The Shock of Strep: Rapid Deaths Due to Group a Streptococcus

Emergence of invasive Streptococcus dysgalactiae subsp. equisimilis in Spain (2012-2022): genomic insights and clinical correlations

OBJECTIVES

An increase in Streptococcus dysgalactiae subsp. equisimilis (SDSE) infections has been documented worldwide. This study aims to analyze invasive disease caused by SDSE (iSDSE) in adults over an 11-year period in Spain.

METHODS

We conducted a retrospective, laboratory-based study of iSDSE detected at Hospital Universitari de Bellvitge (HUB) from 2012 to 2022 (n = 89) and isolates collected in three Spanish hospitals in 2018 (n = 22). Clinical data from HUB were collected. Isolates were tested for antimicrobial susceptibility (European Committee on Antimicrobial Susceptibility Testing 2023), subjected to whole genome sequencing and analyzed for mobile genetic elements (MGEs). A mouse model was used to analyze virulence.

RESULTS

iSDSE episodes at HUB occurred predominantly in older patients with comorbidities (particularly, diabetes, chronic heart disease, and malignancies). Whole genome sequencing revealed a high genetic diversity, with the most common lineages being CC15, CC17, and CC20. Various virulence factors, including the superantigen speG, were identified. Macrolides, lincosamides, and tetracyclines exhibited the highest resistance rates (>27%) and changed over time, linked to multiple MGEs. The mouse model highlighted the virulence of the CC20-stG62647 lineage, but these results were discordant with clinical data.

CONCLUSION

iSDSE incidence is increasing and associated with older patients with comorbidities. Genetically, SDSE is diverse with a high capacity to integrate MGEs carrying resistance determinants. Mouse model studies showed the enhanced virulence of the CC20-stG62647 lineage. These findings underscore the need for ongoing surveillance of this emerging pathogen.

Invasive Group A Streptococcal Infection in Children, 1992-2023

Importance

The resurgence of invasive group A streptococcal (iGAS) infections and progress in GAS vaccine development emphasize the importance of understanding current trends in the epidemiology of iGAS.

Objective

To describe the epidemiology of pediatric iGAS over a 32-year period.

Design, Setting, and Participants

This case series uses population-based surveillance data for iGAS in Toronto and Peel Region, Canada, including emm typing from Canada's National Microbiology Laboratory and population data from Statistics Canada. All children (age <18 years) with iGAS from January 1, 1992, to December 31, 2023, were included. Data were analyzed from July 15, 2023, to September 1, 2024.

Main Outcomes and Measures

Outcomes of interest were disease incidence over time and by age; variation in clinical presentation, disease severity, outcomes and infecting emm types; and antimicrobial resistance.

Results

Overall, 498 iGAS cases (300 [60.2%] male; median [IQR] age, 5.1 [2.7-8.6] years) occurred, including 151 (30.7%) in children with comorbidities. The most common presentations were soft tissue infection (140 cases [28.1%]) and bacteremia without focus (131 cases [26.3%]). iGAS incidence increased from 1.8 events per 100 000 population per year in 1992 to 2011 to 2.4 events per 100 000 population per year in 2012 to 2019 (incidence rate ratio, 1.3 [95% CI, 1.1-1.6]), with the increase occurring in GAS infections of the respiratory tract. Incidence declined to 1.2 events per 100 000 population per year in 2020 and 0.5 events per 100 000 population per year in 2021 before increasing to 6.0 events per 100 000 population per year in 2023. In 2022 to 2023, 18 of 56 children with iGAS (32.0%) had a viral respiratory coinfection. Varicella-associated iGAS cases declined from 23 of 137 children (16.8%) in 1992 to 2001 to 2 of 223 children (0.9%) in 2012 to 2023 (P < .001), after routine varicella vaccination implementation in 2004. Streptococcal toxic shock syndrome occurred in 29 children (5.8%), necrotizing fasciitis in 12 children (2.4%); 10 children (2.0%) died. The most common emm types were emm1 (182 of 471 isolates [38.6%]), emm12 (75 isolates [15.9%]), and emm4 (31 isolates [6.6%]). The M1UK subtype was first identified in 2019 and comprised 32 of 46 emm1 isolates (70.0%) from 2019 to 2023. Compared with other emm types, emm1 was more likely to be associated with pneumonia (odds ratio [OR], 1.99 [95% CI, 1.16-3.40]), bone and joint infections (OR, 1.70 [95% CI, 1.08-2.68]), and intensive care unit admission (OR, 1.67 [95% CI, 1.03-2.68]); emm4 was more likely to be associated with bacteremia without focus (OR, 6.10 [95% CI, 2.83-13.16]). Overall, 437 isolates (92.8%) were of emm types included in the 30-valent GAS vaccine.

