Epidemiological markers of Streptococcus pyogenes strains in Tunisia

To further understand the epidemiology of Streptococcus pyogenes or group A streptococcus (GAS) infections in Tunisia, phenotypic and genomic markers of GAS isolates, including antibiotic susceptibility, biotypes, T and emm types and toxin gene profiles, have been characterized. A total of 103 isolates, collected between 2000 and 2006, were investigated; 47 were recovered from invasive infections, and 56 from non-invasive infections. Rates of tesistance to tetracycline, erythromycin, clindamycin and rifampin were 70.8%, 4.8%, 4.8% and 0.9%, respectively. High levels of resistance to streptomycin and kanamycin were observed in 1.9% and 4.8% of isolates, respectively. Biotype 3 was most common. Twenty different T patterns were observed, with a predominance of T3/13/B3264, and 38 different emm types. In both invasive and non-invasive isolates, emm118 (9.7%), emm42 (8.7%), emm1 (7.8%), st432 (6.8%), emm28 (5.8%) and emm76 (5.8%) were the most prevalent types; emm1, emm76 and emm18 were mainly observed among invasive infections, whereas emm118 (12.5%), emm42 (10.7%) and emm28 (8.9%) were predominant among non-invasive infections. The speB gene was detected in all isolates, but there were variable frequencies of speA, speC and ssa (20.3%, 32% and 25.2% respectively). Significant associations of emm1, emm18 and emm3 with speA and of emm4 and st432 with ssa were found. This first report from Tunisia revealed a unique emm distribution of GAS that differs from those of other regions. This information on the distribution of such emm types will be useful for the development of an appropriate vaccine in a country where the incidence of rheumatic fever remains high.     

Invasive group A streptococcal infection in children: clinical manifestations and molecular characterization in a French pediatric tertiary care center

Invasive group A streptococcal (GAS) infections have a broad and evolving clinical spectrum, associated with various GAS genotypes and/or virulence factors that are only poorly described in children. We aimed to assess the clinical and molecular characteristics of invasive GAS infections in 28 children admitted from 2000 to 2007 at a large French pediatric tertiary care center. The GAS isolates were characterized molecularly by emm-typing and by the determination of the main virulence factors: speA, speB, speC, smeZ-1, ssa, sic, and silC. The median age of the children was 2.9 years. Osteoarticular infection (OAI) was the main clinical manifestation (n?=?15/28, 53%). emm-1 predominated (n?=?10/28), followed by emm-12, 3, and 4. No significant correlation was found between emm type and clinical manifestations, but emm-1 predominated in cases of OAI (n?=?7/15) and was associated with speA, speB, smeZ-1, and sic virulence factor genes. In this pediatric study, we describe a predominance of OAI associated with emm-1 GAS. Further larger international pediatric studies, including host immunity evaluation, are needed in order to better assess the pathogenesis of GAS infection in children.     

Streptococcus pyogenes bacteraemia, emm types and superantigen profiles

The aim of this study was to investigate the emm types and superantigen profiles of bacteraemic group A streptococcal (GAS; Streptococcus pyogenes) isolates and to detect possible associations between the molecular characteristics of isolates and the clinical presentations of disease. In this population-based study, 87 bacteraemic GAS isolates from adult patients in Pirkanmaa Health District (HD), Finland, during the period 1995–2004 were emm typed and genotyped for superantigen (SAg) profiles. The epidemiological and clinical data of the patients were analysed with the microbiological characterisation data. Among the 87 isolates, 18 different emm types were found. emm1, emm28 and emm81 were the three most common types, covering 52% of isolates. The prevalence of specific emm types showed high variability during the 10-year study period. We could not find any association between the emm type and clinical features of bacteraemic infection, such as underlying diseases, disease manifestations or case fatality. Of nine superantigen genes examined, speA and speC were identified in 20 and 30% of the strains, respectively. No association was found between disease manifestation and the presence of single superantigen genes. The 26-valent GAS vaccine would have covered only 62% of isolates causing invasive disease in Pirkanmaa HD during the study period.     

