Invasive group A, C and G streptococcal disease in western Norway: virulence gene profiles, clinical features and outcomes

Clinical Aspects and Disease Severity of Streptococcus dysgalactiae Subspecies equisimilis Bacteremia, Finland1

We conducted a prospective study of 159 cases of Streptococcus dysgalactiae subspecies equisimilis (SDSE) bacteremia in 157 patients at 2 hospitals in Finland during November 2015–November 2019. Cellulitis was associated with nonsevere disease (p = 0.008); necrotizing fasciitis was associated with severe disease (p = 0.004). Fifty percent of patients had > 1 clinical characteristic associated with risk for death. The case-fatality rate was 6%, and 7% of patients were treated in an intensive care unit. Blood leukocyte counts on days 2 (p = 0.032) and 3 (p = 0.020) and C-reactive protein levels on days 3 (p = 0.030) and 4 (p = 0.009) after admission were predictors of severe disease. The Pitt bacteremia score was an accurate predictor of death. Using the Pitt bacteremia score, leukocyte counts, and CRP responses during initial treatment can improve treatment strategies and survival for patients with SDSE.

Clinical manifestations and biomarkers to predict mortality risk in adults with invasive Streptococcus dysgalactiae subsp. equisimilis infections

PURPOSE

The incidence of invasive Streptococcus dysgalactiae subsp. equisimilis (iSDSE) infections is increasing in developed countries, but studies on the risk factors for death in iSDSE infections are scant. Here, we aimed to clarify risk factors and predictors of mortality in adults with iSDSE infections.

METHODS

A multicentre observational study of adults with iSDSE infections was conducted to investigate the effects of host factors, disease severity, biomarkers, and antibiotic regimens, and bacterial factors on 28-day mortality.

RESULTS

The overall mortality rate of 588 patients was 10.4%, with a significant increase in those aged ≥ 60 years. Most of the patients (97.4%) had underlying diseases. The mortality rate (70.4%) of patients with severe disease was significantly higher than that of patients with mild-to-moderate disease (4.3%; p < 0.001). The risk factors for death identified using multivariable analysis were age ≥ 60 years (hazard ratio [HR], 3.4; 95% confidence interval [CI], 1.0-11.3, p = 0.042); severe disease (HR, 15.0; 95% CI 7.7-29.2, p < 0.001); bacteraemia without primary focus (HR, 20.5; 95% CI 2.8-152.3, p = 0.003); serum creatinine ≥ 2.0 mg/dL (HR, 2.2; 95% CI 1.2-4.0, p = 0.010); serum creatine kinase ≥ 300 IU/L (HR, 2.1; 95% CI 1.1-3.8, p = 0.019); and macrolide resistance (HR, 1.8; 95% CI 1.0-3.3, p = 0.048). Treatment regimens and emm types were not associated with poor outcomes.

CONCLUSION

Evaluation of clinical manifestations and biomarkers on admission is important to predict invasive SDSE infection prognosis.

Pathomolecular epidemiology, antimicrobial resistance, and virulence genes of Streptococcus dysgalactiae subsp. equisimilis isolates from slaughtered pigs in India

AIMS

We aimed to investigate the prevalence, pathology, and characterization of Streptococcus dysgalactiae subsp. equisimilis (SDSE) in slaughtered pigs of India.

METHODS AND RESULTS

We collected 1254 morbid tissues (lungs-627 and spleen-627) and 627 heart-blood from 627 slaughtered pigs. The bacterial isolation, antibiogram, virulence gene profiling, and mouse pathogenicity testing were performed for the detection and characterization of SDSE. A total of 177 isolates (heart-blood-160 and tissues-17) were recovered from 627 slaughtered pigs with higher isolation rate in heart-blood (25.51%). The prevalence of SDSE was 11% in morbid tissues by polymerase chain reaction. Majority of isolates showed higher detection of streptolysin O, followed by streptokinase and extracellular phospholipase A virulence genes with higher degree of resistance to azithromycin, clindamycin, erythromycin, and penicillin antibiotics. Mouse pathogenicity testing confirmed virulence based on histopathological lesions and re-isolation of SDSE.

