Primary meningococcal arthritis of the hip due to serogroup W in a pediatric patient

Background: Primary meningococcal arthritis (PMA) is defined as the presence of acute septic arthritis with the identification of Neisseria meningitidis in synovial fluid or blood cultures but no clinical evidence of sepsis or meningitis. This report aimed to describe a clinical case of PMA caused by serogroup W, an uncommon etiology of this disease in Uruguay, and review the available literature. Case report: We report the case of a 5-year-old female, with no past medical history, admitted to the emergency department with a 12-hour history of fever of 39 °C and a limp. The patient was hemodynamically stable and had no clinical evidence of meningitis. Hip ultrasound showed an increase in synovial fluid. Arthrocentesis showed purulent exudate and synovial fluid culture showed no growth after five days. The blood culture showed isolates of N. meningitidis, serogroup W. The patient received treatment with ceftriaxone, and drainage of the affected joint was performed with excellent clinical response. Conclusions: Primary meningococcal arthritis is a rare presentation of meningococcal disease. Systematic arthrocentesis and the adequacy of antibiotic therapy when septic arthritis is clinically suspected are essential for confirming the diagnosis and decompressive drainage of the involved joint. This report is the first of PMA caused by serogroup W in Uruguay. Although the most common serogroup involved in meningococcal arthritis is serogroup B in Uruguay, an increase in serogroup W-related diseases has been reported in Chile and Argentina, emphasizing the need for epidemiological surveillance.