Updated emm-typing protocol for Streptococcus pyogenes

ObjectivesPCR-based typing of the emm gene Streptococcus pyogenes often results in the amplification of multiple bands. This has resulted in the misclassification of strains into types based on non-emm gene sequences. We aimed to improve the specificity of the emm typing PCR reaction using a primer called CDC3, the sequence for which has been previously used to identify emm genes in silico.MethodsThe proposed primer CDC3 was validated in silico from a global database of 1688 GAS genomes and in vitro with 32 isolates. PCR reactions were performed on genomic DNA from each isolate, using the published CDC1 forward primer with the CDC2 reverse primer or the new CDC3 reverse primer. The products were examined by gel electrophoresis, and representative PCR products were sequenced.ResultsIn 1688 S. pyogenes genomes, the previous CDC2 reverse primer annealed in silico in 1671 emm genes and also in 2109 non emm genes in close proximity, whereas the new CDC3 primer annealed in 1669 emm genes only. The remaining 19 genes without a CDC3 binding site were chimeric emm genes. The PCR pair CDC1+CDC3 produced a single band at appropriate molecular weight in all 32 isolates tested, while the CDC1+CDC2 pair produced more than one band in 13 of 32 isolates (40%).ConclusionsThe new CDC3 primer is more specific for emm genes than the previous CDC2 primer and represents a simple solution to reduce the potential for mistyping S. pyogenes strains.     

Molecular Analysis of an Outbreak of Lethal Postpartum Sepsis Caused by Streptococcus pyogenes

Sepsis is now the leading direct cause of maternal death in the United Kingdom, and Streptococcus pyogenes is the leading pathogen. We combined conventional and genomic analyses to define the duration and scale of a lethal outbreak. Two postpartum deaths caused by S. pyogenes occurred within 24 h; one was characterized by bacteremia and shock and the other by hemorrhagic pneumonia. The women gave birth within minutes of each other in the same maternity unit 2 days earlier. Seven additional infections in health care and household contacts were subsequently detected and treated. All cluster-associated S. pyogenes isolates were genotype emm1 and were initially indistinguishable from other United Kingdom emm1 isolates. Sequencing of the virulence gene sic revealed that all outbreak isolates had the same unique sic type. Genome sequencing confirmed that the cluster was caused by a unique S. pyogenes clone. Transmission between patients occurred on a single day and was associated with casual contact only. A single isolate from one patient demonstrated a sequence change in sic consistent with longer infection duration. Transmission to health care workers was traced to single clinical contacts with index cases. The last case was detected 18 days after the first case. Following enhanced surveillance, the outbreak isolate was not detected again. Mutations in bacterial regulatory genes played no detectable role in this outbreak, illustrating the intrinsic ability of emm1 S. pyogenes to spread while retaining virulence. This fast-moving outbreak highlights the potential of S. pyogenes to cause a range of diseases in the puerperium with rapid transmission, underlining the importance of immediate recognition and response by clinical infection and occupational health teams.     

Genetic Relationships Deduced from emm and Multilocus Sequence Typing of Invasive Streptococcus dysgalactiae subsp. equisimilis and S. canis Recovered from Isolates Collected in the United States

