Beta-haemolytic group A, C and G streptococcal infections in Western Norway: a 15-year retrospective survey

Inter-species gene flow drives ongoing evolution of Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging cause of human infection with invasive disease incidence and clinical manifestations comparable to the closely related species, Streptococcus pyogenes. Through systematic genomic analyses of 501 disseminated SDSE strains, we demonstrate extensive overlap between the genomes of SDSE and S. pyogenes. More than 75% of core genes are shared between the two species with one third demonstrating evidence of cross-species recombination. Twenty-five percent of mobile genetic element (MGE) clusters and 16 of 55 SDSE MGE insertion regions were shared across species. Assessing potential cross-protection from leading S. pyogenes vaccine candidates on SDSE, 12/34 preclinical vaccine antigen genes were shown to be present in >99% of isolates of both species. Relevant to possible vaccine evasion, six vaccine candidate genes demonstrated evidence of inter-species recombination. These findings demonstrate previously unappreciated levels of genomic overlap between these closely related pathogens with implications for streptococcal pathobiology, disease surveillance and prevention.

Global Streptococcus pyogenes strain diversity, disease associations, and implications for vaccine development: a systematic review

The high strain diversity of Streptococcus pyogenes serves as a major obstacle to vaccine development against this leading global pathogen. We did a systematic review of studies in PubMed, MEDLINE, and Embase that reported the global distribution of S pyogenes emm-types and emm-clusters from Jan 1, 1990, to Feb 23, 2023. 212 datasets were included from 55 countries, encompassing 74 468 bacterial isolates belonging to 211 emm-types. Globally, an inverse correlation was observed between strain diversity and the UNDP Human Development Index (HDI; r=-0·72; p<0·0001), which remained consistent upon subanalysis by global region and site of infection. Greater strain diversity was associated with a lower HDI, suggesting the role of social determinants in diseases caused by S pyogenes. We used a population-weighted analysis to adjust for the disproportionate number of epidemiological studies from high-income countries and identified 15 key representative isolates as vaccine targets. Strong strain type associations were observed between the site of infection (invasive, skin, and throat) and several streptococcal lineages. In conclusion, the development of a truly global vaccine to reduce the immense burden of diseases caused by S pyogenes should consider the multidimensional diversity of the pathogen, including its social and environmental context, and not merely its geographical distribution.

A Case Report of Streptococcus Dysgalactiae Toxic Shock Syndrome Complicated with Symmetric Peripheral Gangrene

Streptococcus dysgalactiae subspecies equlsimilis (SDSE) is considered an important bacterial pathogen, and attention has also increased with the increasing number of invasive SDSE infections. Here, we report a patient with S. dysgalactiae toxic shock syndrome complicated by symmetrical peripheral gangrene (SPG). Despite surviving active treatment, amputation severely impacts the quality of life of patients. Therefore, we should pay attention to the early treatment of SDSE infection and the prevention and treatment of related complications.

Invasive beta-haemolytic streptococcal infections, Finland, 2006 to 2020: increase in Lancefield group C/G infections

BackgroundInvasive infections with beta-haemolytic streptococci of Lancefield groups A (iGAS), B (iGBS) and C/G (iGCGS) are a major cause of morbidity and mortality worldwide.AimWe studied incidence trends of invasive beta-haemolytic streptococcal infections in Finland, focusing on iGCGS.MethodsWe conducted a retrospective register-based study. Cases were defined as isolations from blood and/or cerebrospinal fluid and retrieved from the National Infectious Disease Register where all invasive cases are mandatorily notified.ResultsBetween 2006 and 2020, the mean annual incidence was 4.1 per 100,000 for iGAS (range: 2.1-6.7), 5.2 for iGBS (4.0-6.3) and 10.1 for iGCGS (5.4-17.6). The incidence displayed an increasing trend for all groups, albeit for iGBS only for individuals 45 years and older. The increase was particularly sharp for iGCGS (8% annual relative increase). The incidence rate was higher in males for iGCGS (adjusted incidence rate ratio (IRR) = 1.6; 95% confidence interval (CI): 1.5-1.8) and iGAS (adjusted IRR = 1.3; 95% CI: 1.1-1.4); for iGBS, the association with sex was age-dependent. In adults, iGCGS incidence increased significantly with age. Recurrency was seen for iGCGS and secondarily iGBS, but not for iGAS. Infections with iGCGS and iGBS peaked in July and August.ConclusionsThe incidence of invasive beta-haemolytic streptococcal infections in Finland has been rising since 2006, especially for iGCGS and among the elderly population. However, national surveillance still focuses on iGAS and iGBS, and European Union-wide surveillance is lacking. We recommend that surveillance of iGCGS be enhanced, including systematic collection and typing of isolates, to guide infection prevention strategies.

Incidence, seasonal pattern, and clinical manifestations of Streptococcus dysgalactiae subspecies equisimilis bacteremia; a population-based study

Streptococcus dysgalactiae subspecies equisimilis (SDSE) is a human pathogen causing severe invasive infections. Population-based studies on SDSE bacteremia are limited. The purpose of this study was to investigate the incidence, seasonal pattern, clinical manifestations, and recurrence of SDSE bacteraemia. Records regarding patients aged ≥ 18 years with SDSE bacteremia in the Pirkanmaa health district in August 2015 to July 2018 were retrospectively reviewed. A total of 230 SDSE bacteremia episodes were identified, with 217 episodes (involving 211 patients) available for analysis. The mean annual incidence rate of SDSE bacteremia was 16.9/100 000 inhabitants. Most episodes (33%) were detected in the summer (June to August) (p = 0.058). Episodes with bacteremic cellulitis were statistically significantly more common during the summer compared with other seasons (p = 0.008). Cellulitis was the most common presenting clinical manifestation of SDSE bacteremia (68% of all episodes). Risk factors of recurring bacteremia were chronic eczema and/or skin erosion (OR 3.96 [95% CI 1.11-14.1]), heart disease (OR 3.56 [95% CI 1.22-10.4]), diabetes (OR 3.77 [95% CI 1.35-10.5]) and a history of cellulitis. We found a remarkably high incidence of SDSE bacteraemia in the Pirkanmaa health district. Bacteraemic cellulitis, which was the predominant clinical manifestation is more often occurred in the summer. Risk factors of recurring SDSE bacteremia were a history of cellulitis, chronic eczema or skin erosion, diabetes, and heart disease.

Genomic epidemiology of Streptococcus dysgalactiae subsp. equisimilis strains causing invasive disease in Norway during 2018

Background

Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an emerging global pathogen, yet the epidemiology and population genetics of SDSE species have not been extensively characterized.

Methods

We carried out whole genome sequencing to characterize 274 SDSE isolates causing bloodstream infections obtained through national surveillance program in 2018. We conducted multilocus sequence typing (MLST), emm-typing, core genome phylogeny, as well as investigated key features associated with virulence. Moreover, comparison to SDSE from other geographic regions were performed in order to gain more insight in the evolutionary dynamics in SDSE.

Results

The phylogenetic analysis indicated a substantial diversity of emm-types and sequence types (STs). Briefly, 17 emm-types and 58 STs were identified that formed 10 clonal complexes (CCs). The predominant ST-types were ST20 (20%), ST17 (17%), and ST29 (11%). While CC17 and CC29 clades showed a substantial heterogeneity with well-separated emm-associated subclades, the CC20 clade harboring the stG62647 emm-type was more homogenous and the most prevalent in the present study. Moreover, we observed notable differences in the distribution of clades within Norway, as well as several disseminated CCs and also distinct geographic variations when compared to data from other countries. We also revealed extensive intra-species recombination events involving surface exposed virulence factors, including the emm gene important for phylogenetic profiling.

