Seven-year surveillance of emm types of pediatric Group A streptococcal pharyngitis isolates in Western Greece

Streptococcal Toxic Shock Syndrome Caused by a Streptococcus pyogenes emm22 Genotype with a CsrS Mutation: a Case Report

A previously healthy 22-year-old woman was admitted to our hospital after an out-of-hospital cardiac arrest. Spontaneous circulation was restored prior to arrival at the hospital. However, the patient's vital signs remained unstable. Vasopressors and hyperhydration therapy were administered. Computed tomography did not reveal a cause of the cardiac arrest. Antibiotics were initiated after obtaining blood culture samples. The patient was admitted to the intensive care unit (ICU). High-dose vasopressors and hyperhydration therapy were continued and fresh frozen plasma was transfused. Two hours after ICU admission, gram staining of a blood smear revealed the presence of Streptococcus, and the antibiotics were switched to penicillin G potassium and clindamycin, and immunoglobulins were administered. Extracorporeal membrane oxygenation was initiated 10 h after ICU admission owing to respiratory failure caused by fluid overload; however, the patient's condition did not improve and she died 40 h after admission. Blood culture results confirmed the presence of Streptococcus pyogenes; the T and M serotypes were unclassifiable. The emm genotype was emm22. Sequencing revealed the presence of streptococcal pyrogenic toxin genes, speA and speB, whereas speC was absent. CsrS, CsrR, and Rgg amino acid sequencing revealed the presence of a CsrS mutation.

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

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

emm Types and clusters and macrolide resistance of pediatric group A streptococcal isolates in Central Greece during 2011-2017

Background

The surveillance of emm types and macrolide susceptibility of group A streptococcus (GAS) in various areas and time periods enhances the understanding of the epidemiology of GAS infections and may guide treatment strategies and the formulation of type-specific vaccines. Greece has emerged as a country with high macrolide use. However, studies suggest a gradual reduction in macrolide consumption after 2007.

Methods

During a 7-year period (2011–2017), 604 GAS isolates were recovered from consecutive children presenting with pharyngeal or nonpharyngeal infections in Central Greece; 517 viable isolates underwent molecular analysis, including emm typing.

Results

Isolates belonged to 20 different emm types (in decreasing order of prevalence: 1, 89, 4, 12, 28, 3, 75 and 6, accounting for 88.2% of total isolates). The emm types comprised 10 emm clusters (five most common clusters: E4, A-C3, E1, A-C4 and A-C5). The emm89 isolates were acapsular (‘new clade‘). Overall macrolide resistance rate was 15.4%, and cMLS_B emerged as the predominant resistance phenotype (56.4%). The lowest annual resistance rates occurred in 2014 (13.1%), 2016 (5.5%) and 2017(8.0%) (P for trend = 0.002). Consumption of macrolide/lincosamide/streptogramin B declined by 22.6% during 2011–2017. Macrolide resistance and emm28 and emm77 types were associated (both P<0.001). The most frequently identified genetic lineages of macrolide-resistant GAS included emm28/ST52, emm77/ST63, emm12/ST36, emm89/ST101 and emm4/ST39. We estimated that 98.8% of the isolates belonged to emm types incorporated into a novel 30-valent M protein vaccine.

Conclusions

In Central Greece during 2011–2017, the acapsular emm89 isolates comprised the second most prevalent type. Susceptibility testing and molecular analyses revealed decreasing GAS macrolide resistance rates, which may be attributed to the reduction in the consumption of macrolides and/or the reduced circulation of macrolide-resistant clones in recent years. Such data may provide valuable baseline information in targeting therapeutic intervention and the formulation of type-specific GAS vaccines.

Changes in epidemiologic characteristics and antimicrobial resistance of Streptococcus pyogenes isolated over 10 years from Japanese children with pharyngotonsillitis

Introduction. Pharyngotonsillitis caused by Streptococcus pyogenes (group A streptococci, or GAS) is among the most common infections treated with antibiotics in pediatric patients.Aim. This study aimed to analyse changes in molecular epidemiology and antibiotic susceptibility among GAS isolates in three study periods spanning 10 years.Methodology. GAS isolated from paediatric patients with pharyngotonsillitis during Period I (mid-2007 to 2008, n=235), Period II (2012, n=210), and Period III (2018, n=189) were analysed for emm type, multilocus sequence type (MLST), antibiotic susceptibility, and macrolide (ML)- and quinolone (QL)-resistance genes.Results. Over 20 % of isolates represented emm1 and emm12 types, remaining common in all three periods. Among other emm types, emm4 was common in Period I, emm28 and emm89 in Period II, and emm3 and emm89 in Period III. All isolates remained highly susceptible to penicillins and cephalosporins. Isolates possessing mefA, ermA, or ermB genes mediating ML resistance increased from 34.9 % in Period I to 60.9 % in Period II, but fell to 27.5 % in Period III. QL-resistant isolates with amino acid substitutions affecting ParC and/or GyrA gradually increased from 11.5 to 14.3 %. Specific sequence types identified by MLST and emm typing were associated closely with ML or QL resistance.Conclusion. Our findings indicate that even in ambulatory care, antibiotic choice for these infections should be based on rapid identification and characterization of causative pathogens.

