Scarlet fever epidemic, Hong Kong, 2011

Detection of toxigenic M1UK lineage group A Streptococcus clones in Taiwan

BACKGROUND

A new sublineage of emm1 group A Streptococcus (GAS), M1UK, has emerged in Europe, North America, and Australia. Notably, a significant portion of emm1 isolates in Asia, particularly in Hong Kong and mainland China, acquired scarlet fever-associated prophages following the 2011 Hong Kong scarlet fever outbreak. However, the presence of the M1UK sublineage has not yet been detected in Asia.

METHODS

This study included 181 GAS isolates (2011-2021). The emm type of these isolates were determined, and 21 emm1 isolates from blood or pleural fluid (2011-2021) and 10 emm1 isolates from throat swabs (2016-2018) underwent analysis. The presence of the scarlet fever-associated prophages and the specific single nucleotide polymorphisms of the M1UK clone were determined by polymerase chain reaction and the genome sequencing.

RESULTS

The M1UK lineage strains from throat swab and blood samples were identified. One of the M1UK strain in Taiwan carried the scarlet fever-associated prophage and therefore acquired the ssa, speC, and spd1 toxin repertoire. Nonetheless, the increase of M1UK was not observed until 2021, and there was a reduction in the diversity of emm types in 2020-2021, possibly due to the COVID-19 pandemic restriction policies in Taiwan.

CONCLUSIONS

Our results suggested that the M1UK lineage clone has introduced in Taiwan. In Taiwan, the COVID-19 restrictions were officially released in March 2023; therefore, it would be crucial to continuously monitor the M1UK expansion and its related diseases in the post COVID-19 era.

Epidemiological characteristics and spatiotemporal clustering of scarlet fever in Liaoning Province, China, 2010-2019

BACKGROUND

To explore the epidemiological characteristics and spatiotemporal distribution of scarlet fever in Liaoning Province, which could provide scientific evidence for the formulation and improvement of prevention and control strategies and measures.

METHODS

Data on scarlet fever cases and population were obtained from the China Information System for Disease Control and Prevention in Liaoning Province between 2010 and 2019. We examined the spatial and spatiotemporal clusters of scarlet fever across Liaoning Province using the Moran's I, local indicators of spatial association, local Gi* hotspot statistics, and Kulldorff's retrospective space-time scan statistical analysis.

RESULTS

Between 1st January 2010 and 31st December 2019, 46,652 cases of scarlet fever were reported in Liaoning Province, with an annual average incidence of 10.67 per 100,000. The incidence of scarlet fever had obvious seasonality with high incidence in early summer June and early winter December. The male-to-female ratio was 1.53:1. The highest incidence of cases occurred in 3-9 year old children. The most likely spatiotemporal cluster and the secondary clusters were detected in urban regions of Shenyang and Dalian, Liaoning Province.

CONCLUSIONS

The incidence of scarlet fever has obvious spatiotemporal clustering, with the high-risk areas mainly concentrated in urban area of Shenyang and Dalian, Liaoning Province. Control strategies need to focus on high-risk season, high-risk areas and high-risk populations in order to reduce the incidence of scarlet fever.

Recrudescence of Scarlet Fever and Its Implications for Dental Professionals

A significant increase in the incidence of scarlet fever, mainly in Europe, has been noted during the COVID-19 postpandemic period. Scarlet fever is caused by a pyrogenic exotoxin-producing streptococcus-Streptococcus pyogenes-responsible for more than 500,000 deaths annually worldwide. Superantigens (SAgs) secreted by this Group A streptococcus (GAS) usually overstimulate the human immune system, causing an amplified hypersensitivity reaction leading to initial symptoms such as sore throat, high fever, and a sandpaper-like skin rash. There could be concurrent oral manifestations known as "strawberry tongue" or "raspberry tongue," which may be first noted by oral health professionals. The early diagnosis and treatment of this disease is critical to obviate the development of local and systemic sequelae such as acute rheumatic fever, endocarditis, and glomerulonephritis. Antibiotics should be prescribed early to mitigate its duration, sequelae, and community spread. Dental practitioners should be aware of the early symptoms of scarlet fever for infection detection, emergency patient management, and appropriate referral. This concise review outlines the prevalence, pathogenicity, oral and systemic manifestations, as well as the dental implications of scarlet fever.

Trends (2007-2019) of major atopic diseases throughout the life span in a large Mexican population

Background

Major atopic diseases such as atopic dermatitis (AD), allergic rhinitis (AR), and asthma share the same atopic background, but they often show differences in their epidemiological behavior.

Objective

We aimed to report the profile of these atopic diseases in a large Mexican population, including their age-related incidences, male:female (M:F) ratios, recent time trends, and association with altitude.

Methods

Registries from the largest, nationwide health institution in Mexico (more than 34 million insured subjects), were reviewed. New cases of AD, AR, and asthma diagnosed each year by family physicians from 2007 to 2019 were adjusted by the corresponding insured population to estimate incidence rates.

Results

Incidences of the 3 atopic diseases were highest in the 0-4 years age-group and progressively decreased thereafter until adolescence. Asthma and AR, but not AD, were more frequent in males during childhood (M:F ratios of 1.5, 1.3, and 0.95, respectively), but predominated in females during adulthood (M:F ratios of 0.52, 0.68, and 0.73, respectively). Time trends showed an initial increasing trend of annual incidences, with a peak around 2009-2011, and a downward trend afterward. This decreasing trend was seen in all age-groups and was more evident for AD (∼50% drop) and asthma (∼40% drop) than for AR (∼20% drop). Geographical distribution suggested that incidences of asthma and AR, but not of AD, had an inverse association with altitude.

Conclusion

Annual incidences of the 3 major atopic diseases have declined in recent years in almost all age groups, and their epidemiological profile during the life span showed contrasting differences according to age, sex, and ecological association with altitude, mainly regarding AD.