Conclusion

Recombination events involving the emm as well as other virulence genes in SDSE, are important mechanisms in shaping the genetic variability in the SDSE population, potentially offering selective advantages to certain lineages. The enhanced phylogenetic resolution offered by whole genome sequencing is necessary to identify and delimitate outbreaks, monitor and properly characterize emerging strains, as well as elucidate bacterial population dynamics.

Epidemiological and Clinical Features of Streptococcus dysgalactiae ssp. equisimilis stG62647 and Other emm Types in Germany

(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.

Analysis of the Genomics and Mouse Virulence of an Emergent Clone of Streptococcus dysgalactiae Subspecies equisimilis

Streptococcus dysgalactiae subsp. equisimilis is a bacterial pathogen that is increasingly recognized as a cause of severe human infections. Much less is known about the genomics and infection pathogenesis of S. dysgalactiae subsp. equisimilis strains compared to the closely related bacterium Streptococcus pyogenes. To address these knowledge deficits, we sequenced to closure the genomes of seven S. dysgalactiae subsp. equisimilis human isolates, including six that were emm type stG62647. Recently, for unknown reasons, strains of this emm type have emerged and caused an increasing number of severe human infections in several countries. The genomes of these seven strains vary between 2.15 and 2.21 Mbp. The core chromosomes of these six S. dysgalactiae subsp. equisimilis stG62647 strains are closely related, differing on average by only 495 single-nucleotide polymorphisms, consistent with a recent descent from a common progenitor. The largest source of genetic diversity among these seven isolates is differences in putative mobile genetic elements, both chromosomal and extrachromosomal. Consistent with the epidemiological observations of increased frequency and severity of infections, both stG62647 strains studied were significantly more virulent than a strain of emm type stC74a in a mouse model of necrotizing myositis, as assessed by bacterial CFU burden, lesion size, and survival curves. Taken together, our genomic and pathogenesis data show the strains of emm type stG62647 we studied are closely genetically related and have enhanced virulence in a mouse model of severe invasive disease. Our findings underscore the need for expanded study of the genomics and molecular pathogenesis of S. dysgalactiae subsp. equisimilis strains causing human infections. IMPORTANCE Our studies addressed a critical knowledge gap in understanding the genomics and virulence of the bacterial pathogen Streptococcus dysgalactiae subsp. equisimilis. S. dysgalactiae subsp. equisimilis strains are responsible for a recent increase in severe human infections in some countries. We determined that certain S. dysgalactiae subsp. equisimilis strains are genetically descended from a common ancestor and that these strains can cause severe infections in a mouse model of necrotizing myositis. Our findings highlight the need for expanded studies on the genomics and pathogenic mechanisms of this understudied subspecies of the Streptococcus family.

Systemic immune activation profiles in streptococcal necrotizing soft tissue infections: A prospective multicenter study

OBJECTIVE

Early stages with streptococcal necrotizing soft tissue infections (NSTIs) are often difficult to discern from cellulitis. Increased insight into inflammatory responses in streptococcal disease may guide correct interventions and discovery of novel diagnostic targets.

METHODS

Plasma levels of 37 mediators, leucocytes and CRP from 102 patients with β-hemolytic streptococcal NSTI derived from a prospective Scandinavian multicentre study were compared to those of 23 cases of streptococcal cellulitis. Hierarchical cluster analyses were also performed.

RESULTS

Differences in mediator levels between NSTI and cellulitis cases were revealed, in particular for IL-1β, TNFα and CXCL8 (AUC >0.90). Across streptococcal NSTI etiologies, eight biomarkers separated cases with septic shock from those without, and four mediators predicted a severe outcome.

CONCLUSION

Several inflammatory mediators and wider profiles were identified as potential biomarkers of NSTI. Associations of biomarker levels to type of infection and outcomes may be utilized to improve patient care and outcomes.

Clonal Expansion of Multidrug-Resistant Streptococcus dysgalactiae Subspecies equisimilis Causing Bacteremia, Japan, 2005-2021

Incidence of Streptococcus dysgalactiae subspecies equisimilis (SDSE) bacteremia is increasing in the Kyoto-Shiga region of Japan. We retrospectively analyzed clinical features of SDSE bacteremia and conducted comparative genomic analyses of isolates collected from 146 bacteremia episodes among 133 patients during 2005-2021. Of those patients, 7.7% required vasopressor support, and 7.0% died while in the hospital. The prevalence of isolates resistant to erythromycin, minocycline, and clindamycin increased from 8.6% during 2005-2017 to 21.6% during 2018-2021. Our genomic analysis demonstrated that sequence type 525 and clonal complex 25 were predominant in SDSE isolates collected during 2018-2021. In addition, those isolates had acquired 2 antimicrobial-resistance genes, ermB and tetM, via Tn916-like integrative and conjugative elements (ICEs). Phylogenetic analysis revealed clonal distribution of Tn916-like ICEs in SDSE isolates. Our findings suggest that Tn916-like ICEs contributed to the emergence and recent increase of multidrug-resistant SDSE bacteremia in this region of Japan.

Streptococcus dysgalactiae Bloodstream Infections, Norway, 1999-2021

Streptococcus dysgalactiae increasingly is recognized as a pathogen of concern for human health. However, longitudinal surveillance data describing temporal trends of S. dysgalactiae are scarce. We retrospectively identified all β-hemolytic streptococcal bloodstream infections reported in Bergen, in western Norway, during 1999-2021. To explore S. dysgalactiae disease burden in a broader context, we mapped the incidence of all microbial species causing bloodstream infections during 2012-2021. We found S. dysgalactiae incidence rates substantially increased during the study period; by 2021, S. dysgalactiae was the fifth most common pathogen causing bloodstream infections in our region. We noted genotypic shifts and found that the rising trend was related in part to the introduction and expansion of the stG62647 emm-type. S. dysgalactiae is among the most common causes of bloodstream infections in western Norway, and increased surveillance and unambiguous species identification are needed to monitor the disease burden attributable to this pathogen.

The effects of air pollutants exposure on the transmission and severity of invasive infection caused by an opportunistic pathogen Streptococcus pyogenes

Currently, urbanization is associated with an increase in air pollutants that contribute to invasive pathogen infections by altering the host's innate immunity and antimicrobial resistance capability. Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is a gram-positive opportunistic pathogen that causes a wide range of diseases, especially in children and immunosuppressed individuals. Diesel exhaust particle (DEP), a significant constituent of particulate matter (PM), are considered a prominent risk factor for respiratory illness and circulatory diseases worldwide. Several clinical and epidemiological studies have identified a close association between PM and the prevalence of viral and bacterial infections. This study investigated the role of DEP exposure in increasing pulmonary and blood bacterial counts and mortality during GAS M1 strain infection in mice. Thus, we characterized the upregulation of reactive oxygen species production and disruption of tight junctions in the A549 lung epithelial cell line due to DEP exposure, leading to the upregulation of GAS adhesion and invasion. Furthermore, DEP exposure altered the leukocyte components of infiltrated cells in bronchoalveolar lavage fluid, as determined by Diff-Quik staining. The results highlighted the DEP-related macrophage dysfunction, neutrophil impairment, and imbalance in pro-inflammatory cytokine production via the toll-like receptor 4/mitogen-activated protein kinase signaling axis. Notably, the tolerance of the GAS biofilms toward potent antibiotics and bacterial resistance against environmental stresses was also significantly enhanced by DEP. This study aimed to provide a better understanding of the physiological and molecular interactions between exposure to invasive air pollutants and susceptibility to invasive GAS infections.

