Group B streptococcus is the most common pathogen for septic arthritis with unique clinical characteristics: data from 12 years retrospective cohort study

BACKGROUND: Group B Streptococcus (GBS) emerged as the frequent pathogen for septic arthritis. There was no study comparing risks, clinical presentations and outcomes between GBS septic arthritis and other bacterial septic arthritis. The aim of this study is to evaluate the differences in risks, clinical presentations, and outcomes of GBS septic arthritis and other bacterial septic arthritis, and identify independent risks and clinical presentations suggesting GBS septic arthritis. METHOD: Medical records of patients diagnosed with non-gonococcal bacterial arthritis admitted in Phramongkutklao Hospital during 2006–2018 were reviewed. Associated risks, clinical presentations and outcomes were compared between GBS septic arthritis (GBS group) and other bacterial septic arthritis (other bacterial group). RESULT: Two hundred and thirty one cases of non-gonococcal bacterial arthritis confirmed by positive joint fluid cultures and/or hemocultures were included. The three most common pathogens were GBS (37.7%), Staphylococcus aureus (23.4%) and Streptococcus viridans (7.4%). GBS group was more commonly found in rainy season than other bacterial group. Patients in GBS group were less likely to have underlying diseases and had more number of involved joints than those in other bacterial group. The clinical presentations more commonly found in GBS group than other bacterial group were oligo-polyarthritis, upper extremities joint involvement, axial joint involvement, tenosynovitis and central nervous system involvement. Multivariate analysis found the independent associated factors of GBS arthritis are tenosynovitis, oligo-polyarthritis and rainy season. CONCLUSIONS: GBS is now the most common pathogen for bacterial septic arthritis. The independent associated factors of GBS arthritis were oligo-polyarthritis, tenosynovitis and rainy season. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s41927-019-0084-5) contains supplementary material, which is available to authorized users.