Beta-hemolytic group C and G streptococci cause a considerable invasive disease burden and sometimes cause disease outbreaks. Little is known about the critical epidemiologic parameter of genetic relatedness between isolates. We determined the emm types of 334 Streptococcus dysgalactiae subsp. equisimilis isolates, and attempted emm typing of 5 Streptococcus canis isolates from a recent population-based surveillance for invasive isolates. Thirty-four emm types were observed, including one from S. canis. We formulated multilocus sequence typing (MLST) primers with six of the seven loci corresponding to the Streptococcus pyogenes MLST scheme. We performed MLST with 65 of the 334 surveillance isolates (61 S. dysgalactiae subsp. equisimilis isolates, 4 S. canis isolates) to represent each emm type identified, including 2 to 3 isolates for each of the 25 redundantly represented emm types. Forty-one MLST sequence types (STs) were observed. Isolates within 16 redundantly represented S. dysgalactiae subsp. equisimilis emm types shared identical or nearly identical STs, demonstrating concordance between the emm type and genetic relatedness. However, seven STs were each represented by two to four different emm types, and 7 of the 10 S. dysgalactiae subsp. equisimilis eBURST groups represented up to six different emm types. Thus, S. dysgalactiae subsp. equisimilis isolates were similar to S. pyogenes isolates, in that strains of the same emm type were often highly related, but they differed from S. pyogenes, in that S. dysgalactiae subsp. equisimilis strains with identical or closely similar STs often exhibited multiple unrelated emm types. The phylogenetic relationships between S. dysgalactiae subsp. equisimilis and S. pyogenes alleles revealed a history of interspecies recombination, with either species often serving as genetic donors. The four S. canis isolates shared highly homologous alleles but were unrelated clones without evidence of past recombination with S. dysgalactiae subsp. equisimilis or S. pyogenes.Streptococcus pyogenes, Streptococcus dysgalactiae subsp. equisimilis, and Streptococcus canis are beta-hemolytic pyogenic species that are highly genetically related on the basis of 16S rRNA sequence comparisons, with S. canis being the closest relative to S. pyogenes (39, 16). In recent years, S. dysgalactiae subsp. equisimilis has increasingly been reported as a cause of invasive disease (11, 24, 36), yet the epidemiology and population genetics of this species is poorly understood. S. canis is a commensal and opportunistic pathogen of dogs and other animals (13, 16). S. canis rarely causes disease in humans (7, 39); however, its incidence in human disease is unknown.As with S. pyogenes, S. dysgalactiae subsp. equisimilis isolates are almost always emm typeable (8, 11, 24, 39), with over 50 known emm types (emm types are downloadable from ftp://ftp.cdc.gov/pub/infectious_diseases/biotech/tsemm/). During 1998, we documented the occurrence of emm type stG1389 from an invasive S. canis infection in a dog (unpublished data), and we also recently noticed the same sequence in the GenBank database (GenBank accession number {"type":"entrez-nucleotide","attrs":{"text":"EU195120","term_id":"162424912","term_text":"EU195120"}}EU195120). To our knowledge, this is the only emm type documented from S. canis. Several other virulence determinants are known to be shared between S. dysgalactiae subsp. equisimilis and S. pyogenes (9, 10, 12, 19, 25). S. pyogenes exotoxin genes have been detected within S. dysgalactiae subsp. equisimilis and S. canis, and lysogenic transfers of prophages carrying superantigen genes between S. pyogenes and S. dysgalactiae subsp. equisimilis have been documented (20, 22, 31, 33, 38).M-protein gene (emm) typing has been useful as a simple genetic tool for identifying and resolving Streptococcus pyogenes strains for epidemiologic studies (18, 27, 29, 35). This is consistent with the observation that within given regions, group A streptococcal (GAS) emm types are often restricted to only one or two defined clonal complexes, and often, these common clones are predominant in diverse locations (15) (available at www.mlst.net). In direct contrast, a previous report described a poor concordance between the emm type and genetic relatedness in S. dysgalactiae subsp. equisimilis (23). That report additionally showed evidence of the lateral movement of housekeeping genes between the two species, with the majority of gene transfer events involving S. pyogenes donors and S. dysgalactiae subsp. equisimilis recipients.We recently carried out population-based surveillance for invasive disease caused by beta-hemolytic streptococci of groups other than A and B, and the results from 2 years of surveillance were reported (7). The majority of case isolates (about 80%) were S. dysgalactiae subsp. equisimilis. The only other emm-typeable species identified by active surveillance was S. canis, of which only one of five S. canis isolates was emm typeable. We found that the burden of invasive disease caused by S. dysgalactiae subsp. equisimilis is comparable to that caused by invasive GAS (29) and affects similar adult populations (7). In the work presented here, we describe newly discovered relationships between multilocus sequence types and emm types among an expanded collection of invasive S. dysgalactiae subsp. equisimilis and S. canis isolates recovered in the United States from 2002 to 2005.     