Incidence and Effects of Acquisition of the Phage-Encoded ssa Superantigen Gene in Invasive Group A Streptococcus

The acquisition of the phage-encoded superantigen ssa by scarlet fever-associated group A Streptococcus (Streptococcus pyogenes, GAS) is found in North Asia. Nonetheless, the impact of acquiring ssa by GAS in invasive infections is unclear. This study initially analyzed the prevalence of ssa+ GAS among isolates from sterile tissues and blood. Among 220 isolates in northern Taiwan, the prevalence of ssa+ isolates increased from 1.5% in 2008–2010 to 40% in 2017–2019. Spontaneous mutations in covR/covS, which result in the functional loss of capacity to phosphorylate CovR, are frequently recovered from GAS invasive infection cases. Consistent with this, Phostag western blot results indicated that among the invasive infection isolates studied, 10% of the ssa+ isolates lacked detectable phosphorylated CovR. Transcription of ssa is upregulated in the covS mutant. Furthermore, in emm1 and emm12 covS mutants, ssa deletion significantly reduced their capacity to grow in human whole blood. Finally, this study showed that the ssa gene could be transferred from emm12-type isolates to the emm1-type wild-type strain and covS mutants through phage infection and lysogenic conversion. As the prevalence of ssa+ isolates increased significantly, the role of streptococcal superantigen in GAS pathogenesis, particularly in invasive covR/covS mutants, should be further analyzed.

Use of meteorological parameters for forecasting scarlet fever morbidity in Tianjin, Northern China

The scarlet fever incidence has increased drastically in recent years in China. However, the long-term relationship between climate variation and scarlet fever remains contradictory, and an early detection system is lacking. In this study, we aim to explore the potential long-term effects of variations in monthly climatic parameters on scarlet fever and to develop an early scarlet-fever detection tool. Data comprising monthly scarlet fever cases and monthly average climatic variables from 2004 to 2017 were retrieved from the Notifiable Infectious Disease Surveillance System and National Meteorological Science Center, respectively. We used a negative binomial multivariable regression to assess the long-term impacts of weather parameters on scarlet fever and then built a novel forecasting technique by integrating an autoregressive distributed lag (ARDL) method with a nonlinear autoregressive neural network (NARNN) based on the significant meteorological drivers. Scarlet fever was a seasonal disease that predominantly peaked in spring and winter. The regression results indicated that a 1 °C increment in the monthly average temperature and a 1-h increment in the monthly aggregate sunshine hours were associated with 17.578% (95% CI 7.674 to 28.393%) and 0.529% (95% CI 0.035 to 1.025%) increases in scarlet fever cases, respectively; a 1-hPa increase in the average atmospheric pressure at a 1-month lag was associated with 12.996% (95% CI 9.972 to 15.919%) decrements in scarlet fever cases. Based on the model evaluation criteria, the best-performing basic and combined approaches were ARDL(1,0,0,1) and ARDL(1,0,0,1)-NARNN(5, 22), respectively, and this hybrid approach comprised smaller performance measures in both the training and testing stages than those of the basic model. Climate variability has a significant long-term influence on scarlet fever. The ARDL-NARNN technique with the incorporation of meteorological drivers can be used to forecast the future epidemic trends of scarlet fever. These findings may be of great help for the prevention and control of scarlet fever.

Prophage exotoxins enhance colonization fitness in epidemic scarlet fever-causing Streptococcus pyogenes

The re-emergence of scarlet fever poses a new global public health threat. The capacity of North-East Asian serotype M12 (emm12) Streptococcus pyogenes (group A Streptococcus, GAS) to cause scarlet fever has been linked epidemiologically to the presence of novel prophages, including prophage ΦHKU.vir encoding the secreted superantigens SSA and SpeC and the DNase Spd1. Here, we report the molecular characterization of ΦHKU.vir-encoded exotoxins. We demonstrate that streptolysin O (SLO)-induced glutathione efflux from host cellular stores is a previously unappreciated GAS virulence mechanism that promotes SSA release and activity, representing the first description of a thiol-activated bacterial superantigen. Spd1 is required for resistance to neutrophil killing. Investigating single, double and triple isogenic knockout mutants of the ΦHKU.vir-encoded exotoxins, we find that SpeC and Spd1 act synergistically to facilitate nasopharyngeal colonization in a mouse model. These results offer insight into the pathogenesis of scarlet fever-causing GAS mediated by prophage ΦHKU.vir exotoxins.

The pathogenesis of Streptococcus pyogenes (GAS) causing scarlet fever has been associated with the presence of prophages, such as ΦHKU.vir, and their products. Here, the authors characterize the exotoxins SpeC and Spd1 of ΦHKU.vir and show these to act synergistically to facilitate nasopharyngeal colonization in mice.

Increase of emm1 isolates among group A Streptococcus strains causing scarlet fever in Shanghai, China

OBJECTIVE

Scarlet fever epidemics caused by group A Streptococcus (GAS) have been ongoing in China since 2011. However, limited data are available on the dynamic molecular characterizations of the epidemic strains.

METHOD

Epidemiological data of scarlet fever in Shanghai were obtained from the National Notifiable Infectious Disease Surveillance System. Throat swabs of patients with scarlet fever and asymptomatic school-age children were cultured. Illumina sequencing was performed on 39emm1 isolates.

RESULTS

The annual incidence of scarlet fever was 7.5-19.4/100,000 persons in Shanghai during 2011-2015, with an average GAS carriage rate being 7.6% in school-age children. The proportion ofemm1 GAS strains increased from 3.8% in 2011 to 48.6% in 2014; they harbored a superantigen profile similar to emm12 isolates, except for the speA gene. Two predominant clones, SH001-emm12, and SH002-emm1, circulated in 66.9% of scarlet fever cases and 44.8% of carriers. Genomic analysis showed emm1 isolates throughout China constituted distinct clades, enriched by the presence of mobile genetic elements carrying the multidrug-resistant determinants ermB and tetM and virulence genes speA, speC, and spd1.

CONCLUSION

A significant increase in the proportion ofemm1 strains occurred in the GAS population, causing scarlet fever in China. Ongoing surveillance is warranted to monitor the dynamic changes of GAS clones.