CONCLUSIONS

Our findings highlight the high prevalence of SDSE in slaughtered pigs. The presence of virulence genes and mouse pathogenicity testing confirm their pathogenic potential.

Empyema caused by Streptococcus dysgalactiae subsp. equisimilis subsequently to bacteraemia

Streptococcus dysgalactiae subsp. equisimilis (SDSE) commonly causes a variety of infections in older individuals. However, respiratory infections are uncommon. We present the case of an older man with empyema due to SDSE subsequently to bacteraemia. He presented with a 1-day history of fever and laboratory findings revealed an increased white blood cell count and C- reactive protein (CRP) level. Chest CT revealed no infiltration and no pleural effusion. SDSE was detected in the blood cultures. Primary bacteraemia was suspected and antibiotic administration was initiated; however, 2 days later, his right breath sound diminished, and chest radiography revealed right pleural effusion. Thoracentesis yielded cloudy fluid with frank pus; thus, he was diagnosed with empyema due to SDSE, and a drainage tube was placed. Thereafter, his fever improved, and his CRP level decreased. Thus, SDSE can cause empyema probably by haemotological spread of SDSE to the pleura.

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.

Assessment of the Relationship between Clinical Manifestation and Pathogenic Potential of Streptococcus pyogenes Strains-Distribution of Genes and Genotypes of Toxins

Streptococcus pyogenes is one of the most important species among beta-haemolytic streptococci, causing human infections of different localization. It is isolated from clinical specimens relatively frequently. In this study, the frequency and co-occurrence of toxin genes (speA, speB, speC, speH, speJ, speK) among 147 S. pyogenes strains were evaluated, using real-time PCR. In addition, the relationship between the occurrence of these genes and the origin of S. pyogenes strains from selected clinical material was assessed. The speB gene was present with the highest incidence (98.6%), while the speK gene was the least frequent (8.2%) among the tested strains. Based on the presence of the detected genes, the distribution of 17 genotypes was determined. The most common (21.8%), was speA (−) speB (+) speC (−) speH (−) speJ (−) speK (−) genotype. Furthermore, significant variation in the presence of some genes and genotypes of toxins in S. pyogenes strains isolated from different types of clinical material was found. There is a considerable variety and disproportion between the frequency of individual genes and genotypes of toxins in S. pyogenes strains. The relationship between the origin of S. pyogenes isolates and the presence of toxins genes indicates their pathogenic potential in the development of infections of selected localization.

Streptococcus dysgalactiae subsp. equisimilis from invasive and non-invasive infections in Spain: combining epidemiology, molecular characterization, and genetic diversity

The purpose of this study was to characterize the antibiotic resistance, virulence, and genetic diversity among invasive and non-invasive Streptococcus dysgalactiae subsp. equisimilis (SDSE) isolates. SDSE were isolated from clinical samples of outpatients and inpatients cares in La Rioja region (Spain) during 2012-2015. The analyses performed were susceptibility testing by disc diffusion, resistance and virulence genes by PCR, emm typing by PCR and sequencing, and other molecular typing by SmaI-PFGE and MLST. Forty-two SDSE isolates were recovered (64.3% non-invasive, 35.7% invasive) that were grouped in 31 PFGE patterns, 17 ST, and 14 emm types, being stC1400, stG6792, and stG62647 the most frequent, and stC74a and stC5345 exclusive in invasive SDSE. Twenty-one SDSE were resistant to at least one antibiotic. The erm(TR) and erm(B) genes were linked with resistance to macrolides; tet(M) and tet(T) to tetracycline; dfrF to trimethoprim; ant(6)-Ia and aph(3')-IIIa to aminoglycosides; and the substitutions Asp80Ala in GyrA and Ser79Phe in ParC with resistance to levofloxacin. The sagA, slo, scpA, and ska virulence genes were amplified in 93% SDSE. Streptococcal superantigenic speG^dys gene was identified in 80% of invasive and 63% of non-invasive SDSE and correlated with certain emm types (e.g., stG62647 or stG6792). SDSE invasive infections were most frequent in elderly patients, and half of our SDSE were resistant to at least one antibiotic tested. This work is the first detection of tet(T), dfrF, and new substitution in GyrA protein in SDSE. A high diversity of circulating genetic lineages was found among our SDSE.

