BACKGROUND Pneumococcal vaccination has been recommended in Germany for adults aged ≥ 60 years (1998) and children aged < 2 years (2006), resulting in a reduction of pneumococcal disease incidence in vaccinated children and unvaccinated individuals through herd protection. AIM We aimed to investigate serotype distribution of invasive pneumococcal disease (IPD) among children and adults in 2017–2024. METHODS We analysed data of an ongoing nationwide surveillance of IPD. All isolates were serotyped by Neufeld’s Quellung reaction. RESULTS In total, 24,122 IPD isolates were analysed by the German Reference Laboratory for Streptococci. Over the study period, case numbers were lower during the COVID-19 pandemic and increased afterwards with higher proportion of pneumococcal conjugate vaccine (PCV)13 serotypes. Serotypes 22F and 33F, included in PCV15 and PCV20, showed only minor variations, whereas PCV20 unique serotypes were less frequently observed in 2022–2024. Serotype 3 persisted in IPD across all age groups, while serotype 4 disappeared in children and adolescents, but increased in adults, most prominently in 18–49-year-olds. Serotype 38 steeply increased in 2023/24, among children aged < 2 years and older adults. CONCLUSION The concerning increase of PCV13 serotype IPD in Germany might be related to low vaccination uptake, resulting in inefficient herd protection. The dominance of serotype 3 and the rise of serotype 4 among adults highlight the importance of direct protection and support the current national vaccination recommendation for adults aged ≥ 60 years. The increase in serotype 38 IPD among young children and older adults might indicate a replacement phenomenon, highlighting the importance of IPD serotype surveillance.

Lactational mastitis is a common condition during breastfeeding, which, in rare cases, can progress to life-threatening necrotising mastitis, particularly in cases where Streptococcus pyogenes is involved. The development of streptococcal toxic shock syndrome (STSS) is associated with a fatality rate of approximately 50%. In this Grand Round, we present the case of a healthy mother, aged 35 years, breastfeeding a child diagnosed with scarlet fever. The mother subsequently developed lactational mastitis, with a high load of S pyogenes, culminating in skin necrosis and STSS. This case, along with six more case reports identified in a thorough literature search, underscores the severity of lactational S pyogenes mastitis. In all cases, the only identifiable risk factor for invasive S pyogenes disease was close contact to individuals exhibiting symptoms of scarlet fever. During breastfeeding, the direct contact of the nipple to the child's pharynx, containing S pyogenes in the case of scarlet fever, presents a probable route of transmission, especially when considering the pathogenicity of the bacterium. Although breastfeeding is generally encouraged, the current literature lacks sufficient guidance regarding breastfeeding practices in children with scarlet fever. This Grand Round proposes a simple strategy to minimise maternal risks, offering valuable insights into clinical management and prevention.

Purpose In late 2022, a surge of severe S. pyogenes infections was reported in several European countries. This study assessed hospitalizations and disease severity of community-acquired bacterial infections with S. pyogenes, S. pneumoniae, N. meningitidis , and H. influenzae among children in North Rhine-Westphalia (NRW), Germany, during the last quarter of 2022 compared to long-term incidences. Methods Hospital cases due to bacterial infections between October and December 2022 were collected in a multicenter study (MC) from 59/62 (95%) children's hospitals in NRW and combined with surveillance data (2016–2023) from the national reference laboratories for streptococci, N. meningitidis , and H. influenzae . Overall and pathogen-specific incidence rates (IR) from January 2016 to March 2023 were estimated via capture–recapture analyses. Expected annual deaths from the studied pathogens were calculated from national death cause statistics. Results In the MC study, 153 cases with high overall disease severity were reported with pneumonia being most common (59%, n = 91). IRs of bacterial infections declined at the beginning of the COVID-19 pandemic and massively surged to unprecedented levels in late 2022 and early 2023 (overall hospitalizations 3.5-fold), with S. pyogenes and S. pneumoniae as main drivers (18-fold and threefold). Observed deaths during the study period exceeded the expected number for the entire year in NRW by far (7 vs. 0.9). Discussion The unprecedented peak of bacterial infections and deaths in late 2022 and early 2023 was caused mainly by S. pyogenes and S. pneumoniae . Improved precautionary measures are needed to attenuate future outbreaks.