Progressive Lameness of a Greater One-Horned Rhinoceros (Rhinoceros unicornis) Associated with a Retroperitoneal Abscess and Thrombus Caused by Streptococcus dysgalactiae Subspecies equisimilis

Simple Summary

Movement disorders can have different origins and certain causes require a particular intervention management. In rhinoceroses, lesions affecting the extremities per se are typical causes. A 3-year-old, male Greater one-horned rhinoceros born in captivity developed progressive lameness, ataxia with dragging of its right, hind hoof. Prior, the animal was housed together with his dam, which was repeatedly aggressive against her offspring. Despite therapy, the symptoms aggravated and the animal died spontaneously. At necropsy, a large abscess in the abdomen under the spine and a thrombus of the artery of the right hind limb were diagnosed as the cause of lameness. The pyogenic bacterium Streptococcus dysgalactiae subspecies equisimilis was isolated from the abscess and from mucous membranes of the healthy mother. Such an unusual origin for lameness should be considered in rhinoceroses in the future.

Abstract

In rhinoceroses, lameness is an occasionally seen symptom primarily caused by lesions affecting the feet and interdigital space. A 3-year-old male Greater one-horned rhinoceros developed a progressive, severe movement disorder of the right hind limb with subsequent death. The pathological analysis diagnosed a severe, retroperitoneal abscess and chronic thrombosis of the right iliac artery. Streptococci detected in the abscess were further identified as Streptococcus dysgalactiae subspecies equisimilis by culture and molecular techniques. The identical isolate was also identified in a vaginal swab of the dam. The list of differential diagnoses for lameness in rhinoceroses must be expanded by processes affecting other than the extremities per se.

Invasive group A streptococcal disease in pregnant women and young children: a systematic review and meta-analysis

BACKGROUND

The incidence of invasive disease caused by group A streptococcus (GAS) has increased in multiple countries in the past 15 years. However, despite these reports, to the best of our knowledge, no systematic reviews and combined estimates of the incidence of invasive GAS have been done in key high-risk groups. To address this, we estimated the incidence of invasive GAS disease, including death and disability outcomes, among two high-risk groups-namely, pregnant women and children younger than 5 years.

METHODS

We did a systematic review and meta-analyses on invasive GAS outcomes, including incidence, case fatality risks, and neurodevelopmental impairment risk, among pregnant women, neonates (younger than 28 days), infants (younger than 1 year), and children (younger than 5 years) worldwide and by income region. We searched several databases for articles published from Jan 1, 2000, to June 3, 2020, for publications that reported invasive GAS outcomes, and we sought unpublished data from an investigator group of collaborators. We included studies with data on invasive GAS cases, defined as laboratory isolation of Streptococcus pyogenes from any normally sterile site, or isolation of S pyogenes from a non-sterile site in a patient with necrotising fasciitis or streptococcal toxic shock syndrome. For inclusion in pooled incidence estimates, studies had to report a population denominator, and for inclusion in pooled estimates of case fatality risk, studies had to report aggregate data on the outcome of interest and the total number of cases included as a denominator. We excluded studies focusing on groups at very high risk (eg, only preterm infants). We assessed heterogeneity with I2.

FINDINGS

Of the 950 published articles and 29 unpublished datasets identified, 20 studies (seven unpublished; 3829 cases of invasive GAS) from 12 countries provided sufficient data to be included in pooled estimates of outcomes. We did not identify studies reporting invasive GAS incidence among pregnant women in low-income and middle-income countries (LMICs) nor any reporting neurodevelopmental impairment after invasive GAS in LMICs. In nine studies from high-income countries (HICs) that reported invasive GAS in pregnancy and the post-partum period, invasive GAS incidence was 0·12 per 1000 livebirths (95% CI 0·11 to 0·14; I2=100%). Invasive GAS incidence was 0·04 per 1000 livebirths (0·03 to 0·05; I2=100%; 11 studies) for neonates, 0·13 per 1000 livebirths (0·10 to 0·16; I2=100%; ten studies) for infants, and 0·09 per 1000 person-years (95% CI 0·07 to 0·10; I2=100%; nine studies) for children worldwide; 0·12 per 1000 livebirths (95% CI 0·00 to 0·24; I2=100%; three studies) in neonates, 0·33 per 1000 livebirths (-0·22 to 0·88; I2=100%; two studies) in infants, and 0·22 per 1000 person-years (0·13 to 0·31; I2=100%; two studies) in children in LMICs; and 0·02 per 1000 livebirths (0·00 to 0·03; I2=100%; eight studies) in neonates, 0·08 per 1000 livebirths (0·05 to 0·11; I2=100%; eight studies) in infants, and 0·05 per 1000 person-years (0·03 to 0·06; I2=100%; seven studies) in children for HICs. Case fatality risks were high, particularly among neonates in LMICs (61% [95% CI 33 to 89]; I2=54%; two studies).

INTERPRETATION

We found a substantial burden of invasive GAS among young children. In LMICs, little data were available for neonates and children and no data were available for pregnant women. Incidences of invasive GAS are likely to be underestimates, particularly in LMICs, due to low GAS surveillance. It is essential to improve available data to inform development of prevention and management strategies for invasive GAS.

FUNDING

Wellcome Trust.

Necrotizing Bacterial Myositis as the Initial Presentation of Severe Aplastic Anaemia

Introduction

Necrotizing soft tissue infections are rapidly progressing infections associated with severe inflammation and cytokine release. Early recognition and surgical intervention are key factors to secure survival. The current case presents a patient with multifocal necrotizing soft tissue infection as the initial presentation of severe aplastic anaemia. Case Presentation. A man in his fifties was admitted with septic shock with multiorgan failure and severe pancytopenia, after two days of malaise with high fever and right flank pain. The diagnosis streptococcal necrotizing myositis was significantly delayed due to atypical clinical findings. After initial surgical exploration, the decision was made to defer from surgical debridement due to extensive involvement of several muscle groups, grave pancytopenia, and suspected dismal prognosis. Surprisingly, the patient stabilized after antibiotics and intensive care treatment. Based on severe pancytopenia and hypocellular bone marrow, with no evidence of other bone marrow disorders, the patient was diagnosed with aplastic anaemia. Treatment for aplastic anaemia with antithymocyte globulin, cyclosporine, and eltrombopaq was started, and 2 months later, a partial haematological recovery was observed. The patient could be discharged from hospital without antibiotic treatment.

Conclusions

This case illustrates the crucial role of a multidisciplinary approach on admission and further during the clinical course. Clinical improvement despite severe neutropenia and stabilization during immunosuppressive therapy suggest that immunological factors modulate clinical course in necrotizing soft tissue infections.

Seasonal variations in use and outcome of rapid antigen detection tests and cultures in pharyngotonsillitis: a register study in primary care

Background

Diagnosis and treatment of pharyngotonsillitis are commonly focused on group A streptococci (GAS), although the disease is often associated with other pathogens. While the incidence of pharyngotonsillitis is known to vary with season, seasonal variations in the prevalence of potential pathogens are sparsely explored. The aim of this study was to explore any seasonal variations in the use and outcome of rapid antigen detection tests (RADTs) for GAS and throat cultures among patients diagnosed with pharyngotonsillitis in primary care.

Methods

We retrieved and combined retrospective data from the electronic medical record system and the laboratory information system in Kronoberg County, Sweden. Primary care visits resulting in a diagnosis of tonsillitis or pharyngitis were included, covering the period 2013–2016. The monthly rate of visits was measured, along with the use and outcome of RADTs for GAS and throat cultures obtained on the date of diagnosis. The variations between calendar months were then analysed.

Results

We found variations between calendar months, not only in the mean rate of visits resulting in a diagnosis of pharyngotonsillitis (p < 0.001), but in the mean proportion of RADTs being positive for GAS among the diagnosed (p < 0.001), and in the mean proportion of visits associated with a throat culture (p < 0.001). A lower mean rate of visits in August and September coincided with a lower proportion of RADTs being positive for GAS among them, which correlated with a higher proportion of visits associated with a throat culture.