Epidemiological study of scarlet fever in Shenyang, China

Background

Since 2011, there has been an increase in the incidence of scarlet fever across China. The main objective of this study was to depict the spatiotemporal epidemiological characteristics of the incidence of scarlet fever in Shenyang, China, in 2018 so as to provide the scientific basis for effective strategies of scarlet control and prevention.

Methods

Excel 2010 was used to demonstrate the temporal distribution at the month level and ArcGIS10.3 was used to demonstrate the spatial distribution at the district/county level. Moran’s autocorrelation coefficient was used to examine the spatial autocorrelation and the Getis-Ord statistic was used to determine the hot-spot areas of scarlet fever.

Results

A total of 2314 scarlet fever cases were reported in Shenyang in 2018 with an annual incidence of 31.24 per 100,000. The incidence among males was higher than that among females(p<0.001). A vast majority of the cases (96.89%) were among children aged 3 to 11 years. The highest incidence was 625.34/100,000 in children aged 5–9 years. In 2018 there were two seasonal peaks of scarlet fever in June (summer-peak) and December (winter-peak). The incidence of scarlet fever in urban areas was significantly higher than that in rural areas(p<0.001). The incidence of scarlet fever was randomly distributed in Shenyang. There are hotspot areas located in seven districts.

Conclusions

Urban areas are the hot spots of scarlet fever and joint prevention and control measures between districts should be applied. Children aged 3–11 are the main source of scarlet fever and therefore the introduction of prevention and control into kindergarten and primary schools may be key to the control of scarlet fever epidemics.

Analysis of Epidemiological Characteristics of Scarlet Fever in Zhejiang Province, China, 2004-2018

Objective: The aim of this study was to analyze the trends and epidemiological characteristics of scarlet fever in Zhejiang Province in 2004–2018, intending to provide a basis for targeted prevention and control of this disease. Method: We collated the epidemiological data for cases of scarlet fever from the China Information System for Disease Control and Prevention (CISDCP) in Zhejiang province between 1 January 2004 and 31 December 2018. Descriptive statistical analysis was used to analyze epidemiological characteristics of scarlet fever, whereas the Getis-Ord Gi* statistic was used to determine the hotspot incidence of scarlet fever. Results: In 2004–2018, a total of 22,194 cases of scarlet fever were reported in Zhejiang Province, with no death reports. The annual average of scarlet fever incidence was 2.82/100,000 (range,1.12 to 6.34/100,000). The male incidence was higher than that among female (χ² = 999.834, p < 0.05), and a majority of the cases (86.42%) occurred in children aged 3–9 years. Each year, the incidence of scarlet fever in Zhejiang Province appeared two seasonal peaks: the first peak occurred from March to June (the constituent ratio was 49.06%), the second peak was lower than the first one during November and the following January (the constituent ratio was 28.67%). The two peaks were almost in accordance with the school spring semester and autumn–winter semester, respectively. The incidence in the northern regions of the province was generally higher than that in the southern regions. High-value clusters were detected in the central and northern regions, while low-value clusters occurred in the southern regions via the Getis-Ord Gi* statistical analysis. Conclusions: The prevalence of scarlet fever in Zhejiang Province showed a marked seasonality variation and mainly clustered in the central and northern regions in 2004–2018. Children under 15 years of age were most susceptible to scarlet fever. Kindergartens and primary schools should be the focus of prevention and control, and targeted strategies and measures should be taken to reduce the incidence.

Effect of meteorological factors on scarlet fever incidence in Guangzhou City, Southern China, 2006-2017

OBJECTIVE

To explore the relationship between meteorological factors and scarlet fever incidence from 2006 to 2017 in Guangzhou, the largest subtropical city of Southern China, and assist public health prevention and control measures.

METHODS

Data for weekly scarlet fever incidence and meteorological variables from 2006 to 2017 in Guangzhou were collected from the National Notifiable Disease Report System (NNDRS) and the Guangzhou Meteorological Bureau (GZMB). Distributed lag nonlinear models (DLNMs) were conducted to estimate the effect of meteorological factors on weekly scarlet fever incidence in Guangzhou.

RESULTS

We observed nonlinear effects of temperature, relative humidity, and wind velocity. The risk was the highest when the weekly mean temperature was 31 °C during lag week 14, yielding a relative risk (RR) of 1.48 (95% CI: 1.01-2.17). When relative humidity was 43.5% during lag week 0, the RR was 1.49 (95% CI: 1.04-2.12); the highest RR (1.55, 95% CI: 1.20-1.99) was reached when relative humidity was 93.5% during lag week 20. When wind velocity was 4.4 m/s during lag week 13, the RR was highest at 3.41 (95% CI: 1.57-7.44). Positive correlations were observed among weekly temperature ranges and atmospheric pressure with scarlet fever incidence, while a negative correlation was detected with aggregate rainfall. The cumulative extreme effect of meteorological variables on scarlet fever incidence was statistically significant, except for the high effect of wind velocity.

CONCLUSION

Weekly mean temperature, relative humidity, and wind velocity had double-trough effects on scarlet fever incidence; high weekly temperature range, high atmospheric pressure, and low aggregate rainfall were risk factors for scarlet fever morbidity. Our findings provided preliminary, but fundamental, information that may be useful for a better understanding of epidemic trends of scarlet fever and for developing an early warning system. Laboratory surveillance for scarlet fever should be strengthened in the future.

Detecting spatio-temporal hotspots of scarlet fever in Taiwan with spatio-temporal Gi* statistic

A resurgence of scarlet fever has caused many pediatric infections in East Asia and the United Kingdom. Although scarlet fever in Taiwan has not been a notifiable infectious disease since 2007, the comprehensive national health insurance data can still track its trend. Here, we used data from the open data portal of the Taiwan Centers for Disease Control. The scarlet fever trend was measured by outpatient and hospitalization rates from 2009 to 2017. In order to elucidate the spatio-temporal hotspots, we developed a new method named the spatio-temporal Gi* statistic, and applied Joinpoint regression to compute the annual percentage change (APC). The overall APCs in outpatient and hospitalization were 15.1% (95% CI: 10.3%-20.2%) and 7.7% (95%CI: 4.5% -10.9%). The major two infected groups were children aged 5-9 (outpatient: 0.138 scarlet fever diagnoses per 1,000 visits; inpatient: 2.579 per 1,000 visits) and aged 3-4 (outpatient: 0.084 per 1,000 visits; inpatient: 1.469 per 1,000 visits). We found the counties in eastern Taiwan and offshore counties had the most hotspots in the outpatient setting. In terms of hospitalization, the hotspots mostly occurred in offshore counties close to China. With the help of the spatio-temporal statistic, health workers can set up enhanced laboratory surveillance in those hotspots.

