Long-term surveillance of invasive group A streptococcal disease in The Netherlands, 1994-2003

Invasive Streptococcus pyogenes disease in Spain: a microbiological and epidemiological study covering the period 2007-2019

The aim of this study is to present the first nationwide microbiological and epidemiological study of invasive group A Streptococcus (iGAS) disease in Spain. One thousand eight hundred ninety-three iGAS isolates were analyzed over 2007-2019. emm typing was performed by sequencing the gene's variable 5' end, exotoxin genes were identified by PCR, and antimicrobial susceptibility explored via the E test and disk diffusion. Five hundred twenty-three isolates were associated with sepsis, 292 with cellulitis, 232 with scarlet fever, 153 with pneumonia, 141 with streptococcal toxic shock syndrome, and 94 with necrotizing fasciitis. The most prevalent emm types were emm1 (449/1893 isolates), emm89 (210/1893), emm3 (208/1893), emm4 (150/1893), emm12 (112/1893) emm6 (107/1893), emm87 (89/1893), emm28 (88/1893), emm75 (78/1893), emm77 (78/1893), emm11 (58/1893), and emm22 (35/1893). emm1, emm3, emm4, and emm6 were the predominant types affecting children (mostly respiratory infections), while emm11, emm77, and emm89 prevailed in the elderly (mostly skin infections). Each emm type was associated with one or more exotoxin gene (spe, sme, and ssa) profiles. speA was detected in 660 isolates, speB in 1829, speC in 1014, speF in 1826, speG in 1651, speJ in 716, speH in 331, smeZ in 720, and ssa in 512. Isolates with speA were associated with the most severe infections. Penicillin susceptibility was universal. Two hundred twenty-four isolates were resistant to tetracycline, 169 to erythromycin, and 81 to clindamycin. Tetracycline, erythromycin, and clindamycin resistance rates declined over the study period. The above information could serve as the basis for continued surveillance efforts designed to control disease cause by this bacterium.

Genomic Surveillance of Streptococcus pyogenes Strains Causing Invasive Disease, United States, 2016-2017

BACKGROUND

Streptococcus pyogenes is a major cause of severe, invasive infections in humans. The bacterial pathogen harbors a wide array of virulence factors and exhibits high genomic diversity. Rapid changes of circulating strains in a community are common. Understanding the current prevalence and dynamics of S. pyogenes lineages could inform vaccine development and disease control strategies.

METHODS

We used whole-genome sequencing (WGS) to characterize all invasive S. pyogenes isolates obtained through the United States Center for Disease Control and Prevention's Active Bacterial Core surveillance (ABCs) in 2016 and 2017. We determined the distribution of strain features, including emm type, antibiotic resistance determinants, and selected virulence factors. Changes in strain feature distribution between years 2016 and 2017 were evaluated. Phylogenetic analysis was used to identify expanding lineages within emm type.

RESULTS

Seventy-one emm types were identified from 3873 isolates characterized. The emm types targeted by a 30-valent M protein-based vaccine accounted for 3230 (89%) isolates. The relative frequencies of emm types collected during the 2 years were similar. While all isolates were penicillin-susceptible, erythromycin-resistant isolates increased from 273 (16% of 2016 isolates) to 432 (23% of 2017 isolates), mainly driven by increase of the erm-positive emm types 92 and 83. The prevalence of 24 virulence factors, including 11 streptococcal pyrogenic toxins, ranged from 6 to 90%. In each of three emm types (emm 49, 82, and 92), a subgroup of isolates significantly expanded between 2016 and 2017 compared to isolates outside of the subgroup (P-values < 0.0001). Specific genomic sequence changes were associated with these expanded lineages.

CONCLUSIONS

While the overall population structure of invasive S. pyogenes isolates in the United States remained stable, some lineages, including several that were antibiotic-resistant, increased between 2016 and 2017. Continued genomic surveillance can help monitor and characterize bacterial features associated with emerging strains from invasive infections.

