Clinical and microbial characteristics of invasive Streptococcus pyogenes disease in New Caledonia, a region in Oceania with a high incidence of acute rheumatic fever

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.

Case Report: Septic arthritis in children caused by Streptococcus pyogenes-rational use of antibiotics

To investigate the clinical characteristics and treatment of septic arthritis caused by Streptococcus pyogenes(S. pyogenes) in children, we retrospectively analyzed the clinical data, laboratory results, treatments and outcomes of three pediatric cases of septic arthritis caused by S. pyogenes occurring from 2016-2018. The three cases of septic arthritis included 1 boy and 2 girls, aged from 2-7 years. Two patients experienced fever, and in all three cases, the affected joints showed redness, swelling, an increased local skin temperature, tenderness and restricted limb movement. At the first visit, all three cases showed a significantly increased white blood cell count [(27.68-32.02)×10⁹/mL] and a significantly increased erythrocyte sedimentation rate (113-134 mm/h). The C-reactive protein level was significantly increased in two cases (67 mg/L, 147.7 mg/L) and normal in one case. The procalcitonin level was normal in 1 case, elevated in 1 case, and undetected in 1 case. S. pyogenes isolated from cases 1 and 2 were emm1/ST28 and from case 3 was emm12/ST36. All patients were treated by abscess incision and drainage, and S. pyogenes was cultured in the abscess puncture fluid. All patients were treated with intravenous antibiotics after admission, and all patients were cured and discharged. The patients were followed up for 2 months, and their condition was improved and stable. No sequelae such as heart and kidney damage were detected. In conclusion, for children with septic arthritis, early diagnosis and timely treatment with incision and drainage followed by culture of the abscess puncture fluid are important. Once S. pyogenes infection is confirmed, β-lactam antibiotics provide effective treatment, avoiding use of broad-spectrum antibiotics.

Scabies incidence and association with skin and soft tissue infection in Loyalty Islands Province, New Caledonia: A 15-year retrospective observational study using electronic health records

Background

Scabies and its complications are a public health problem in the low- and middle-income countries of the Western Pacific region. However, no data are available for the relatively wealthy French territory of New Caledonia. This study aimed to determine the incidence of scabies and its association with skin and soft tissue infection (SSTI) in Loyalty Islands Province (LIP) (20,000 inhabitants), New Caledonia.

Methodology/Principal findings

This retrospective observational study reviewed cases of scabies and SSTI extracted from the electronic health record databases of LIP clinics for the period 2004–2018. Data were validated through double sampling. The overall scabies incidence rate (IR) and scabies IRs by sex and age group were calculated. Scabies seasonality was evaluated. For children <5 years, the presence of SSTI was compared between the 3-month period preceding scabies diagnosis/treatment and the 3-month period preceding the 1-year anniversary of scabies diagnosis/treatment (self-matching).

A total of 16,843 scabies cases were extracted using a detection algorithm with a sensitivity of 96.7% and a specificity of 99.9%. From 2004 to 2018, the average overall scabies IR was 5.9% and the average scabies IR in children <1 year was 18.4%. Almost two-thirds of children aged 14 years had a history of scabies. Females were more affected, especially in the 20–39 age group (sex ratio>2). A strong seasonality was observed, with a 30% increase in winter. In children <5 years, SSTIs were 4.3 times more frequent in the 3 months preceding the scabies diagnosis than in the 3 months preceding the 1-year anniversary of scabies treatment (p<0.001).

Conclusions

Although health care is much better in New Caledonia than in neighboring countries, scabies is highly endemic in LIP. The disease is especially common in children <2 years and is associated with many SSTIs in children <5 years. Mass drug administration should be considered.

Scabies is a known public health problem in the Pacific region. This study aimed to determine the importance of scabies and associated skin infections in the Loyalty Island Province (LIP) of New Caledonia (20,000 inhabitants).

The provincial electronic medical database was searched for all cases of scabies and skin infection that occurred in the LIP population between 2004 and 2018. To evaluate the impact of scabies on skin infections, we measured the decrease in the number of skin infections in children <5 years one year after scabies treatment.