Increased Risk for Invasive Group A Streptococcus Disease for Household Contacts of Scarlet Fever Cases, England, 2011-2016

The incidence of scarlet fever in England and Wales is at its highest in 50 years. We estimated secondary household risk for invasive group A Streptococcus (iGAS) disease within 60 days after onset of scarlet fever. Reports of scarlet fever in England during 2011–2016 were matched by residential address to persons with laboratory-confirmed iGAS infections. We identified 11 iGAS cases in ≈189,684 household contacts and a 60-day incidence rate of 35.3 cases/100,000 person-years, which was 12.2-fold higher than the background rate (2.89). Infants and contacts >75 years of age were at highest risk. Three cases were fatal; sepsis and cellulitis were the most common manifestations. Typing for 6 iGAS cases identified emm 1.0 (n = 4), emm 4.0 (n = 1), and emm 12.0 (n = 1). Although absolute risk in household contacts was low, clinicians assessing household contacts should be aware of the risk to expedite diagnosis and initiate life-saving treatment.

Molecular Epidemiology, Ecology, and Evolution of Group A Streptococci

The clinico-epidemiological features of diseases caused by group A streptococci (GAS) is presented through the lens of the ecology, population genetics, and evolution of the organism. The serological targets of three typing schemes (M, T, SOF) are themselves GAS cell surface proteins that have a myriad of virulence functions and a diverse array of structural forms. Horizontal gene transfer expands the GAS antigenic cell surface repertoire by generating numerous combinations of M, T, and SOF antigens. However, horizontal gene transfer of the serotype determinant genes is not unconstrained, and therein lies a genetic organization that may signify adaptations to a narrow ecological niche, such as the primary tissue reservoirs of the human host. Adaptations may be further shaped by selection pressures such as herd immunity. Understanding the molecular evolution of GAS on multiple levels-short, intermediate, and long term-sheds insight on mechanisms of host-pathogen interactions, the emergence and spread of new clones, rational vaccine design, and public health interventions.

Phosphorylation at the D53 but Not the T65 Residue of CovR Determines the Repression of rgg and speB Transcription in emm1- and emm49-Type Group A Streptococci

CovR/CovS is a two-component regulatory system in group A Streptococcus and primarily acts as a transcriptional repressor. The D53 residue of CovR (CovR_D53) is phosphorylated by the sensor kinase CovS, and the phosphorylated CovR_D53 protein binds to the intergenic region of rgg-speB to inhibit speB transcription. Nonetheless, the transcription of rgg and speB is suppressed in covS mutants. The T65 residue of CovR is phosphorylated in a CovS-independent manner, and phosphorylation at the D53 and T65 residues of CovR is mutually exclusive. Therefore, how phosphorylation at the D53 and T65 residues of CovR contributes to the regulation of rgg and speB expression was elucidated. The transcription of rgg and speB was suppressed in the strain that cannot phosphorylate the D53 residue of CovR (CovR_D53A mutant) but restored to levels similar to those of the wild-type strain in the CovR_T65A mutant. Nonetheless, inactivation of the T65 residue phosphorylation in the CovR_D53A mutant cannot derepress the rgg and speB transcription, indicating that phosphorylation at the T65 residue of CovR is not required for repressing rgg and speB transcription. Furthermore, trans complementation of the CovR_D53A protein in the strain that expresses the phosphorylated CovR_D53 resulted in the repression of rgg and speB transcription. Unlike the direct binding of the phosphorylated CovR_D53 protein and its inhibition of speB transcription demonstrated previously, the present study showed that inactivation of phosphorylation at the D53 residue of CovR contributes dominantly in suppressing rgg and speB transcription.IMPORTANCE CovR/CovS is a two-component regulatory system in group A Streptococcus (GAS). The D53 residue of CovR is phosphorylated by CovS, and the phosphorylated CovR_D53 binds to the rgg-speB intergenic region and acts as the transcriptional repressor. Nonetheless, the transcription of rgg and Rgg-controlled speB is upregulated in the covR mutant but inhibited in the covS mutant. The present study showed that nonphosphorylated CovR_D53 protein inhibits rgg and speB transcription in the presence of the phosphorylated CovR_D53 in vivo, indicating that nonphosphorylated CovR_D53 has a dominant role in suppressing rgg transcription. These results reveal the roles of nonphosphorylated CovR_D53 in regulating rgg transcription, which could contribute significantly to invasive phenotypes of covS mutants.

Seasonality and trend prediction of scarlet fever incidence in mainland China from 2004 to 2018 using a hybrid SARIMA-NARX model

Background

Scarlet fever is recognized as being a major public health issue owing to its increase in notifications in mainland China, and an advanced response based on forecasting techniques is being adopted to tackle this. Here, we construct a new hybrid method incorporating seasonal autoregressive integrated moving average (SARIMA) with a nonlinear autoregressive with external input(NARX) to analyze its seasonality and trend in order to efficiently prevent and control this re-emerging disease.

Methods

Four statistical models, including a basic SARIMA, basic nonlinear autoregressive (NAR) method, traditional SARIMA-NAR and new SARIMA-NARX hybrid approaches, were developed based on scarlet fever incidence data between January 2004 and July 2018 to evaluate its temporal patterns, and their mimic and predictive capacities were compared to discover the optimal using the mean absolute percentage error, root mean square error, mean error rate, and root mean square percentage error.

