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

Streptococcus pyogenes bloodstream infections in an Italian hospital: A ten-year genomic picture

BACKGROUND

During 2022 and 2023, a large upsurge of cases of Group A Streptococcus (GAS) infection has struck many countries worldwide. This large epidemic event was caused by a diminished level of immunity after COVID-19 social restrictions and was fostered mainly by the emm1 genotype of the bacterium.

METHODS

We characterized the genomes of the GAS isolates that caused bloodstream infections in the last ten years in a 900-bed hospital in Northern Italy. We obtained short-read genomes, which we used for emm typing and to analyze the antimicrobial resistance and virulence gene content. Moreover, we contextualized the isolates in an epidemiological point of view using both ortholog-based and SNP-based phylogeny.

RESULTS

In the last ten years, we registered two upsurges of GAS cases in the study hospital: one in 2023 (in line with the global epidemiological situation), and one in 2016 (local, but observed also in another recent Italian study). The genomic analysis of the bloodstream infection isolates showed the circulation of multiple emm types, of which emm1, emm12, and emm4 characterized the two large epidemic events. Notably, the 2016 peak was mainly fostered by the M1Global and emm4 genotypes, in contrast with the rise of M1UK observed in the UK in the pre-pandemic years. Phylogeny analysis showed the presence of multiple monophyla of local strains. Despite our genomes being obtained from blood-culture isolates, we did not observe any increased presence of virulence or antimicrobial resistance genes.

CONCLUSIONS

Our results further confirm the role of emm1 as the most prevalent genotype worldwide. However, we also unveiled the central role of genotype emm4 in the 2016 epidemic event, described in the study hospital. Finally, our results suggest the presence of multiple locally persistent strains. Among these, we underlined the presence of a multi-drug resistant strain of emm92.

Molecular and Clinical Characterization of Invasive Streptococcus pyogenes Isolates: Insights from Two Northern-Italy Centers

Streptococcus pyogenes (Group A Streptococcus, GAS) is a Gram-positive pathogen responsible for both superficial and invasive infections (iGAS), with increasing global incidence in recent years. This study aims to characterize the molecular and clinical features of iGAS cases in Bologna and Imola (Italy) between 2022 and 2024. Thirty-five invasive isolates were analyzed through whole-genome sequencing (WGS) to investigate the distribution of emm types, antimicrobial resistance (AMR) genes, and virulence factors. Clinical and epidemiological data were retrospectively collected and analyzed. The majority of cases (80%) were recorded in 2023, predominantly among patients aged over 65 (60%). Bloodstream infections were present in 97.1% of cases, and comorbidities such as diabetes and immunosuppression were common. Empirical antibiotic therapy often involved penicillin/β-lactam inhibitors, while oxazolidinones were the most frequently used in targeted regimens. The in-hospital mortality rate was 20%. Genomic analysis identified emm1, emm12, and emm89 as the most prevalent types, associated with specific virulence profiles and resistance determinants. This study highlights the critical role of emm typing and genomic characterization in understanding the pathogenicity of GAS. These findings contribute to the identification of risk factors for severe outcomes and underscore the need for targeted prevention and treatment strategies in vulnerable populations.

Characterization of Streptococcus pyogenes Strains from Tonsillopharyngitis and Scarlet Fever Resurgence, 2023-FIRST Detection of M1UK in Bulgaria

Recently a resurgence of Streptococcus pyogenes infections has arisen, with concerns around the highly virulent M1UK lineage. Our aim was to characterize S. pyogenes, the immune responses it causes, and to determine the presence of the M1UK lineage in Sofia, Bulgaria. In our study, the infections were confirmed by culture testing or rapid antigen test. Identification was performed by MALDI-TOF and was followed up by antibiotic susceptibility testing (EUCAST). Virulence factors were identified using multiplex PCR and whole genome sequencing (WGS). Immune responses were measured through detection of serum complement levels, lymphocyte subsets, and cytokine profiling. Out of 82 children, 38 had scarlet fever and the rest had streptococcal pharyngitis. Strains were susceptible to penicillin (β-lactams), macrolides, clindamycin, tetracyclines, co-trimoxazole, fluoroquinolones, and linezolid. Superantigen profiles were identified: SpeA + SpeJ (45%), SpeC, and SpeI + SpeH (27.5% each). A novel Multilocus sequence typing (MLST) haplotype in the mutS gene (d90b) was found in four strains. The M1UK lineage was detected for the first time in Bulgaria. We observed an increase in complement fractions C3 and C4 and a decrease in T lymphocytes. A significant increase in the levels of IFN-γ, IL-6, and IL-10 with corresponding reduction in IL-17A were revealed. In conclusion, the studied S. pyogenes strains were characterized by their susceptibility to antibiotics and the predominance of SpeA superantigen; for the first time in Bulgaria the presence of M1UK and a novel SNP variation in the mutS gene (d90b) were found. A mixed pattern of pro- and anti-inflammatory immune responses in patients was observed.

