M Protein Gene ( emm Type) Analysis of Group A Beta-Hemolytic Streptococci from Ethiopia Reveals Unique Patterns

Abstract

The genetic diversity of group A streptococcal (GAS) isolates obtained in 1990 from Ethiopian children with various streptococcal diseases was studied by using emm gene sequence analysis. A total of 217 GAS isolates were included: 155 and 62 isolates from throat and skin, respectively. A total of 78 different emm/st types were detected among the 217 isolates. Of these, 166 (76.5%) belonged to 52 validated reference emm types, 26 (11.9%) belonged to 16 already recognized sequence types (st types) and 25 (11.5%) belonged to 10 undocumented new sequence types. Resistance to tetracycline (148 of 217) was not correlated to emm type. Isolation rate of the classical rheumatogenic and nephritogenic strains was low from cases of acute rheumatic fever (ARF) and acute glomerulonephritis (AGN), respectively. Instead, the recently discovered st types were overrepresented among isolates from patients with ARF (3 of 7) and AGN (9 of 16) (P < 0.01) compared to isolates from subjects with tonsillitis and from healthy carriers (10 of 57 and 16 of 90, respectively). In contrast to rheumatogenic strains from the temperate regions, more than half of the isolates from ARF (four of seven) carried the genetic marker for skin preference, emm pattern D, although most of them (six of seven) were isolated from throat. Of 57 tonsillitis-associated isolates, 16 (28%) belonged to emm pattern D compared to <1% in temperate regions. As in other reports emm patterns A to C were strongly associated with throat, whereas emm pattern D did not correlate to skin. This first large-scale emm typing report from Africa has demonstrated a heterogeneous GAS population and contrasting nature of GAS epidemiology in the region.Accurate identification and typing of group A hemolytic streptococci (GAS) is an essential part of epidemiological and pathogenetic studies of streptococcal diseases. A serotyping system based on antigenic variation of a surface exposed M protein and developed by Rebecca Lancefield has been in use since 1928. Although additional serotyping systems, the T and OF typing, were developed as valuable and practical substitutes, the M typing system was considered the gold standard. However, a limited supply of antisera and the high nontypeability rate among isolates, in particular those from the tropics, challenged its continued usage. In recent years, several molecular typing systems have been reported as alternatives for M typing (4,19,25). Most of the knowledge that has been accumulated concerning GAS epidemiology is based on M typing system; hence, a molecular system that correlates with this system has practical significance. The emm typing system (4, 25) which is based on sequence analysis of PCR products of the N-terminal hypervariable region of the M protein gene, concurs with M serotyping almost 1:1 (17). In addition to its simplicity, this typing system has allowed the detection of several previously unknown GAS types from different geographic regions (5,24,32,36).

High Incidence of Invasive Group A Streptococcus Disease Caused by Strains of Uncommon emm Types in Thunder Bay, Ontario, Canada

“…3B). Similar results were observed among Australian remote Aboriginal communities (30) and in Ethiopia (31). Thorough comparisons (underway in our laboratories) of the newly generated genomes for 3 generalist and 2 skin emm types to genomes available in public databases hold the promise of enhancing our understanding of GAS tissue tropism and its role in the different diseases caused by this organism.…”

Rapid Emergence of emm84 among Invasive Streptococcus pyogenes Infections in Finland

“…A recent publication from Hungary described two erythromycin-and clindamycin-sensitive emm84 isolates among invasive infections with fatal outcome (11). Apart from these findings, sporadic infections by emm84 with variability in macrolide resistance have been reported (15,21,28,30). Our findings are limited in some respects.…”

Acute Post-Streptococcal Glomerulonephritis in the Northern Territory of Australia: A Review of 16 Years Data and Comparison with the Literature

“…Sequence type emm 55 GAS was identified as being associated with an outbreak and has also been reported from a previous APSGN outbreak in the NT in 1983 10 and from outbreaks in Trinidad 29 and cases in Ethiopia. 30 A prospective household study swabbing throats and skin sores for GAS in two of the outbreak communities, 14 performed during the period of the APSGN outbreak in 2005, showed a peak of isolation of emm 55 GAS corresponding with the outbreak. This study showed that emm 55 GAS was the predominant type isolated in the communities during this time over a 3-month period and emm 55 GAS was not isolated prior, or subsequently.…”