Septic arthritis of the sternoclavicular joint is usually caused by Gram-positive cocci, and accounts for under 1% of orthopedic infections. Gram-negative organisms, especially those by Salmonella sp. are particularly rare. This report follows the case of a 42-year-old lady presenting with MRI-confirmed multifocal infective arthritis extending to the pectoralis major. Joint aspirate yielded Salmonella Group B, and a prior Widal test suggested Salmonella Paratyphi B exposure. Targeted specific antibiotic therapy resolved the patient’s symptoms. This case highlights the importance of comprehensive bacteriological workup in atypical cases, and the efficacy of early and culture-guided treatment in rare infections, to prevent complications.