Factors associated with Group A <it>Streptococcus emm </it>type diversification in a large urban setting in Brazil: a cross-sectional study

• Main Authors: Reis Mitermayer G, Andrade Aurelio N, Ramos Regina T, Reis Joice N, Tartof Sara Y, Riley Lee W
• Format: Article
• Language: English
• Published: BMC 2010-11-01
• Series: BMC Infectious Diseases
• Online Access: http://www.biomedcentral.com/1471-2334/10/327

<p>Abstract</p> <p>Background</p> <p>Group A <it>Streptococcus </it>(GAS) strain diversity varies across different regions of the world, according to low versus high-income countries. These differences may be related to geographic, environmental, socioeconomic, or host-related factors. However, local factors may also affect strain diversity. We compared the <it>emm </it>types of GAS isolates from children with and without sore throat in one large urban setting in Brazil.</p> <p>Methods</p> <p>Children 3-15 years of age were consecutively recruited from slum and non-slum pediatric outpatient clinics between April-October, 2008. Throat cultures were performed and data intake forms were completed. GAS isolates were typed by <it>emm </it>sequencing.</p> <p>Results</p> <p>From 2194 children, 254 (12%) GAS isolates were obtained. Of 238 GAS isolates that were <it>emm</it>-typed, 61 unique <it>emm </it>types were identified. Simpson's diversity index of the <it>emm </it>types was higher among isolates from slum children [97% (96%-98%)] than those of non-slum children [92% (89%-96%)]. Two <it>emm </it>types (66.0, 12.0) were more frequently isolated from children with sore throat (p < 0.05), and one <it>emm </it>type (27G.0) demonstrated a protective effect.</p> <p>Conclusions</p> <p>The <it>emm </it>type diversity from children attending slum clinics resembled the <it>emm </it>diversity of low income countries rather than that of children attending a non-slum clinic in the same city. Local factors, such as crowding, may enhance the frequency of GAS transmission and horizontal gene transfers that contribute to increased strain diversity in the slums. GAS vaccine coverage and control of GAS infections will need to take these local factors and strain differences into consideration.</p>