Over the study period, the average number of scabies cases occurring each year was 6 per 100 inhabitants. In children <1 year, this number was 18 per 100 inhabitants. We found that 80% of children aged 15 years had experienced at least one episode of scabies. We also observed a fourfold decrease in the number of skin infections in children <5 years 1 year after treatment. Scabies was more frequent (+30%) in winter.

Prospective surveillance for invasive Staphylococcus aureus and group A Streptococcus infections in a setting with high community burden of scabies and impetigo

BACKGROUND

Invasive Staphylococcus aureus (iSA) and group A Streptococcus (iGAS) impose significant health burdens globally. Both bacteria commonly cause skin and soft tissue infections (SSTIs), which can result in invasive disease. Understanding of the incidence of iSA and iGAS remains limited in settings with a high SSTI burden.

METHODS

Prospective surveillance for admissions with iSA or iGAS was conducted at the referral hospital in Fiji's Northern Division over 48 weeks between July 2018 and June 2019.

RESULTS

There were 55 admissions for iSA and 15 admissions for iGAS (incidence 45.2 and 12.3 per 100,000 person-years, respectively). The highest incidence was found in patients aged ≥65 years (59.6 per 100,000 person-years for iSA and iGAS). The incidence of iSA was higher in indigenous Fijians (iTaukei) (71.1 per 100,000 person-years) compared with other ethnicities (incidence rate ratio 9.7, 95% confidence interval 3.5-36.9). SSTIs were found in the majority of cases of iSA (75%) and iGAS (53.3%). Thirteen of the 14 iGAS strains isolated belonged to emm cluster D (n = 5) or E (n = 8). The case fatality rate was high for both iSA (10.9%) and iGAS (33.3%).

CONCLUSIONS

The incidence of iSA and iGAS in Fiji is very high. SSTIs are common clinical foci for both iSA and iGAS. Both iSA and iGAS carry a substantial risk of death. Improved control strategies are needed to reduce the burden of iSA and iGAS in Fiji.

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.

Acute rheumatic fever diagnosis and management: Review of the global implications of the new revised diagnostic criteria with a focus on Saudi Arabia

Rheumatic fever (RF) is a common cause of acquired heart disease in children worldwide. It is a delayed, nonsuppurative, autoimmune phenomenon following pharyngitis, impetigo, or scarlet fever caused by group A β-hemolytic streptococcal (GAS) infection. RF diagnosis is clinical and based on revised Jones criteria. The first version of the criteria was developed by T. Duckett Jones in 1944, then subsequently revised by the American Heart Association (AHA) in 1992 and 2015. However, RF remains a diagnostic challenge for clinicians because of the lack of specific clinical or laboratory findings. As a result, it has been difficult for some time to maintain a balance between over- and underdiagnosis of RF cases. The Jones criteria were revised in 2015 by the AHA, and the main modifications were as follows: the population was subdivided into moderate- to high-risk and low risk; the concept of subclinical carditis was introduced; and monoarthritis was included as a feature of musculoskeletal inflammation in the moderate- to high-risk population. This review will highlight the major changes in the AHA 2015 revised Jones criteria for pediatricians and general practitioners.

Antibiotic Resistance in Pacific Island Countries and Territories: A Systematic Scoping Review

Several studies have investigated antimicrobial resistance in low- and middle-income countries, but to date little attention has been paid to the Pacific Islands Countries and Territories (PICTs). This study aims to review the literature on antibiotic resistance (ABR) in healthcare settings in PICTs to inform further research and future policy development for the region. Following the PRISMA-ScR checklist health databases and grey literature sources were searched. Three reviewers independently screened the literature for inclusion, data was extracted using a charting tool and the results were described and synthesised. Sixty-five studies about ABR in PICTs were identified and these are primarily about New Caledonia, Fiji and Papua New Guinea. Ten PICTs contributed the remaining 21 studies and nine PICTs were not represented. The predominant gram-positive pathogen reported was community-acquired methicillin resistant S. aureus and the rates of resistance ranged widely (>50% to <20%). Resistance reported in gram-negative pathogens was mainly associated with healthcare-associated infections (HCAIs). Extended spectrum beta-lactamase (ESBL) producing K. pneumoniae isolates were reported in New Caledonia (3.4%) and Fiji (22%) and carbapenem resistant A. baumannii (CR-ab) isolates in the French Territories (24.8%). ABR is a problem in the PICTs, but the epidemiology requires further characterisation. Action on strengthening surveillance in PICTs needs to be prioritised so strategies to contain ABR can be fully realised.