Prevalence and Characterization ofStreptococcus pyogenesClinical Isolates from Different Hospitals and Clinics in Mansoura

Streptococcus pyogenesare associated with many bacterial diseases in both humans and animals and are capable of causing a multitude of human diseases.S. pyogenesisolates were identified by their bacitracin sensitivity, positivespy1258detection, and positive GAS latex agglutination. Different isolates were typed serotypically and genotypically by BOX-PCR. Different virulence factors were identified inS. pyogenesisolates. In addition, antimicrobial resistance was tested to eleven different antibiotics. Furthermore, the resistance mechanisms were determined phenotypically by the disc diffusion method. Finally, the correlation between both molecular and serotypes identified and the profile of virulence factors and clinical and geographical sources was determined for all isolates. Thirty-eightS. pyogenesisolates were collected from different clinical sources. Resistance testing indicated high resistance to mostly used antibiotics except amoxicillin/clavulanic acid, amoxicillin, and ampicillin. Serotyping results indicated five different serotypes, M1, M2, M3, M4, and M6, inS. pyogenesisolates, while six isolates were identified as untypeable. In addition, positive PCR results identified most of the tested SAgs genes in whichspeJgene was mostly identified followed byspeI, speC,andssagenes being identified in 81.6%, 63.3%, 60.5%, and 60.5%, respectively. However,speHwas the least detected. In contrast,speL, speM, andsmeZgenes could not be detected in all tested isolates. Finally, BOX-PCR molecular typing was a more effective clustering method when compared to the serotyping method in allS. pyogenes.In conclusion, the isolates in this study were highly resistant to mostly used antibiotics. M1 was the most identified serotype. No significant association was found between serotypes, BOX-PCR cluster groups, and SAgs genes profiles. However, by the application of BOX-PCR, effective molecular typing was obtained.

Group A streptococcal bacteremias in Southwest Finland 2007-2018: epidemiology and role of infectious diseases consultation in antibiotic treatment selection

The incidence of invasive group A streptococcal (GAS) infections has shown a fluctuating but increasing trend in Finland. The impact of infectious diseases specialist consultation (IDSC) on the antimicrobial therapy of GAS bacteremia has not been studied earlier. A retrospective study on adult GAS bacteremia in The Hospital District of Southwest Finland (HDSWF) was conducted from 2007 to 2018. Data on incidence of bacteremic GAS cases were gathered from the National Infectious Disease Register. Clinical data were obtained by reviewing the electronic patient records. The overall incidence of GAS bacteremia in HDSWF was 3.52/100,000, but year-to-year variation was observed with the highest incidence of 7.93/100,000 in 2018. A total of 212 adult GAS bacteremia cases were included. A record of IDSC was found (+) in 117 (55.2%) cases, not found (−) in 71 (33.5%) cases and data were not available in 24 (11.3%) cases. Among IDSC+ cases, 57.3% were on penicillin G treatment whereas in the group IDSC− only 22.5%, respectively (OR = 4.61, 95% CI 2.37–8.97; p < 0.001). The use of clindamycin as adjunctive antibiotic was more common among IDSC+ (54.7%) than IDSC− (21.7%) (OR = 4.51, 95% CI 2.29–8.87; p < 0.001). There was an increasing trend in incidence of GAS bacteremia during the study period. Narrow-spectrum beta-lactam antibiotics were chosen, and adjunctive clindamycin was more commonly used, if IDSC took place. This highlights the importance of availability of IDSC but calls for improved practice among infectious diseases specialists by avoiding combination therapy with clindamycin in non-severe invasive GAS infections.