Results

The four preferred models identified were comprised of the SARIMA(0,1,0)(0,1,1)₁₂, NAR with 14 hidden neurons and five delays, SARIMA-NAR with 33 hidden neurons and five delays, and SARIMA-NARX with 16 hidden neurons and 4 delays. Among which presenting the lowest values of the aforementioned indices in both simulation and prediction horizons is the SARIMA-NARX method. Analyses from the data suggested that scarlet fever was a seasonal disease with predominant peaks of summer and winter and a substantial rising trend in the scarlet fever notifications was observed with an acceleration of 9.641% annually, particularly since 2011 with 12.869%, and moreover such a trend will be projected to continue in the coming year.

Conclusions

The SARIMA-NARX technique has the promising ability to better consider both linearity and non-linearity behind scarlet fever data than the others, which significantly facilitates its prevention and intervention of scarlet fever. Besides, under current trend of ongoing resurgence, specific strategies and countermeasures should be formulated to target scarlet fever.

Epidemiology of Reemerging Scarlet Fever, Hong Kong, 2005-2015

Annual incidence of scarlet fever in Hong Kong remained elevated after an upsurge in 2011. Incidence increased from 3.3/10,000 children <5 years of age during 2005–2010 to 18.1/10,000 during 2012–2015. Incidence was higher among boys and was 32%–42% lower in the week following school holidays.

Complete Genome Sequence of a Streptococcus pyogenes Serotype M12 Scarlet Fever Outbreak Isolate from China, Compiled Using Oxford Nanopore and Illumina Sequencing

The incidence of scarlet fever cases remains high in China. Here, we report the complete genome sequence of a Streptococcus pyogenes isolate of serotype M12, which has been confirmed as the predominant serotype in recent outbreaks. Genome sequencing was achieved by a combination of Oxford Nanopore MinION and Illumina methodologies.

Identification and Characterization of Fluoroquinolone Non-susceptible Streptococcus pyogenes Clones Harboring Tetracycline and Macrolide Resistance in Shanghai, China

Streptococcus pyogenes, also known as group A Streptococcus (GAS), is one of the top 10 infectious causes of death worldwide. Macrolide and tetracycline resistant GAS has emerged as a major health concern in China coinciding with an ongoing scarlet fever epidemic. Furthermore, increasing rates of fluoroquinolone (FQ) non-susceptibility within GAS from geographical regions outside of China has also been reported. Fluoroquinolones are the third most commonly prescribed antibiotic in China and is an therapeutic alternative for multi-drug resistant GAS. The purpose of this study was to investigate the epidemiological and molecular features of GAS fluoroquinolone (FQ) non-susceptibility in Shanghai, China. GAS (n = 2,258) recovered between 2011 and 2016 from children and adults were tested for FQ-non-susceptibility. Efflux phenotype and mutations in parC, parE, gyrA, and gyrB were investigated and genetic relationships were determined by emm typing, pulsed-field gel electrophoresis and phylogenetic analysis. The frequency of GAS FQ-non-susceptibility was 1.3% (30/2,258), with the phenotype more prevalent in GAS isolated from adults (14.3%) than from children (1.2%). Eighty percent (24/30) of FQ-non-susceptible isolates were also resistant to both macrolides (ermB) and tetracycline (tetM) including the GAS sequence types emm12, emm6, emm11, and emm1. Genomic fingerprinting analysis of the 30 isolates revealed that non-susceptibility may arise in various genetic backgrounds even within a single emm type. No efflux phenotype was observed in FQ non-susceptible isolates, and molecular analysis of the quinolone resistance-determining regions (QRDRs) identified several sequence polymorphisms in ParC and ParE, and none in GyrA and GyrB. Expansion of this analysis to 152 publically available GAS whole genome sequences from Hong Kong predicted 7.9% (12/152) of Hong Kong isolates harbored a S79F ParC mutation, of which 66.7% (8/12) were macrolide and tetracycline resistant. Phylogenetic analysis of the parC QRDR sequences suggested the possibility that FQ resistance may be acquired through inter-species lateral gene transfer. This study reports the emergence of macrolide, tetracycline, and fluoroquinolone multidrug-resistant clones across several GAS emm types including emm1 and emm12, warranting continual surveillance given the extensive use of fluoroquinolones in clinical use.

Immunogenicity and Safety of a Chemically Synthesized Divalent Group A Streptococcal Vaccine

BACKGROUND

Group A streptococcus (GAS) infections and poststreptococcal sequelae remain a health problem worldwide, which necessitates searching for an effective vaccine, while no licensed GAS vaccine is available. We have developed a divalent peptide vaccine composed of 84 amino acids to cover the main GAS serotypes (M1 and M12 streptococci) in China, and herein, we aimed to evaluate immunogenicity and safety of this vaccine.

METHODS

Mice were immunized with the vaccine. ELISA, indirect bactericidal test, and immunofluorescent assay were used to study immunogenicity. GAS challenge assay was used to test the protective effect. Safety was tested by histopathological analysis.

RESULTS

Immunized group mice (n=16) developed higher titer antibody after immunization than nonimmunized group mice (n=16) did. This antibody can deposit on the surface of GAS and promote killing of GAS, resulting in 93.1% decrease of M1 GAS and 89.5% of M12 GAS. When challenged with M1 and M12 streptococci, immunized group mice had a higher survival rate (87.5% and 75%) than nonimmunized group mice (37.5% and 25%). No autoimmune reactions were detected on organs of mice.

CONCLUSION

The results suggest that this vaccine shows fair immunogenicity and safety, which will lead our research on GAS vaccine into clinical trial.

Scarlet Fever Upsurge in England and Molecular-Genetic Analysis in North-West London, 2014

Scarlet fever notifications surged across the United Kingdom in spring 2014. Molecular epidemiologic investigation of Streptococcus pyogenes infections in North-West London highlighted increased emm4 and emm3 infections coincident with the upsurge. Unlike outbreaks in other countries, antimicrobial resistance was uncommon, highlighting an urgent need to better understand the drivers of scarlet fever activity.

