News and Events

Case of the Month - August 2012

Dr Rena Hoffmann, Microbiologist, National Health Laboratory Service, Tygerberg Hospital

A 44-year old man was referred to Tygerberg Hospital with one-month progressive right-sided weakness, speech impairment and new onset convulsions. His medical history is remarkable for longstanding alcohol dependence with poor social circumstances. Clinical evaluation at the time of admission confirmed a right-sided hemiplegia with aphasia. He remained afebrile during his hospital stay and intermittent right-sided focal convulsions were observed in the ward.

On initial special investigations, the white blood cell count was within normal limits and HIV serology was negative. A contrasted CT-scan of the brain demonstrated a left parietal brain abscess resulting in midline shift.

An emergency craniotomy was performed and 40ml of non-offensive pus was drained. Based on the findings at craniotomy, empiric ceftriaxone, metronidazole and Rifafour were started. His focal seizures were controlled with phenytoin.

Pus was sent for routine Microscopy, Culture & Sensitivity (MC&S) as well as Mycobacterial MC&S. The Gram stain showed a moderate amount of neutrophils, but no bacteria were observed. Two days later the aerobic bacterial culture yielded an organism with features suggestive of a Nocardia species. The Gram stain of these colonies showed delicate Gram-positive filamentous branching bacilli. A modified Ziel Neelsen stain of the isolate was positive. The colony morphology on the blood agar plate was chalky white and had the aroma of wet soil, which although not pathognomonic, is suggestive of Nocardia). Based on these findings and current Western Cape Academic hospitals antimicrobial recommendations, high dose Trimethoprim-Sulphamethoxazole (TMP-SMX), one tablet (80/400mg) for each 4 kg body weight per day was started. Subsequent PCR and DNA sequencing of the 16SrRNA gene confirmed a Nocardia abscessus infection. Antimicrobial susceptibility testing (E-test method; AB Biodisk Solna, Sweden) confirmed that the isolate was sensitive to TMP-SMX with a MIC of 0.03µg/ml. The ceftriaxone, metronidazole and Rifafour were discontinued.

The patient’s neurological deficits resolved after 6 weeks of treatment and he was discharged on a lower dose of TMP-SMX and is being followed up on an outpatient basis.

Question 1: What are the main clinical manifestations of infection with Nocardia species?

Continue to Answer 1