Conclusions and Relevance

This case series found that pediatric iGAS incidence increased in south-central Ontario prior to and after the COVID-19 pandemic in association with increased iGAS infections of the respiratory tract. Respiratory viral coinfections were common. Different emm types were associated with differing presentations and severity.

Cannabinoids as Antibacterial Agents: A Systematic and Critical Review of In Vitro Efficacy Against Streptococcus and Staphylococcus

BACKGROUND

Two major bacterial pathogens, Staphylococcus aureus and Streptococcus pyogenes, are becoming increasingly antibiotic-resistant. Despite the urgency, only a few new antibiotics have been approved to address these infections. Although cannabinoids have been noted for their antibacterial properties, a comprehensive review of their effects on these bacteria has been lacking.

OBJECTIVE

This systematic review examines the antibacterial activity of cannabinoids against S. aureus, including methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) strains, and S. pyogenes.

METHODS

Databases, including CINAHL, Cochrane, Medline, Scopus, Web of Science, and LILACS, were searched. Of 3510 records, 24 studies met the inclusion criteria, reporting on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration of cannabinoids.

RESULTS

Cannabidiol (CBD) emerged as the most effective cannabinoid, with MICs ranging from 0.65 to 32 mg/L against S. aureus, 0.5 to 4 mg/L for MRSA, and 1 to 2 mg/L for VRSA. Other cannabinoids, such as cannabichromene, cannabigerol (CBG), and delta-9-tetrahydrocannabinol (Δ9-THC), also exhibited significant antistaphylococcal activity. CBD, CBG, and Δ9-THC also showed efficacy against S. pyogenes, with MICs between 0.6 and 50 mg/L. Synergistic effects were observed when CBD and essential oils from Cannabis sativa when combined with other antibacterial agents.

CONCLUSION

Cannabinoids' antibacterial potency is closely linked to their structure-activity relationships, with features like the monoterpene region, aromatic alkyl side chain, and aromatic carboxylic groups enhancing efficacy, particularly in CBD and its cyclic forms. These results highlight the potential of cannabinoids in developing therapies for resistant strains, though further research is needed to confirm their clinical effectiveness.

A highly sensitive 3base™ assay for detecting Streptococcus pyogenes in saliva during controlled human pharyngitis

Streptococcus pyogenes (Group A Streptococcus; GAS) is a Gram-positive bacterium responsible for substantial human mortality and morbidity. Conventional diagnosis of GAS pharyngitis relies on throat swab culture, a low-throughput, slow, and relatively invasive 'gold standard'. While molecular approaches are becoming increasingly utilized, the potential of saliva as a diagnostic fluid for GAS infection remains largely unexplored. Here, we present a novel, high-throughput, sensitive, and robust speB qPCR assay that reliably detects GAS in saliva using innovative 3base™ technology (Genetic Signatures Limited, Sydney, Australia). The assay has been validated on baseline, acute, and convalescent saliva samples generated from the Controlled Human Infection for Vaccination Against Streptococcus (CHIVAS-M75) trial, in which healthy adult participants were challenged with emm75 GAS. In these well-defined samples, our high-throughput assay outperforms throat culture and conventional qPCR in saliva respectively, affirming the utility of the 3base™ platform, demonstrating the feasibility of saliva as a diagnostic biofluid, and paving the way for the development of novel non-invasive approaches for the detection of GAS and other oropharyngeal pathogens.

Necrotizing Fasciitis: When skin confuses - An autopsy case report

Necrotizing Fasciitis (NF) is a severe life-threatening soft tissue infection characterized by the rapid destruction of muscle, fat and fascial layers. This report details an autopsy case report of a 40year old male, unclaimed body lacking the complete history except that given by the Police personnel accompanying in which there is no prior history of trauma. This person succumbed to septic shock secondary to NF, despite clinical interventions. This case emphasizes the importance of early diagnosis and the need for heightened clinical awareness to improve patient outcomes.