Conclusions

This study suggests that the role of GAS in pharyngotonsillitis in Sweden is less prominent in August and September than during the rest of the year.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06774-5.

Trends in beta-hemolytic Streptococcus infections within Veterans' Affairs medical centers from 2009 to 2018

OBJECTIVE

The purpose of this study was to describe the recent trends of invasive and noninvasive β-hemolytic Streptococcus cultures in the Veterans' Affairs (VA) cohort from 2009 to 2018.

DESIGN

Retrospective cohort study from January 1, 2009, to January 1, 2019.

SETTING

Veterans' Affairs medical centers.

PATIENTS OR PARTICIPANTS

All patients aged 18 years and older with cultures positive for β-hemolytic Streptococcus at a VA facility were included in the study.

INTERVENTION(S)

Data were retrieved from the VA Corporate Data Warehouse using structure query language through the SQL Server Management Studio software.

RESULTS

Between 2009 and 2018, there were 40,625 patients with cultures with β-hemolytic Streptococcus. The median age was 64 years (interquartile range [IQR], 55-71) and the median Charlson comorbidity index was 4 (IQR, 2-7). Distributions for each type of β-hemolytic Streptococcus based on site of culture are provided. The 30-day all-cause mortality rate from all invasive β-hemolytic Streptococcus cases was 2.3%, and the 90-day all-cause mortality rate was 4.4%. The 30- and 90-day all-cause mortality rates for Streptococcus cases were higher for group A (3.9% and 6.1% respectively) and for groups C and G combined (3.2% and 6.1%, respectively) than for group B (2.0% and 4.0%, respectively).

CONCLUSIONS

Trends of cultures for invasive and noninvasive β-hemolytic Streptococcus suggest an association with disease and mortality. The burden associated with β-hemolytic Streptococcus infections should not be underestimated.

The Place of Group A Streptococci in Moroccan Children with Pharyngitis and Emm Type Distribution

Background: Streptococcus pyogenes is responsible for a wide variety of diseases, including noninvasive and severe invasive infections. The emm gene encodes the M protein that is the virulence factor and immunological determinant of group A streptococci. Emm typing is the group A Streptococci (GAS) standard molecular typing method based on the amplification of the N terminal hypervariable region of the emm gene. Objectives: The aim of the present study was to determine the prevalence of GAS in children with pharyngitis and determine different types of emm gene in the GAS isolates using emm typing. Methods: The study was carried out over a period of 14 months (from February 2017 to March 2018). Throat samples were collected from cases aged ≤ 18 years with pharyngitis referring to a primary health care center in Fez, Morocco. GAS isolates were subjected to conventional tests to confirm species identification. Antimicrobial susceptibility testing was performed using the standard disk diffusion method. We researched emm gene by a polymerase chain reaction (PCR). Emm types were determined by a sequence-based protocol. Demographic and clinical data were recorded from each patient. Results: From a total of 177 throat samples, 11 isolates (6.2%) were identified as GAS in children with pharyngitis. Antibiotic sensitivity testing revealed that all the GAS isolates were sensitive to penicillin. The sequencing of the PCR products of the emm gene revealed that emm90 was the most obtained emm type (30,77%); while emm75 was the least type observed (7.7%). Conclusions: The emm90 is the most prevalent type detected from patients with tonsillitis. Penicillin and erythromycin are still the foremost effective antibiotics to treat GAS pharyngitis.

A Review of Streptococcus pyogenes: Public Health Risk Factors, Prevention and Control

Streptococcus pyogenes, (colloquially named “group A streptococcus” (GAS)), is a pathogen of public health significance, infecting 18.1 million people worldwide and resulting in 500,000 deaths each year. This review identified published articles on the risk factors and public health prevention and control strategies for mitigating GAS diseases. The pathogen causing GAS diseases is commonly transmitted via respiratory droplets, touching skin sores caused by GAS or through contact with contaminated material or equipment. Foodborne transmission is also possible, although there is need for further research to quantify this route of infection. It was found that GAS diseases are highly prevalent in developing countries, and among indigenous populations and low socioeconomic areas in developed countries. Children, the immunocompromised and the elderly are at the greatest risk of S. pyogenes infections and the associated sequelae, with transmission rates being higher in schools, kindergartens, hospitals and residential care homes. This was attributed to overcrowding and the higher level of social contact in these settings. Prevention and control measures should target the improvement of living conditions, and personal and hand hygiene. Adherence to infection prevention and control practices should be emphasized in high-risk settings. Resource distribution by governments, especially in developed countries, should also be considered.

Severe Group C Streptococcus infection in a veterinarian

Group C Streptococcus (GCS) is part of the normal commensal flora of the upper airway, as well as frequently colonizes the skin, gastrointestinal tract, and female genital tract. It can also be implicated in mono- and polymicrobial infections of the skin and soft tissue, pharyngitis, bacteremia, endocarditis, septic arthritis, osteomyelitis, and meningitis. Our case study features a previously healthy 65-year-old male, who retired as a veterinarian one month prior, with Group C Streptococcus bacteremia complicated by septic polyarthritis, native mitral valve endocarditis, and lumbar discitis/osteomyelitis.

Streptococcal Throat Carriage among Primary School Children Living in Uyo, Southern Nigeria

Surveillance of the carrier state for β-hemolytic streptococcal (BHS) throat infections remains essential for disease control. Recent published works from Sub-Saharan Africa have suggested a changing epidemiology in the burden of BHS throat infections. The objective of the present study was therefore to determine the prevalence and pattern of BHS throat carriage in school-aged children in Uyo, Akwa Ibom State. This was a prospective cross-sectional study of 276 primary school children in Uyo. Subjects were recruited by multistage random sampling. Obtained throat swabs were cultured on 5% sheep blood agar. Lancefield grouping on positive cultures was done by using the Oxoid Streptococcal Grouping Latex Agglutination Kit, United Kingdom. Antimicrobial susceptibility testing was done with the disk diffusion method. Associations were tested with Fischer's exact test. The prevalence of BHS carriage was 3.3%. Group C Streptococcus was identified in 89% of isolates and Group G Streptococcus in 11%. Younger age and larger household size were associated with asymptomatic streptococcal throat infections. Antimicrobial susceptibility was highest with cefuroxime and clindamycin (89% of isolates each), while 78% of isolates were susceptible to penicillin. None of the tested isolates was susceptible to co-trimoxazole. The prevalence of streptococcal throat carriage in the study area was low. There were no Group A Streptococcus isolates suggesting an evolving epidemiology of BHS disease in the study area.

Beta-Haemolytic Group A, C and G Streptococcal Infections in Southern Hungary: A 10-Year Population-Based Retrospective Survey (2008-2017) and a Review of the Literature

Introduction

Pyogenic β-hemolytic streptococci (including Group A, C and G Streptococcus) are some of the most important Gram-positive bacterial pathogens in human medicine. Although effective therapy is available, invasive streptococcal infections are associated with a significant disease burden.

Methods

In this retrospective study, the epidemiological characteristics of invasive Group A (iGAS) and Group C and G (iGCGS) streptococci, along with tonsillo-pharyngitis-causing pGAS and pGCGS infections, were assessed in Southern Hungary. A total of 1554 cases of streptococcal tonsillo-pharyngitis infections (26.5–44.1/100,000 persons, pGAS: 95.5%; n=1484) and 1104 cases of invasive streptococcal infections were detected (12.5–31.4/100,000 persons, iGAS: 77.9%; n=861).