Characterization of levofloxacin non-susceptible clinical Streptococcus pyogenes isolated in the central part of Italy

We investigated the prevalence, genetics, and clonality of fluoroquinolone non-susceptible isolates of Streptococcus pyogenes in the central part of Italy. S. pyogenes strains (n?=?197) were isolated during 2012 from patients with tonsillopharyngitis, skin, wound or invasive infections and screened for fluoroquinolone non-susceptibility (resistance to norfloxacin and levofloxacin minimum inhibitory concentration (MIC) = 2 mg/L) following EUCAST guidelines. First-step topoisomerase parC and gyrA substitutions were investigated using sequencing analysis. Clonality was determined by pulsed field gel electrophoresis (PFGE; SmaI digestion) and by emm typing. The fluoroquinolone non-susceptible phenotype was identified in 18 isolates (9.1 %) and correlated with mutations in parC, but not in gyrA, the most frequent leading to substitution of the serine at position 79 with an alanine. Most of the fluoroquinolone non-susceptible isolates belonged to the emm-type 6, even if other emm-types were also represented (emm75, emm89, and emm2). A significant level of association was measured between PFGE and both emm type and substitutions in parC. The prevalence of fluoroquinolone non-susceptible Streptococcus pyogenes isolates in Italy is of concern and, although the well-known emm type 6 is dominant, other types are appearing and spreading.     

Streptococcus pyogenesstrains containingemm12 andemm55 possess a novel gene coding for distantly related SIC protein

Streptococcus pyogenesinfection and acute glomerulonephritis (AGN), a non-suppurtave disease, are endemic in the Aboriginal people of the Northern Territory (NT) of Australia. Vir typing, a locus-specific polymerase chain reaction (PCR)-based typing method [Gardiner, Hartas, Currieet alPCR Meth Appl19954: 288–93], has revealed high divergence among the NT streptococcal strains. A total of 76 Vir types (VTs) representing about 95% of the NT isolates were screened forsic, a gene for streptococcal inhibitor of complement function, by PCR and hybridization. This revealed that seven VTs are positive forsic, and there are two classes of the gene: those closely related tosic(CRS) originally described by Akesson, Sjoholm & Bjorck [J. Biol. Chem.1996271: 1081–8] and those distantly related tosic(DRS). Among the CRS-positive VTs, VT16, VT78 and VT91 haveemm(gene for M protein) encoding type 1 M protein or related specificity, and VT8 and VT101 containemm57 or related alleles. Chromosomal location of CRS inemm57 is different from that inemm1 or related strains. The DRS-positive VT18 and VT52 containedemm55 andemm12 respectively, which are phylogenetically related. Strains ofS. pyogenestypes 1, 12, 55 and 57 are known to be associated with AGN. Restricted distribution of CRS and DRS among the M types historically associated with AGN suggests that thesesicalleles may have a role in AGN pathogenesis.     

Microbiological investigation of a hospital outbreak of invasive group A streptococcal disease in Krakow,Poland

The present study reports the epidemiological investigations undertaken in one of Krakow’s city hospitals regarding the source of infection and the routes of transmission of a group A streptococcus (Streptococcus pyogenes), using fluorescent in situ hybridization as a rapid method for detecting S. pyogenes carriage in the medical personnel involved. Four patients from the gynaecology department and two patients from the surgery department presented with clinical signs of infection. Characteristics of the S. pyogenes strains isolated from patients and from one medical staff member, including the emm gene and superantigens encoding genes, are described. All patients (four confirmed and two probable cases) survived; the operating theatre aid was identified as an S. pyogenes carrier and the source of the infections.     