Canada-Wide Epidemic of emm74 Group A Streptococcus Invasive Disease

Background

The number of invasive group A Streptococcus (iGAS) infections due to hitherto extremely rare type emm74 strains has increased in several Canadian provinces since late 2015. We hypothesized that the cases recorded in the different provinces are linked and caused by strains of an emm74 clone that recently emerged and expanded explosively.

Methods

We analyzed both active and passive surveillance data for iGAS infections and used whole-genome sequencing to investigate the phylogenetic relationships of the emm74 strains responsible for these invasive infections country-wide.

Results

Genome analysis showed that highly clonal emm74 strains, genetically different from emm74 organisms previously circulating in Canada, were responsible for a country-wide epidemic of >160 invasive disease cases. The emerging clone belonged to multilocus sequence typing ST120. The analysis also revealed dissemination patterns of emm74 subclonal lineages across Canadian provinces. Clinical data analysis indicated that the emm74 epidemic disproportionally affected middle-aged or older male individuals. Homelessness, alcohol abuse, and intravenous drug usage were significantly associated with invasive emm74 infections.

Conclusions

In a period of 20 months, an emm74 GAS clone emerged and rapidly spread across several Canadian provinces located more than 4500 km apart, causing invasive infections primarily among disadvantaged persons.

Obesity and risk of infection: results from the Danish Blood Donor Study

BACKGROUND

It is well known that obesity complicates the course of several diseases. However, it is unknown whether obesity affects the risk of infection among healthy individuals.

METHODS

We included 37,808 healthy participants from the Danish Blood Donor Study, who completed a questionnaire on health-related items. Obesity was defined as a body mass index ≥ 30 kg/m(2). Infections among participants were identified by relevant ICD-10 codes in the Danish National Patient Register and Anatomical Therapeutic Chemical (ATC) codes in the Danish Prescription Register. Multivariable Cox proportional hazards analysis with age as the underlying timescale was used as the statistical model.

RESULTS

During 113,717 person-years of observation, 1,233 participants were treated for infection at a hospital. Similarly, during 58,411 person-years of observation, 15,856 participants filled at least one prescription of antimicrobials. Obesity was associated with risk of hospital-based treatment for infection (women: hazard ratio [HR] = 1.5, 95% confidence interval [CI] = 1.1, 1.9; men: HR = 1.5, 95% CI = 1.2, 1.9). For specific infections, obesity was associated with increased risk of abscesses (both sexes), infections of the skin and subcutaneous tissue (men), and respiratory tract infections and cystitis (women). Similarly, obesity was associated with filled prescriptions of antimicrobials overall (women: HR = 1.22, 95% CI = 1.14, 1.30; men: HR = 1.23, 95% CI: 1.15, 1.33) and particularly with phenoxymethylpenicillin, macrolides, dicloxacillin and flucloxacillin, and broad-spectrum penicillins.

CONCLUSIONS

In a large cohort of healthy individuals, obesity was associated with risk of infection. This result warrants further studies of metabolism and the immune response.