Asymptomatic carriage of Streptococcus pyogenes among school children in Sana'a city, Yemen

OBJECTIVES

Streptococcus pyogenes is the most frequent cause of pharyngitis and skin infections in children. It is also the causative agent of dangerous immune-complications such as rheumatic fever and rheumatic heart disease which are common in Yemen. The aim of this study was to determine the throat carriage rate of Streptococcus pyogenes among asymptomatic school children in Sana'a city.

RESULTS

A cross-sectional study was conducted from December to March of years 2012-2016. A total of 813 asymptomatic school children whose antistreptolysin O test was negative were included. The mean age of the students was 10.5 ± 2.8 years with a range from 5 to 15 years old. Throat swab and blood sample were taking from each student. One hundred and four (12.8%) healthy students were found to be Streptococcus pyogenes carriers. Pharyngeal Streptococcus pyogenes carriage rate was statistically insignificant among different age groups. However, it was found to be more common among females (66, 15%) than males (38, 10%) with statistically significant difference (χ² = 4.52, P = 0.04). This study showed a high asymptomatic carriage rate of Streptococcus pyogenes in the throat of healthy school children in Sana'a city, Yemen.

The Evaluation and Management of Toxic Shock Syndrome in the Emergency Department: A Review of the Literature

BACKGROUND

Toxic shock syndrome (TSS) is a severe, toxin-mediated illness that can mimic several other diseases and is lethal if not recognized and treated appropriately.

OBJECTIVE

This review provides an emergency medicine evidence-based summary of the current evaluation and treatment of TSS.

DISCUSSION

The most common etiologic agents are Staphylococcus aureus and Streptococcus pyogenes. Sources of TSS include postsurgical wounds, postpartum, postabortion, burns, soft tissue injuries, pharyngitis, and focal infections. Symptoms are due to toxin production and infection focus. Early symptoms include fever, chills, malaise, rash, vomiting, diarrhea, and hypotension. Diffuse erythema and desquamation may occur later in the disease course. Laboratory assessment may demonstrate anemia, thrombocytopenia, elevated liver enzymes, and abnormal coagulation studies. Diagnostic criteria are available to facilitate the diagnosis, but they should not be relied on for definitive diagnosis. Rather, specific situations should trigger consideration of this disease process. Treatment involves intravenous fluids, source control, and antibiotics. Antibiotics should include a penicillinase-resistant penicillin, cephalosporin, or vancomycin (in methicillin-resistant S. aureus prevalent areas) along with either clindamycin or linezolid.

CONCLUSION

TSS is a potentially deadly disease requiring prompt recognition and treatment. Focused history, physical examination, and laboratory testing are important for the diagnosis and management of this disease. Understanding the evaluation and treatment of TSS can assist providers with effectively managing these patients.

Epidemiology of Invasive Group A Streptococcal Infections in the United States, 2005-2012

BACKGROUND

Invasive group A Streptococcus (GAS) infections are associated with significant morbidity and mortality rates. We report the epidemiology and trends of invasive GAS over 8 years of surveillance.

METHODS

From January 2005 through December 2012, we collected data from the Centers for Disease Control and Prevention's Active Bacterial Core surveillance, a population-based network of 10 geographically diverse US sites (2012 population, 32.8 million). We defined invasive GAS as isolation of GAS from a normally sterile site or from a wound in a patient with necrotizing fasciitis (NF) or streptococcal toxic shock syndrome (STSS). Available isolates were emm typed. We calculated rates and made age- and race-adjusted national projections using census data.

RESULTS

We identified 9557 cases (3.8 cases per 100 000 persons per year) with 1116 deaths (case-fatality rate, 11.7%). The case-fatality rates for septic shock, STSS, and NF were 45%, 38%, and 29%, respectively. The annual incidence was highest among persons aged ≥65 years (9.4/100 000) or <1 year (5.3) and among blacks (4.7/100 000). National rates remained steady over 8 years of surveillance. Factors independently associated with death included increasing age, residence in a nursing home, recent surgery, septic shock, NF, meningitis, isolated bacteremia, pneumonia, emm type 1 or 3, and underlying chronic illness or immunosuppression. An estimated 10 649-13 434 cases of invasive GAS infections occur in the United States annually, resulting in 1136-1607 deaths. In a 30-valent M-protein vaccine, emm types accounted for 91% of isolates.