Variability in the Distribution of Genes Encoding Virulence Factors and Putative Extracellular Proteins of Streptococcus pyogenes in India,a Region with High Streptococcal Disease Burden,and Implication for Development of a Regional Multisubunit Vaccine

Streptococcus pyogenes causes a wide variety of human diseases and is a significant cause of morbidity and mortality. Attempts to develop a vaccine were hampered by the genetic diversity of S. pyogenes across different regions of the world. This study sought to identify streptococcal antigens suitable for a region-specific vaccine in India. We used a two-step approach, first performing epidemiological analysis to identify the conserved antigens among Indian isolates. The second step consisted of validating the identified antigens by serological analysis. The 201 streptococcal clinical isolates from India used in this study represented 69 different emm types, with emm12 being the most prevalent. Virulence profiling of the North and South Indian S. pyogenes isolates with a custom-designed streptococcal virulence microarray identified seven conserved putative vaccine candidates. Collagen-like surface protein (SCI), putative secreted 5′-nucleotidase (PSNT), and C5a peptidase were found in 100% of the isolates, while R28, a putative surface antigen (PSA), and a hypothetical protein (HYP) were found in 90% of the isolates. A fibronectin binding protein, SfbI, was present in only 78% of the isolates. In order to validate the identified potential vaccine candidates, 185 serum samples obtained from patients with different clinical manifestations were tested for antibodies. Irrespective of clinical manifestations, serum samples showed high antibody titers to all proteins except for SCI and R28. Thus, the data indicate that PSNT, C5a peptidase, PSA, HYP, and SfbI are promising candidates for a region-specific streptococcal vaccine for the different parts of India.     

Prevalence and molecular diversity of invasive <Emphasis Type="Italic">Streptococcus dysgalactiae</Emphasis> and <Emphasis Type="Italic">Streptococcus pyogenes</Emphasis> in a German tertiary care medical centre

Prevalence of invasive ß-haemolytic streptococci (BHS) at a tertiary care hospital and molecular diversity of S. pyogenes and S. dysgalactiae was studied. Between 2012 and 2016, all blood culture sets (n?=?55,839), CSF (n?=?8413) and soft tissue (n = 20,926) samples were analysed for BHS positivity using HYBASE software. Molecular profiles of 99 S. pyogenes and S. dysgalactiae were identified by sequencing of M protein genes (emm types) and multiplex PCR typing of 20 other virulence determinants. Streptococci contributed to 6.2% of blood, 10.7% of CSF and 14.5% of soft tissue isolates, being among the most common invasive isolates. The overall rates of invasive S. pyogenes, S. agalactiae, S. dysgalactiae and S. pneumoniae were 2.4, 4.4, 2.1, and 5.3%. Whereas S. pneumoniae was 1.5% more common in CSF samples, BHS isolates were 2-fold and 11-fold higher in bacteraemia and invasive soft tissue infections. Genetic BHS typing revealed wide molecular diversity of invasive and noninvasive group A and group G BHS, whereas one emm-type (stG62647.0) and no other virulence determinants except scpA were detected in invasive group C BHS. BHS were important invasive pathogens, outpacing S. pneumoniae in bacteraemia and invasive soft tissue infections. The incidence of S. dysgalactiae infections was comparable to that of S. pyogenes even with less diversity of molecular virulence. The results of this study emphasise the need for awareness of BHS invasiveness in humans and the need to develop BHS prevention strategies.     

Preliminary validation of a novel high-resolution melt-based typing method based on the multilocus sequence typing scheme of Streptococcus pyogenes

The major limitation of current typing methods for Streptococcus pyogenes, such as emm sequence typing and T typing, is that these are based on regions subject to considerable selective pressure. Multilocus sequence typing (MLST) is a better indicator of the genetic backbone of a strain but is not widely used due to high costs. The objective of this study was to develop a robust and cost-effective alternative to S. pyogenes MLST. A 10-member single nucleotide polymorphism (SNP) set that provides a Simpson's Index of Diversity (D) of 0.99 with respect to the S. pyogenes MLST database was derived. A typing format involving high-resolution melting (HRM) analysis of small fragments nucleated by each of the resolution-optimized SNPs was developed. The fragments were 59–119 bp in size and, based on differences in G+C content, were predicted to generate three to six resolvable HRM curves. The combination of curves across each of the 10 fragments can be used to generate a melt type (MelT) for each sequence type (ST). The 525 STs currently in the S. pyogenes MLST database are predicted to resolve into 298 distinct MelTs and the method is calculated to provide a D of 0.996 against the MLST database. The MelTs are concordant with the S. pyogenes population structure. To validate the method we examined clinical isolates of S. pyogenes of 70 STs. Curves were generated as predicted by G+C content discriminating the 70 STs into 65 distinct MelTs.     