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.

Bloodstream infection due to β-hemolytic streptococci: a population-based comparative analysis

PURPOSE

Although the burden of illness due to Streptococcus pyogenes is widely recognized, other β-hemolytic streptococci are also important causes of invasive infections. The objective of this study was to compare the population-based epidemiology of groups A, B, and C/G β-hemolytic streptococcal bloodstream infection (BSI).

METHODS

Population-based surveillance was conducted in the western interior of British Columbia, Canada, 2011-2018.

RESULTS

A total of 210 episodes were identified for an incidence of 14.4 per 100,000; the incidences of groups A, B and C/G streptococcal BSI were 4.2, 4.7, and 5.5 per 100,000, respectively. There was an increasing annual incidence of β-hemolytic streptococcal BSI from 2011 through to a peak incidence in 2016 that decreased thereafter. Fifty-two percent (110) of BSIs were community associated, 43% (91) were healthcare associated, and 4% (9) were hospital onset. Patients with group A were younger, more likely to be female, and have fewer co-morbidities than patients with groups B and C/G streptococcal BSI. The most common focus of infection was soft tissue (109/52%), followed by primary (33; 16%), and bone and joint (20; 10%) and these varied by streptococcal species (p < 0.001). The 30-day all-cause case fatality rate was 11% (24/210) and did not significantly vary by group (p = 0.7).

CONCLUSION

Although the determinants vary, the overall burden of disease related to BSI is similar amongst groups A, B and C/G β-hemolytic streptococci.

Incidence, clinical characteristics, and outcomes of Streptococcus dysgalactiae subspecies equisimilis bacteremia in a tertiary hospital: comparison with S. agalactiae bacteremia

The clinical characteristics and outcomes of Streptococcus dysgalactiae subspecies equisimilis (SDSE) bacteremia cases have not been adequately evaluated. We retrospectively enrolled consecutive adult patients with SDSE or S. agalactiae (group B streptococci, GBS) bacteremia at a tertiary care hospital (Republic of Korea) from August 2012 to December 2016. We compared the incidence, seasonality, clinical characteristics, and outcomes of 52 SDSE bacteremia cases with 151 GBS bacteremia cases. The incidence of SDSE and GBS bacteremia in these patients was 1.28/100,000 and 4.22/100,000 person-days, respectively. Most SDSE bacteremia cases were of community-onset infection (SDSE 94.2% vs GBS 83.4%; p = 0.052). Lancefield group G was the most common bacteria type among SDSE isolates (43/47; 91.5%). Patients with SDSE bacteremia were older (median, 68.0 years vs 61.0 years; p = 0.03). In both groups, solid tumor was the most common underlying disease, and more than half of the patients were immunocompromised (51.9% vs 54.3%; p = 0.77). Chronic kidney disease was more common in the SDSE group (19.2% vs 5.3%; p < 0.01). Cellulitis was the most common clinical syndrome of SDSE bacteremia and was more common in the SDSE group (59.6% vs 29.1%; p < 0.01). SDSE bacteremia cases occurred more frequently in the warm season compared with GBS bacteremia cases (65.4% vs 37.1%; p < 0.01); in-hospital mortalities were not significantly different between the groups (3.8% vs 10.6%; p = 0.17). In conclusion, SDSE bacteremia is commonly associated with cellulitis, especially in older and immunocompromised patients during the warm season.

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.

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.