Results

The average age of the affected patients in the various groups were the following: pGAS: 13.2±13.1 years, pGCGS: 21.0±15.0 years (p=0.039), iGAS: 49.1±12.8 years, iGCGS: 58.7±18.5 years (p>0.05). iGAS isolates originated from abscesses (47.1%), blood culture samples (24.1%), surgical samples (16.7%), biopsies (4.6%), pleural fluid (3.5%), pus (2.0%), synovial fluid (1.3%) and cerebrospinal fluid samples (0.7%). In contrast, iGCGS isolates mainly originated from blood culture samples (53.8%), abscesses (22.9%), surgical samples (12.3%), synovial fluid (5.1%), pleural fluid (3.7%), pus (1.8%) and cerebrospinal fluid samples (0.4%). All respective isolates were susceptible to benzyl-penicillin; overall resistance levels for erythromycin (10.5% for GAS, 21.4% for GCGS) and clindamycin (9.2% for GAS, 17.2% for GCGS) were significantly higher in GCGS isolates, while resistance levels for norfloxacin were higher in GAS isolates (13.5% for GAS, 6.9% for GCGS).

Conclusion

The rates of resistance to macrolides and clindamycin are a cause for concern (especially among GCGS isolates); however, resistance levels are still relatively low, compared to Southern European countries.

Emerging Threat of Antimicrobial Resistance in β-Hemolytic Streptococci

Highly variable resistance rates to erythromycin and clindamycin have been reported in the β-hemolytic streptococcal species Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus dysgalactiae, depending on geographic and temporal context. In the present study we aimed to examine the longitudinal trends of antimicrobial resistance in these three species in a northern European setting. Furthermore, we used whole genome sequencing to identify resistance determinants and the mobile genetic elements involved in their dissemination, as well as elucidate phylogenetic relationships. All cases of invasive β-hemolytic streptococcal diseases in Health Region Bergen, western Norway, in the period 2004 to 2018 were retrospectively identified, comprising 271, 358, and 280 cases of S. pyogenes, S. agalactiae, and S. dysgalactiae, respectively. Antimicrobial susceptibility testing revealed a gradual but significant increase in erythromycin and clindamycin resistance for S. agalactiae and S. dysgalactiae during the study period. Whole genome sequencing of the erythromycin and clindamycin resistant bacterial population revealed a substantial phylogenetic diversity in S. agalactiae and S. dysgalactiae. However, the mobile genetic elements harboring the resistance determinants showed remarkable intra- and interspecies similarities, suggesting a dissemination of antimicrobial resistance predominantly through conjugative transfer rather than clonal expansion of resistant strains in these two species. Conversely, antimicrobial resistance in S. pyogenes remained low, apart from a transient outbreak of a clindamycin and erythromycin resistant emm11/ST403-clone in 2010–2012. Increased epidemiological attentiveness is warranted to monitor the emerging threat of antimicrobial resistance in β-hemolytic streptococci, particularly in S. agalactiae and S. dysgalactiae.

Treatment of Necrotizing Soft Tissue Infections: Antibiotics

Necrotizing soft tissue infections (NSTIs) are severe, life-threatening infections, and early therapeutic intervention is essential. Prompt administration of potent antimicrobial agents is pivotal, but inadequate empirical therapy is unfortunately common. Optimization of the antibiotic treatment strategy in NSTIs requires consideration of local epidemiology of causative pathogens and antimicrobial resistance patterns, knowledge on common pathogenetic mechanisms in NSTIs, and adaptations to pharmacokinetic and pharmacodynamic physiological changes in critically ill patients. In the present article we address all these issues, as well as review and compare contemporary guidelines for antimicrobial treatment of NSTIs from around the world.

Beta-Hemolytic Streptococci and Necrotizing Soft Tissue Infections

β-hemolytic streptococci are major causes of necrotizing soft tissue infections (NSTIs), Streptococcus pyogenes (group A streptococcus; GAS) in particular. NSTIs caused by Streptococcus dysgalactiae (SD) have also been reported. In the INFECT cohort of 409 NSTIs patients, more than a third of the cases were caused by GAS (31%) or SD (7%). Risk factors of streptococcal NSTIs compared to streptococcal cellulitis have previously been largely unknown. The INFECT study confirmed blunt trauma as an important risk factor. In addition, absence of pre-existing skin lesions and a lower BMI were associated with NSTIs. The study also confirmed that septic shock is more frequent in GAS cases than in other types of NSTIs. Septic shock was also among several predictors of mortality. The role of intravenous immunoglobulin (IVIG) in streptococcal NSTIs has been unclear. In the INFECT cohort, IVIG treatment was associated with increased survival. As in other studies, a significant microbial diversity was observed, but with predominance of a few emm types. Overall, the INFECT study gives a comprehensive and contemporary picture of the clinical characteristics and the microbes involved in streptococcal NSTIs. The reported severity of disease underscores the need for new efforts aimed at identifying novel diagnostic measures and improved treatment.

Virulence of beta-hemolytic streptococci in infective endocarditis

BACKGROUND

Streptococci involved in infective endocarditis (IE) primarily comprise alpha- or non-hemolytic streptococci (ANHS). Moreover, beta-hemolytic streptococci (BHS) can be involved, and guidelines recommend the addition of gentamicin for the first 2 weeks of treatment and the consideration of early surgery in such cases. This study compared the morbidity and mortality associated with IE depending on the microorganisms involved (BHS, ANHS, staphylococci, and enterococci).

METHODS

We conducted a retrospective observational study between 2012 and 2017 in a single hospital in France. The endpoints were overall in-hospital mortality, 1-year mortality and the occurrence of complications.

RESULTS

We analyzed 316 episodes of definite IE including 150 (38%), 96 (25%), 46 (12%), and 24 cases (6%) of staphylococcal, ANHS, enterococcal, and BHS IE, respectively. In-hospital mortality was significantly higher in the staphylococcal (n = 40; 26.7%) and BHS groups (n = 6; 25.0%) than in the ANHS (n = 9; 9.4%) and enterococcal groups (n = 5; 10.9%) (all p < 0.01). The rates of septic shock and cerebral emboli were also higher in the BHS group than in the ANHS group [n = 7 (29.2%) vs. n = 3 (3.1%), p < 0.001; n = 7 (29.2%) vs. n = 12 (12.5%); p = 0.05, respectively].

CONCLUSION

This study confirmed that BHS IE has a more severe prognosis than ANHS IE. The virulence of BHS may be similar to that of staphylococci, justifying increased monitoring of these patients and more 'aggressive' treatments such as early surgery.

Necrotizing skin and soft-tissue infections in the intensive care unit

BACKGROUND

Necrotizing skin and soft-tissue infections (NSTI) are rare but potentially life-threatening and disabling infections that often require intensive care unit admission.

OBJECTIVES

To review all aspects of care for a critically ill individual with NSTI.

SOURCES

Literature search using Medline and Cochrane library, multidisciplinary panel of experts.

CONTENT

The initial presentation of a patient with NSTI can be misleading, as features of severe systemic toxicity can obscure sometimes less impressive skin findings. The infection can spread rapidly, and delayed surgery worsens prognosis, hence there is a limited role for additional imaging in the critically ill patient. Also, the utility of clinical scores is contested. Prompt surgery with aggressive debridement of necrotic tissue is required for source control and allows for microbiological sampling. Also, prompt administration of broad-spectrum antimicrobial therapy is warranted, with the addition of clindamycin for its effect on toxin production, both in empirical therapy, and in targeted therapy for monomicrobial group A streptococcal and clostridial NSTI. The role of immunoglobulins and hyperbaric oxygen therapy remains controversial.

IMPLICATIONS

Close collaboration between intensive care, surgery, microbiology and infectious diseases, and centralization of care is fundamental in the approach to the severely ill patient with NSTI. As many aspects of management of these rare infections are supported by low-quality data only, multicentre trials are urgently needed.