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.     

Description of macrolide-resistant and potential virulent clones of Streptococcus pyogenes causing asymptomatic colonization during 2000–2006 in the Lisbon area

The asymptomatic oropharyngeal colonization rate by Streptococcus pyogenes was 10.7% in children (901 among 8,405 children 0–16 years old) and 3.3% in adults (37 among 1,126 households of children) in the Lisbon area during 2000–2006. Macrolide-resistant S. pyogenes from children (n = 149) was variable with time: 9.8–10.7% in 2000–2002, 28.1% in 2003, 19.6–2.7% in 2004–2005 and 14.6% in 2006. Eight lineages (97.3% of isolates) were identified based on at least 80% similarity of PFGE patterns, T types, emm types and multilocus sequence types (ST). The elevated frequency of macrolide resistance was associated with M phenotype lineages I (emm12/ST36) and V (emm4, emm75/ST39 and a novel emmstMrp6 type) and with one cMLS_B lineage IV (emm28/ST52) known to be associated with upper respiratory tract and invasive infections. Significant associations (p < 0.05) between emm type/virulence genotype were found, such as emm1/speA ⁺ ssa ^-, emm4/ssa ⁺ prtF1 ⁺, emm12/speA ^- ssa ^-. The high prevalence (>20%) of speC, prtF1 or ssa was probably caused either by clonal dissemination (speC), or to horizontal gene transfer events (prtF1 and ssa). This report contributes to a better understanding of the molecular epidemiology and evolution of macrolide-resistant S. pyogenes causing symptom-free oropharyngeal colonization. These colonizing strains carry macrolide resistance and virulence genes capable of being transferred to other bacterial species sharing the same niche.     

Group A Streptococcal Vir Types Are M-Protein Gene (emm) Sequence Type Specific

The M-protein genes (emm genes) of 103 separate impetiginous Streptococcus pyogenes isolates were sequenced and the sequence types were compared to the types obtained by Vir typing. Vir typing is based on restriction fragment length polymorphism (RFLP) analysis of a 4- to 7-kb pathogenicity island encoding emm and other virulence genes. By using both HaeIII and HinfI to generate RFLP profiles, complete concordance between Vir type and emm sequence type was found. Comparison of the emm sequences with those in GenBank revealed new sequence types sharing less than 90% identity with known types. Diversity in the emm sequence was generated by corrected frameshift mutations, point mutations, and small in-frame mutations.     

Epidemiology Analysis of Streptococcus pyogenes in a Hospital in Southern Taiwan by Use of the Updated emm Cluster Typing System

emm typing is the most widely used molecular typing method for the human pathogen Streptococcus pyogenes (group A streptococcus [GAS]). emm typing is based on a small variable region of the emm gene; however, the emm cluster typing system defines GAS types according to the nearly complete sequence of the emm gene. Therefore, emm cluster typing is considered to provide more information regarding the functional and structural properties of M proteins in different emm types of GAS. In the present study, 677 isolates collected between 1994 and 2008 in a hospital in southern Taiwan were analyzed by the emm cluster typing system. emm clusters A-C4, E1, E6, and A-C3 were the most prevalent emm cluster types and accounted for 67.4% of total isolates. emm clusters A-C4 and E1 were associated with noninvasive diseases, whereas E6 was significantly associated with both invasive and noninvasive manifestations. In addition, emm clusters D4, E2, and E3 were significantly associated with invasive manifestations. Furthermore, we found that the functional properties of M protein, including low fibrinogen-binding and high IgG-binding activities, were correlated significantly with invasive manifestations. In summary, the present study provides updated epidemiological information on GAS emm cluster types in southern Taiwan.     