Invasive group A streptococcal infections as a consequence of coexisting or previous viral infection in the post-COVID-19 pandemic period

BACKGROUND

Group A Streptococci (GAS) may cause infections of the pharynx and soft tissues and invasive infections in children (iGAS). A significant increase in severe iGAS infections has been reported in Europe since the fall of 2022.

OBJECTIVES

This retrospective study aims to analyse clinical data of children with invasive and non-invasive GAS infections in the post-COVID-19 pandemic era, searching for predisposing factors to developing invasive infections.

METHODS

History and clinical data of patients hospitalised due to or with coexisting GAS infections were analysed. iGAS and non-iGAS infections were compared.

RESULTS

The cohort comprised 45 children (median age 7 years). 31(69 %) children developed iGAS infections - sepsis with toxic shock syndrome (TSS) (4 children-13 %), deep soft tissue infections (3-10 %), meningitis (2-6 %), pneumonia (2-6 %) or respiratory tract infections - sinusitis or otitis (4-12 %). iGAS children developed complications more frequently (100 % vs 21 %, p < 0.0001) and required prolonged treatment (median 15 vs 10 days, p = 0.0001). Preceding or coexisting viral infections were more common in iGAS children (87 % vs 14 %; p < 0.0001). CRP and PCT were significantly higher in the iGAS group (median 17.95 vs 3.97 mg/dl, p = 0.0002; 6.8 vs 0.05 ng/ml, p = 0.0001, respectively). The multiple logistic regression revealed that preceding or coexisting viral infections and the rise in CRP level increased the risk of iGAS infections. The CRP cut-off > 14.94 mg/dl showed 68.2 % sensitivity (CI 45.13-86.14 %) and 100 % specificity (69.15-100 %).

CONCLUSION

Our study shows increased incidence and severity of GAS infections among hospitalised children. Previous or coexisting viral infections and CRP with cut-off > 14.94 mg/dl were significant risk factors.

Group A Streptococcus vulvovaginitis in Spain, 2011-2023: antibiotic resistance and emm-type distribution

An increase in Group A Streptococcus vulvovaginitis was detected in 2023: The average number of cases per year was 13 during 2011-2017. Twenty-five and 27 cases were reported in 2018 and 2019 followed by a decline coinciding with the COVID-19 pandemic. The 2023 increase surpassed previous data. The most frequent resistances were to erythromycin (11.3%;) and tetracycline (8.8%). Eleven different emm-types were detected among 30 GAS isolated in 2023: emm 1 was predominant (36.7%) followed by emm 89 (20%), emm 87 (10%) and emm 28 (6.7%). GAS should be increasingly considered in women with vulvovaginitis.

Has COVID-19 Affected the Course of Chickenpox in Children?

OBJECTIVES OF THE STUDY

The aim of this study was to assess the impact of the COVID-19 pandemic on the epidemiology and clinical course of chickenpox in children based on 6 years of self-reported observations.

MATERIAL AND METHODS

The medical records of 350 patients under 18 years of age hospitalised in the Department of Paediatrics, Infectious Diseases, and Hepatology between 1 January 2018 to 31 December 2023 were analysed retrospectively.

RESULTS

During the analysed period, 350 children were hospitalised due to chickenpox, the fewest in the pandemic period, the greatest number in 2023. Complications of chickenpox were diagnosed in 297 children (84.86%). The most commonly diagnosed complications were bacterial dermatitis (168, 48%) and lower respiratory tract infections (13.42%). After the pandemic period, a generalised inflammatory reaction was observed significantly more often (p ≤ 0.01069). Among children hospitalised in 2023, 5.90% of patients with bacterial dermatitis required surgical intervention due to skin abscess or fasciitis. In 2023, 41.46% of cultures from swabs taken from skin lesions grew Streptococcus pyogenes. After the pandemic, children with chickenpox and gastrointestinal symptoms were hospitalised significantly less frequently (p ≤ 0.00001).

CONCLUSIONS

In the post-pandemic period, there were more hospitalisations of patients with chickenpox complicated by bacterial skin infection progressing to a generalised inflammatory reaction or septicaemia, related to the increase in invasive group A streptococcal infections observed in Europe. On the other hand, thanks to the widespread adaption of hygiene practices and infection prevention measures, the number of patients with gastrointestinal symptoms significantly decreased.

Chains of misery: surging invasive group A streptococcal disease

PURPOSE OF REVIEW

We describe the epidemiology of the recent global surge in invasive group A streptococcal (GAS) disease and consider its proximate and distal causes. We highlight important knowledge gaps regarding clinical management and discuss potential strategies for prevention.

