Group A Streptococcus virulence factors genes in north India & their association with emm type in pharyngitis

Group A streptococcal (GAS) pharyngitis, especially among children, leads to high prevalence of rheumatic fever (RF)/rheumatic heart disease (RHD) in India, as compared to the western world where invasive diseases are common. GAS encodes numerous virulence factors that cause diseases by exhibiting e...

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Bibliographic Details
Published in:Indian journal of medical research (New Delhi, India : 1994) India : 1994), 2011-01, Vol.133 (1), p.110-115
Main Authors: Dhanda, V, Vohra, H, Kumar, R
Format: Article
Language:English
Subjects:
Adolescent
Bacterial genetics
Carrier State
Child
Child, Preschool
Complications and side effects
Genetic aspects
Genotype
Humans
India
Original
Pharyngitis
Pharyngitis - complications
Pharyngitis - microbiology
Physiological aspects
Rheumatic Fever - etiology
Rheumatic Fever - microbiology
Rheumatic heart disease
Risk factors
Streptococcus
Streptococcus pyogenes
Streptococcus pyogenes - genetics
Streptococcus pyogenes - pathogenicity
Virulence (Microbiology)
Virulence Factors - genetics
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Summary:Group A streptococcal (GAS) pharyngitis, especially among children, leads to high prevalence of rheumatic fever (RF)/rheumatic heart disease (RHD) in India, as compared to the western world where invasive diseases are common. GAS encodes numerous virulence factors that cause diseases by exhibiting extraordinary biological diversity. Hence, we studied the virulence factors genes of GAS isolated from the throat of children with pharyngitis and also asymptomatic carriers. Fifty GAS isolates cultured from throats of north Indian children aged 5-15 yr with mild pharyngitis (20), severe pharyngitis (24) and asymptomatic pharyngeal carriers (6), during 2000-2003 along with reference M1 strain were emm typed and characterized for virulence factors genes by PCR. The presence of virulence factors was also checked for their association with emm type in pharyngitis. Twenty emm types, six sequence types, and one non-typeable strain were found circulating in north India. The five most prevalent types were emm 74 (12%), 11 & StI129 (8% each) and emm 68 and NS292 (6% each). The spe B gene was found to be significantly higher (P=0.0007) in opacity factor (OF) negative isolates. emm 3, 11, 77, 86, 87, 109 and StI129 showed maximum virulence factors genes. GAS isolates collected from throats of children from north India possess highly virulent antigens. This study also supports concept of isolate-associated virulence rather than type relatedness.
ISSN:0971-5916