs. 2021-2023). Fisher's exact test, with Monte Carlo simulation, was used to assess association between the increase in nGAS and iGAS infections by year. Results There was a statistically significant association in the increase in pharyngitis, superficial, and invasive group A Streptococcus infections (GAS) (p-value &amp;lt; 0.0001) and in nGAS and iGAS (p-value = 0.0001), when comparing pre- and post-2020. We found statistically significant associations in the increase of pharyngitis, superficial, and invasive GAS cases (p-value = 0.0005) and of nGAS and iGAS cases (p-value = 0.0005). Conclusion Our data shows a significant increase in cases from pre-pandemic years for nGAS and iGAS infections. iGAS is correlated with nGAS, even with further stratification of nGAS into pharyngitis and superficial. Notably, increases in nGAS were significantly more than the increase in iGAS, which has unexpectedly persisted beyond the typical winter viral infection peak. Continued monitoring or GAS, particularly iGAS, is justified. Disclosures All Authors: No reported disclosures

1678. Non-Invasive and invasive Pediatric Group A Streptococcus Infections (iGAS) Admissions During 2021 and 2022 at a Tertiary Health Care Center: Resurgence and Concomitant Viral Infections

Abstract Background A resurgence of invasive Group A Streptococcus (iGAS) infection in children was observed in Colorado and Minnesota by the Centers For Disease Control and Prevention (CDC) during the fall of 2022. Cases were accompanied by hospitalizations for respiratory syncytial virus (RSV) and influenza. We describe hospital admissions with iGAS and non iGAS infections at a tertiary health care center in Augusta, GA during 2021 and 2022; the only children’s Hospital with 150 licensed beds and a population of 201.196 as of 2021. Methods We used the iGAS definition by the CDC as a Group A Streptococcus (GAS) isolated by culture in specimens obtained from a sterile body site, or GAS isolated from wound culture and necrotizing fasciitis or streptococcal toxic shock syndrome. We conducted a retrospective chart review of iGAS and non iGAS cases admitted to the Children’s Hospital of Georgia during January to December 2021 and January to December 2022. We collected demographics, site of infection, concomitant viral infections diagnosed by nasopharyngeal (NP) PCR, intensive care unit (ICU) admission and mortality. Results During 2021, only 1 patient was admitted with non iGAS, a 7-year-old with a wound infection. In 2022, 15 patients were diagnosed with GAS infection, 7 of them had iGAS and 8 had noninvasive disease. We included positive peritoneal and pleural fluid, joint/bone aspirates, bronchoalveolar lavage samples, and blood cultures for iGAS. The age range for iGAS was 6-17 years and for noninvasive, 16 mo to 11 years. In 2022, 25% of noninvasive cases had concomitant influenza compared to 43% of iGAS cases. Only one patient with non iGAS tested positive for RSV. 2 patients had rhinovirus, one had adenovirus. One patient with iGAS was positive for metapneumovirus (HMPV). 57% of iGAS cases were admitted to the ICU (n=4). 50% of noninvasive cases (n=4) were admitted to the ICU. One iGAs case died. All noninvasive cases survived. Conclusion There was increase in iGAS and noninvasive GAS infections during 2022 compared to 2021 in our institution. iGAS was more common in older children. Of iGAS cases, the only coexisting viruses were influenza and HMPV. Most cases were seen during Fall of 2022. The cause of reappearance of iGAS and non iGAS is still unknown but believed to be related to end of mask mandates for COVID 19 infections. Disclosures All Authors: No reported disclosures