Infective Endocarditis Associated with Streptococcal Toxic Shock Syndrome due to Streptococcus dysgalactiae subsp. equisimilis Infection in a Hemodialysis Patient

The risk of infective endocarditis in chronic hemodialysis patients is markedly higher than that in the general population. We report the first case of a hemodialysis patient with infective endocarditis caused by Streptococcus dysgalactiae subsp. equisimilis (SDSE) who presented with streptococcal toxic shock syndrome. In the last decade, there has been an increase in the incidence of SDSE infections. Therefore, it is important to recognize SDSE as a possible causative agent of infective endocarditis in an immunocompromised population, such as hemodialysis patients.

Association between cytokine response, the LRINEC score and outcome in patients with necrotising soft tissue infection: a multicentre, prospective study

Early assessment of necrotising soft tissue infection (NSTI) is challenging. Analysis of inflammatory markers could provide important information about disease severity and guide decision making. For this purpose, we investigated the association between cytokine levels and the Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC)-score, disease severity and mortality in NSTI patients. In 159 patients, plasma was analysed for IL-1β, IL-6, IL-10 and TNF-α upon admission. The severity of NSTI was assessed by SAPS, SOFA score, septic shock, microbial aetiology, renal replacement therapy and amputation. We found no significant difference in cytokine levels according to a LRINEC- score above or below 6 (IL-1β: 3.0 vs. 1.3; IL-6: 607 vs. 289; IL-10: 38.4 vs. 38.8; TNF-α: 15.1 vs. 7.8 pg/mL, P > 0.05). Patients with β-haemolytic streptococcal infection had higher level of particularly IL-6. There was no difference in mortality between patients with a LRINEC-score above or below 6. In the adjusted analysis assessing 30-day mortality, the association was strongest for IL-1β (OR 3.86 [95% CI, 1.43-10.40], P = 0.008) and IL-10 (4.80 [1.67-13.78], P = 0.004). In conclusion, we found no significant association between the LRINEC-score and cytokine levels on admission. IL-6 was consistently associated with disease severity, whereas IL-1β had the strongest association with 30-day mortality.

Molecular Characterization of Invasive Streptococcus dysgalactiae subsp. equisimilis, Japan

We collected β-hemolytic streptococci (1,611 isolates) from patients with invasive streptococcal infections in Japan during April 2010-March 2013. Streptococcus dysgalactiae subsp. equisimilis (SDSE) was most common (n = 693); 99% of patients with SDSE infections were elderly (mean age 75 years, SD ±15 years). We aimed to clarify molecular and epidemiologic characteristics of SDSE isolates and features of patient infections. Bacteremia with no identified focus of origin and cellulitis were the most prevalent manifestations; otherwise, clinical manifestations resembled those of S. pyogenes infections. Clinical manifestations also differed by patient's age. SDSE isolates were classified into 34 emm types; stG6792 was most prevalent (27.1%), followed by stG485 and stG245. Mortality rates did not differ according to emm types. Multilocus sequence typing identified 46 sequence types and 12 novel types. Types possessing macrolide- and quinolone-resistance genes were 18.4% and 2.6%, respectively; none showed β-lactam resistance. Among aging populations, invasive SDSE infections are an increasing risk.

Prevalence of the M Protein Gene in Group C and Group G Streptococci Isolated from Patients in Thailand

We surveyed group C and group G β-hemolytic streptococci for emm and emmL (emm -like) genes which encode the M protein, as well as determined their antimicrobial susceptibilities. A total of 97 isolates 79 GCS/GGS isolates and 18 isolates from other groups were tested for the M protein gene by PCR. Focusing on invasive infections with group A (GAS), group C (GCS), and group G (GGS) β-hemolytic streptococci isolated from blood, the M protein gene was found in 90.0%, 84.6%, and 78.3% of isolates, respectively. The hypervariable N terminal region of the emm was sequenced from 62 isolates, and 26 types of the emm gene were identified. Based on these results, type emm222.2 may be endemic to Thailand. The results of antimicrobial susceptibility testing of groups C, G, and non-groups A to G isolates indicated high susceptibility (range 82-100%) to penicillin, cefotaxime, chloramphenicol, clindamycin, erythromycin, linezolid, ofloxacin, and vancomycin, whereas the isolates showed low susceptibility (range 0-15.6%) to tetracycline.

