Clinical and epidemiological aspects of invasive Streptococcus pyogenes infections in Denmark during 2003-2004

Dept. of Medical Microbiology, Inst. of Laboratory Medicine, Lund University, Lund, Sweden; Streptococcus Unit, Statens Serum Institut, Copenhagen, Denmark; German National Reference Center for Streptococci, Dept. of Medical Microbiology, University Hospital RWTH Aachen, Aachen, Germany; National Center for Antimicrobials and Infection Control, Statens Serum Institut, Denmark; Dept. of Anaesthesia and Intensive Care, Copenhagen University Hospital Gentofte, Denmark

^* To whom correspondence should be addressed. Email: aftab.jasir{at}med.lu.se.

	Abstract

Active surveillance of invasive group A streptococcal (GAS) infections was conducted in Denmark during 2003 -2004 as a part of the Strep-EURO initiative. The main objectives were to improve understanding of the epidemiology of invasive GAS disease in Denmark. During the two years, 278 cases were reported, corresponding to a mean annual incidence of 2.6 cases per 100,000 inhabitants. The vast majority of isolates, 253 (91%) were from blood, remaining 25 (9%) being from CSF, joint, or other normally sterile sites. The mean case fatality rate (CFR) was 20% being higher in patients more than 70 years of age (36.5%). For streptococcal toxic shock syndrome (STSS) and necrotising fasciitis (NF) the CFR was 53% and 25%, respectively. Out of 16 T-types recorded, three predominated: T28 (23%), T1 (22%), and the cluster T3/13/B3264 (14%). Among 29 different emm-types, emm28 and emm1 accounted for 51% of strains, followed by emm3 (11%), emm89 (7%), and emm12 (5.5%). Low resistance rates were detected for MLS_B antibiotics (3%) and tetracycline (8%); two isolates exhibited co-resistance to tetracycline and macrolides. Of nine pyrogenic exotoxin (superantigen) genes examined, speA and speC were identified in 58% and 40% of the strains, respectively; either of the genes was present in all strains causing STSS. Most strains harboured speG (99%). ssa accounted for 14% of the isolates only. In Denmark, as in comparable countries, GAS invasive disease shows a sustained, high endemicity, with involvement of both established and emerging streptococcal emm and T-types.