Uterine cervical ulceration caused by group C streptococcal infection during pregnancy: A case report

Causes of cervical ulceration include infection, collagen disease, malignant tumors and external stimuli. Cervical ulceration during pregnancy is rare. We present a case of cervical ulceration caused by group C streptococcal infection during pregnancy. A 36-year-old woman (gravida 1, para 0) complained of metrorrhagia, and a circular cervical ulcer of about 1.5 cm in diameter was detected on her cervix at 37 weeks' gestation. A biopsy and a cultivation test of the ulcer were performed, and pathological diagnosis was made as suppurative inflammation, and group C streptococcal infection was detected by the cultivation test. The ulcer had expanded to about 3 cm in diameter at the onset of labor at 40 weeks' gestation. An emergency cesarean section was performed because of failed induction of labor, and she was delivered of a male baby. The ulcer became gradually smaller after delivery, and completely disappeared on the 35th day after delivery.

Infections Caused by Group C and G Streptococcus (Streptococcus dysgalactiae subsp. equisimilis and Others): Epidemiological and Clinical Aspects

Streptococci carrying serogroup C and G antigens, and in particular, Streptococcus dysgalactiae subsp. equisimilis (SDSE), are emerging human pathogens that are increasingly isolated from patients with a myriad of infections that range from mundane to life-threatening. SDSE is microbiologically similar to Streptococcus pyogenes. These streptococci frequently cause infections of the throat and skin and soft tissues. Moreover, they may invade the bloodstream and disseminate widely to many deep tissue sites, including the endocardium. Life-threatening invasive infections due to SDSE, including the streptococcal toxic shock syndrome, occur most frequently in patients with severe underlying medical diseases. Treatment with penicillin is adequate under most circumstances, but treatment failure occurs. SDSE may also be resistant to other antibiotic classes including tetracyclines, macrolides, and clindamycin. Most human infections caused by groups C and G streptococci are transmitted from person to person, but infections due to Streptococcus equi subsp. zooepidemicus (and, rarely, to S. equi subsp. equi) are zoonoses. Transmission of these latter species occurs by animal contact or by contamination of food products and has been associated with the development of poststreptococcal glomerulonephritis. Members of the Streptococcus anginosus group, usually classified with the viridans group of streptococci, are associated with a variety of pyogenic infections.

Septic arthritis due to streptococci and enterococci in native joints: a 13 year retrospective study

OBJECTIVES

Streptococcal species are the second most common cause of native joint septic arthritis (SA). However, there are few systematic data about streptococcal SA.

METHODS

The medical records of adults with SA caused by streptococci, pneumococci, and enterococci at our tertiary care centre between 2003 and 2015 were reviewed.

RESULTS

71 patients (34% female) with 83 affected joints were included. Median age was 62 years. A single joint was involved in 62 patients (87%). One or more comorbidities were present in 58 patients (82%). 16 patients (23%) had a concomitant soft-tissue infection overlying the affected joint. The hematogenous route was the dominating pathogenesis (42/71, 59%). 9 (13%) patients were diagnosed with endocarditis. The knee was the most commonly affected joint (27/83, 33%) followed by shoulder (13/83, 16%). ß-haemolytic streptococci were most commonly identified (37/71, 52%) followed by polymicrobial infections (12/71, 17%). Surgical interventions included arthroscopic irrigation and debridement in 31 (44%), arthrotomy in 23 (32%), and amputation in five patients (7%). Median duration of antimicrobial therapy was 42 days. Antibiotic treatment without any surgical intervention was performed in 5 (7%) patients. Outcome was good in 55 (89%) patients; mortality was 13% with four of nine deaths attributed to joint infection. Age and pathogen group independently predicted poor outcome in recursive partitioning analysis.

CONCLUSIONS

Streptococcal SA was mostly due to ß-haemolytic streptococci in older and polymorbid patients. Old age, anginosus group streptococci, enterococci, and polymicrobial infections predicted poor outcome, while antibiotic treatment duration can likely be shortened.

Age-related differences in clinical characteristics of invasive group G streptococcal infection: Comparison with group A and group B streptococcal infections

Purpose

Invasive Group G streptococcal infection (iGGS) has increasingly been recognized as a cause of severe disease, mainly among elderly people with chronic illnesses. This study aimed to examine age-related differences in clinical characteristics of iGGS and describe its characteristics among very elderly individuals (≥80 years).

Methods

Fifty-four iGGS patients for whom detailed clinical information was available were identified from 2002 to 2014 in a tertiary care hospital in Japan. iGGS (n = 54) was compared with invasive Group A (iGAS; n = 17) and B streptococcal infection patients (iGBS; n = 52) based on patient age.

Results

The incidence of iGGS in our catchment area significantly increased during the study period. The prevalence of iGGS in the very elderly population was higher than that of iGAS or iGBS (p<0.001). Among iGGS patients, cardiovascular disease, chronic kidney disease, oxygen demand, and bacteremia with unknown focus of infection were more frequent in the very elderly population (p = 0.009, p = 0.02, p = 0.04, and p = 0.04, respectively). Altered mental status was present in half of iGGS patients aged ≥60 years (p = 0.03). In contrast, alcohol drinking and liver cirrhosis were significantly more frequent in patients with iGGS aged <60 years than in other age groups (p<0.001, p = 0.001, respectively). Levofloxacin resistance in GBS isolates was significantly more frequent among very elderly patients than among other age groups (p<0.001).

Conclusions

The burden of iGGS has been increasing in our catchment area. Different iGGS-associated clinical characteristics were found in each age group. Unclear and atypical clinical manifestations and syndromes were likely to be observed in very elderly patients. Alcohol drinking and liver cirrhosis may contribute to iGGS even in patients aged <60 years. Understanding these age-related differences could be helpful for optimal diagnosis and treatment.

Secular trends in incidence of invasive beta-hemolytic streptococci and efficacy of adjunctive therapy in Quebec, Canada, 1996-2016

Objectives

To examine secular changes in the incidence of invasive beta-hemolytic streptococcal infections, and to assess the efficacy of immunoglobulins and clindamycin as adjunctive therapies in the management of Streptococcus pyogenes infections.

Methods

Retrospective cohort study of all cases of invasive group A (GAS), B (GBS), C or G (GCGS) streptococcal infections managed in a Canadian tertiary center from 1996–2016. Population incidence was measured for diabetics and non-diabetics. Adjusted odds ratios (AOR) and their 95% confidence intervals (CI) were calculated by logistic regression.

Results

741 cases were identified (GAS: 249; GBS: 304; GCGS: 188). While the incidence of invasive GAS infections fluctuated with no clear trend, incidence of invasive GBS and GCGS increased over time and were 8.4 and 6.3 times higher in diabetics. Mortality of invasive GAS infections decreased from 16% (6/37) in 1996–2001 to 4% (4/97) in 2011–15. Among patients with GAS infections, clindamycin administered concomitantly with a beta-lactam within 24 hours of admission decreased mortality (AOR: 0.04, 95%CI: 0.003–0.55, P = 0.02. Immunoglobulins had no such effect (AOR: 1.66, 95%CI: 0.16–17.36, P = 0.67). The protective effect of clindamycin was similar in patients with pneumonia/empyema compared to all others.

Conclusion

Incidence of GBS and GCGS infections increased due to an expansion of the high-risk population (elderly diabetics), but also rose in non-diabetics. No such secular change was seen for invasive GAS infections. The decrease in mortality in patients with invasive GAS infections presumably reflects better case-management. Adjunctive clindamycin reduced mortality in invasive GAS infections; immunoglobulins did not, but power was limited. The highest mortality was seen in patients with GAS pneumonia/empyema, for whom clindamycin was protective but underused.

An unusual presentation of rectal carcinoma with group G streptococcal sepsis in the early third trimester

We report a case of atypical presentation of advanced colorectal cancer with maternal group G streptococcal bacterial sepsis in the early third trimester.

