Imperial College London


Faculty of MedicineDepartment of Infectious Disease

Professor of Infectious Diseases



+44 (0)20 3313 3135s.sriskandan




8N4CWBHammersmith HospitalHammersmith Campus





Gram Positive Pathogenesis

We research the potential mechanisms by which serious Gram positive pathogens cause disease, using the group A streptococcus (Streptococcus pyogenes) as a paradigm. 

Group A strep on agar (Photo: David Goulding WTSI)S. pyogenes causes a spectrum of disease ranging from pharyngitis to invasive infections such as necrotising fasciitis, peripartum sepsis and toxic shock. In the developing world, S. pyogenes infections are associated with development of rheumatic fever, a major cause of valvular heart disease, and glomerulonephritis.

Our research examines the interface between pathogen molecular microbiology and host immune response, and is informed by extreme phenotypes of infection, and epidemiological trends in disease over time, leading to recognition of the importance of recombination-related genome remodelling in disease frequency, and the impacts that changes in human behaviour might have.

SMEZ-2, courtesy Prof Ted Baker, Univ of AucklandOne focus is the role of bacterial superantigens in streptococcal disease, for example, the classical phage-encoded scarlet fever toxins, SPEA  and SPEC, as well as the staphylococcal superantigens that can triggerboth  menstrual and non-menstrual toxic shock. 


Cleavage of CXCL8 by SpyCEP

Evasion of the innate immune response is a trademark of S. pyogenes and we have a keen interest in the function and regulation of the CXC chemokine cleaving protease SpyCEP (cepA), as well as interactions with the complement system, and the potential role of capsule loss and gain in progression of disease and interaction with lymphatic system. 



Professor Sriskandan is theme lead for the NIHR Health Protection Research Unit (HPRU) in Healthcare Associated Infection and Antimicrobial Resistance. Together with Public Health England colleague Neil Woodford, Professor Sriskandan leads the ‘Applied Molecular Bacteriology’ theme, which explores the molecular basis for bacterial infections relevant to the healthcare setting, antimicrobial resistance, and haemolytic streptococal infections that are of public health importance. The HPRU, which was established on 1 April 2014, is a partnership between Imperial College London, Public Health England, Cambridge University Veterinary School, the Wellcome Trust Sanger Institute (WTSI) and Imperial College Health Partners North West London Academic Health Science Network.


  • Puerperal sepsis and the Colebrook Study (see Research tab)
  • SpyCEP and S. pyogenes virulence
  • Molecular anatomy of S. pyogenes and scarlet fever  in UK (with PHE & WTSI)
  • Immunity to S. pyogenes and vaccine options 
  • S. pyogenes capsule and host-pathogen interaction
  • Staphylococcal toxic shock epidemiology 
  • Biobank for adult sepsis admissions  (with Graham Cooke, Hugo Donaldson)
  • Interaction of S. pyogenes with complement  
  • NIHR HPRU  E. coli bacteremia; GBS nosocomial spread; see link above

CUrrent colLaboratIONS

  • Imperial:  James Pease (Leukocyte Biology). 
  • MRC Centre for Molecular Bacteriology and Infection (CMBI). Associate member 
  • Public Health England (Androulla Efstratiou Theresa Lamagni Angela Kearns Neil Woodford)
  • University College London/UCH (Mahdad Noursadeghi) BioAID partner
  • University of Oxford (David Jackson)
  • University of Lund (Lars Bjork and Inga-Maria Frick)  
  • University of Auckland (Siouxsie Wiles, John Fraser and Thomas Proft).
  • Wellcome Trust Sanger Institute (WTSI: Julian Parkhill, Matthew Holden, Stephen Bentley, David Goulding)
  • University of Cambridge (Sharon Peacock)

Selected Publications

Journal Articles

Lynskey NN, Jauneikaite E, Li H-K, et al., 2019, Emergence of dominant toxigenic M1T1 Streptococcus pyogenes clone during increased scarlet fever activity in England: a population-based molecular epidemiological study, Lancet Infectious Diseases, Vol:19, ISSN:1473-3099, Pages:1209-1218

Lynskey NN, Reglinski M, Calay D, et al., 2017, Multi-functional mechanisms of immune evasion by the streptococcal complement inhibitor C5a peptidase, PLOS Pathogens, Vol:13, ISSN:1553-7366

Turner CE, Pyzio M, Song B, et al., 2016, Scarlet Fever Upsurge in England and Molecular-Genetic Analysis in North-West London, 2014, Emerging Infectious Diseases, Vol:22, ISSN:1080-6059

Reglinski M, Lynskey NN, Choi YJ, et al., 2016, Development of a multicomponent vaccine for Streptococcus pyogenes based on the antigenic targets of IVIG, Journal of Infection, Vol:72, ISSN:1532-2742, Pages:450-459

Turner CE, Lamagni T, Holden MT, et al., 2015, Turner et al. Reply to “Emergence of the Same Successful Clade among Distinct Populations of emm89 Streptococcus pyogenes in Multiple Geographic Regions”, Mbio, Vol:6, ISSN:2161-2129

Lynskey NN, Banerji S, johnson L, et al., Rapid lymphatic dissemination of encapsulated group A streptococci via lymphatic vessel endothelial receptor-1 interaction, PLOS Pathogens, Vol:11, ISSN:1553-7366

Moore LS, Leslie A, Meltzer M, et al., 2015, Corynebacterium ulcerans cutaneous diphtheria., The Lancet Infectious Diseases, Vol:15, ISSN:1474-4457, Pages:1100-1107

Turner CE, Abbott J, Lamagni T, et al., 2015, Emergence of a new highly successful acapsular group A Streptococcus clade of the genotype emm89 in the United Kingdom, Mbio, Vol:6, ISSN:2161-2129

Lamb LEM, Sriskandan S, Tan LKK, 2014, Bromine, bear-claw scratch fasciotomies, and the Eagle effect: management of group A streptococcal necrotising fasciitis and its association with trauma, The Lancet Infectious Diseases, Vol:15, ISSN:1474-4457, Pages:109-121

Lynskey NN, Goulding DA, Gierula M, et al., 2013, RocA truncation underpins hyper-encapsulation, carriage longevity and transmissibility of serotype M18 group A streptococci, Plos Pathogens, Vol:9, ISSN:1553-7374

Alam FM, Turner CE, Smith K, et al., 2013, Inactivation of the CovR/S Virulence Regulator Impairs Infection in an Improved Murine Model of Streptococcus pyogenes Naso-Pharyngeal Infection, PLOS One, Vol:8, ISSN:1932-6203

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