RECENT FINDINGS

Rates of invasive GAS (iGAS) disease were increasing globally prior to the COVID-19 pandemic. Since mid-2022, following the worst years of the pandemic in 2020 and 2021, many countries with systems to monitor GAS syndromes have reported surges in cases of iGAS concurrent with increased scarlet fever, pharyngitis, and viral co-infections. The emergence of the hypervirulent M1 UK strain as a cause of iGAS, particularly in high income countries, is concerning. New data are emerging on the transmission dynamics of GAS. GAS remains universally susceptible to penicillin but there are increasing reports of macrolide and lincosamide resistance, particularly in invasive isolates, with uncertain clinical consequences. Intravenous immunoglobulin is used widely for streptococcal toxic shock syndrome and necrotizing soft tissue infections, although there is limited clinical evidence, and none from a completed randomized controlled trial. Intensive and expensive efforts at population-level control of GAS infections and postinfectious autoimmune complications have been only partially successful. The great hope for control of GAS diseases remains vaccine development. However, all modern vaccine candidates remain in the early development stage.

SUMMARY

In many countries, iGAS rates surged from mid-2022 in the aftermath of pandemic control measures and physical distancing. The emergence of a dominant hypervirulent strain is an important but incomplete explanation for this phenomenon. Clinical management of iGAS remains highly empirical and new data has not emerged. A vaccine remains the most likely means of achieving a sustainable reduction in the burden of iGAS.

Invasive group A Streptococcus infection (Streptococcus pyogenes): Current situation in Spain

Group A ß-hemolytic Streptococcus (S. pyogenes), also known as GAS, is a Gram-positive bacterium. It can be easily identified in the microbiology laboratory by its ability to hemolyse blood in culture media. This bacterium is highly virulent due to its production of enzymes and toxins, and its ability to cause immunologically mediated diseases such as rheumatic fever and post-streptococcal glomerulonephritis. GAS is the primary cause of bacterial pharyngotonsillitis, although it is typically a benign and non-invasive disease. However, it also has the potential to cause severe skin and soft tissue infections, necrotising fasciitis, bacteraemia and endocarditis, pneumonia and empyema, and streptococcal toxic shock syndrome, without any age or predisposition limits. The term invasive GAS disease (iGAS) is used to refer to this group of conditions. In more developed countries, iGAS disease has declined thanks to improved hygiene and the availability of antibiotics. For example, rheumatic fever has practically disappeared in countries such as Spain. However, recent data suggests a potential increase in some iGAS diseases, although the accuracy of this data is not consistent. Because of this, the COVID and Emerging Pathogens Committee of the Illustrious Official College of Physicians of Madrid (ICOMEM) has posed several questions about invasive GAS infection, especially its current situation in Spain. The committee has enlisted the help of several experts in the field to answer these questions. The following lines contain the answers that we have collaboratively produced, aiming to assist not only the members of ICOMEM but also anyone interested in this topic.

Impact of the SARS-CoV-2 Pandemic on the Epidemiology of Streptococcus pyogenes: A Five-Year Retrospective Study

The SARS-CoV-2 pandemic significantly affected the epidemiology of Streptococcus pyogenes, a pathogen associated with various clinical presentations such as pharyngitis, scarlet fever, and invasive diseases. This study analyzed the incidence and characteristics of S. pyogenes infections between 2018 and 2023, examining 915 cases categorized as either respiratory or non-respiratory. Respiratory infections predominantly affected children, accounting for 76% of cases, with a median age of 5 [3, 8] years, while non-respiratory infections were more common in adults, with a median age of 46.5 [34, 64] years. Invasive respiratory infections, such as pneumonia and empyema, were more frequent in children (54.8%), whereas invasive non-respiratory infections, such as primarily cellulitis, were predominantly seen in adults (90.5%). A sharp decline in S. pyogenes infections was observed during the pandemic, with respiratory cases decreasing tenfold in 2020 compared to the previous year, and non-respiratory cases experiencing a twofold reduction. However, infection rates returned to pre-pandemic levels by 2022 and 2023, with a notable resurgence of invasive respiratory infections in children following a public health alert in the United Kingdom in late 2022. These findings highlight distinct infection patterns between pediatric and adult populations and emphasize the significant impact of the pandemic on respiratory infections, particularly in children.