CONCLUSIONS

The burden of invasive GAS infection in the United States remains substantial. Vaccines under development could have a considerable public health impact.

Epidemiology of Invasive Group A Streptococcal Disease in Alaska, 2001 to 2013

The Arctic Investigations Program (AIP) began surveillance for invasive group A streptococcal (GAS) infections in Alaska in 2000 as part of the invasive bacterial diseases population-based laboratory surveillance program. Between 2001 and 2013, there were 516 cases of GAS infection reported, for an overall annual incidence of 5.8 cases per 100,000 persons with 56 deaths (case fatality rate, 10.7%). Of the 516 confirmed cases of invasive GAS infection, 422 (82%) had isolates available for laboratory analysis. All isolates were susceptible to penicillin, cefotaxime, and levofloxacin. Resistance to tetracycline, erythromycin, and clindamycin was seen in 11% (n = 8), 5.8% (n = 20), and 1.2% (n = 4) of the isolates, respectively. A total of 51 emm types were identified, of which emm1 (11.1%) was the most prevalent, followed by emm82 (8.8%), emm49 (7.8%), emm12 and emm3 (6.6% each), emm89 (6.2%), emm108 (5.5%), emm28 (4.7%), emm92 (4%), and emm41 (3.8%). The five most common emm types accounted for 41% of isolates. The emm types in the proposed 26-valent and 30-valent vaccines accounted for 56% and 78% of all cases, respectively. GAS remains an important cause of invasive bacterial disease in Alaska. Continued surveillance of GAS infections will help improve understanding of the epidemiology of invasive disease, with an impact on disease control, notification of outbreaks, and vaccine development.

Invasive group a streptococcal disease: epidemiology, pathogenesis and management

Invasive group A streptococcal infections are uncommon, although serious, infections with high case fatality rates. Periodic resurgences in invasive group A streptococcal infections in industrialized countries have been reported from the 1980s onwards, with current estimates of incidence in these countries of approximately 3–4 per 100000 population. Infants, pregnant women and the elderly are at increased risk of invasive group A streptococcal infection. The group A streptococcus has an array of virulence factors that underpin its invasive capacity and, in approximately 10% of cases, super-antigen toxins produced by the bacteria stimulate a large proportion of T cells, leading to streptococcal toxic shock syndrome. Given the rapid clinical progression, effective management of invasive group A streptococcal infections hinges on early recognition of the disease and prompt initiation of supportive care (often intensive care) together with antibacterial therapy. In cases of toxic shock syndrome, it is often difficult to distinguish between streptococcal and staphylococcal infection before cultures become available and so antibacterial choice must include coverage of both of these organisms. In addition, clindamycin is an important adjunctive antibacterial because of its anti-toxin effects and excellent tissue penetration. Early institution of intravenous immunoglobulin therapy should be considered in cases of toxic shock syndrome and severe invasive infection, including necrotizing fasciitis. Early surgical debridement of necrotic tissue is also an important part of management in cases of necrotizing fasciitis.

Invasive group a streptococcal disease: epidemiology, pathogenesis and management

Invasive group A streptococcal infections are uncommon, although serious, infections with high case fatality rates. Periodic resurgences in invasive group A streptococcal infections in industrialized countries have been reported from the 1980s onwards, with current estimates of incidence in these countries of approximately 3-4 per 100 000 population. Infants, pregnant women and the elderly are at increased risk of invasive group A streptococcal infection. The group A streptococcus has an array of virulence factors that underpin its invasive capacity and, in approximately 10% of cases, superantigen toxins produced by the bacteria stimulate a large proportion of T cells, leading to streptococcal toxic shock syndrome. Given the rapid clinical progression, effective management of invasive group A streptococcal infections hinges on early recognition of the disease and prompt initiation of supportive care (often intensive care) together with antibacterial therapy. In cases of toxic shock syndrome, it is often difficult to distinguish between streptococcal and staphylococcal infection before cultures become available and so antibacterial choice must include coverage of both of these organisms. In addition, clindamycin is an important adjunctive antibacterial because of its anti-toxin effects and excellent tissue penetration. Early institution of intravenous immunoglobulin therapy should be considered in cases of toxic shock syndrome and severe invasive infection, including necrotizing fasciitis. Early surgical debridement of necrotic tissue is also an important part of management in cases of necrotizing fasciitis.

