Pubic osteomyelitis caused by Staphylococcus simulans.

A 77 year old previously active and independent woman presented in June 1988 with a profound right hemiparesis and dense dysphasia due to a left cerebral hemisphere infarction. Serum C-reactive protein (CRP) at this time was less than 10 mg/l. She had had non-insulin-dependent diabetes mellitus for 14 years controlled with diet and tolbutamide, and psoriasis since childhood in virtual remission on admission with no treatment. Recovery from her stroke was slow and hampered by a painful left hip due to pre-existing osteoarthritis. In December 1988 she developed a painful right groin with tenderness over the right pubic bone. Neither plain X-rays nor isotope bone scan showed any abnormalities in the pelvis and in particular the region of the pubic bones was normal (Figure la). The diagnosis was unclear but the pain responded to a right ilio-inguinal nerve block. Later that month further pain in the right groin was diagnosed as an adductor femoris tear or tendinitis, and responded to a steroid and local anaesthetic injection at the right adductor tubercle. CRP at this time was again less than 10 mg/l. In March 1989 local treatment with a salicylate derivative was initiated for a large psoriatic lesion on the scalp which had developed since her admission. This lesion was not cultured and healed rapidly. A month later deterioration in her functional ability was noted and the CRP was 252 mg/l, the total white cell count was 17.5 x 109/l. Daily physical examinations, including regular temperature measurements, were normal for 6 days, as were urine microscopy and culture and a chest X-ray. On the seventh day a tender pubic symphysis was noted and her CRP was 67 mg/l. A clinical diagnosis of pubic osteomyelitis was made. Two sets of blood cultures grew S. simulans in all bottles, fully sensitive to all anti-staphylococcal antibiotics, and treatment was started with flucloxacillin, 2 g intravenously 6 hourly for 11 days followed by 500 mg 6 hourly by mouth, and fusidic acid 500 mg orally three times daily. Initially the pubic symphysis was radiologically normal but within a week rarefaction was detected (Figure 1 b) and an isotope bone scan revealed a localized hot spot at the pubic symphysis (Figure 2). Clinical examination, repeated urine examination and two echocardiograms were otherwise unremarkable. Her pain settled and antibiotics were therefore discontinued after 25 days of therapy. The pain recurred three days later and the CRP was 44 mg/l. In view of this flucloxacillin and fusidic acid were restarted and continued until not only her symptoms had resolved but the CRP had fallen to less than 10 mg/l. This was achieved after a further 31 days of therapy. Following cessation of antibiotics there were no clinical signs of recurrence of infection. Rehabilitation continued and she was discharged from hospital in August 1989, and has remained well.