A middle-aged post-menopausal woman who was previously well presented with intermittent fever and lower abdominal pain for a month. She had lost 3 kg over this time time period. She had otherwise no symptoms suggestive of urinary tract infection, no change in bowel habits and no significant discharge per vagina. Clinical examination revealed mild tenderness over the lower abdomen.

Her white cell count was elevated at 17,000 per cubic millimetre (predominantly neutrophils), and her C-reactive protein was 127 mg/L. A CT abdomen/pelvis revealed the presence of a bulky uterus with possibly a small uterine abscess as well as an intra-uterine device (IUD). The patient subsequently recalled that the IUD had been inserted “decades ago”.

The patient was started on IV ceftriaxone and oral doxycycline, and the IUD was removed. Gram-stain and culture of pus from the abscess yielded the following results:

Gram stain: Gram-positive bacilli 4+
Culture: Escherichia coli (ESBL-producing) and Proteus mirabilis (sensitive to ampicillin and ceftriaxone)

Questions:

1. What is the clinical diagnosis?
2. How should this patient be managed?

[Updated 23 May 2017]

The clue lies in the fact that the Gram stain showed bacteria that were completely different compared to the final culture results (both E. coli and P. mirabilis are Gram-negative rods). It is very likely (especially after reviewing the Gram stain with an experienced microbiologist) that the patient had pelvic actinomycosis, which is very commonly associated with IUDs, but because the organism (Actinomyces spp.) grows slowly, non-sterile culture specimens can be overgrown by other bacteria.

Treatment – after removal of the IUD – is with a prolonged course of high-dose penicillin (or amoxicillin).