Scarlet Fever Epidemic in China Caused by Streptococcus pyogenes Serotype M12: Epidemiologic and Molecular Analysis

From 2011, Hong Kong and mainland China have witnessed a sharp increase in reported cases, with subsequent reports of epidemic scarlet fever in North Asia and the United Kingdom. Here we examine epidemiological data and investigate the genomic context of the predominantly serotype M12 Streptococcus pyogenes scarlet fever isolates from mainland China. Incident case data was obtained from the Chinese Nationwide Notifiable Infectious Diseases Reporting Information System. The relative risk of scarlet fever in recent outbreak years 2011–2016 was calculated using the median age-standardised incidence rate, compared to years 2003–2010 prior this outbreak. Whole genome sequencing was performed on 32 emm12 scarlet fever isolates and 13 emm12 non-scarlet fever isolates collected from different geographic regions of China, and compared with 203 published emm12 S. pyogenes genomes predominantly from scarlet fever outbreaks in Hong Kong (n = 134) and the United Kingdom (n = 63). We found during the outbreak period (2011–2016), the median age-standardised incidence in China was 4.14/100,000 (95% confidence interval (CI) 4.11-4.18), 2.62-fold higher (95% CI 2.57-2.66) than that of 1.58/100,000 (95% CI 1.56-1.61) during the baseline period prior to the outbreak (2003 − 2010). Highest incidence was reported for children 5 years of age (80.5/100,000). Streptococcal toxin encoding prophage φHKU.vir and φHKU.ssa in addition to the macrolide and tetracycline resistant ICE-emm12 and ICE-HKU397 elements were found amongst mainland China multi-clonal emm12 isolates suggesting a role in selection and expansion of scarlet fever lineages in China. Global dissemination of toxin encoded prophage has played a role in the expansion of scarlet fever emm12 clones. These findings emphasize the role of comprehensive surveillance approaches for monitoring of epidemic human disease.

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The study used all epidemiological data from 1950 to 2016, and describe increased incidence levels for the current outbreak.

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Using global emm12 scarlet fever isolate genome sequences, the multiclonal nature of the outbreak was confirmed.

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Global surveillance of GAS toxin and drug resistance mobile genes in the scarlet fever outbreak is necessary.

Our study provides a detailed report of scarlet fever epidemiology and genomic analysis for mainland China since the 2011 outbreak began. We also provide a comprehensive comparison of the genomic relationship of scarlet fever outbreak emm12 isolates from China, Hong Kong and the United Kingdom, countries experiencing an unparalleled re-emergence of scarlet fever. Our observations implicate an important role for GAS toxin and drug resistance related mobile genes in the outbreak and reveal different evolutionary patterns, and identify common themes relating to the acquisition of toxin carrying prophage elements. This work emphasizes the importance of comprehensive nationwide surveillance to track scarlet fever, GAS emm types, exotoxin-encoding prophage and antibiotic resistance genes in a global context.

Resurgence of scarlet fever in England, 2014-16: a population-based surveillance study

BACKGROUND

After decades of decreasing scarlet fever incidence, a dramatic increase was seen in England beginning in 2014. Investigations were launched to assess clinical and epidemiological patterns and identify potential causes.

METHODS

In this population-based surveillance study, we analysed statutory scarlet fever notifications held by Public Health England from 1911 to 2016 in England and Wales to identify periods of sudden escalation of scarlet fever. Characteristics of cases and outbreaks in England including frequency of complications and hospital admissions were assessed and compared with the pre-upsurge period. Isolates from throat swabs were obtained and were emm typed.

FINDINGS

Data were retrieved for our analysis between Jan 1, 1911, and Dec 31, 2016. Population rates of scarlet fever increased by a factor of three between 2013 and 2014 from 8·2 to 27·2 per 100 000 (rate ratio [RR] 3·34, 95% CI 3·23-3·45; p<0·0001); further increases were observed in 2015 (30·6 per 100 000) and in 2016 (33·2 per 100 000), which reached the highest number of cases (19 206) and rate of scarlet fever notifcation since 1967. The median age of cases in 2014 was 4 years (IQR 3-7) with an incidence of 186 per 100 000 children under age 10 years. All parts of England saw an increase in incidence, with 620 outbreaks reported in 2016. Hospital admissions for scarlet fever increased by 97% between 2013 and 2016; one in 40 cases were admitted for management of the condition or potential complications. Analysis of strains (n=303) identified a diversity of emm types with emm3 (43%), emm12 (15%), emm1 (11%), and emm4 (9%) being the most common. Longitudinal analysis identified 4-yearly periodicity in population incidence of scarlet fever but of consistently lower magnitude than the current escalation.

INTERPRETATION

England is experiencing an unprecedented rise in scarlet fever with the highest incidence for nearly 50 years. Reasons for this escalation are unclear and identifying these remains a public health priority.

FUNDING

None.

Effects of meteorological factors on incidence of scarlet fever during different periods in different districts of China

OBJECTIVE

To reveal the difference of meteorological effect on scarlet fever in Beijing and Hong Kong, China, during different periods among 2004-2014.

METHODS

The data of monthly incidence of scarlet fever and meteorological variables from 2004 to 2014 in Beijing and Hong Kong were collected from Chinese science data center of public health, meteorological data website and Hong Kong observatory website. The whole study period was separated into two periods by the outbreak year 2011 (Jan 2004-Dec 2010 and Jan 2011-Dec 2014). A generalized additive Poisson model was conducted to estimate the effect of meteorological variables on monthly incidence of scarlet fever during two periods in Beijing and Hong Kong, China.

RESULTS

Incidence of scarlet fever in two districts were compared and found the average incidence during period of 2004-2010 were significantly different (Z=203.973, P<0.001) while average incidence became generally equal during 2011-2014 (Z=2.125, P>0.05). There was also significant difference in meteorological variables between Beijing and Hong Kong during whole study period, except air pressure (Z=0.165, P=0.869). After fitting GAM model, it could be found monthly mean temperature showed a negative effect (RR=0.962, 95%CI: 0.933, 0.992) on scarlet fever in Hong Kong during the period of 2004-2010. By comparison, for data in Beijing during the period of 2011-2014, the RRs of monthly mean temperature range growing 1°C and monthly sunshine duration growing 1h was equal to 1.196(1.022, 1.399) and 1.006(1.001, 1.012), respectively. The changes of meteorological effect on scarlet fever over time were not significant both in Beijing and Hong Kong.