Increased cytotoxicity and streptolysin O activity in group G streptococcal strains causing invasive tissue infections

Streptococcus dysgalactiae subsp. equisimilis (SDSE) has emerged as an important cause of severe skin and soft tissue infections, but little is known of the pathogenic mechanisms underlying tissue pathology. Patient samples and a collection of invasive and non-invasive group G SDSE strains (n = 69) were analyzed with respect to virulence factor expression and cytotoxic or inflammatory effects on human cells and 3D skin tissue models. SDSE strains efficiently infected the 3D-skin model and severe tissue pathology, inflammatory responses and altered production of host structural framework proteins associated with epithelial barrier integrity were evident already at 8 hours post-infection. Invasive strains were significantly more cytotoxic towards keratinocytes and expressed higher Streptokinase and Streptolysin O (SLO) activities, as compared to non-invasive strains. The opposite was true for Streptolysin S (SLS). Fractionation and proteomic analysis of the cytotoxic fractions implicated SLO as a factor likely contributing to the keratinocyte cytotoxicity and tissue pathology. Analyses of patient tissue biopsies revealed massive bacterial load, high expression of slo, as well as immune cell infiltration and pro-inflammatory markers. Our findings suggest the contribution of SLO to epithelial cytotoxicity and tissue pathology in SDSE tissue infections.

Prevalence of emm types and antimicrobial susceptibility of Streptococcus dysgalactiae subsp. equisimilis in Austria

OBJECTIVES

An increase of severe infections caused by Streptococcus dysgalactiae subsp. equisimilis (SDSE) similar to infections caused by Streptococcus pyogenes has been reported over the last years. Little is known about infections with SDSE in Austria. Therefore, we investigated a collection of 113 SDSE invasive and non-invasive isolates from different infection sites and type of infections as well as patients' characteristics.

METHODS

The isolates were phenotypically identified and emm typed using the enlarged emm database from the Centers for Disease Control and Prevention. Additionally, 13 antimicrobial agents were tested using EUCAST guidelines and virulence genes were investigated.

RESULTS

Severe SDSE infections were most common in elderly men with underlying diseases especially diabetes mellitus. With VitekMS identification of SDSE isolates was successful to the species level only. Emm typing revealed 24 different emm types, one new type and one new subtype. StG485, stG6, stC74a, stG643, and stG480 were the predominant types in this study, stC74a and stG652 in invasive infections and stG643, stC74a and stG485 in non-invasive infections. Resistance was observed to tetracycline (62%), macrolides (13%) with one M phenotype, and clindamycin (12%) presenting 6 constitutive MLS(B) phenotypes and 8 inducible MLS(B) phenotypes. Levofloxacin resistance was detected only in one isolate. All isolates tested for virulence genes were positive for scpA, ska, saga and slo. Superantigenic genes were negative except speG(dys) (positive 17/34; 50%).

CONCLUSION

This paper presents the first report of SDSE infections in Austria. Severe SDSE infections were found mainly in elderly men with underlying diseases. SDSE isolates demonstrated substantial emm type diversity without association with infections site or invasiveness. Analysis of virulence genes showed no significant difference between invasive and non-invasive infections.

New tricks from an old cow: infective endocarditis caused by Streptococcus dysgalactiae subsp. dysgalactiae

We present a case of infective endocarditis caused by Streptococcus dysgalactiae subsp. dysgalactiae, a major cause of bovine mastitis and previously thought to be an animal-restricted pathogen. The patient reported no direct contact with animals, and the clinical course was severe and complicated.