Evolving epidemiologic characteristics of invasive group a streptococcal disease in Utah, 2002-2010

BACKGROUND

Invasive group A Streptococcus (GAS) infections are associated with substantial morbidity and mortality. Recent national surveillance data report stable rates of invasive GAS disease, although these may not capture geographic variation.

METHODS

We performed a population-based, retrospective laboratory surveillance study of invasive GAS disease among Utah residents from 2002-2010. We used Intermountain Healthcare's electronic medical records and data warehouse to identify patients from whom GAS was isolated by culture. We defined clinical syndromes of invasive GAS disease on the basis of International Classification of Diseases, Ninth Revision codes. We abstracted demographic information, comorbidities, and microbiologic and laboratory findings.

RESULTS

From 2002-2010, we identified 1514 cases of invasive GAS disease among Utah residents. The estimated mean annual incidence rate was 6.3 cases/100,000 persons, which was higher than the national rate of 3.6 cases/100,000 (P < .01). The incidence of invasive GAS disease in Utah rose from 3.5 cases/100,000 persons in 2002 to 9.8 cases/100,000 persons in 2010 (P = .01). Among children aged <18 years, the incidence of invasive GAS increased from 3.0 cases/100,000 children in 2002 to 14.1 cases/100,000 children in 2010 (P < .01). The increase in the pediatric population was due, in part, to an increase in GAS pneumonia (P = .047). The rate of invasive GAS disease in adults aged 18-64 years increased from 3.4 cases/100 000 persons in 2002 to 7.6 cases/100,000 persons in 2010 (P = .02). Rates among those aged ≥65 years were stable. The incidence of acute rheumatic fever declined from 6.1 to 3.7 cases/100,000 (P = .04).

CONCLUSIONS

The epidemiologic characteristics of invasive GAS disease in Utah has changed substantially over the past decade, including a significant increase in the overall incidence of invasive disease-driven primarily by increasing disease in younger persons-that coincided temporally with a decrease in the incidence of acute rheumatic fever.

Vitamin D and respiratory infection in adults

Vitamin D insufficiency is a global issue that has significant implications for health. The classical role of vitamin D in bone mineralisation is well known; vitamin D deficiency leads to rickets, osteomalacia or osteoporosis. The role of vitamin D in an immune system is less known. Vitamin D is not an actual vitamin but a secosteroid hormone produced in the skin from 7-dehydrocholesterol after exposure to sunlight UVB radiation. Nutrition and supplements are main sources of vitamin D in wintertime in northern countries as sunlight exposure is inadequate for the production. For activation vitamin D needs to be hydroxylated in liver to form 25-hydroxyvitamin D and in kidney to 1,25-dihydroxyvitamin D, the most active hormone in Ca absorption in the gut. For determination of vitamin D status serum 25-hydroxyvitamin D level, the major circulating form of the hormone is to be measured. Vitamin D regulates gene expression through binding with vitamin D receptors, which dimerises with retinoid X receptor. This complex binds to vitamin D-responsive elements inside the promoter regions of vitamin D-responsive genes. Vitamin D has a key role in innate immunity activation; the production of antimicrobial peptides (cathelicidin and defensins) following Toll-like receptor stimulation by pathogen lipopeptides is dependent on sufficient level of 25-hydroxyvitamin D. Clinically, there is evidence of the association of vitamin D insufficiency and respiratory tract infections. There is also some evidence of the prevention of infections by vitamin D supplementation. Randomised controlled trials are warranted to explore this preventive effect.

