[Pyogenic arthritis caused by Streptococcus agalactiae: report of four cases and a review of the literature].

Most infections by group B streptococcus of the Lancefield classification (Streptococcus agalactiae), were reported in pregnant women or during the puerperal period, as well as in neonates. During the past three decades there have been reports of increasingly invasive infections in adults unrelated to pregnancy, although arthritis and osteomyelitis are still very rare. In this article, we describe four new adult patients with arthritis by S. agalactiae (two postmenopausal women and two men), two of them with affection of the sternoclavicular joint. We also review the medical literature.