As a potential side effect of the severe acute respiratory syndrome coronavirus type 2 pandemic, invasive group A Streptococcus (iGAS) infections in Europe have increased dramatically in both children and adults in the end of 2022. This epidemiological and molecular study describes the distributions of streptococcal genes encoding the M antigen (emm types) and superantigens in patients with invasive and non-invasive GAS infections. From December 2022 to December 2023, a total of 163 GAS isolates were collected from sterile and non-sterile sites of patients at five hospitals in Germany including two tertiary care centers. Genes encoding M protein and superantigens were determined following the guidelines of CDC Streptococcus laboratory. Patients' characteristics were reviewed retrospectively. Correlations of clinical factors, emm types, and superantigens with rates of invasive infections were analyzed. Of the 163 included GAS cases, 112 (69%) were considered as invasive. In total, 33 different emm types were observed, of which emm1.0 (n = 49; 30%), emm89.0 (n = 15; 9%), and emm12.0 (n = 14; 9%) were most prevalent. In total, 70% of emm1.0 isolates belonged to M1UK lineage. No difference in invasive infections was observed for the M1UK lineage compared with other emm1.0 isolates. However, the emm1.0 type, presence of speA1-3, speG, or speJ, as well as adulthood were significantly associated with invasive infections. In contrast, emm12.0 isolates were significantly less associated with invasive infections. Multivariable analysis confirmed a significant influence of speJ and adulthood on iGAS infections. This study underlines the importance of continuous monitoring of genomic trends and identification of emerging GAS variants. This may aid in delineating pathogenicity factors of Streptococcus pyogenes that propel invasive infections.

(1) Background: Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an important β-hemolytic pathogen historically described as mainly affecting animals. Studies epidemiologically assessing the pathogenicity in the human population in Germany are rare. (2) Methods: the present study combines national surveillance data from 2010 to 2022 with a single-center clinical study conducted from 2016 to 2022, focusing on emm type, Lancefield antigen, antimicrobial resistance, patient characteristics, disease severity, and clinical infection markers. (3) Results: The nationwide reported invasive SDSE infections suggest an increasing infection burden for the German population. One particular emm type, stG62647, increased over the study period, being the dominant type in both study cohorts, suggesting a mutation-driven outbreak of a virulent clone. The patient data show that men were more affected than women, although in the single-center cohort, this trend was reversed for patients with stG62647 SDSE. Men affected by stG62647 developed predominantly fascial infections, whereas women suffering from superficial and fascial non-stG62647 SDSE infections were significantly younger than other patients. Increasing age was a general risk factor for invasive SDSE infections. (4) Conclusions: further studies are needed to further elucidate the raised questions regarding outbreak origin, underlying molecular mechanisms as well as sex-dependent pathogen adaptation.

The identification of the novel pneumococcal serotype 7D by Neufeld quellung reaction requires significant expertise. To circumvent this, we developed a simple serotype-specific PCR method to discriminate serotype 7D from the closely related serotypes 7C, 7B and 40. The established PCR was validated with the strain collection of the German National Reference Center for Streptococci (GNRCS). However, no isolate initially assigned as serotype 7B, 7C or 40 was identified as serotype 7D.

Background In late 2022, a surge of severe bacterial infections caused by S. pyogenes was reported in several European countries, including Germany. This study assessed disease burden and severity of hospitalizations for community-acquired bacterial infections with S. pyogenes, S. pneumoniae, N. meningitidis , and H. influenzae among children in North Rhine-Westphalia (NRW), Germany, during the last quarter of 2022 compared to long-term incidences. Methods Hospital cases due to bacterial infections between October and December 2022 were collected from 59/62 (95 %) children’s hospitals in NRW and combined with surveillance data (2016 - 2023) from the national reference laboratories for streptococci, N. meningitidis , and H. influenzae . Total cases in NRW and incidence rates from January 2016 to March 2023 were estimated by capture-recapture analyses. Expected annual deaths from the studied pathogens were calculated from national death cause statistics. Results Between October and December 2022, 153 cases with high overall disease severity were reported with pneumonia being most common (59 %, n = 91). Incidence rates of bacterial infections declined at the beginning of the COVID-19 pandemic. In late 2022 and early 2023 a massive surge to levels unprecedented since 2016 was observed, mainly driven by S. pyogenes and S. pneumoniae . Observed deaths during the study period exceeded the expected number for the entire year in NRW by far (7 vs. 0.9). Discussion The unprecedented peak of bacterial infections in late 2022 and early 2023 was caused by various mechanisms intertwined that require close surveillance and improved precautionary measures for future outbreaks.

