An unreported case of Streptococcus cristatus septic arthritis of wrist in a neonate.

Septic Arthritis of the wrist is rare in the paediatric population due to its extraarticular metaphysis. We report here a case of wrist septic arthritis in a neonate caused by an uncommon causative organism, Streptococcus cristatus. A 15 days old male child was referred with the complaint of swelling and decreased movement of the left wrist for 5 days. Local examination revealed warm, tender, erythematous and fluctuant swelling over the dorso-ulnar aspect of the left wrist. Ultrasonography of the affected region was suggestive of focal fluid collection in the wrist and periosteal elevation of the distal ulna. Aspiration followed by arthrotomy of the wrist joint was performed and multiple holes were made in the distal ulnar metaphysis using 0.8mm k-wire. The pus culture was positive for Streptococcus cristatus, sensitive to vancomycin, which was given for a total of 4 weeks. At one year follow up the child had a full, painless range of motion with no functional deficit. Final follow up x rays of the left wrist were normal. Streptococcus cristatus strains are described as Gram-positive, catalase-negative cocci, approximately 1 μm in diameter growing in chains and were originally isolated from the human throat and oral cavities. Its association with bone and joint infections has not been described in the literature. To our knowledge, this is the first case of isolated septic arthritis of wrist in a 15 days old child caused by Streptococcus cristatus. To conclude, wrist septic arthritis in a neonate is a rare entity. With the advanced diagnostics, species-level identification of rare organism like Streptococcus cristatus is possible along with antibiotic sensitivity for appropriate therapy. Early surgical decompression and intravenous culture-directed antibiotics are the mainstays of management.