Molecular epidemiology of group A streptococcus from pharyngeal isolates in Auckland, New Zealand, 2013

The New Zealand medical journal 01/2014; 127(1388):55-60.
Source: PubMed


To describe the molecular epidemiology of emm types associated with circulating pharyngeal group A streptococcus (GAS) isolates in Auckland, New Zealand.
GAS isolates were collected over a 10-day period from a community pathology provider in Auckland. PCR analysis and sequencing of the emm gene was performed at the Institute of Environmental Science and Research.
A total of 52 emm types were identified from 278 GAS isolates. The three most common emm types were emm1, emm89 and emm12. Overall, the experimental 30-valent GAS M protein vaccine covered 19 / 52 (37%) of emm types in our study.
Our study provides baseline data on the circulating pharyngeal GAS emm types in Auckland. Future clinical and molecular surveillance of GAS pharyngitis is essential in the context of ongoing GAS vaccine development.

5 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Group A Streptococcus (GAS) is responsible for a wide range of diseases ranging from superficial infections, such as pharyngitis and impetigo to life-threatening diseases like toxic shock syndrome and acute rheumatic fever (ARF). GAS pili are hair-like extensions protruding from the cell surface and consist of highly immunogenic structural proteins; the backbone pilin (BP) and one or two accessory pilins (AP1 and AP2). The protease-resistant BP builds the pilus shaft and has been recognised as the T-antigen, which forms the basis of a major serological typing scheme that is often used as a supplement to M-typing. A previous sequence analysis of the bp gene (tee gene) in 39 GAS isolates revealed 15 different bp/tee types. In this study, we sequenced the bp/tee gene from 101 GAS isolates obtained from patients with pharyngitis, ARF or invasive disease in New Zealand. We found 20 new bp/tee alleles and 4 new bp/tee types/subtypes. No association between bp/tee type and clinical outcome was observed. We confirmed earlier reports that emm-type and tee-type are strongly associated, but we also found exceptions, where multiple tee-type can be found in certain M/emm type strains, such as M/emm89. We also report, for the first time, the existence of a chimeric bp/tee allele, which was assigned into a new subclade (bp/tee 5.1). A strong sequence conservation of the bp/tee gene was observed within the individual bp/tee types/subtypes (>97% sequence identity), as well as between historical and contemporary New Zealand, and international GAS strains. This temporal and geographical sequence stability provides further evidence for the potential use of the BP/T-antigen as a vaccine target.
    Journal of Medical Microbiology 09/2014; 63(Pt_12). DOI:10.1099/jmm.0.080804-0 · 2.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives To analyse the incidence, demographics and molecular epidemiology of invasive group A streptococcal (GAS) disease in New Zealand between 2002 and 2012. Methods Using laboratory-based surveillance data, invasive GAS isolates were identified from the Institute of Environmental Science and Research, New Zealand. Hospitalization and mortality data were obtained from the New Zealand Ministry of Health. Molecular typing was performed by sequence analysis of the emm gene. Results The incidence of invasive GAS infections increased from 3.9 per 100,000 population in 2002 to 7.9 per 100,000 population (P < 0.001) in 2012. The incidence was highest in the over 75-year age group, and in Pacific peoples. There was temporal variation in emm types associated with invasive GAS disease, with emm1 being the overall predominant emm type. The diversity of emm types varied significantly according to ethnicity. Overall, 59% of GAS isolates were theoretically covered by an experimental M-protein vaccine. Conclusions Our study provides valuable data on the epidemiology of invasive GAS disease in New Zealand, and represents one of the few studies to assess such longitudinal data across an entire nation. The increase in invasive GAS disease is concerning, and reasons for this should be explored further.
    Journal of Infection 09/2014; 70(2). DOI:10.1016/j.jinf.2014.09.001 · 4.44 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Group A Streptococcus (GAS) strains are lately classified on the basis of sequence variations in the emm gene encoding the M protein, but despite the high number of distinct emm genotypes, the spectrum of phenotypes varying from invasive suppurative to non-suppurative GAS-related disorders has still to be defined. The relationship of GAS types with the uprising of acute rheumatic fever (ARF), a multisystemic disease caused by misdirected anti-GAS response in predisposed people, is also obscure. Studies published over the last 15 years were retrieved from PubMed using the keywords: "Streptococcus pyogenes" or "group A Streptococcus" and "acute rheumatic fever": the prevalence of peculiar emm types across different countries of the world is highly variable, depending on research designs, year of observation, country involved, patients' age, and gender. Most studies revealed that a relatively small number of specific emm/M protein types can be considered "rheumatogenic", as potentially characterized by the possibility of inducing ARF, with remarkable differences between developing and developed countries. The association between emm types and post-streptococcal manifestations is challenging, however surveillance of disease-causing variants in a specific community with high rate of ARF should be reinforced with the final goal of developing a potential primary prophylaxis against GAS infections. Copyright © 2015 Elsevier B.V. All rights reserved.
    Autoimmunity Reviews 03/2015; 14(7). DOI:10.1016/j.autrev.2015.03.001 · 7.93 Impact Factor
Show more

Similar Publications