CONCLUSION

This study suggests that meteorological variables were important factors for incidence of scarlet fever during different period in Beijing and Hong Kong. It also support that some meteorological effects were opposite in different period although these differences might not completely statistically significant.

The Association between Environmental Factors and Scarlet Fever Incidence in Beijing Region: Using GIS and Spatial Regression Models

(1) Background: Evidence regarding scarlet fever and its relationship with meteorological, including air pollution factors, is not very available. This study aimed to examine the relationship between ambient air pollutants and meteorological factors with scarlet fever occurrence in Beijing, China. (2) Methods: A retrospective ecological study was carried out to distinguish the epidemic characteristics of scarlet fever incidence in Beijing districts from 2013 to 2014. Daily incidence and corresponding air pollutant and meteorological data were used to develop the model. Global Moran’s I statistic and Anselin’s local Moran’s I (LISA) were applied to detect the spatial autocorrelation (spatial dependency) and clusters of scarlet fever incidence. The spatial lag model (SLM) and spatial error model (SEM) including ordinary least squares (OLS) models were then applied to probe the association between scarlet fever incidence and meteorological including air pollution factors. (3) Results: Among the 5491 cases, more than half (62%) were male, and more than one-third (37.8%) were female, with the annual average incidence rate 14.64 per 100,000 population. Spatial autocorrelation analysis exhibited the existence of spatial dependence; therefore, we applied spatial regression models. After comparing the values of R-square, log-likelihood and the Akaike information criterion (AIC) among the three models, the OLS model (R² = 0.0741, log likelihood = −1819.69, AIC = 3665.38), SLM (R² = 0.0786, log likelihood = −1819.04, AIC = 3665.08) and SEM (R² = 0.0743, log likelihood = −1819.67, AIC = 3665.36), identified that the spatial lag model (SLM) was best for model fit for the regression model. There was a positive significant association between nitrogen oxide (p = 0.027), rainfall (p = 0.036) and sunshine hour (p = 0.048), while the relative humidity (p = 0.034) had an adverse association with scarlet fever incidence in SLM. (4) Conclusions: Our findings indicated that meteorological, as well as air pollutant factors may increase the incidence of scarlet fever; these findings may help to guide scarlet fever control programs and targeting the intervention.

Spatiotemporal Pattern Analysis of Scarlet Fever Incidence in Beijing, China, 2005-2014

Objective: To probe the spatiotemporal patterns of the incidence of scarlet fever in Beijing, China, from 2005 to 2014. Methods: A spatiotemporal analysis was conducted at the district/county level in the Beijing region based on the reported cases of scarlet fever during the study period. Moran’s autocorrelation coefficient was used to examine the spatial autocorrelation of scarlet fever, whereas the Getis-Ord Gi* statistic was used to determine the hotspot incidence of scarlet fever. Likewise, the space-time scan statistic was used to detect the space-time clusters, including the relative risk of scarlet fever incidence across all settings. Results: A total of 26,860 scarlet fever cases were reported in Beijing during the study period (2005–2014). The average annual incidence of scarlet fever was 14.25 per 100,000 population (range, 6.76 to 32.03 per 100,000). The incidence among males was higher than that among females, and more than two-thirds of scarlet fever cases (83.8%) were among children 3–8 years old. The seasonal incidence peaks occurred from March to July. A higher relative risk area was mainly in the city and urban districts of Beijing. The most likely space-time clusters and secondary clusters were detected to be diversely distributed in every study year. Conclusions: The spatiotemporal patterns of scarlet fever were relatively unsteady in Beijing from 2005 to 2014. The at-risk population was mainly scattered in urban settings and dense districts with high population, indicating a positive relationship between population density and increased risk of scarlet fever exposure. Children under 15 years of age were the most susceptible to scarlet fever.

Transfer of scarlet fever-associated elements into the group A Streptococcus M1T1 clone

The group A Streptococcus (GAS) M1T1 clone emerged in the 1980s as a leading cause of epidemic invasive infections worldwide, including necrotizing fasciitis and toxic shock syndrome123. Horizontal transfer of mobile genetic elements has played a central role in the evolution of the M1T1 clone45, with bacteriophage-encoded determinants DNase Sda16 and superantigen SpeA27 contributing to enhanced virulence and colonization respectively. Outbreaks of scarlet fever in Hong Kong and China in 2011, caused primarily by emm12 GAS8910, led to our investigation of the next most common cause of scarlet fever, emm1 GAS89. Genomic analysis of 18 emm1 isolates from Hong Kong and 16 emm1 isolates from mainland China revealed the presence of mobile genetic elements associated with the expansion of emm12 scarlet fever clones1011 in the M1T1 genomic background. These mobile genetic elements confer expression of superantigens SSA and SpeC, and resistance to tetracycline, erythromycin and clindamycin. Horizontal transfer of mobile DNA conferring multi-drug resistance and expression of a new superantigen repertoire in the M1T1 clone should trigger heightened public health awareness for the global dissemination of these genetic elements.

Molecular epidemiology and genomics of group A Streptococcus

Streptococcus pyogenes (group A Streptococcus; GAS) is a strict human pathogen with a very high prevalence worldwide. This review highlights the genetic organization of the species and the important ecological considerations that impact its evolution. Recent advances are presented on the topics of molecular epidemiology, population biology, molecular basis for genetic change, genome structure and genetic flux, phylogenomics and closely related streptococcal species, and the long- and short-term evolution of GAS. The application of whole genome sequence data to addressing key biological questions is discussed.