Infective endocarditis due to Streptococcus dysgalactiae: clinical presentation and microbiological features

Knowledge of infective endocarditis (IE) caused by Streptococcus dysgalactiae (SD) is limited. This study aimed to identify the clinical and microbiological features of SD-caused IE and to investigate any possible synergy between penicillin and gentamicin on SD isolates. Cases of IE 2008-2016 due to SD reported to the Swedish Registry of Infective Endocarditis (SRIE) were identified. Isolates were emm typed and synergy between antibiotics was determined in time-kill experiments. Medical records were reviewed and SD-cases were compared to cases of IE due to other pathogens reported to the SRIE. Fifty cases of SD-caused IE were confirmed. emm types stC74a, stG62647, and stG643 were most commonly encountered. The patients had a median age of 74 years (range 38-93) and were significantly older compared to patients with Staphylococcus aureus-caused IE, (65 years (p = 0.003)). The median time to diagnosis from symptom onset was 1 day for patients with SD-caused IE which was less compared to patients with IE due to the other pathogens (2-15 days). Embolization was seen in 46% and the in-hospital mortality was 8%. Etest-based methods did not indicate any synergy between penicillin and gentamicin whereas synergy was noted for four out of nine isolates applying time-kill assays. This is the largest study of SD-caused IE, a condition with an acute onset predominantly affecting elderly people. Synergy between penicillin and gentamicin against some SD isolates was distinguished but the potential benefit of this must be weighed against the risk of aminoglycoside side effects.

The Use of Antibiograms in Orthopedic Surgery

PURPOSE OF REVIEW

Organism identification and antibiotic selection remain a critical component of periprosthetic joint infection (PJI) treatment. Prior to organism identification and/or the availability of antibiotic sensitivities, empiric antibiotics are routinely started. A basic understanding of a region or institutions antibiogram is paramount for selection of an empiric treatment regimen. Evolving antibiogram results and regional antibiotic resistance are important to follow as this may change antibiotic selection in some patient populations.

RECENT FINDINGS

The Clinical Laboratory and Standards Institute (CLSI) has created guidelines and standards for the creation and maintenance of antibiograms that should be followed by institutions. The infecting organism during PJI may be different in acute vs chronic infections and empiric therapy may change depending on the timing. Antibiotic prophylaxis for major procedures in certain patient populations should be critically evaluated based on regional and national antibiogram results. The CLSI guides recommendations and antibiotic resistance testing techniques and should be consulted when creating an antibiogram. The local and regional antibiogram should be consulted prior to administration of empiric and prophylactic antibiotics.

Infective endocarditis in Western Norway: a 20-year retrospective survey

BACKGROUND

To investigate epidemiological trends of infective endocarditis (IE) in western Norway a retrospective study was performed.

METHODS

Characteristics of 706 IE admissions from 1996 to 2005 and 2006 to 2015 were analysed and compared using the Chi-square test for categorical variables and the t-test for age. Survival was analysed by multiple Cox regression and reported by the hazard ratio (HR).

RESULTS

Mean annual incidence rates increased from 4.6 to 7.4 per 100,000 inhabitants (rate ratio: 1.97, 95% confidence interval: 1.52-2.56, p < .001). Non-viridans streptococci, enterococci and Staphylococcus aureus (S. aureus), were all independently associated with increased mortality. The frequency of IE caused by enterococci increased from 3.7 to 13.0% (p < .001). The proportion of intravenous drug users (IVDU) increased from 16.5 to 23.5% (p = .015) and had increasing aortic valve involvement (p = .023). Prosthetic valve endocarditis (PVE) constituted 30% of IE cases in both decades with biological PVE increasing from 9.4 to 22.1% (p < .001) and mechanical PVE decreasing from 18.7 to 8.9% (p < .001). In the last decade, valve replacement surgery was performed in 37.6% of the patients, of which 85.5% received a bioprosthesis.

CONCLUSIONS

The incidence of IE increased significantly. Non-viridans streptococci, enterococci and S. aureus were all significantly associated with increased mortality. The increased number of enterococcal IE and the increased number of IVDUs with left-sided IE constituted new challenges. Biological implants were preferred in a majority of patients requiring surgery.

Prevalence and molecular diversity of invasive Streptococcus dysgalactiae and Streptococcus pyogenes in a German tertiary care medical centre

Prevalence of invasive ß-haemolytic streptococci (BHS) at a tertiary care hospital and molecular diversity of S. pyogenes and S. dysgalactiae was studied. Between 2012 and 2016, all blood culture sets (n = 55,839), CSF (n = 8413) and soft tissue (n = 20,926) samples were analysed for BHS positivity using HYBASE software. Molecular profiles of 99 S. pyogenes and S. dysgalactiae were identified by sequencing of M protein genes (emm types) and multiplex PCR typing of 20 other virulence determinants. Streptococci contributed to 6.2% of blood, 10.7% of CSF and 14.5% of soft tissue isolates, being among the most common invasive isolates. The overall rates of invasive S. pyogenes, S. agalactiae, S. dysgalactiae and S. pneumoniae were 2.4, 4.4, 2.1, and 5.3%. Whereas S. pneumoniae was 1.5% more common in CSF samples, BHS isolates were 2-fold and 11-fold higher in bacteraemia and invasive soft tissue infections. Genetic BHS typing revealed wide molecular diversity of invasive and noninvasive group A and group G BHS, whereas one emm-type (stG62647.0) and no other virulence determinants except scpA were detected in invasive group C BHS. BHS were important invasive pathogens, outpacing S. pneumoniae in bacteraemia and invasive soft tissue infections. The incidence of S. dysgalactiae infections was comparable to that of S. pyogenes even with less diversity of molecular virulence. The results of this study emphasise the need for awareness of BHS invasiveness in humans and the need to develop BHS prevention strategies.

Streptococcal group A, C and G pharyngitis in school children: a prospective cohort study in Southern India

Diagnosing streptococcal pharyngitis in children on the basis of clinical appearance and throat culture is complicated by high colonisation rates and by the ability of other pathogens to cause clinically similar disease. To characterise the epidemiology of Lancefield Group A, C and G β-haemolytic streptococcus (GAS, GCS and GGS, respectively) in children, we conducted a 2-year prospective study of 307 school children between 7 and 11 years old. GGS and GAS were commonly identified organisms both for silent streptococcal colonisation and symptomatic sore throat, while GCS was uncommonly found. Streptococcal culture positivity at the time of clinical pharyngitis was estimated to reflect true streptococcal pharyngitis in only 26% of instances, with the frequency varying from 54% for children rarely colonised to 1% for children frequently colonised. Numerous GAS emm types were identified, including several types previously associated with severe pharyngitis (e.g. emm types 1, 3 and 28). No severe complications were seen in any child. These data suggest that the clinical diagnosis of streptococcal pharyngitis is likely to remain difficult and that treatment decisions will remain clouded by uncertainty. There remains a need for organism-specific rapid point-of-care streptococcal diagnostic tests and tests that can distinguish between streptococcal colonisation and disease.

Prevalent emm Types among Invasive GAS in Europe and North America since Year 2000

BACKGROUND

Streptococcus pyogenes or group A streptococcus (GAS) is an important human pathogen responsible for a broad range of infections, from uncomplicated to more severe and invasive diseases with high mortality and morbidity. Epidemiological surveillance has been crucial to detect changes in the geographical and temporal variation of the disease pattern; for this purpose the M protein gene (emm) gene typing is the most widely used genotyping method, with more than 200 emm types recognized. Molecular epidemiological data have been also used for the development of GAS M protein-based vaccines.