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

Pyogenic streptococci cause significant morbidity and mortality, and the incidence of invasive group C and G streptococcal disease appears to be increasing. In this retrospective study we describe the epidemiological characteristics of invasive group A, C and G, along with non-invasive group C and G streptococcal infections in Western Norway from 1999 to 2013. A total of 512 invasive streptococcal infections were identified, of these 297 (58%) were group A (GAS), 24 (5%) group C (GCS) and 188 (37%) group G streptococci (GGS). In the non-invasive group, 4935 GCS and GGS-infections were identified. GCS and GGS were treated as one group (GCGS) for statistical purposes. All microbial categories displayed increasing incidence with age, seasonal variation and a male predominance. The incidence of invasive GCGS infections increased significantly from 1.4/100,000 inhabitants in 1999 to 6.3/100,000 in 2013 (p <0.001). Conversely, the annual rates of invasive GAS infection exhibited marked fluctuations, ranging from 2.7/100,000 (2000) to 8.3/100,000 (1999), but no significant temporal trends were observed. The incidence of non-invasive GCGS infections decreased significantly during the study period (p <0.001). The most frequently encountered emm-types among the 209 iGAS-isolates analysed were emm1 (24%), emm3 (14%) and emm28 (14%); whereas stG643 (19%), stG485 (15%) and stG6 (13%) were most prevalent among the 122 iGCGS-isolates available for typing. The increasing burden of invasive β-haemolytic streptococcal disease in our community calls for sustained attentiveness to the clinical and molecular aspects of GAS, GCS and GGS infections.

Current views of haemolytic streptococcal pathogenesis

PURPOSE OF REVIEW

Increasing disease caused by beta-haemolytic streptococci indicates the need for improved understanding of pathogenesis.

RECENT FINDINGS

Streptococcus pyogenes, or group A Streptococcus (GAS), causes significant disease worldwide. The closely related Streptococcus dysgalactiae subspecies equisimilis (SDSE) is increasingly recognized as causing a similar disease spectrum. Whole-genome sequencing applied to the study of outbreaks may reveal factors that contribute to pathogenesis and changes in epidemiology. The role of quorum sensing in biofilm formation, and interspecies communication with other streptococci, is discussed. GAS has evolved multiple mechanisms to evade the humoral arm of innate immunity, including complement, which is well known in protecting the host from bacteria, and the coagulation-fibrinolytic system, which is increasingly recognized as an innate immune effector.

SUMMARY

Molecular biology has enhanced our understanding of the intricate balance of host-pathogen interactions that result in clearance or establishment of invasive streptococcal infection. Although the skin and oropharynx remain the usual ecological niche of GAS and SDSE, occasionally the bacteria find themselves within deeper tissues and blood. Recent research has armed us with better knowledge of bacterial adaptations to this alternative environment. However, the challenge is to translate this knowledge into clinical practice, through the development of novel therapeutic options and ultimately a vaccine against GAS.

Streptococcus dysgalactiae subsp. equisimilis bacteremia: an emerging infection

The importance of group C and G Streptococcus dysgalactiae subspecies equisimilis (S. dysgalactiae subsp. equisimilis) as a significant pathogen has recently been better recognized. S. dysgalactiae subsp. equisimilis disease can range in severity from milder skin and soft-tissue conditions such as wound infection, erysipelas, and cellulitis, to life-threatening necrotizing fasciitis and streptococcal toxic shock syndrome, thus sharing the clinical picture with S. pyogenes. The most common clinical manifestation of bacteremia is cellulitis. An increase in the incidence of S. dysgalactiae subsp. equisimilis bacteremia has been recognized. Invasive forms of this infection are most commonly found in elderly patients with underlying comorbidities and skin breakdown. The case fatality in bacteremia has been reported to be 15-18%. In this review, the epidemiology, clinical characteristics, and emm types of S. dysgalactiae subsp. equisimilis bacteremia are summarized.

Staphylococcal and streptococcal superantigen exotoxins

SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.