Management of children with persistent group A streptococcal carriage

INTRODUCTION

Chronic GAS carrier state is best defined as the prolonged presence of group A β-haemolytic Streptococcus (GAS) in the pharynx without evidence of infection or inflammation. Chronic GAS carriers have a low risk of immune mediated complications. Persistent pharyngeal carriage often raises management issues. In this study, we review the evidence on the management of persistent GAS carriage in children and propose a management algorithm. Areas covered: Chronic GAS pharyngeal carriage is quite common affecting 10-20% of school-aged children. Pathogenesis of carriage has been related to the pharynx microflora and to special properties of GAS, but several aspects are yet to be elucidated. Management greatly depends on whether the individual child belongs to a 'high-risk' group and might benefit from eradication regimens or not, when observation-only and reassurance are enough. Penicillin plus rifampin and clindamycin monotherapy have been recommended for eradication; limited evidence of effectiveness of azithromycin has been reported. Surgical intervention is not indicated. Expert commentary: GAS infection is a common reason for antibiotic use and abuse in children and asymptomatic carriers constitute the major reservoir of GAS in the community. Several aspects are yet to be elucidated and well-designed studies are needed for firm conclusions to be drawn.

Epidemiology of invasive group A streptococcal infections in Norway 2010-2014: A retrospective cohort study

Streptococcus pyogenes or group A streptococcus (GAS) causes mild to severe infections in humans. GAS genotype emm1 is the leading cause of invasive disease worldwide. In the Nordic countries emm28 has been the dominant type since the 1980s. Recently, a resurgence of genotype emm1 was reported from Sweden. Here we present the epidemiology of invasive GAS (iGAS) infections and their association with emm-types in Norway from 2010-2014. We retrospectively collected surveillance data on antimicrobial susceptibility, multilocus sequence type and emm-type, and linked them with demographic and clinical manifestation data to calculate age and sex distributions, major emm- and sequence types and prevalence ratios (PR) on associations between emm-types and clinical manifestations. We analysed 756 iGAS cases and corresponding isolates, with overall incidence of 3.0 per 100000, median age of 59 years (range, 0-102), and male 56 %. Most frequent clinical manifestation was sepsis (49 %) followed by necrotizing fasciitis (9 %). Fifty-two different emm-types and 67 sequence types were identified, distributed into five evolutionary clusters. The most prevalent genotype was emm1 (ST28) in all years (range, 20-33 %) followed by 15 % emm28 in 2014. All isolates were susceptible to penicillin, 15 % resistant to tetracycline and <4 % resistant to erythromycin. A PR of 4.5 (95 % CI, 2.3-8.9) was calculated for emm2 and necrotizing fasciitis. All emm22 isolates were resistant to tetracycline PR 7.5 (95 % CI, 5.8-9.9). This study documented the dominance of emm1, emergence of emm89 and probable import of tetracycline resistant emm112.2 into Norway (2010-2014). Genotype fluctuations between years suggested a mutual exclusive dominance of evolutionary clades.

Molecular analysis of Streptococcus pyogenes macrolide resistance of paediatric isolates during a 7 year period (2007-13)

OBJECTIVES

The molecular characterization of paediatric group A Streptococcus (GAS) isolates regarding macrolide resistance and relevant emm types in Athens, Greece.

METHODS

Pharyngeal and non-pharyngeal GAS isolates were collected during a 7 year period (2007-13) and examined for antibiotic susceptibility, macrolide resistance genes [mef(A), erm(A) and erm(B)] and relevant emm types.

RESULTS

Overall, 20.4% (270/1324) of GAS isolates were resistant to macrolides. The macrolide resistance rate varied during the study period with a maximum rate observed in 2008 (29.57%) and a minimum rate observed in 2013 (10.95%) (P value for trend = 0.007). During the same period, consumption of macrolides was gradually reduced by 56.6%. No difference was observed in macrolide resistance between pharyngeal and non-pharyngeal isolates (P = 0.7). Among macrolide-resistant isolates, mef(A) was detected in 87 (32.2%), erm(A) in 136 (50.4%), erm(B) in 44 (16.3%) and both mef(A) and erm(A) in 3 (1.1%) isolates. The most prevalent emm types among macrolide-resistant isolates were emm77 (31.5%), emm4 (18.1%) and emm12 (10.7%). Ten emm types (77, 4, 12, 28, 1, 22, 11, 2, 44 and 89) accounted for 90.3% of macrolide-resistant isolates. emm types 4, 22, 44 and 77 were more prevalent in macrolide-resistant compared with macrolide-susceptible isolates, whereas emm types 1, 3, 5, 6, 75 and 89 were more prevalent in macrolide-susceptible compared with macrolide-resistant isolates.