Bacterial cholesterol-dependent cytolysins and their interaction with the human immune response

PURPOSE OF REVIEW

Many cholesterol-dependent cytolysin (CDC)-producing pathogens pose a significant threat to human health. Herein, we review the pore-dependent and -independent properties CDCs possess to assist pathogens in evading the host immune response.

RECENT FINDINGS

Within the last 5 years, exciting new research suggests CDCs can act to inhibit important immune functions, disrupt critical cell signaling pathways, and have tissue-specific effects. Additionally, recent studies have identified a key region of CDCs that generates robust immunity, providing resources for the development of CDC-based vaccines.

SUMMARY

This review provides new information on how CDCs alter host immune responses to aid bacteria in pathogenesis. These studies can assist in the design of more efficient vaccines and therapeutics against CDCs that will enhance the immune response to CDC-producing pathogens while mitigating the dampening effects CDCs have on the host immune response.

Pathogenesis, epidemiology and control of Group A Streptococcus infection

Streptococcus pyogenes (Group A Streptococcus; GAS) is exquisitely adapted to the human host, resulting in asymptomatic infection, pharyngitis, pyoderma, scarlet fever or invasive diseases, with potential for triggering post-infection immune sequelae. GAS deploys a range of virulence determinants to allow colonization, dissemination within the host and transmission, disrupting both innate and adaptive immune responses to infection. Fluctuating global GAS epidemiology is characterized by the emergence of new GAS clones, often associated with the acquisition of new virulence or antimicrobial determinants that are better adapted to the infection niche or averting host immunity. The recent identification of clinical GAS isolates with reduced penicillin sensitivity and increasing macrolide resistance threatens both frontline and penicillin-adjunctive antibiotic treatment. The World Health Organization (WHO) has developed a GAS research and technology road map and has outlined preferred vaccine characteristics, stimulating renewed interest in the development of safe and effective GAS vaccines.

Fatal Pediatric Streptococcal Infection: A Clinico-Pathological Study

PURPOSE AND CONTEXT

Streptococcal Infection (SI) is an important cause of pediatric death in children, yet limited reports exist on autopsy findings in fatal SI cases.

METHOD

Case records (1997-2019) of SI with no pre-existing risk factors were reviewed and selected. Their clinical and pathological findings in the autopsy reports were analyzed.

RESULTS

In our cohort of 38 cases based on bacterial culture results, SI was most commonly caused by Streptococcus pneumoniae (SPn; 45%) and Streptococcus pyogenes (SPy; 37%). 92% of decedents had some prodromal symptoms prior to terminal presentation. The clinical course was often rapid, with 89% found unresponsive, suddenly collapsing, or dying within 24 hours of hospital admission. 64% of deaths were attributed to sepsis, more frequently diagnosed in the SPy group than in the SPn group (71% vs 48%). Pneumonia was found in both SPn and SPy groups, whereas meningitis was exclusively associated with SPn.

CONCLUSION

Our study shows fatal SI is most commonly caused by either SPn or SPy, both of which are frequently associated with prodromal symptoms, rapid terminal clinical course, and evidence of sepsis. Postmortem diagnosis of sepsis is challenging and should be correlated with clinical features, bacterial culture results, and autopsy findings.

The Role of Autophagy and Autophagy Receptor NDP52 in Microbial Infections

Autophagy is a general protective mechanism for maintaining homeostasis in eukaryotic cells, regulating cellular metabolism, and promoting cell survival by degrading and recycling cellular components under stress conditions. The degradation pathway that is mediated by autophagy receptors is called selective autophagy, also named as xenophagy. Autophagy receptor NDP52 acts as a ‘bridge’ between autophagy and the ubiquitin-proteasome system, and it also plays an important role in the process of selective autophagy. Pathogenic microbial infections cause various diseases in both humans and animals, posing a great threat to public health. Increasing evidence has revealed that autophagy and autophagy receptors are involved in the life cycle of pathogenic microbial infections. The interaction between autophagy receptor and pathogenic microorganism not only affects the replication of these microorganisms in the host cell, but it also affects the host’s immune system. This review aims to discuss the effects of autophagy on pathogenic microbial infection and replication, and summarizes the mechanisms by which autophagy receptors interact with microorganisms. While considering the role of autophagy receptors in microbial infection, NDP52 might be a potential target for developing effective therapies to treat pathogenic microbial infections.