Arrangement and number of clustered regularly interspaced short palindromic repeat spacers are associated with erythromycin susceptibility in emm12, emm75 and emm 92 of group A streptococcus

Clustered regularly interspaced short palindromic repeats (CRISPR) are composed of numerous repeat-spacer units and are considered a prokaryotic defence system against foreign nucleic acids. Since antibiotic-resistant genes are frequently encoded in foreign nucleic acids, the aim of this study was to test whether erythromycin susceptibility in group A streptococcus (<Streptococcus pyogenes) is associated with characteristics of CRISPR elements. Erythromycin susceptibility of 330 isolates collected between 1997 and 2003 was analysed. Among 29 emm types, emm12, emm75 and emm92 showed significant changes in erythromycin-resistance rates. By sequencing the spacers from two CRISPR loci, spacer contents in emm12, emm75 and emm92 strains were associated with erythromycin susceptibility. Strains with fewer spacers were more resistant to erythromycin. Moreover, in emm4 strains, which showed no significant change in their annual erythromycin-resistance rate, CRISPR type and number of spacers were not correlated with erythromycin susceptibility. These results highlight a novel association between CRISPR spacer content and erythromycin susceptibility in group A streptococcus.     

Outbreak of Streptococcus pyogenes emm type 58 in a high dependency unit of a level-1 trauma center of India

Background and Aims:

Group A Streptococcus (GAS) can cause illnesses ranging from self-limited to severe, life-threatening, invasive infections. The objective of the following study was to investigate a suspected Streptococcus pyogenes outbreak in a high dependency unit (HDU) of our trauma center.

Materials and Methods:

All the isolates of beta hemolytic Streptococci were identified by standard microbiological methods, Vitek 2 system and latex agglutination tests. Antimicrobial susceptibility testing was performed as recommended by Clinical Laboratory Standards Institute. Exotoxin genes, including speA, speB, speC, speF, smeZ, ssa, speG, speH, speJ, speL, speM and speI were detected by polymerase chain reaction (PCR). The emm types of isolates of S. pyogenes were determined by sequencing the variable 5’ end of emm gene after amplification by PCR.

Results:

In a 28 bedded poly-trauma ward with a four bedded HDU three out of four patients developed S. pyogenes emm type 58 infection. The strain was macrolide and tetracycline resistant and produced the Streptococcal pyrogenic exotoxins speB, speC, speG, speF and smeZ. Surveillance sampling was done for investigation from patients, health-care workers and environmental samples.

Conclusion:

An outbreak of GAS infections was established caused by the uncommonly reported emm type 58. The outbreak was controlled by prompt treatment, intensive surveillance, feedback and training.     

Emergence of type I restriction modification system‐negative emm1 type Streptococcus pyogenes clinical isolates in Japan

Streptococcus pyogenes emm1 type is the dominant cause of streptococcal toxic shock syndrome (STSS) in Japan and many other developed countries. Recently, the number of STSS patients in Japan was reported to be increasing. Hence, we analyzed the S. pyogenes clinical isolates detected in Japan after 2005. We found that the regions encoding the Spy1908–1910 two‐component regulatory system and the adjacent type I restriction modification system were deleted in some emm1 type isolates. The isolates with the deletion were detected only in the emm1 strains that were isolated between 2010 and 2013, but not before 2010. Twenty‐six of 46 (56.5%) emm1 type isolates were isolated in 2010–2013, and among these isolates, five of seven (71.4%) emm1 type STSS isolates were shown to have that deletion. PFGE and PCR analysis for the presence of several pyrogenic exotoxin‐related genes suggested that the emm1 isolates with and without the deletion shared the same genetic background. The emm1 isolates with the deletion could incorporate exogenous plasmids by experimental electroporation transformation far more efficiently. These results suggested that the novel emm1 isolates have occupied a fairly large part of total emm1 isolates.