CONCLUSIONS

GAS macrolide resistance remained significant in our area during the study period. A substantial decline in the resistance rate was observed in the last year of the study, which may be related to reduced consumption of macrolides.

Trading Capsule for Increased Cytotoxin Production: Contribution to Virulence of a Newly Emerged Clade of emm89 Streptococcus pyogenes

Strains of emm89 Streptococcus pyogenes have become one of the major causes of invasive infections worldwide in the last 10 years. We recently sequenced the genome of 1,125 emm89 strains and identified three major phylogenetic groups, designated clade 1, clade 2, and the epidemic clade 3. Epidemic clade 3 strains, which now cause the great majority of infections, have two distinct genetic features compared to clade 1 and clade 2 strains. First, all clade 3 organisms have a variant 3 nga promoter region pattern, which is associated with increased production of secreted cytolytic toxins SPN (S. pyogenes NADase) and SLO (streptolysin O). Second, all clade 3 strains lack the hasABC locus mediating hyaluronic acid capsule synthesis, whereas this locus is intact in clade 1 and clade 2 strains. We constructed isogenic mutant strains that produce different levels of SPN and SLO toxins and capsule (none, low, or high). Here we report that emm89 strains with elevated toxin production are significantly more virulent than low-toxin producers. Importantly, we also show that capsule production is dispensable for virulence in strains that already produce high levels of SPN and SLO. Our results provide new understanding about the molecular mechanisms contributing to the rapid emergence and molecular pathogenesis of epidemic clade 3 emm89 S. pyogenes.

S. pyogenes (group A streptococcus [GAS]) causes pharyngitis (“strep throat”), necrotizing fasciitis, and other human infections. Serious infections caused by emm89 S. pyogenes strains have recently increased in frequency in many countries. Based on whole-genome sequence analysis of 1,125 strains recovered from patients on two continents, we discovered that a new emm89 clone, termed clade 3, has two distinct genetic features compared to its predecessors: (i) absence of the genes encoding antiphagocytic hyaluronic acid capsule virulence factor and (ii) increased production of the secreted cytolytic toxins SPN and SLO. emm89 S. pyogenes strains with the clade 3 phenotype (absence of capsule and high expression of SPN and SLO) are highly virulent in mice. These findings provide new understanding of how new virulent clones emerge and cause severe infections worldwide. This newfound knowledge of S. pyogenes virulence can be used to help understand future epidemics and conduct new translational research.

Epidemiology and emm types of invasive group A streptococcal infections in Finland, 2008-2013

Invasive Streptococcus pyogenes (group A streptococcus, GAS) infections are a major global cause of morbidity and mortality. We analysed the surveillance data on invasive GAS and the microbiological characteristics of corresponding isolates to assess the incidence and emm type distribution of invasive GAS infections in Finland. Cases defined as patients with isolations of blood and cerebrospinal fluid S. pyogenes are mandatorily notified to the National Infectious Disease Registry and sent to the national reference laboratory for emm typing. Antimicrobial data were collected through the network including all clinical microbiology laboratories. Pulsed-field gel electrophoresis (PFGE) analysis was performed to assess clonality. In total, 1165 cases of invasive GAS were reported in Finland during 2008-2013; the median age was 52 years (range, 0-100) and 54% were male. The overall day 7 case fatality rate was 5.1% (59 cases). The average annual incidence was 3.6 cases per 100,000 population. A total of 1122 invasive GAS isolates (96%) were analysed by emm typing; 72 different emm types were identified, of which emm28 (297 isolates, 26%), emm89 (193 isolates, 12%) and emm1 (132 isolates, 12%) were the most common types. During 2008-2013, an increase of erythromycin resistance (1.9% to 8.7%) and clindamycin (0.9% to 9.2%) was observed. This resistance increase was in parallel with the introduction of a novel clone emm33 into Finland. The overall incidence of invasive GAS infections remained stable over the study period in Finland. We identified clonal spread of macrolide-resistant invasive emm33 GAS type, highlighting the importance of molecular surveillance.

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.