Geoepidemiological hints about Streptococcus pyogenes strains in relationship with acute rheumatic fever

Group A Streptococcus (GAS) strains are lately classified on the basis of sequence variations in the emm gene encoding the M protein, but despite the high number of distinct emm genotypes, the spectrum of phenotypes varying from invasive suppurative to non-suppurative GAS-related disorders has still to be defined. The relationship of GAS types with the uprising of acute rheumatic fever (ARF), a multisystemic disease caused by misdirected anti-GAS response in predisposed people, is also obscure. Studies published over the last 15 years were retrieved from PubMed using the keywords: "Streptococcus pyogenes" or "group A Streptococcus" and "acute rheumatic fever": the prevalence of peculiar emm types across different countries of the world is highly variable, depending on research designs, year of observation, country involved, patients' age, and gender. Most studies revealed that a relatively small number of specific emm/M protein types can be considered "rheumatogenic", as potentially characterized by the possibility of inducing ARF, with remarkable differences between developing and developed countries. The association between emm types and post-streptococcal manifestations is challenging, however surveillance of disease-causing variants in a specific community with high rate of ARF should be reinforced with the final goal of developing a potential primary prophylaxis against GAS infections.

The emm-cluster typing system for Group A Streptococcus identifies epidemiologic similarities across the Pacific region

BACKGROUND

Group A Streptococcus (GAS)-related disease is responsible for high mortality and morbidity in the Pacific region. The high diversity of circulating strains in this region has hindered vaccine development due to apparently low vaccine coverage of type-specific vaccines.

METHOD

Prospective passive surveillance of all GAS isolates in New Caledonia was undertaken in 2012 using emm typing and emm-cluster typing. Molecular data were compared with the results from a prior study undertaken in the same country and with data from 2 other Pacific countries, Fiji and Australia.

RESULTS

A high incidence of invasive infection was demonstrated at 43 cases per 100 000 inhabitants (95% confidence interval, 35-52 cases per 100 000 inhabitants). Three hundred eighteen GAS isolates belonging to 47 different emm types were collected. In Noumea, only 30% of the isolates recovered in 2012 belonged to an emm type that was present in the same city in 2006, whereas 69% of the isolates collected in 2012 belonged to an emm cluster present in 2006. When comparing New Caledonian, Australian, and Fijian data, very few common emm types were found, but 79%-86% of the isolates from each country belonged to an emm cluster present in all 3 countries. A vaccine that could protect against the 10 most frequent emm clusters in the Pacific region would potentially provide coverage ranging from 83% to 92%.

CONCLUSIONS

This study confirms the high disease burden of GAS infection in New Caledonia and supports the added value of the emm-cluster typing system to analyze GAS epidemiology and to help inform global GAS vaccine formulation.

Pediatric invasive streptococcal infection in northern and eastern regions of Hokkaido, Japan from 2010 to 2012

BACKGROUND

The frequency of occurrence of pediatric invasive streptococcal infection in Japan has not been studied, therefore the aim of this study was to survey the northern and eastern regions of Hokkaido from 2010 to 2012.

METHOD

Survey sheets were sent to the pediatric departments at 17 facilities where children in the subject region can be hospitalized. Responses were obtained from all of the 17 facilities.

RESULTS

Seven patients developed group A streptococcal infection over the 3 years, and their ages ranged from 1 day after the birth to 15 years old. Sepsis was diagnosed in five children, and empyema and arthritis in the knee were found in one child each, respectively. The number of cases in children under 15 years old was six excluding the child who was 15 years old, and the incidence rate per 100,000 population was 1.00. Eight children developed group B streptococcal infection, and their ages ranged from 0 days to 2 months after birth. Two cases were the early onset type (age within 7 days) and six cases were the late onset type. Five children developed sepsis and three children developed meningitis. The frequency of occurrence was 0.24 per 1000 births; which was 0.06 per 1000 births for the early onset type and was 0.18 per 1000 births for the late onset type. No reports for group C or group G hemolytic streptococcal infection were obtained.

CONCLUSIONS

The incidence rates identified in the present survey are similar to those in other advanced countries, and appear to be valid.

