Efficient method for mycobacterial DNA extraction in blood cultures aids rapid PCR identification of Mycobacterium tuberculosis and Mycobacterium avium.

The study presented here evaluated the utility of several methods of extracting mycobacterial nucleic acids from positive blood culture samples and examined the effect of each method on the performance of an in-house PCR used directly in the peripheral blood of 80 patients with AIDS to identify Mycobacterium spp. The modified Boom method for extracting DNA from blood cultures proved to be the most efficient, with subsequent PCR analysis yielding 100% positivity (7 samples positive for M. avium and 5 for M. tuberculosis). Only three of 12 patients with a positive blood culture had a PCR result positive for M. avium in peripheral blood. The identification of mycobacteria by PCR in blood culture took about 3 days, reducing the time to diagnosis by several weeks. These results demonstrate that PCR is a sensitive and quick method for identifying mycobacteria, especially when a good DNA extraction method is applied.

Oral ciprofloxacin for treatment of severe infections.

Twenty adult patients with severe infections were treated with oral ciprofloxacin, 500 or 750 mg twice daily. Treatment ranged from 8 to 25 days. Efficacy was good: 14 patients (70%) were cured, four (20%) improved and there were only two (10%) failures. Tolerance was very satisfactory, the most common side-effects being mild gastrointestinal symptoms (three patients). Only one adverse laboratory result was observed: a transient rise in blood urea nitrogen and creatinine levels. None of the adverse effects led to discontinuation of treatment. Thus, ciprofloxacin presents as a promising drug for treatment of severe infections caused by susceptible organisms when ambulatorial therapy, at least during a large part of the treatment, is possible and desirable.