Susceptibility of Group A Streptococcus to Antimicrobial Agents in Northern Israel: A Surveillance Study

BACKGROUND

Resistant pathogens are an increasing threat affecting millions of people globally. More complicated patients are presented with pathogens harboring new resistance mechanisms, while the pipeline of new antimicrobials hardly proposes solutions. In such a scenario, more severely ill patients remain with no adequate treatment to offer. In addition, massive misuse of antimicrobials, including excessive length of treatment or wrong dosage, also contributes to increasing the rate of pathogens resistance to antimicrobials. Isolation of Streptococcus pyogenes (Group A Streptococcus-GAS) is the main indication for antibiotic treatment to patients diagnosed with acute tonsillitis. Hence, GAS resistance to antibiotics requires periodic monitoring.

OBJECTIVES

To assess susceptibility rates of GAS to penicillin, macrolides, clindamycin, and tetracycline in northern Israel and to compare the findings to the high antimicrobial susceptibility of GAS isolates reported in the same region in 2004 and to other geographical areas.

METHODS

Throat samples from 300 outpatients were collected and cultured at the regional laboratory of Emek Medical Center during September to October 2011.

RESULTS

In 300 samples, the susceptibility rates of GAS to penicillin, erythromycin, azithromycin, clindamycin, and tetracycline in northern Israel still remain very high.

CONCLUSIONS

Continuous control of antimicrobials usage and periodic surveillance of susceptibility rates, together with educational programs and appropriate and targeted treatment protocols, are essential and highly recommended to keep these high susceptibility rates for as long as possible.

Streptococcus pyogenes emm Types and Clusters during a 7-Year Period (2007 to 2013) in Pharyngeal and Nonpharyngeal Pediatric Isolates

Group A streptococcus (GAS) is an important cause of morbidity and mortality worldwide. Surveillance of emm types has important implications, as it can provide baseline information for possible implementation of vaccination. A total of 1,349 GAS pediatric isolates were collected during a 7-year period (2007 to 2013); emm typing was completed for 1,282 pharyngeal (84%) or nonpharyngeal (16%) isolates, and emm clusters and temporal changes were analyzed. Thirty-five different emm types, including 14 subtypes, were identified. The most prevalent emm types identified were 1 (16.7%), 12 (13.6%), 77 (10.9%), 4 (10.8%), 28 (10.4%), 6 (6.8%), 3 (6.6%), and 89 (6.6%), accounting for 82.3% of total isolates. Rheumatogenic emm types comprised 16.3% of total isolates. The emm types 12, 4, and 77 were more prevalent among pharyngeal isolates, and the emm types 1, 89, 6, 75, and 11 were more prevalent among nonpharyngeal isolates. The emm types identified belonged to 13 emm clusters, and the 8 most prevalent clusters comprised 97% of all isolates. There were statistically significant decreases in the prevalence of emm types 12, 4, 5, and 61 and increases in the prevalence of emm types 89, 75, and 11, compared with the period 2001 to 2006. The proposed 30-valent GAS vaccine, which is currently in preclinical studies, encompasses 97.2% of the emm types detected in our study and 97.4% of the erythromycin-resistant strains. In addition, it includes 93.3% of the emm types involved in bacteremia. A much greater diversity of GAS emm types was identified in our area than described previously. Seasonal fluctuations and the introduction of new emm types were observed. Continuous surveillance of emm types is needed in order to evaluate the possible benefits of an M protein-based GAS vaccine.

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.

Antimicrobial susceptibility patterns, emm type distribution and genetic diversity of Streptococcus pyogenes recovered in Brazil

Streptococcus pyogenes is responsible for a variety of infectious diseases and immunological complications. In this study, 91 isolates of S. pyogenes recovered from oropharynx secretions were submitted to antimicrobial susceptibility testing, emm typing and pulsed-field gel electrophoresis (PFGE) analysis. All isolates were susceptible to ceftriaxone, levofloxacin, penicillin G and vancomycin. Resistance to erythromycin and clindamycin was 15.4%, which is higher than previous reports from this area, while 20.9% of the isolates were not susceptible to tetracycline. The macrolide resistance phenotypes were cMLSB (10) and iMLSB (4). The ermB gene was predominant, followed by the ermA gene. Thirty-two emm types and subtypes were found, but five (emm1, emm4, emm12, emm22, emm81) were detected in 48% of the isolates. Three new emm subtypes were identified (emm1.74, emm58.14, emm76.7). There was a strong association between emm type and PFGE clustering. A variety of PFGE profiles as well as emm types were found among tetracycline and erythromycin-resistant isolates, demonstrating that antimicrobial resistant strains do not result from the expansion of one or a few clones. This study provides epidemiological data that contribute to the development of suitable strategies for the prevention and treatment of such infections in a poorly studied area.