Epidemiology and molecular characterization of macrolide-resistant Streptococcus pyogenes in Taiwan

Our multicenter nationwide surveillance data indicated that erythromycin (ERY) resistance among group A Streptococcus (GAS) isolates in Taiwan declined from 53.1% in 1998 and 2000 to 14.6% in 2002 and 2004 and 10.7% in 2006 to 2010 (P < 0.01). The present study aimed to assess the epidemiology of GAS in Taiwan and identify factors associated with ERY resistance. All 127 ERY-resistant (ERY(r)) isolates and 128 randomly selected ERY-susceptible (ERY(s)) isolates recovered from 1998 to 2010 were emm typed. ERY(r) isolates were also characterized by ERY resistance phenotype and mechanisms and pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing was performed on selected ERY(r) isolates. The predominant emm types in ERY(r) isolates were emm22 (n = 33, 26.0%), emm12 (n = 24, 18.9%), emm4 (n = 21, 16.5%), and emm106 (n = 15, 11.8%). In ERY(s) isolates, emm12 (n = 27, 21.9%), emm1 (n = 18, 14.1%), emm106 (n = 16, 12.5%), and emm11 (n = 9, 7.1%) predominated. The most common ERY resistance phenotype was the M phenotype (resistant to macrolides) (70.9%), with all but one isolate carrying mef(A), followed by the constitutive macrolide-lincosamide-streptogramin B resistance (cMLSB) phenotype (26.8%), with isolates carrying erm(B) or erm(TR). ERY(r) isolates of the emm12-sequence type 36 (ST36) lineage with the cMLSB phenotype were mostly present before 2004, while those of the emm22-ST46 lineage with the M phenotype predominated in later years. Recovery from respiratory (throat swab) specimens was an independent factor associated with ERY resistance. emm1 and emm11 GAS isolates were significantly associated with ERY(s), while emm22 was detected only in ERY(r) GAS. In addition, emm106 isolates were prevalent among the abscess/pus isolates, whereas emm12 isolates were strongly associated with a respiratory (throat) origin. In addition to identifying factors associated with ERY resistance in GAS, our study provides helpful information on the changing GAS epidemiology in Taiwan.

High prevalence of rheumatic heart disease in schoolchildren detected by echocardiography screening in New Caledonia

AIM

Despite the well-documented burden of rheumatic heart disease (RHD) in several Pacific countries, the disease is poorly understood in New Caledonia. The aim of this study was to assess the prevalence of RHD detected by echocardiographic screening in school children.

METHODS

An annual RHD screening programme is conducted by the Health and Social Agency of New Caledonia for school-aged children in their fourth year of primary school. For the purpose of this study, we used data collected during this echocardiographic screening between 2008 and 2010.

RESULTS

Of 12,728 children screened, 50.2% were male and the mean age was 9.6 ± 0.6 years. Between 2008 and 2010, 114 children had RHD, corresponding to a prevalence of 8.9 cases per 1000 (95% confidence interval (CI) (7.3-10.6)). Prevalence of RHD was higher on the main island outside Greater Noumea (13.7 per 1000; 95% CI (9.8-17.5)) and in the outlying island groups (14.6 per 1000; 95% CI (8.4-20.9)) than in Greater Noumea (5.8 per 1000; 95% CI (4.1-7.5)). RHD was more prevalent in Melanesian children (13.5 per 1000; 95% CI (10.9-16.1)) than in European (1.8 per 1000; 95% CI (0.4-3.1)).

CONCLUSION

This study documented a high prevalence of RHD in New Caledonia, particularly in districts located outside Noumea and in children of Melanesian heritage. These results uncover a hitherto unknown burden of disease in New Caledonia and underline the importance of delivering secondary prophylaxis to reduce the prevalence of RHD.

Current insights in invasive group A streptococcal infections in pediatrics

A rising incidence of invasive group A Streptococcus infections (IGASI) has been noted in children in the past three decades. The relative frequency of the infection types showed marked differences to IGASI in adults, and severity of the disease resulted in a mortality rate usually comprising between 3.6% and 8.3%. The emm1-type group A Streptococcus (GAS) subclone displaying a particular pattern of virulence factors was widely disseminated and prevalent in children with IGASI while the emm3-type GAS subclone appeared as a recent emerging genotype. However, the implication of these hypervirulent clones in the increase of IGASI in children is still controversial. Recent advances in our knowledge on pathogenesis of IGASI underlined that deregulation of virulence factor production, individual susceptibility, as well as exuberant cytokine response are important factors that may account for the severity of the disease in children. Future changes in IGASI epidemiology are awaited from current prospects for a safe and effective vaccine against GAS. IGASI are complex infections associating septic, toxic, and immunological disorders. Treatment has to be effective on both the etiologic agent and its toxins, due to the severity of the disease associated to the spread of highly virulent bacterial clones. More generally, emergence of virulent clones responsible for septic and toxic disease is a matter of concern in pediatric infectiology in the absence of vaccination strategy.