Streptococcal superantigens: categorization and clinical associations

Superantigens are key virulence factors in the immunopathogenesis of invasive disease caused by group A streptococcus. These protein exotoxins have also been associated with severe group C and group G streptococcal infections. A number of novel streptococcal superantigens have recently been described with some resulting confusion in their classification. In addition to clarifying the nomenclature of streptococcal superantigens and proposing guidelines for their categorization, this review summarizes the evidence supporting their involvement in various clinical diseases including acute rheumatic fever.

Sequence diversity of sicG among group C and G Streptococcus dysgalactiae subspecies equisimilis isolates associated with human infections in western Norway

Streptococcal inhibitor of complement (SIC) and distantly related to SIC (DRS) are well-characterized extracellular virulence factors produced by only a few emm types among group A streptococci. The prevalence and sequence variations of the sic-like gene (sicG) in clinical samples of group C and G Streptococcus dysgalactiae subspecies equisimilis (SDSE), however, have not been widely investigated. We constructed primers targeting sicG and screened 129 geographically matched and previously emm-typed non-invasive (n = 64) and invasive (n = 65) SDSE isolates for the presence of this gene. sicG was detected in seven non-invasive and eight invasive isolates belonging to eight different emm types. Within five of these emm types, sicG-negative isolates were also detected. All three isolates of stG2078.0 possessed sicG and were associated with severe soft tissue infections. Altogether, six sicG alleles (sicG1-6) were identified, and sequence variations were mainly caused by single nucleotide polymorphisms and deletion/insertion mutations. sicG1-6 were predicted to encode SICG proteins of varying length, composition, and homology with SIC and DRS proteins of group A streptococci. Our findings indicate an unpredictable association between sicG and emm type, a limited distribution and substantial sequence diversity of sicG, and no obvious relation between its presence and disease severity.

Adult invasive and noninvasive infections due to Streptococcus dysgalactiae subsp. equisimilis in France from 2006 to 2010

We characterized 182 Streptococcus dysgalactiae subsp. equisimilis isolates and analyzed the epidemiological data on the corresponding infections. stG6, stG485, and stG6792 were the 3 most prevalent invasive emm types among the 27 different emm types recovered. High rates of antimicrobial resistance were observed for macrolides (26.4%) and tetracycline (34.6%).

Antimicrobial susceptibility pattern of β-haemolytic group A, C and G streptococci isolated from North India

The objective of this study was to determine the antibiotic resistance amongst beta-haemolytic streptococci (BHS) from North India. A total of 155 BHS isolates, comprising group A streptococci (GAS) (102), group C streptococci (GCS) (25) and group G streptococci (GGS) (28), collected from patients with pharyngitis, rheumatic fever, skin disease and invasive disease were analysed for their antimicrobial susceptibility to 20 antibiotics using the Kirby-Bauer disc diffusion method. The MICs of penicillin, tetracycline, clarithromycin, azithromycin and erythromycin were also determined using the HiComb test, following the Clinical and Laboratory Standards Institute guidelines. The results showed that 37.4% of BHS isolates were susceptible to all antibiotics and 19.4% were highly resistant to tetracycline; however, only 2.6-5.2% were resistant to macrolides. The tetracycline resistance (P<0.05) of BHS was found to be statistically significant. GAS isolates from different sources of infection also showed statistically significant antibiotic resistance to azithromycin (P=0.029). Multi-drug resistance was found irrespective of streptococcal emm types. No association between GAS emm types and drug resistance was seen. MIC determination showed all isolates to be susceptible to the five antibiotics tested, except for two GAS and one GGS isolates that were resistant to clarithromycin, and one GAS skin isolate that was resistant to tetracycline. This study suggests that the variation in antibiotic resistance amongst BHS isolates from North India is independent of the isolation source and emm type distribution, hence emphasizing the need for a longitudinal surveillance in different regions of India.