Molecular epidemiology of Streptococcus agalactiae in non-pregnant populations: a systematic review

Founou, Luria Leslie; Khan, Uzma Basit; Medugu, Nubwa; Pinto, Tatiana C. A.; Darboe, Saffiatou; Chendi, Zhu; Founou, Raspail Carrel; To, Ka-Ning; Jamrozy, Dorota; Karampatsas, Konstantinos; Carr, Victoria R.; Pepper, Kevin; Dangor, Ziyaad; Ip, Margaret; Le Doare, Kirsty; Bentley, Stephen D.

doi:10.1099/mgen.0.001140

Cited by 3 publications

(1 citation statement)

References 35 publications

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“…For example, the signature mutations acquired by the highly transmissible Omicron variant of SARS-CoV-2 have resulted in decreased immune control in persons with previous COVID-19 as well as thwarted immunization efforts [5][6][7][8]. With the increasing availability of whole genome sequencing of large cohorts of microbial pathogens, it has become apparent that emerging strains are often separated from precursors by a small number of genetic differences which provide opportunities to dissect molecular mechanisms driving clonal epidemics [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Emergentemm4group AStreptococcusevidences a survival strategy during interaction with immune effector cells

Odo,

Vega,

Mukherjee

et al. 2024

Preprint

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The major gram-positive pathogen group AStreptococcus(GAS) is a model organism for studying microbial epidemics as it causes waves of infections. Since 1980, several GAS epidemics have been ascribed to the emergence of clones producing increased amounts of key virulence factors such as streptolysin O (SLO). Herein, we sought to identify mechanisms underlying our recently identified temporal clonal emergence amongstemm4GAS, given that emergent strains did not produce augmented levels of virulence factors relative to historic isolates. Through the creation and analysis of isoallelic strains, we determined that a conserved mutation in a previously undescribed gene encoding a putative carbonic anhydrase was responsible for the defectivein vitrogrowth observed in the emergent strains. We also identified that the emergent strains survived better inside macrophages and killed macrophages at lower rates relative to the historic strains. Via creation of isogenic mutant strains, we linked the emergent strain “survival” phenotype to the downregulation of the SLO encoding gene and upregulation of themsrABoperon which encodes proteins involved in defense against extracellular oxidative stress. Our findings are in accord with recent surveillance studies which found high ratio of mucosal (i.e., pharyngeal) relative to invasive infections amongstemm4GAS. Inasmuch as ever-increasing virulence is unlikely to be evolutionary advantageous for a microbial pathogen, our data furthers understanding of the well described oscillating patterns of virulent GAS infections by demonstrating mechanisms by which emergent strains adapt a “survival” strategy to outcompete previously circulating isolates.

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Section: Introductionmentioning

confidence: 99%

Emergentemm4group AStreptococcusevidences a survival strategy during interaction with immune effector cells

Odo,

Vega,

Mukherjee

et al. 2024

Preprint

View full text Add to dashboard Cite

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An opportunistic pathogen under stress: how Group B Streptococcus responds to cytotoxic reactive species and conditions of metal ion imbalance to survive

Goh,

Desai,

Thapa

et al. 2024

FEMS Microbiology Reviews

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Group B Streptococcus (GBS; also known as Streptococcus agalactiae) is an opportunistic bacterial pathogen that causes sepsis, meningitis, pneumonia and skin and soft tissue infections in neonates and healthy or immunocompromised adults. GBS is well-adapted to survive in humans due to a plethora of virulence mechanisms that afford responses to support bacterial survival in dynamic host environments. These mechanisms and responses include counteraction of cell death from exposure to excess metal ions that can cause mismetallation and cytotoxicity, and strategies to combat molecules such as reactive oxygen and nitrogen species that are generated as part of innate host defence. Cytotoxicity from reactive molecules can stem from damage to proteins, DNA, and membrane lipids, potentially leading to bacterial cell death inside phagocytic cells or within extracellular spaces within the host. Deciphering the ways in which GBS responds to the stress of cytotoxic reactive molecules within the host will benefit the development of novel therapeutic and preventative strategies to manage the burden of GBS disease. This review summarises knowledge of GBS carriage in humans and the mechanisms used by the bacteria to circumvent killing by these important elements of host immune defence: oxidative stress, nitrosative stress, and stress from metal ion intoxication/mismetallation.

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Emergent emm4 group A Streptococcus evidences a survival strategy during interaction with immune effector cells

Odo,

Vega,

Mukherjee

et al. 2024

Infect Immun

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The major gram-positive pathogen group A Streptococcus (GAS) is a model organism for studying microbial epidemics as it causes waves of infections. Since 1980, several GAS epidemics have been ascribed to the emergence of clones producing increased amounts of key virulence factors such as streptolysin O (SLO). Herein, we sought to identify mechanisms underlying our recently identified temporal clonal emergence among emm4 GAS, given that emergent strains did not produce augmented levels of virulence factors relative to historic isolates. By creating and analyzing isoallelic strains, we determined that a conserved mutation in a previously undescribed gene encoding a putative carbonic anhydrase was responsible for the defective in vitro growth observed in the emergent strains. We also identified that the emergent strains survived better inside macrophages and killed macrophages at lower rates than the historic strains. Via the creation of isogenic mutant strains, we linked the emergent strain “survival” phenotype to the downregulation of the SLO encoding gene and upregulation of the msrAB operon which encodes proteins involved in defense against extracellular oxidative stress. Our findings are in accord with recent surveillance studies which found a high ratio of mucosal (i.e., pharyngeal) relative to invasive infections among emm4 GAS. Since ever-increasing virulence is unlikely to be evolutionarily advantageous for a microbial pathogen, our data further understanding of the well-described oscillating patterns of virulent GAS infections by demonstrating mechanisms by which emergent strains adapt a “survival” strategy to outcompete previously circulating isolates.

show abstract

Molecular epidemiology of Streptococcus agalactiae in non-pregnant populations: a systematic review

Cited by 3 publications

References 35 publications

Emergentemm4group AStreptococcusevidences a survival strategy during interaction with immune effector cells

Emergentemm4group AStreptococcusevidences a survival strategy during interaction with immune effector cells

An opportunistic pathogen under stress: how Group B Streptococcus responds to cytotoxic reactive species and conditions of metal ion imbalance to survive

Emergent emm4 group A Streptococcus evidences a survival strategy during interaction with immune effector cells

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