Characterization of streptokinases from group A Streptococci reveals a strong functional relationship that supports the coinheritance of plasminogen-binding M protein and cluster 2b streptokinase

Group Astreptococcus (GAS) strains secrete the protein streptokinase (SK), which functions by activating host human plasminogen (hPg) to plasmin (hPm), thus providing a proteolytic framework for invasive GAS strains. The types of SK secreted by GAS have been grouped into two clusters (SK1 and SK2) and one subcluster (SK2a and SK2b). SKs from cluster 1 (SK1) and cluster 2b (SK2b) display significant evolutionary and functional differences, and attempts to relate these properties to GAS skin or pharynx tropism and invasiveness are of great interest. In this study, using four purified SKs from each cluster, new relationships between plasminogen-binding group A streptococcal M (PAM) protein and SK2b have been revealed. All SK1 proteins efficiently activated hPg, whereas all subclass SK2b proteins only weakly activated hPg in the absence of PAM. Surface plasmon resonance studies revealed that the lower affinity of SK2b to hPg served as the basis for the attenuated activation of hPg by SK2b. Binding of hPg to either human fibrinogen (hFg) or PAM greatly enhanced activation of hPg by SK2b but minimally influenced the already effective activation of hPg by SK1. Activation of hPg in the presence of GAS cells containing PAM demonstrated that PAM is the only factor on the surface of SK2b-expressing cells that enabled the direct activation of hPg by SK2b. As the binding of hPg to PAM is necessary for hPg activation by SK2b, this dependence explains the coinherant relationship between PAM and SK2b and the ability of these particular strains to generate the proteolytic activity that disrupts the innate barriers that limit invasiveness.

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.

Clinical and microbiologic characteristics of invasive Streptococcus pyogenes infections in north and south India

The lack of epidemiologic data on invasive Streptococcus pyogenes infections in many developing countries is concerning, as S. pyogenes infections are commonly endemic in these areas. Here we present the results of the first prospective surveillance study of invasive Streptococcus pyogenes infections in India. Fifty-four patients with invasive S. pyogenes infections were prospectively enrolled at two study sites, one in the north and one in the south of India. Sterile-site isolates were collected, and clinical information was documented using a standardized questionnaire. Available acute-phase sera were tested for their ability to inhibit superantigens produced by the patient's own isolate using a cell-based neutralizing assay. The most common clinical presentations were bacteremia without focus (30%), pneumonia (28%), and cellulitis (17%). Only two cases of streptococcal toxic shock syndrome and no cases of necrotizing fasciitis were identified. Characterization of the isolates revealed great heterogeneity, with 32 different emm subtypes and 29 different superantigen gene profiles being represented among the 49 sterile-site isolates. Analyses of acute-phase sera showed that only 20% of the cases in the north cohort had superantigen-neutralizing activity in their sera, whereas 50% of the cases from the south site had neutralizing activity. The results demonstrate that there are important differences in both clinical presentation and strain characteristics between invasive S. pyogenes infections in India and invasive S. pyogenes infections in Western countries. The findings underscore the importance of epidemiologic studies on streptococcal infections in India and have direct implications for current vaccine developments.

Obesity and the skin

Obesity is a serious global health problem, perhaps the biggest public health issue of our times. Excess body weight may be a factor in carcinogenesis in general, as well as contributing to the pathogenesis of metabolic, cardiovascular and musculoskeletal disorders. Obesity also has many cutaneous features, which form the basis for this review article. Many of these clinical entities are common to the majority of obese patients, e.g. striae distensae, plantar hyperkeratosis and an increased risk of skin infections. However, it may also be associated with poor wound healing, malignant melanoma and an increased risk of inflammatory dermatoses, such as psoriasis, as well as some rarer disorders. Therapeutic interventions for obesity, whether over-the-counter, prescription medicines or surgical interventions, are increasingly commonplace. All of these treatment modalities potentially have dermatological side-effects too.