Bromine, bear-claw scratch fasciotomies, and the Eagle effect: management of group A streptococcal necrotising fasciitis and its association with trauma

Necrotising fasciitis is a rare, but potentially fatal, soft-tissue infection. Historical depictions of the disease have been described since classical times and were mainly recorded in wartime reports of battle injuries. Although several different species of bacteria can cause necrotising fasciitis, perhaps the most widely known is group A streptococcus (GAS). Infection control, early surgical debridement, and antibiotic therapy are now the central tenets of the clinical management of necrotising fasciitis; these treatment approaches all originate from those used in wars in the past 150 years. We review reports from the 19th century, early 20th century, and mid-20th century onwards to show how the management of necrotising fasciitis has progressed in parallel with prevailing scientific thought and medical practice. Historically, necrotising fasciitis has often, but not exclusively, been associated with penetrating trauma. However, along with a worldwide increase in invasive GAS disease, recent reports have cited cases of necrotising fasciitis following non-combat-related injuries or in the absence of antecedent events. We also investigate the specific association between GAS necrotising fasciitis and trauma. In the 21st century, molecular biology has improved our understanding of GAS pathogenesis, but has not yet affected attributable mortality.

Macrolide-resistant Streptococcus pyogenes: prevalence and treatment strategies

Although penicillin remains the first-choice treatment for Streptococcus pyogenes infection, macrolides are important alternatives for allergic patients and lincosamides are recommended together with β-lactams in invasive infections. S. pyogenes may exhibit macrolide resistance because of active efflux (mef genes) or target modification (erm genes), the latter conferring cross resistance to lincosamides and streptogramin B. Worldwide, resistance is restricted to a limited number of genetic lineages, despite resistance genes being encoded on mobile genetic elements. For reasons that are not completely clear, resistance and the associated phenotypes are highly variable across countries. Although resistance remains high in several countries, particularly in Asia, an overall decreasing trend of resistance has been noted in recent years, mostly in Europe. This decrease is not always accompanied by declines in macrolide consumption, suggesting significant roles of other factors in determining the dynamics of macrolide-resistant clones. Continued surveillance is needed to obtain further insights into the forces governing macrolide resistance in S. pyogenes.

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.

Sortase A induces Th17-mediated and antibody-independent immunity to heterologous serotypes of group A streptococci

Group A streptococci (GAS) are associated with a variety of mucosal and invasive human infections. Recurrent infections by highly heterologous serotypes indicate that cross-serotype immunity is critical for prevention of GAS infections; however, mechanisms underlying serotype-independent protection are poorly understood. Here we report that intranasal vaccination of mice with Sortase A (SrtA), a conserved cell wall bound protein, reduced colonization of nasal-associated lymphoid tissue (NALT) by heterologous serotypes of GAS. Vaccination significantly increased CD4⁺ IL-17A⁺ cells in NALT and depletion of IL-17A by neutralizing antibody prevented GAS clearance from NALT which was dependent on immunization with SrtA. Vaccination also induced high levels of SrtA-specific antibodies; however, immunized, B cell-deficient mice cleared streptococcal challenges as efficiently as wild type mice, indicating that the cross-serotype protection is Th17-biased and antibody-independent. Furthermore, efficient GAS clearance from NALT was associated with a rapid neutrophil influx into NALT of immunized mice. These results suggest that serotype independent immune protection against GAS mucosal infection can be achieved by intranasal vaccination with SrtA and enhanced neutrophil function is critical for anti-GAS defense and might be a target for prevention of GAS infections.

Increase in scarlet fever notifications in the United Kingdom, 2013/2014

Increases in scarlet fever above usual seasonal levels are currently being seen across the United Kingdom. Medical practitioners have been alerted to the exceptional increase in incidence. Given the potential for this to signal a population increase in invasive group A streptococcal disease, close monitoring of invasive disease is essential.

Scarlet fever is caused by a limited number of Streptococcus pyogenes lineages and is associated with the exotoxin genes ssa, speA and speC

BACKGROUND

Several outbreaks of scarlet fever caused by Streptococcus pyogenes were recently reported. Scarlet fever is historically considered a toxin-mediated disease, dependent on the production of the exotoxins SpeA and SpeC, but a strict association between scarlet fever and these exotoxins is not always detected. The aims of this study were to characterize the scarlet fever bacterial isolates recovered from patients in a Lisbon hospital and to identify any distinctive characteristics of such isolates.

METHODS

We characterized a collection of 303 pharyngeal S. pyogenes collected between 2002 and 2008. One-hundred and one were isolated from scarlet fever patients and 202 were associated to a diagnosis of tonsillo-pharyngitis. Isolates were characterized by T and emm typing, pulsed field gel electrophoresis profiling and superantigen gene profiling.

RESULTS

The diversity of the scarlet fever isolates was lower than that of the pharyngitis isolates. Specific lineages of emm87, emm4 and emm3 were overrepresented in scarlet fever isolates but only 1 pulsed field gel electrophoresis major lineage was significantly associated with scarlet fever. Multivariate analysis indicated associations of ssa, speA and speC with scarlet fever.

CONCLUSIONS

In nonoutbreak conditions, scarlet fever is caused by a number of distinct genetic lineages. The lower diversity of these isolates and the association with specific exotoxin genes indicates that some lineages are more prone to cause this presentation than others even in nonoutbreak conditions.

Characteristics of group A Streptococcus strains circulating during scarlet fever epidemic, Beijing, China, 2011

Scarlet fever is one of a variety of diseases caused by group A Streptococcus (GAS). During 2011, a scarlet fever epidemic characterized by peak monthly incidence rates 2.9–6.7 times higher than those in 2006–2010 occurred in Beijing, China. During the epidemic, hospital-based enhanced surveillance for scarlet fever and pharyngitis was conducted to determine characteristics of circulating GAS strains. The surveillance identified 3,359 clinical cases of scarlet fever or pharyngitis. GAS was isolated from 647 of the patients; 76.4% of the strains were type emm12, and 17.1% were emm1. Almost all isolates harbored superantigens speC and ssa. All isolates were susceptible to penicillin, and resistance rates were 96.1% to erythromycin, 93.7% to tetracycline, and 79.4% to clindamycin. Because emm12 type GAS is not the predominant type in other countries, wider surveillance for the possible spread of emm12 type GAS from China to other countries is warranted.