Invasive Group B Streptococcal Disease in Non-pregnant Adults, Réunion Island, 2011

• Our study reveals one of the highest incidence rates of iGBS disease ever reported in non-pregnant adults (10.1 per 100,000).
• This high incidence rate can be explained by the combination of several risk factors highly prevalent in Réunion island, such as obesity, type 2 diabetes mellitus, black (African) descent or hyper precocious sexuality.
• The most prominent clinical forms were osteo-articular and skin/soft tissue infections, as a consequence of diabetic foot infection.

SummaryObjectivesWhile the prevalence of Group B streptococcus (GBS) colonization is important, little is known about invasive GBS (iGBS) disease in tropical areas. Our objective was to assess the burden of iGBS disease among non-pregnant adults.MethodsA prospective hospital-based study of all non-pregnant adult patients with iGBS disease was conducted between January and December 2011 in Saint Pierre, Réunion Island, to assess its cumulative incidence rate (CIR). Capsular serotyping and multilocus sequence typing were performed to characterize GBS isolates. Case-control study was done to identify risk factors.ResultsThe overall CIR of iGBS disease was 10.1 per 100,000. The CIR in elderly patients (≥ 65 yrs) was estimated at 40.6 per 100.000, and that of adults (15-64 years) at 6.7 per 100.000. Aboriginal origin in the Indian Ocean and overweight were both associated with iGBS disease. The most prominent clinical forms were osteo-articular and skin/soft tissue infections, as a consequence of diabetic foot. The serotypes were classic, type-Ia being the most prevalent. The hyper virulent ST-17 (CC17) was associated with type-III.ConclusionsThe incidence of iGBS disease found in Réunion island is twofold that usually reported. This burden is linked to overweight in aboriginal people from the Indian Ocean.