Molecular markers for the study of streptococcal epidemiology

Diseases caused by Streptococcus pyogenes (Group A streptococcus, GAS) range from superficial infections such as pharyngitis and impetigo to potentially fatal rheumatic heart disease and invasive disease. Studies spanning emm-typing surveillance to population genomics are providing new insights into the epidemiology, pathogenesis, and biology of this organism. Such studies have demonstrated the differences that exist in the epidemiology of streptococcal disease between developing and developed nations. In developing nations, where streptococcal disease is endemic, the diversity of GAS emm-types circulating is much greater than that found in developed nations. An association between emm-type and disease, as observed in developed countries is also lacking. Intriguingly, comparative genetic studies suggest that emm-type is not always a good predictor of the evolutionary relatedness of geographically distant isolates. A view of GAS as a highly dynamic organism, in possession of a core set of virulence genes that contribute to host niche specialization and common pathogenic processes, augmented by accessory genes that change the relative virulence of specific lineages is emerging. Our inability to definitively identify genetic factors that contribute to specific disease outcome underscores the complex nature of streptococcal diseases.

Molecular insight into invasive group A streptococcal disease

Streptococcus pyogenes is also known as group A Streptococcus (GAS) and is an important human pathogen that causes considerable morbidity and mortality worldwide. The GAS serotype M1T1 clone is the most frequently isolated serotype from life-threatening invasive (at a sterile site) infections, such as streptococcal toxic shock-like syndrome and necrotizing fasciitis. Here, we describe the virulence factors and newly discovered molecular events that mediate the in vivo changes from non-invasive GAS serotype M1T1 to the invasive phenotype, and review the invasive-disease trigger for non-M1 GAS. Understanding the molecular basis and mechanism of initiation for streptococcal invasive disease may expedite the discovery of novel therapeutic targets for the treatment and control of severe invasive GAS diseases.

Epidemiological and molecular analysis of Streptococcus pyogenes isolates causing invasive disease in Spain (1998-2009): comparison with non-invasive isolates

The incidence, clinical manifestations, and circulating clones involved in Streptococcus pyogenes invasive disease was analyzed in two regions of Spain between 1998 and 2009. The annual average incidence of invasive disease was 2 episodes per 100,000 inhabitants (3.1 for children and 1.9 for adults). The most frequent clinical manifestations were cellulitis (41.3%), bacteremia without focus (19.0%), streptococcal toxic shock syndrome (12.6%), and pneumonia (7.7%). Among 247 invasive isolates analyzed, the most prevalent clones were emm1/ST28 (27.9%), emm3/ST15-406 (9.8%), and emm4/ST39 (6.5%). The emm1/ST28 clone was the only clone detected each year throughout the study period and was associated with more than one third of all fatal outcomes. When invasive isolates were compared with 1,189 non-invasive isolates, the emm1/ST28 clone was significantly associated with invasive disease. The speA and ssa genes were more frequent among invasive emm1 and emm4 isolates, respectively. Forty-two (17%) invasive isolates were resistant to erythromycin (21 harbored the mef gene and 21 the ermB or ermA genes). Twenty-two (8.9%) isolates had reduced susceptibility to ciprofloxacin (minimum inhibitory concentration [MIC] 2-8 μg/mL) and 32 (13%) were tetracycline-resistant (tetM or tetO gene). In conclusion, the emm1 type was overrepresented among invasive cases and was associated with high mortality rates.

The worldwide epidemiology of acute rheumatic fever and rheumatic heart disease

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are significant public health concerns around the world. Despite decreasing incidence, there is still a significant disease burden, especially in developing nations. This review provides background on the history of ARF, its pathology and treatment, and the current reported worldwide incidence of ARF and prevalence of RHD.