Procalcitonin tests help control antibiotic prescribing

Procalcitonin is a serum marker for bacterial infections and a potentially useful guide to antibiotic prescribing for people with lower respiratory tract infections. The biggest trial so far suggests that treatment informed by a rapid procalcitonin test can reduce patients’ exposure to antibiotics and protect them from side effects without adversely affecting clinical outcomes.

All the participating patients presented to Swiss emergency departments with symptoms of lower respiratory tract infection. Doctors treating the intervention group used an algorithm based on serum procalcitonin concentration to determine whether to prescribe antibiotics. Doctors treating the control group used one based on current guidelines for antibiotic prescribing. After 30 days, a similar proportion of both groups had died, been admitted to intensive care, had a complication, or had a recurrent infection (15.4% (103/671) of the procalcitonin group v 18.9% (130/688) of controls; difference -3.5%, 95% confidence interval -7.6% to 0.4%). Controls received antibiotics for three days longer than patients treated according to the procalcitonin algorithm (8.7 days v 5.7 days), and were considerably more likely to experience side effects (28.1% (193/688) v 19.8% (133/671); -8.2%, -12.7% to -3.7%). Two thirds of participants in this trial had community acquired pneumonia.⇑

These results are encouraging but preliminary, says an editorial (p 1115-6). Further trials in other populations should be done and should consider costs as well as effectiveness.

Natalizumab linked to more cases of progressive multifocal leucoencephalopathy

Progressive multifocal leucoencephalopathy is a rare but potentially devastating side effect of natalizumab, a monoclonal antibody used to treat multiple sclerosis. It’s actually an opportunistic infection caused by a polyomavirus. Demyelination of the central nervous system is the main feature, so it’s relatively easy to miss in people with multiple sclerosis.

Two recent case reports of progressive multifocal leucoencephalopathy in patients receiving natalizumab bring the total number of cases to 14 in the United States and Europe. …