Group G streptococcal bacteraemia and emm types
Abstract number: P1824
Rantala S., Vähäkuopus S., Vuopio-Varkila J., Vuento R., Syrjänen J.
Objectives: We studied clinical features and severity of disease in bacteraemia caused by group G beta-haemolytic streptococci (GGS) in relation to emm type of the isolates.
Methods: The medical records of all adult (over 16 years of age) patients in the Pirkanmaa Health District (460 000 inhabitants), Finland, with one or more blood cultures positive for GGS during the 10-year period from January 1995 to December 2004 were retrospectively reviewed. Mortality was recorded within 30 days from the positive blood culture. A severe disease was defined as death during the 30 days or admittance to Intensive Care Unit. Disseminated intravascular coagulation (DIC) was defined as a platelet count lower than 100 x 109 /l. The streptococci were classified for their group antigen G and the isolates were emm sequenced.
Results: GGS grew in 128 cultures; 126 of isolates were analysed, two are underway. 14 different emm types were found; stG480 (27 isolates), stG6 (22 isolates), stG485 (17 isolates), stG643 (10 isolates), stC6979 (9 isolates), stG166b (6 isolates), and stC74a (5 isolates) were the seven most common emm types covering 76% of all isolates. Fifteen isolates remained nontypable (NT). We divided bacteraemia episodes into two groups: those caused by the seven most common emm types (96 episodes, ie. common types) and those caused by less common or NT emm types (30 episodes, ie. rare types). Age or underlying diseases did not differ between the groups. Instead, patients with an ultimately or rapidly fatal underlying disease were more often linked to bacteraemia caused by rare types than that caused by common types [18/30 vs. 36/96; OR 2.5 (95% CI 1.1 to 5.8)]. Mortality was higher in bacteraemia caused by rare types than that caused by common types [10/30 vs. 9/96; OR 4.8 (1.7 to 13.2)]. A severe disease was caused more often by rare types than common types [12/30 vs. 10/96; OR 5.7 (2.0 to 14.2)]. The association between a severe disease and a rare type remained statistically significant also in a multivariate model which was adjusted for the occurrence of an ultimately or rapidly fatal underlying disease and for age [OR 4.8 (1.7 to 13.2)]. DIC was also a more common finding in patients suffering from bacteraemia caused by rare types than common types [5/30 vs. 1/96; OR 19.0 (2.1 to 170.1)].
Conclusion: GGS bacteraemia is caused by variety of emm types, seven of them covering 76% of all isolates. Rare emm types were associated with a more severe disease.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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