Prevalence 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 avirulence 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.

1891. Invasive Group A Streptococcus Infections Among Residents of Multiple Nursing Homes—Denver, Colorado, 2017–2018

Background Older adults residing in nursing homes (NH) are at increased risk for invasive group A Streptococcus (GAS) infections due to advanced age, presence of wounds, and comorbidities; approximately one-third of infected patients die. Beginning in 2015, increasing numbers of GAS infections in NH residents and several NH clusters were reported from the Denver metropolitan area. Colorado Department of Public Health and Environment (CDPHE) and CDC investigated to characterize cases and assess if outbreaks resulted from interfacility transmission. Methods We reviewed data from Active Bacterial Core surveillance (ABCs) in the 5-county Denver area from January 2017 to June 2018. We defined a case as isolation of GAS from a normally sterile site in an NH resident. GAS isolates underwent whole-genome sequencing (WGS) at CDC’s Streptococcus Laboratory to determine emm types for genotyping. Among isolates with the same emm type, pairwise single-nucleotide polymorphism (SNP) distances were calculated using Nucmer software. In October 2018, a CDPHE-CDC team assessed infection control at NHs with cases of the most common emm type. Results Over 18 months, among >100 NHs in the Denver area, ≥1 GAS case was identified in 29 NHs, with 6 having ≥3 cases. During this period, 68 cases in NH residents were identified. WGS identified 17 emm types among isolates from these cases; most common was emm11.10 (34%, n = 22), a rare subtype in ABCs. All emm11.10 isolates had nearly identical genomes (average pairwise SNP distance: 3.2), and were isolated from 10 NHs, with 2 NHs having ≥ 4 cases. Multiple infection control lapses were noted during site visits to 8 NHs. Conclusion Multiple outbreaks due to GAS were noted in 5-county Denver area NHs in 2017–2018. WGS of surveillance isolates identified a rarely seen emm subtype 11.10 from multiple facilities with temporal and genomic clustering suggesting interfacility GAS transmission. Disclosures All Authors: No reported Disclosures.

230. Molecular Typing of Streptococcus pyogenes Isolates Collected at Mongolian Hospital (Ulaanbaatar, Mongolia)

Background Streptococcus pyogenes is a significant cause of morbidity and mortality worldwide causing an estimated 1.8 million cases and 517,000 deaths each year. S. pyogenes infections disproportionately affect low-income countries where routine surveillance is not available. The objective of this study was to investigate the molecular epidemiology and antibiotic resistance of clinically relevant S. pyogenes isolates in Ulaanbaatar, Mongolia, to better understand the burden in this under-served population. Methods Clinical S. pyogenes isolates (n = 41) collected at the Bacteriological Reference Laboratory, National Center for Communicable Diseases, Ulaanbaatar, Mongolia, were cultured and characterized using PCR techniques. The emm gene was sequenced and emm type was assigned as per Centers for Disease Control and Prevention (CDC) methods and guideline. Multi-locus sequence typing (MLST) was carried out on selected isolates (n = 15). Antibiotic susceptibility testing (AST) was done via the Vitek-2 system as per manufacturer’s instructions. Results We observed 18 distinct emm types among the 41 S. pyogenes isolates. stG6792.0 was the most common emm type, accounting for more than one-third of the isolates (15/41) followed by emm2.0 (ST55) (5/41) and emm 82.0 (ST314) (2/41). A total of seven sequence types (STs) were detected among 15 tested isolates. The most common ST type was ST55 accounting for one-third of the isolates (5/15). Most of the isolates were susceptible to all tested drugs. Conclusion The findings of this study provided some insights regarding the molecular characteristics of S. pyogenes in Mongolia that will be crucial for future surveillance studies. Five isolates of this study had similar emm types (emm74.0, emm66.0, stG480.0, emm83.1, emm89.0) compared with a previous surveillance study. emm89.0 (ST101) was a major epidemiological isolate in the United States between 2000 and 2004. emm89.0 was also implicated with a recent single-clone outbreak in China. This information suggests the possibility of a shifting epidemiological trend of S. pyogenes on the global stage. The information about antibiotic susceptibility patterns and molecular types can help to devise better treatment strategies for S. pyogenes infections, and potentially inform vaccine development. Disclosures All authors: No reported disclosures.

The Limitations of the Rheumatogenic Concept for Group A Streptococcus: Systematic Review and Genetic Analysis

Background The concept that a minority of group A streptococcus (GAS) emm types are more “rheumatogenic” than others has been widely disseminated. We aimed to provide a comprehensive list of acute rheumatic fever–associated GAS isolates and assess the presence of associated rheumatogenic motifs. Methods Articles reporting GAS emm-type or emm-type–specific antibody responses associated with rheumatic fever were identified from 1 January 1944 to 31 July 2018. The revised Jones criteria were used to define rheumatic fever with a maximum period of 4 weeks between disease onset and microbiological characterization. A database of 175 representative M-protein sequences was used to analyze the protein diversity of rheumatic fever–associated strains in a phylogenetic tree and to identify the presence of 10 previously recognized rheumatogenic motifs. Results We included 411 cases of rheumatic fever, for which microbiological characterization identified 73 different emm types associated with the disease. The classic rheumatogenic emm types represented only 12.3% of the 73 emm types and were responsible for 31.6% of the 411 clinical cases. Rheumatic fever–associated emm types were disseminated throughout the phylogeny, suggesting they belong to various genetic backgrounds. Rheumatic fever–associated motifs were present in only 15.1% of the rheumatic fever–associated emm types and only 24.8% of clinical cases. Conclusions The concept of rheumatogenicity should be extended to include strains other than those classically described. Our results highlight significant knowledge gaps in the understanding of rheumatic fever pathogenesis and suggest that a GAS vaccine candidate should offer broad coverage against a variety of GAS genetic variants in order to protect against this serious sequela.