BACKGROUND:Necrotizing soft-tissue infections (NSTI) are life-threatening conditions often caused by β-hemolytic streptococci, group A Streptococcus (GAS) in particular. Optimal treatment is contentious. The INFECT cohort includes the largest set of prospectively enrolled streptococcal NSTI cases to date.METHODS:From the INFECT cohort of 409 adults admitted with NSTI to 5 clinical centers in Scandinavia, patients culture-positive for GAS or Streptococcus dysgalactiae (SD) were selected. Risk factors were identified by comparison with a cohort of nonnecrotizing streptococcal cellulitis. The impact of baseline factors and treatment on 90-day mortality was explored using Lasso regression. Whole-genome sequencing of bacterial isolates was used for emm typing and virulence gene profiling.RESULTS:The 126 GAS NSTI cases and 27 cases caused by SD constituted 31% and 7% of the whole NSTI cohort, respectively. When comparing to nonnecrotizing streptococcal cellulitis, streptococcal NSTI was associated to blunt trauma, absence of preexisting skin lesions, and a lower body mass index. Septic shock was significantly more frequent in GAS (65%) compared to SD (41%) and polymicrobial, nonstreptococcal NSTI (46%). Age, male sex, septic shock, and no administration of intravenous immunoglobulin (IVIG) were among factors associated with 90-day mortality. Predominant emm types were emm1, emm3, and emm28 in GAS and stG62647 in SD.CONCLUSIONS:Streptococcal NSTI was associated with several risk factors, including blunt trauma. Septic shock was more frequent in NSTI caused by GAS than in cases due to SD. Factors associated with mortality in GAS NSTI included age, septic shock, and no administration of IVIG.

Analyses of plasma collected pre- and postadministration of intravenous immunoglobulin (IVIG) from patients with group A Streptococcus necrotizing soft tissue infections demonstrated a negative correlation between IVIG dose and toxin-triggered T-cell proliferation (r=-.67, P<.0001). One 25-g IVIG dose was sufficient to yield plasma-neutralizing activity against streptococcal superantigens.

Necrotizing soft tissue infections (NSTIs) are devastating infections caused by either a single pathogen, predominantly Streptococcus pyogenes , or by multiple bacterial species. A better understanding of the pathogenic mechanisms underlying these different NSTI types could facilitate faster diagnostic and more effective therapeutic strategies. Here, we integrate microbial community profiling with host and pathogen(s) transcriptional analysis in patient biopsies to dissect the pathophysiology of streptococcal and polymicrobial NSTIs. We observe that the pathogenicity of polymicrobial communities is mediated by synergistic interactions between community members, fueling a cycle of bacterial colonization and inflammatory tissue destruction. In S. pyogenes NSTIs, expression of specialized virulence factors underlies infection pathophysiology. Furthermore, we identify a strong interferon-related response specific to S. pyogenes NSTIs that could be exploited as a potential diagnostic biomarker. Our study provides insights into the pathophysiology of mono- and polymicrobial NSTIs and highlights the potential of host-derived signatures for microbial diagnosis of NSTIs.

Beta haemolytic Group A streptococcus (GAS) or Streptococcus pyogenes are strict human pathogens responsible for mild to severe fatal invasive infections. Even with enormous number of reports exploring the role of S. pyogenes exotoxins in its pathogenesis, inadequate knowledge on the biofilm process and the potential role of exotoxins in bacterial dissemination from matured biofilms has been a hindrance in development of effective and targeted treatments. Therefore, the present study was aimed in investigating the uncharted role of these exotoxins in biofilm process. Through our study the putative role of ciaRH in the SpeA dependent ablation of biofilm formation could be speculated and thus helping in bacterial dissemination. The seed-dispersal effect of SpeA was time and concentration dependent and seen to be consistent within various streptococcal species. Transcriptome analysis of SpeA treated S. pyogenes biofilms revealed the involvement of many transcriptional regulators ( ciaRH ) and response genes ( luxS, shr, shp, SPy_0572 ), hinting towards specific mechanisms underlying the dispersal effect by SpeA. This finding opens up a discussion towards understanding a new mechanism involved in the pathogenesis of Streptococcus pyogenes and might help in understanding the bacterial infections in a better way.