Invasive group A streptococcal infection and vaccine implications, Auckland, New Zealand

We aimed to assess the effect of invasive group A streptococcal (GAS) infection and the potential effects of a multivalent GAS vaccine in New Zealand. During January 2005–December 2006, we conducted prospective population-based laboratory surveillance of Auckland residents admitted to all public hospitals with isolation of GAS from normally sterile sites. Using emm typing, we identified 225 persons with confirmed invasive GAS infection (median 53 years of age; range 0–97 years). Overall incidence was 8.1 cases per 100,00 persons per year (20.4/100,000/year for Maori and Pacific Islanders; 24.4/100,000/year for persons >65 years of age; 33/100,000/year for infants <1 year of age). Nearly half (49%) of all cases occurred in Auckland’s lowest socioeconomic quintile. Twenty-two persons died, for an overall case-fatality rate of 10% (63% for toxic shock syndrome). Seventy-four percent of patients who died had an underlying condition. To the population in our study, the proposed 26-valent vaccine would provide limited benefit.

Epidemiology of invasive Streptococcus pyogenes disease in Germany during 2003-2007

A nationwide laboratory-based surveillance study of invasive Streptococcus pyogenes infections was conducted in Germany. Invasive isolates (n=586) were obtained between 2003 and 2007. Most isolates were obtained from blood (53.9%) or skin lesions (17.6%). The most common emm types were emm 1 (30.5%), emm 28 (18.3%) and emm 3 (9.6%). Overall, speA was positive in 45.9%, speC in 44.7% and ssa in 14.8% of isolates. SpeA was common in emm type 1 (100%) and emm type 3 (96.4%), whereas speC was often observed in emm type 28 (93.5%). The most frequent clinical manifestations included sepsis (40.1%), necrotizing fasciitis (20.8%) and streptococcal toxic shock syndrome (16.6%). All isolates were susceptible to penicillin G, cefotaxime and levofloxacin. Tetracycline shows the highest rate of resistant or intermediate isolates with 11.6%, followed by clarithromycin (5.5%) and clindamycin (1.2%). The most prominent trend is the reduction of tetracycline-nonsusceptible isolates from 18.6% in 2003 to 8.9% in 2007.

Group A streptococcal puerperal sepsis: initial characterization of virulence factors in association with clinical parameters

Group A beta-hemolytic streptococcus (GAS) is an uncommon but potentially fatal source of postpartum infection. Pathogenesis in invasive GAS infections has been linked to bacterial virulence factors. In this study, we sought to provide an initial description of potential virulence factors in association with puerperal morbidity by virtue of specific M-protein type antigens. Women with confirmed GAS puerperal infection in the Salt Lake City region were prospectively identified over a 6-year interval (1991-1997). From this cohort, GAS isolates were analyzed with respect to M-serotype and presence of genes encoding the Streptococcal Pyogenic Exotoxins A and B (SPE-A and SPE-B). Bacterial isolates from 18 subjects with GAS puerperal infection underwent M-serotyping and PCR-based genotyping for the speA and speB genes. Among these, 8/18 subjects manifest criteria of severe disease. All 18 isolate strains expressed speB; 6/18 isolates expressed speA. Of the M-serotypes, 8/8 severe disease isolates expressed M-types 1 (N=3) or 28 (N=5). Pulse-field gel electrophoresis did not indicate an outbreak strain among similar isolates. We conclude that in this initial characterization, morbidity among women with GAS puerperal infection is associated with M-types 1 and 28, but not speB genotype.

Streptococcal Infections

The streptococci are a large heterogeneous group of gram-positive spherically shaped bacteria widely distributed in nature. They include some of the most important agents of human disease as well as members of the normal human flora. Some streptococci have been associated mainly with disease in animals, while others have been domesticated and used for the culture of buttermilk, yogurt, and certain cheeses. Those known to cause human disease comprise two broad categories: First are the pyogenic streptococci, including the familiar β-hemolytic streptococci and the pneumococcus. These organisms are not generally part of the normal flora but cause acute, often severe, infections in normal hosts. Second are the more diverse enteric and oral streptococci, which are nearly always part of the normal flora and which are more frequently associated with opportunistic infections.