Group A Streptococcus Infections in Children: Epidemiological Insights Before and After the COVID-19 Pandemic

Group A streptococcus (GAS) is the cause of both mild and invasive infections in humans with a high morbidity and mortality rate. The transmission of disease usually occurs via droplets, so the implementation of infection mitigation strategies (IMS) during the COVID-19 pandemic altered the incidence of GAS infection. This review aims to provide an overview of the influence of the COVID-19 pandemic on the incidence of GAS infection in children (invasive or non-invasive). A surge in the incidence of invasive GAS infection was noted in December 2022 after the reversal of IMS. A global uprise in GAS infection (invasive and non-invasive) was noted, especially concerning the pediatric population. Children younger than 5 years old were mostly affected, with complicated pneumonia being the leading clinical manifestation, causing many deaths worldwide. Emm1, specifically M1UK, was recognized as the dominant lineage in Europe and correlated with invasive disease. Healthcare professionals need to be alert about the severity of GAS-related infections, leading to early identification and treatment.

COVID-19 complicated with severe M1UK-lineage Streptococcus pyogenes infection in elderly patients: A report of two cases

Case 1: A 71-year-old man was admitted to our hospital with progressive fever and dyspnea, which had developed three days after the onset of COVID-19. Initial chest computed tomography (CT) revealed a pulmonary lesion consistent with a secondary bacterial infection. Streptococcus pyogenes was isolated from cultures of primary sputum collected from the endotracheal tube, and identified as the causative microorganism. Case 2: A 91-year-old man was transferred to our hospital with severe hypotension, which had developed nine days after the onset of COVID-19. A chest CT revealed pericardial effusion and pericardiocentesis yielded purulent fluid. S. pyogenes was isolated from the fluid specimens and was identified as the causative microorganism of the secondary bacterial pericarditis. Isolates from both patients were subsequently identified as M1UK-lineage S. pyogenes via genetic analysis. This report implicates COVID-19 as a potential risk factor for severe M1UK infection via the respiratory tract.

Bactofencin YH, a novel bacteriocin with high inhibitory activity against clinical Streptococcus species

Strain Lactiplantibacillus plantarum D1 with bacteriocin producing ability was found in the intestine of Gambusia affinis. The bacteriocin was found to have high inhibitory activity against multiple Streptococcus species and several other Gram-positive and Gram-negative bacteria. Bacteriocin was purified from culture supernatant by ion-exchange chromatography, Sep-Pak C18 cartridge, and reverse-phase high-performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectral analysis determined that purified bacteriocin has a molecular mass of 2,731 Da. A partial N-terminal sequence KRKKHKXQIYNNGM was obtained from the Edman analysis. The N-terminal sequence was employed to search against a translation of the draft genome of strain D1. The translated full amino acid sequence of the mature peptide is as follows: NH2- KRKKHKCQIYNNGMPTGQYRWC, which has a molecular weight of 2738 Da. A BLAST search revealed that this bacteriocin was most similar to bactofencin A but differed from it with three amino acid residues. No identical peptide or protein has been previously reported, and this peptide, termed bactofencin YH, was therefore considered to be a new bacteriocin produced by Lactiplantibacillus plantarum D1.

CENTRAL NERVOUS SYSTEM INFECTION BY GROUP A STREPTOCOCCUS IN CHILDREN IN SPAIN (2019-2023)

Central nervous system infections in children caused by group A Streptococcus are rare. This study, conducted across 52 hospitals in Spain from 2019 to 2023, identified 32 cases of central nervous system infections in children caused by group A Streptococcus, with a significant increase from October 2022 onward (1.1% vs. 5.9%, P = 0.002). Half required pediatric intensive care unit admission, 12.5% exhibited sequelae and the mortality rate was 6.2%. Mastoiditis was the predominant primary infection.

Tracking progress on antimicrobial resistance by the quadripartite country self-assessment survey (TrACSS) in G7 countries, 2017-2023: opportunities and gaps

Antimicrobial resistance (AMR) poses serious challenges to the healthcare systems worldwide. Multiple factors and activities contribute to the development and spread of antimicrobial-resistant microorganisms. Monitoring progress in combating AMR is fundamental at both global and national levels to drive multisectoral actions, identify priorities, and coordinate strategies. Since 2017, the World Health Organization (WHO) has collected data through the Tracking AMR Country Self-Assessment Survey (TrACSS). TrACSS data are published in a publicly-available database. In 2023, 71 (59.9%) out of 177 responding countries reported the existence of a monitoring and evaluation plan for their National Action Plan (NAP) on AMR, and just 20 countries (11.3%) the allocation of funding to support NAP implementation. Countries reported challenges including limited financial and human resources, lack of technical capacity, and variable political commitment. Even across the Group of Seven (G7) countries, which represent some of the world's most advanced economies, many areas still need improvement, such as full implementation of infection prevention and control measures, adoption of WHO access/watch/reserve (AWaRe) classification of antibiotics, effective integration of laboratories in AMR surveillance in the animal health and food safety sectors, training and education, good manufacturing and hygiene practices in food processing, optimising pesticides use and environmental residues of antimicrobial drugs. Continuous and coordinated efforts are needed to strengthen multisectoral engagement to fight AMR.