Necrotizing Soft Tissue Infections (NSTIs), often reaching the deep fascia and muscle, are mainly caused by group A Streptococcus (GAS) and to a lesser extent by Staphylococcus aureus (SA). Conversely SA is a leading etiologic agent of pyomyositis suggesting that SA could have a specific tropism for the muscle. To assess the pathogenicity of these two bacterial species for muscles cells in comparison to keratinocytes, adhesion and invasion of NSTI-GAS and NSTI-SA were assessed on these cells. Bloodstream infections (BSI) SA isolates and non-invasive coagulase negative Staphylococci (CNS) isolates were used as controls. SA isolates from NSTI and from BSI exhibited stronger internalization into human keratinocytes and myoblasts than CNS or NSTI-GAS. While the median level of SA internalization culminated at 2% in human keratinocytes, it reached over 30% in human myoblasts due to a higher percentage of infected myoblasts (>11%) as compared to keratinocytes (<3%) assessed by transmission electron microscopy. Higher cytotoxicity for myoblasts of NSTI-SA as compared to BSI-SA, was attributed to higher levels of psm α and RNAIII transcripts in NSTI group as compared to hematogenous group. However, the two groups were not discriminated at the genomic level. The cellular basis of high internalization rate in myoblasts was attributed to higher expression of α5β1 integrin in myoblasts as compared to keratinocytes. Major contribution of FnbpAB-integrin α5β1 pathway to internalization was confirmed by isogenic mutants. Our findings suggest the contribution of NSTI-SA severity by its unique propensity to invade and kill myoblasts, a property not shared by NSTI-GAS. Importance Necrotizing Soft Tissue Infection (NSTI) is a severe infection caused mainly by group A Streptococcus (GAS) and occasionally by S. aureus (SA); the latter being more often associated with pyomyositis. NSTIs frequently involve the deep fascia and may provoke muscle necrosis. The goal of this study was to determine the tropism and pathogenicity of these two bacterial species for muscle cells. The results revealed a high tropism of SA for myoblasts and myotubes followed by cytotoxicity as opposed to GAS that did not invade these cells. This study uncover a novel mechanism of SA contribution to NSTI with a direct muscle involvement, while in GAS NSTI this is likely indirect, for instance, secondary to vascular occlusion.

Background Necrotizing soft tissue infections (NSTIs) caused by group A Streptococcus (GAS) and occasionally by Staphylococcus aureus (SA) frequently involve the deep fascia and often lead to muscle necrosis. Methods To assess the pathogenicity of GAS and S. aureus for muscles in comparison to keratinocytes, adhesion and invasion of NSTI-GAS and NSTI-SA isolates were assessed in these cells. Bloodstream infections (BSI-SA) and noninvasive coagulase-negative staphylococci (CNS) isolates were used as controls. Results NSTI-SA and BSI-SA exhibited stronger internalization into human keratinocytes and myoblasts than NSTI-GAS or CNS. S. aureus internalization reached over 30% in human myoblasts due to a higher percentage of infected myoblasts (>11%) as compared to keratinocytes (<3%). Higher cytotoxicity for myoblasts of NSTI-SA as compared to BSI-SA was attributed to higher levels of psmα and RNAIII transcripts in NSTI-SA. However, the 2 groups were not discriminated at the genomic level. The cellular basis of high internalization rate in myoblasts was attributed to higher expression of α5β1 integrin in myoblasts. Major contribution of FnbpAB-integrin α5β1 pathway to internalization was confirmed by isogenic mutants. Conclusions Our findings suggest a factor in NSTI-SA severity is the strong invasiveness of S. aureus in muscle cells, a property not shared by NSTI-GAS isolates.

A prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both immunological and nonimmunological pathways. Here, we report a fatal case of an immunocompetent healthy female presenting with toxic shock and purpura fulminans caused by group B streptococcus (GBS; serotype III, CC19). The strain (LUMC16) was pigmented and hyperhemolytic. Stimulation of human primary cells with hyperhemolytic LUMC16 and STSS/NF-HH strains and pigment toxin resulted in a release of proinflammatory mediators, including tumor necrosis factor, interleukin (IL)-1β, and IL-6. In addition, LUMC16 induced blood clotting and showed factor XII activity on its surface, which was linked to the presence of the pigment. The expression of pigment was not linked to a mutation within the CovR/S region. In conclusion, our study shows that the hemolytic lipid toxin contributes to the ability of GBS to cause systemic hyperinflammation and interferes with the coagulation system.

Streptococcus dysgalactiae subsp. equisimilis (SDSE), belonging to the group C and G streptococci, are human pathogens reported to cause clinical manifestations similar to infections caused by Streptococcus pyogenes. To scrutinize the distribution of gene coding for S. pyogenes virulence factors in SDSE, 255 isolates were collected from humans infected with SDSE in Vellore, a region in southern India, with high incidence of SDSE infections. Initial evaluation indicated SDSE isolates comprising of 82.35% group G and 17.64% group C. A multiplex PCR system was used to detect 21 gene encoding virulence-associated factors of S. pyogenes, like superantigens, DNases, proteinases, and other immune modulatory toxins. As validated by DNA sequencing of the PCR products, sequences homologous to speC, speG, speH, speI, speL, ssa and smeZ of the family of superantigen coding genes and for DNases like sdaD and sdc were detected in the SDSE collection. Furthermore, there was high abundance (48.12% in group G and 86.6% in group C SDSE) of scpA, the gene coding for C5a peptidase in these isolates. Higher abundance of S. pyogenes virulence factor genes was observed in SDSE of Lancefield group C as compared to group G, even though the incidence rates in former were lower. This study not only substantiates detection of S. pyogenes virulence factor genes in whole genome sequenced SDSE but also makes significant contribution towards the understanding of SDSE and its increasing virulence potential.

Background. Necrotizing soft-tissue infections (NSTI) are the most severe form of bacterial-induced tissue pathology. Their unpredictable onset and rapid development into life-threatening conditions considerably complicate patient treatment. Understanding the risk factors for NSTI in individual patients is necessary for selecting the appropriate therapeutic option. Methods. We investigated the role of pathogen-specific antibodies in the manifestation of NSTI by performing a comparative serologic approach, using plasma samples and bacterial isolates from patients with clinical NSTIs or nonnecrotizing STIs caused by Streptococcus pyogenes. We also evaluated the potential beneficial effect of intravenous immunoglobulin (IVIG) treatment. Results. We identified a hitherto overlooked state of serologic susceptibility in patients with NSTIs during the earliest stages of the infection that is potentially linked to disease progression. Thus, all patients with NSTIs included in this study exhibited a deficiency in specific antibodies directed against the causative S. pyogenes strains and the majority of their exotoxins during the initial stage of the infection. We also showed that the clinical use of IVIG during the course of infection compensates the observed antibody deficiency but is unable to halt the disease progression, once tissue necrosis has developed. Conclusion. These observations emphasize the requirement of preexisting pathogen-specific antibodies to prevent the irreversible progression of tissue infections into severely spreading NSTIs and urge further investigations on the beneficial effect of IVIG-based early phase intervention strategies to prevent the severe effects of this devastating bacterial infection.

Conventionally categorized as commensals, the Streptococci of the species S. anginosus are facultative human pathogens that are difficult to diagnose and often overlooked. Furthermore, detailed investigation and diagnosis of S. anginosus infections is hampered by unexplored taxonomy and widely elusive molecular pathogenesis. To explore their pathogenic potential, S. anginosus isolates collected from patients of two geographical locations (Vellore, India and Leipzig, Germany) were subjected to multi-locus sequence analysis (MLSA). This analysis revealed the potential presence of a new distinct clade of the species S. anginosus, tentatively termed here as genomosubspecies vellorensis. A complementary PCR-based screening for S. pyogenes virulence factor as well as antibiotic resistance genes revealed not only the presence of superantigen- and extracellular DNase coding genes identical to corresponding genes of S. pyogenes, but also of erythromycin and tetracycline resistance genes in the genomes of the analyzed S. anginosus isolates, thus posing a matter of significant health concern. Identification of new pathogenic S. anginosus strains capable of causing difficult to treat infections may pose additional challenges to the diagnosis and treatment of Streptococcus based infections.

