A Case of Dual Septic Foci in Both the Joint and Pleural Cavity Caused by Streptococcus agalactiae.

Group B Streptococcus (GBS or Streptococcus agalactiae) is a common component of the human flora. However, infections in adults are infrequent, and occurrences of infectious pleurisy or septic arthritis are exceedingly uncommon. To our knowledge, the concurrent manifestation of both conditions has not been previously documented. We present the case of a 61-year-old man who exhibited an unusual association of infectious pleurisy and septic arthritis in the knee, both attributed to GBS. The patient was admitted to the hospital due to thoracic pain and discomfort in the left knee. Clinical examination revealed a pleural effusion in the left lung and arthritis in the left knee. Synovial and pleural fluid samples were sent to the bacteriology laboratory for cytobacteriological examination, confirming the presence of GBS in both fluids. The patient is diabetic and has a history of undergoing total cystoprostatectomy for a urothelial tumor, with the placement of a mono J catheter. The prevailing hypothesis suggests that the colonization of the mono J catheter, followed by hematogenous dissemination, is the probable source of the infection. This unusual clinical case underscores GBS's ability to induce severe invasive infections in adults, particularly in those with underlying medical conditions.