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Eraso JM, Olsen RJ, Long SW, Gadd R, Boukthir S, Faili A, Kayal S, Musser JM. Integrative genomic, virulence, and transcriptomic analysis of emergent Streptococcus dysgalactiae subspecies equisimilis (SDSE) emm type stG62647 isolates causing human infections. mBio 2024:e0257824. [PMID: 39417630 DOI: 10.1128/mbio.02578-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2024] [Accepted: 09/16/2024] [Indexed: 10/19/2024] Open
Abstract
Streptococcus dysgalactiae subspecies equisimilis (SDSE) is a Gram-positive bacterial pathogen that infects humans and is closely related to group A streptococcus (GAS). Compared with GAS, far less is known about SDSE pathobiology. Increased rates of invasive SDSE infections have recently been reported in many countries. One SDSE emm type (stG62647) is known to cause severe diseases, including necrotizing soft-tissue infections, endocarditis, and osteoarticular infections. To increase our understanding of the molecular pathogenesis of stG62647 SDSE isolates causing human infections, we sequenced to closure the genomes of 120 stG62647 SDSE isolates. The genomes varied in size from 2.1 to 2.24 Mb pairs. The great majority of stG62647 isolates had IS1548 integrated into the silB gene, thereby inactivating it. Regions of difference, such as mobile genetic elements, were the largest source of genomic diversity. All 120 stG62647 isolates were assayed for virulence using a well-established mouse model of necrotizing myositis. An unexpectedly wide range of virulence was identified (20% to 95%), as assessed by near-mortality data. To explore the molecular mechanisms underlying virulence differences, we analyzed RNAseq transcriptome profiles for 38 stG62647 isolates (comprising the 19 least and most virulent) grown in vitro. Genetic polymorphisms were identified from whole-genome sequence data. Collectively, the results suggest that these SDSE isolates use multiple genetic pathways to alter virulence phenotype. The data also suggest that human genetics and underlying medical conditions contribute to disease severity. Our study integrates genomic, mouse virulence, and RNAseq data to advance our understanding of SDSE pathobiology and its molecular pathogenesis. IMPORTANCE This study integrated genomic sequencing, mouse virulence assays, and bacterial transcriptomic analysis to advance our understanding of the molecular mechanisms contributing to Streptococcus dysgalactiae subsp. equisimilis emm type stG62647 pathogenesis. We tested a large cohort of genetically closely related stG62647 isolates for virulence using an established mouse model of necrotizing myositis and discovered a broad spectrum of virulence phenotypes, with near-mortality rates ranging from 20% to 95%. This variation was unexpected, given their close genetic proximity. Transcriptome analysis of stG62647 isolates responsible for the lowest and highest near-mortality rates suggested that these isolates used multiple molecular pathways to alter their virulence. In addition, some genes encoding transcriptional regulators and putative virulence factors likely contribute to SDSE emm type stG62647 pathogenesis. These data underscore the complexity of pathogen-host interactions in an emerging SDSE clonal group.
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Affiliation(s)
- Jesus M Eraso
- Laboratory for Molecular and Translational Human Infectious Diseases Research, Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York, USA
| | - Randall J Olsen
- Laboratory for Molecular and Translational Human Infectious Diseases Research, Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York, USA
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA
| | - S Wesley Long
- Laboratory for Molecular and Translational Human Infectious Diseases Research, Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York, USA
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA
| | - Ryan Gadd
- Laboratory for Molecular and Translational Human Infectious Diseases Research, Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
| | - Sarrah Boukthir
- CHU de Rennes, Service de Bacteriologie-Hygiène Hospitalière, Rennes, France
- INSERM, CIC 1414, Rennes, France
- Université Rennes 1, Faculté de Médecine, Rennes, France
| | - Ahmad Faili
- INSERM, CIC 1414, Rennes, France
- Université Rennes 1, Faculté de Pharmacie, Rennes, France
- OSS-Oncogenesis, Stress, and Signaling, INSERM 1242, Rennes, France
| | - Samer Kayal
- CHU de Rennes, Service de Bacteriologie-Hygiène Hospitalière, Rennes, France
- INSERM, CIC 1414, Rennes, France
- Université Rennes 1, Faculté de Médecine, Rennes, France
- OSS-Oncogenesis, Stress, and Signaling, INSERM 1242, Rennes, France
| | - James M Musser
- Laboratory for Molecular and Translational Human Infectious Diseases Research, Center for Infectious Diseases, Houston Methodist Research Institute, Houston, Texas, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York, USA
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA
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Infections Caused by Group C and G Streptococcus ( Streptococcus dysgalactiae subsp. equisimilis and Others): Epidemiological and Clinical Aspects. Microbiol Spectr 2019; 7. [PMID: 30977463 DOI: 10.1128/microbiolspec.gpp3-0016-2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Streptococci carrying serogroup C and G antigens, and in particular, Streptococcus dysgalactiae subsp. equisimilis (SDSE), are emerging human pathogens that are increasingly isolated from patients with a myriad of infections that range from mundane to life-threatening. SDSE is microbiologically similar to Streptococcus pyogenes. These streptococci frequently cause infections of the throat and skin and soft tissues. Moreover, they may invade the bloodstream and disseminate widely to many deep tissue sites, including the endocardium. Life-threatening invasive infections due to SDSE, including the streptococcal toxic shock syndrome, occur most frequently in patients with severe underlying medical diseases. Treatment with penicillin is adequate under most circumstances, but treatment failure occurs. SDSE may also be resistant to other antibiotic classes including tetracyclines, macrolides, and clindamycin. Most human infections caused by groups C and G streptococci are transmitted from person to person, but infections due to Streptococcus equi subsp. zooepidemicus (and, rarely, to S. equi subsp. equi) are zoonoses. Transmission of these latter species occurs by animal contact or by contamination of food products and has been associated with the development of poststreptococcal glomerulonephritis. Members of the Streptococcus anginosus group, usually classified with the viridans group of streptococci, are associated with a variety of pyogenic infections.
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