Epidemiology of severe Streptococcus pyogenes disease in Europe

The past 2 decades have brought worrying increases in severe Streptococcus pyogenes diseases globally. To investigate and compare the epidemiological patterns of these diseases within Europe, data were collected through a European Union FP-5-funded program (Strep-EURO). Prospective population-based surveillance of severe S. pyogenes infection diagnosed during 2003 and 2004 was undertaken in 11 countries across Europe (Cyprus, the Czech Republic, Denmark, Finland, France, Germany, Greece, Italy, Romania, Sweden, and the United Kingdom) using a standardized case definition. A total of 5,522 cases were identified across the 11 countries during this period. Rates of reported infection varied, reaching 3/100,000 population in the northern European countries. Seasonal patterns of infection showed remarkable congruence between countries. The risk of infection was highest among the elderly, and rates were higher in males than in females in most countries. Skin lesions/wounds were the most common predisposing factor, reported in 25% of cases; 21% had no predisposing factors reported. Skin and soft tissue were the most common foci of infection, with 32% of patients having cellulitis and 8% necrotizing fasciitis. The overall 7-day case fatality rate was 19%; it was 44% among patients who developed streptococcal toxic shock syndrome. The findings from Strep-EURO confirm a high incidence of severe S. pyogenes disease in Europe. Furthermore, these results have identified targets for public health intervention, as well as raising awareness of severe S. pyogenes disease across Europe.

Epidemiology of invasive Streptococcus pyogenes infections in Germany, 1996–2002: results from a voluntary laboratory surveillance system

A nationwide voluntary laboratory-based surveillance study of invasive Streptococcus pyogenes (group A streptococcus; GAS) infections was conducted in Germany between 1996 and 2002. Demographical and clinical information concerning the patients was obtained from the medical files. Multiple logistic regression analysis was used to determine risk-factors for fatal outcome. Invasive isolates were obtained from 475 patients, with 251 (52.8%) of the isolates cultured from blood. The most frequent emm types were emm1 (36.4%), emm28 (8.8%) and emm3 (8%). The speA, speC and ssa genes were present at variable frequencies in different emm types. The highest frequencies of speA and speC were found in emm1 (speA, 93.6%) and emm4 (speC, 94.7%), respectively. The estimated annual incidence of invasive GAS disease for 1997-2002 was 0.1 cases/100 000 individuals. This apparently low incidence rate might be explained by the voluntary nature of the surveillance system, resulting in relatively few cases being referred to the laboratory. Complete clinical information was available for 165 cases. The overall case fatality rate was 40.6%, and was highest (65.2%) in the group aged 60-69 years. Shock, an age of >or=30 years and adult respiratory distress syndrome were predictors of a fatal outcome in a multiple logistic regression analysis. Overall, 6.7% of the cases were considered to be nosocomial, and nine cases of puerperal sepsis were observed. The study underscores the importance of invasive S. pyogenes disease in Germany.

Genetic variation in group A streptococci

Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clinical manifestations and severity. While numerous virulence factors have been described, the way these factors interact to promote different streptococcal diseases is less clear. In order to identify multifactorial relationships between GAS and the human host, novel high-throughput techniques such as microarrays are necessary. We have performed comparative studies using custom-designed virulence arrays to enhance our understanding of the high degree of genotypic variation that occurs in streptococci. This study has pointed to mobile genetic elements as the major agents that promote variation. Our results show that multiple combinations of genes might bring about similar clinical pictures. This adds further complexity to the intricate relationship between pathogen and host.