Streptococcus pyogenes serotype M1 is a frequent cause of severe infections in humans. Some M1 isolates are pathogenic in mice and used in studies on infection pathogenesis. We observed marked differences in murine infections caused by M1 strain SF370, 5448, 5448AP or AP1 which prompted us to sequence the whole genome of isolates 5448 and AP1 for comparative analysis. Strain 5448 is known to acquire inactivating mutations in the CovRS two-component system during mouse infection, producing hypervirulent progeny such as 5448AP. Isolates AP1 and 5448AP, more than 5448, caused disseminating infections that became systemic and lethal. SF370 was not pathogenic. Phages caused gross genetic differences and increased the gene content of AP1 by 8% as compared to 5448 and SF370. Each of six examined M1 genomes contained two CRISPR-Cas systems. Phage insertion destroyed a type II CRISPR-Cas system in AP1 and other strains of serotypes M1, M3, M6 and M24, but not in M1 strains 5448, SF370, MGAS5005, A20 or M1 476. A resulting impaired defence against invading genetic elements could have led to the wealth of phages in AP1. AP1 lacks genetic features of the MGAS5005-like clonal complex including the streptodornase that drives selection for hypervirulent clones with inactivated CovRS system. Still, inactivating mutations in covS were a common genetic feature of AP1 and the MGAS5005-like isolate 5448AP. Abolished expression of the cysteine proteinase SpeB, due to CovRS inactivation could be a common cause for hypervirulence of the two isolates. Moreover, an additional protein H-coding gene and a mutation in the regulator gene rofA distinguished AP1 form other M1 isolates. In conclusion, hypervirulence of S. pyogenes M1 in mice is not limited to the MGAS5005-like genotype.

The complement anaphylatoxin C5a contributes to host defense against Staphylococcus aureus. In this study, we investigated the functional role of the two known C5a receptors, C5aR1 and C5aR2, in the host response to S. aureus. We found that C5aR1−/− mice exhibited greater susceptibility to S. aureus bloodstream infection than wild type and C5aR2−/− mice, as demonstrated by the significantly higher bacterial loads in the kidneys and heart at 24 h of infection, and by the higher levels of inflammatory IL-6 in serum. Histological and immunohistochemistry investigation of infected kidneys at 24 h after bacterial inoculation revealed a discrete infiltration of neutrophils in wild type mice but already well-developed abscesses consisting of bacterial clusters surrounded by a large number of neutrophils in both C5aR1−/− and C5aR2−/− mice. Furthermore, blood neutrophils from C5aR1−/− mice were less efficient than those from wild type or C5aR2−/− mice at killing S. aureus. The requirement of C5aR1 for efficient killing of S. aureus was also demonstrated in human blood after disrupting C5a-C5aR1 signaling using specific inhibitors. These results demonstrated a role for C5aR1 in S. aureus clearance as well as a role for both C5aR1 and C5aR2 in the orchestration of the inflammatory response during infection.

In both prokaryotes and eukaryotes, insight into gene function is typically obtained by in silico homology searches and/or phenotypic analyses of strains bearing mutations within open reading frames. However, the studies herein illustrate how mRNA function is not limited to the expression of a cognate protein. We demonstrate that a stress-induced protein-encoding mRNA (irvA) from the dental caries pathogen Streptococcus mutans directly modulates target mRNA (gbpC) stability through seed pairing interactions. The 5' untranslated region of irvA mRNA is a trans riboregulator of gbpC and a critical activator of the DDAG stress response, whereas IrvA functions independently in the regulation of natural competence. The irvA riboregulatory domain controls GbpC production by forming irvA-gbpC hybrid mRNA duplexes that prevent gbpC degradation by an RNase J2-mediated pathway. These studies implicate a potentially ubiquitous role for typical protein-encoding mRNAs as riboregulators, which could alter current concepts in gene regulation.