Clonal Diversity of Group A Streptococci Causing Human Infections in Southern India.

Reena Raj Kumari, B (2009) Clonal Diversity of Group A Streptococci Causing Human Infections in Southern India. Doctoral thesis, Christian Medical College, Vellore.


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GAS, commonly known as Group A Streptococcus (GAS), is a bacterial pathogen that infects the throat and skin and is able to cause a wide range of diseases in humans [1]. This ranges from pharyngitis (strep throat) and impetigo to more serious and fatal diseases such as acute post streptococcal glomerulonephritis, rheumatic heart disease and invasive diseases. Acute rheumatic fever (RF) is an autoimmune sequela of GAS infection which occurs in approximately 0.3- 3% of GAS infected patients aged between 5 and 15 years of all streptococcal sore throats [2]. GAS is a major global pathogen with a variety of clinical manifestations. Over 7 million visit pediatricians each year in the United States alone for complaints of “sore throat” and almost a fourth of these visits are due to streptococcal pharyngitis [3]. Acute rheumatic fever and rheumatic heart disease, which are well recognized non-suppurative sequelae of infection by this organism, have devastating public health implications worldwide. An apparent resurgence of acute rheumatic fever in the mid 1980s in the US [4, 5] with ongoing new cases [6] and estimated 10,000 cases of invasive streptococcal disease reported annually in the US [7] confirm that an improved standard of living and use of antibiotic have not adequately reduced the impact of GAS infections. Thus, there is need for a safe, efficacious and cost effective vaccine against GAS infection. The clonal diversity of GAS causing human infections in Southern India (or) population genetic structure of GAS disease in South India. These facets of this study have been poorly reported from India. This is the first study in India utilizing the technique multi locus sequence typing (MLST) for GAS which increased the information on diversity of GAS infections. From our study we have found out GAS isolates in relation to emm typing, shows high heterogeneity. Our MLST studies indicated that, there are new sequence types found which were not reported in any part of the world. It also depicted the high heterogeneity found within individual emm types in respect to sequence types. There was no association found between sequence types and to their site of isolation. The sequence types found based on their allelic profile of GAS isolates clearly explained there is no association between their STs and their site of isolation. eBURST population snap shot identified the clonal complexes present in the GAS isolates from the community and the hospital isolates and indicated that two third of the GAS population are clonal in nature with young clonal complexes.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Clonal; Diversity; Streptococci; Causing; Human; Infections; Southern India.
Subjects: MEDICAL > Microbiology
Depositing User: Ravindran C
Date Deposited: 18 Jun 2017 07:20
Last Modified: 21 Jun 2017 03:04

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