Clinical and epidemiological aspects of invasive Streptococcus pyogenes infections in Denmark during 2003 and 2004

Active surveillance of invasive group A streptococcal (GAS) infections was conducted in Denmark during 2003 and 2004 as a part of the Strep-EURO initiative. The main objective was to improve understanding of the epidemiology of invasive GAS disease in Denmark. During the 2 years, 278 cases were reported, corresponding to a mean annual incidence of 2.6 cases per 100,000 inhabitants. The vast majority of isolates, 253 (91%), were from blood, with the remaining 25 (9%) being from cerebrospinal fluid, joints, or other normally sterile sites. The mean case fatality rate (CFR) was 20%, with the rate being higher in patients more than 70 years of age (36.5%). For streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis the CFRs were 53% and 25%, respectively. Out of 16 T types recorded, three predominated: T28 (23%), T1 (22%), and the cluster T3/13/B3264 (14%). Among 29 different emm types, emm28 and emm1 accounted for 51% of strains, followed by emm3 (11%), emm89 (7%), and emm12 (5.5%). Low resistance rates were detected for macrolide-lincosamide-streptogramin B (MLS(B)) antibiotics (3%) and tetracycline (8%); two isolates exhibited coresistance to tetracycline and macrolides. Of nine pyrogenic exotoxin (superantigen) genes examined, speA and speC were identified in 58% and 40% of the strains, respectively; either of the genes was present in all strains causing STSS. Most strains harbored speG (99%). ssa was present in 14% of the isolates only. In Denmark, as in comparable countries, GAS invasive disease shows a sustained, high endemicity, with involvement of both established and emerging streptococcal emm and T types.

Nonoutbreak surveillance of group A streptococci causing invasive disease in Portugal identified internationally disseminated clones among members of a genetically heterogeneous population

The typing of 160 invasive Streptococcus pyogenes isolates confirmed the importance of pulsed-field gel electrophoresis and multilocus sequence typing for defining clones. The results identified an extremely diverse population and highlighted the importance of both internationally disseminated and local clones not previously associated with invasive disease.

Determination of the relationship between group A streptococcal genome content, M type, and toxic shock syndrome by a mixed genome microarray

Group A streptococci (GAS), or Streptococcus pyogenes, are associated with a remarkable variety of diseases, ranging from superficial infections to life-threatening diseases such as toxic-shock-like syndrome (TSS). GAS strains belonging to M types M1 and M3 are associated with TSS. This study aims to obtain insight into the gene profiles underlying different M types and disease manifestations. Genomic differences between 76 clinically well characterized GAS strains collected in The Netherlands were examined using a mixed-genome microarray. Inter-M-type genomic differences clearly outweighed intra-M-type genome variation. Phages were major contributors to observed genome diversification. We identified four novel genes, including two genes encoding fibronectin-binding-like proteins, which are highly specific to a subset of M types and thus may contribute to M-type-associated disease manifestations. All M12 strains were characterized by the unique absence of the citrate lyase complex and reduced growth under hypoxic, nutrient-deprived conditions. Furthermore, six virulence factors, including genes encoding a complement-inhibiting protein (sic), an exotoxin (speA), iron(III) binding factor, collagen binding factor (cpa), and fibrinogen binding factor (prt2-like), were unique to M1 and/or M3 strains. These virulence factors may contribute to the potential of these strains to cause TSS. Finally, in contrast to M-type-specific virulence profiles, we did not identify a common virulence profile among strains associated with TSS irrespective of their M type.

Epidemiological considerations following long-term surveillance of invasive group A streptococcal disease in The Netherlands, 1992-2003

A nationwide laboratory-based surveillance system for invasive group A streptococcal (GAS) infections was conducted in The Netherlands from March 1992 until December 2003. Until 1996, all isolates submitted were evaluated clinically and demographically. During this period there was a transition from passive to active surveillance for some of the participating laboratories, corresponding to a national coverage of 50%. During active surveillance, participating laboratories submitted twice as many isolates from invasive GAS disease, whereas the relative submission of isolates representing very severe manifestations (toxic shock-like syndrome, fatality) did not increase. From 1997 onwards, invasiveness was defined solely on the basis of source of isolation (without clinical evaluation). During the period of microbiological and clinical evaluation, microbiological evaluation alone was found to be specific (> 99%), but had limited sensitivity (66%). Estimation of the true rate of invasive GAS disease should be based on an active surveillance system with inclusion of both microbiological and clinical data.