Sternoclavicular joint infection is rare. While it is usually treated surgically, we wish to report a case of non-operative treatment of such infection caused by an atypical organism. A 51-year-old woman, known case of diabetes mellitus, hypertension, dyslipidaemia and hyperthyroidism presented with pain over the left upper chest for two weeks associated with redness and fever for one week. The patient was diagnosed to have left sternoclavicular joint septic arthritis with medial end left clavicular osteomyelitis, left sternocleidomastoid, left anterior chest wall abscesses and left lower lobe posterior basal segment cavitating lung lesion with a single nodule in the lingular segment. The blood culture and sensitivity grew extended spectrum beta lactamase (ESBL) Klebsiella pneumonia and the patient was treated with two weeks of meropenem. Computed Tomography was then repeated 2 months later and features were suggestive resolving of left sternoclavicular joint septic arthritis with medial end left clavicular osteomyelitis. The patient is still under surveillance and is currently symptom free 1 year later. We present a case to our knowledge is the first case of rare gram negative rod organism, ESBL Klebsiella pneumoniae infection which caused the left sternoclavicular septic arthritis with medial end left clavicular osteomyelitis, left sternocleidomastoid and left anterior chest wall abscesses. The patient is most likely immunocompromised from being a diabetic with hyperthyroidism. First line treatment can be with antibiotics and when that fails, patient can be treated surgically. Two weeks of antibiotics therapy is possible in selected patients with monitoring of the infective markers.