METHODS

The aim of this paper was to provide an updated scenario of the most prevalent GAS emm types responsible for invasive infections in developed countries as Europe and North America (US and Canada), from 1st January 2000 to 31st May 2017. The search, performed in PubMed by the combined use of the terms ("emm") and ("invasive") retrieved 264 articles, of which 38 articles (31 from Europe and 7 from North America) met the inclusion criteria and were selected for this study. Additional five papers cited in the European articles but not retrieved by the search were included.

RESULTS

emm1 represented the dominant type in both Europe and North America, replaced by other emm types in only few occasions. The seven major emm types identified (emm1, emm28, emm89, emm3, emm12, emm4, and emm6) accounted for approximately 50-70% of the total isolates; less common emm types accounted for the remaining 30-50% of the cases. Most of the common emm types are included in either one or both the 26-valent and 30-valent vaccines, though some well-represented emm types found in Europe are not.

CONCLUSION

This study provided a picture of the prevalent emm types among invasive GAS (iGAS) in Europe and North America since the year 2000 onward. Continuous surveillance on the emm-type distribution among iGAS infections is strongly encouraged also to determine the potential coverage of the developing multivalent vaccines.

Exploring the arthritogenicity of Streptococcus dysgalactiae subspecies equisimilis

BACKGROUND

During the past decades, Streptococcus dysgalactiae subspecies equisimilis (SDSE) has been increasingly recognized as an important human pathogen. Osteoarticular infections is one of the predominant disease manifestations of SDSE, but the pathogenetic rationale for its arthritogenicity has yet to be unravelled. We aimed to explore if the rising incidence of osteoarticular infections caused by this pathogen in our region emanated from clonal expansion of strains with enhanced tropism for bone and joint tissue components or orthopaedic implants.

RESULTS

Twenty-nine SDSE-isolates associated with osteoarticular infections were retrospectively identified. Their genomic content and affinity for fibronectin, collagen and stainless steel were compared to 24 temporally and geographically matched SDSE blood culture isolates obtained from patients without bone or joint infections. Despite a thorough genetic and phenotypic dissection, neither the presence or absence of any single gene, nor the binding abilities of the SDSE isolates, were predictive of clinical entity. SNP analysis revealed a heterogenous population, and a correlation between phylogenetic relationships and disease manifestation was not evident. However, we identified a strong concordance between phenotypic binding abilities and genetic variations in the pilus-region, also denoted as the FCT-region (Fibronectin binding, Collagen binding and T-antigen). This observation could be related to the ample and varied repertoire of putative adhesins residing within this region, including proteins predicted to adhere to fibronectin and collagen, as well as fibrinogen.

CONCLUSIONS

SDSE strains associated with osteoarticular infections do not emanate from subpopulation characterized by distinct genetic or phenotypic traits. The genetic architecture of the pilus region was predictive of the adhesive properties of the SDSE-isolates, but its role in tissue tropism needs further investigation. To the best of our knowledge, this is the first comprehensive characterization of the genetic landscape of the SDSE pilus region.

Emergence of a Streptococcus dysgalactiae subspecies equisimilis stG62647-lineage associated with severe clinical manifestations

Increasing incidence rates of invasive Streptococcus dysgalactiae subspecies equisimilis (SDSE) infections have been reported worldwide, but the evolutionary mechanisms underlying this development remain elusive. Through prospective surveillance of invasive SDSE infections in western Norway, we observed the emergence of a novel and virulent SDSE genotype, stG62647. This emm-type, rarely encountered as a cause of invasive disease during 1999–2012, emerged in 2013 as the predominant SDSE-genotype. The stG62647-infections were associated with an aggressive clinical course, including the occurrence of streptococcal toxic shock syndrome, necrotizing soft-tissue infections and endocarditis. All the invasive stG62647-isolates were subjected to whole genome sequencing, attempting to explore the genetic events underpinning its epidemicity. Although 10% of the genomes was unique for stG62647-genotype, notably 18 out of 19 isolates contained a disrupted streptococcal invasive locus (sil) due to the insertion of a transposase, IS1548, into the silB-gene. We postulate that the virulence of stG6267-isolates could be partly attributable to the abrogation of the attenuating control normally exerted by this regulon, although experimental verification was not performed. To the best of our knowledge, this is the first study employing large scale whole genome sequencing to illuminate the genetic landscape of epidemic lineages in SDSE.

Pathogenicity of Virulent Species of Group C Streptococci in Human

Group C streptococci (GCS) are livestock pathogens and they often cause zoonotic diseases in humans. They are Gram-positive, in mostly β-hemolytic and facultative anaerobes. Because of their close evolutionary kinship with group A streptococci (GAS), GCS share many common virulence factors with GAS and cause a similar range of diseases. Due to the exchange of genetic material with GAS, GCS belong to bacteria that are difficult to be distinguished from group A streptococci; GCS are often treated in microbiological diagnostics as contamination of the culture. This report focuses mainly on the pathogenicity of virulent species of GCS and their association with human diseases. The condition that is most frequently quoted is pharyngitis. In this paper, the virulence factors have also been mentioned and an interesting link has been made between GCS and the pathogenesis of rheumatic diseases among the native people of India and Aboriginal populations.

Clinical and molecular characteristics of infective β-hemolytic streptococcal endocarditis

Streptococcus pyogenes (S. pyogenes) and Streptococcus dysgalactiae subspecies equisimilis (SDSE) cause considerable morbidity and mortality, and show similarities in disease manifestations and pathogenic mechanisms. Their involvement in infective endocarditis, however, has not been well described. Invasive S. pyogenes and SDSE infections in Health Region Bergen, Norway, in the period 1999-2013 were reviewed, and sixteen cases of endocarditis were identified. The median duration of symptoms was 2.5days, the frequency of embolic events 50%, 38% received valve replacement and the 30-day mortality was 25%. In S. pyogenes, a significant correlation was observed between the repertoire of fibronectin-binding genes, phenotypic binding ability to fibronectin and disease manifestations. Conversely, no associations between phenotypic and genotypic characteristics were detected in SDSE. S. pyogenes and SDSE endocarditis is characterized by rapid and severe clinical manifestations. The pathogenesis is multifactorial, but our results infer a potential role of fibronectin binding in the development of S. pyogenes endocarditis.

Temporal trends of β-haemolytic streptococcal osteoarticular infections in western Norway

BACKGROUND

Beta-haemolytic streptococci are important contributors to the global burden of osteoarticular infections (OAI). Knowledge on the disease traits specific for streptococcal OAI, however, remains scarce. We wished to explore temporal trends of OAI caused by Group A Streptococci (GAS), Group B Streptococci (GBS) and Group C and G Streptococci (GCGS), and furthermore, to describe the associated host and pathogen characteristics.

METHODS

All cases of microbiologically verified β-haemolytic streptococcal OAI in Health Region Bergen, Norway, in the period 1999-2013 were retrospectively identified. Clinical data were extracted from medical records. Microbial isolates were submitted to antibiotic susceptibility testing and molecular typing.

RESULTS

A total of 24 GAS, 45 GBS and 42 GCGS acute OAI were identified. The cumulative incidence of GCGS OAI, but not GAS or GBS OAI, increased significantly from the first to the last 5-year period (IRR 5.7, p = 0.0003), with the annual incidence peaking at 1.9/100 000 in 2013. GAS OAI generally produced the most acute and severe clinical presentation, whereas GBS and GCGS predominantly affected the elderly, and were significantly associated with the presence of host risk factors of systemic and focal origin, respectively.

CONCLUSIONS

We found a significantly increasing incidence of GCGS OAI, likely related to the presence of host susceptibility factors, including prosthetic material and pre-existing joint disease. With an increasing application of therapeutic and diagnostic bone and joint procedures, the rising trend of OAI caused by GCGS is likely to continue. Sustained epidemiological attentiveness to GCGS seems warranted.