Formalin disinfection of biopsy needle minimizes the risk of sepsis following prostate biopsy

Purpose: We describe a simple and effective method to reduce the risk of infection after prostate biopsy.

Materials and methods: A total of 1,642 consecutive prostate biopsy procedures during a 4-year period (2008 to 2012) were included in the study. Inclusion criteria consisted of pre-biopsy negative urine culture, bisacodyl enema and fluoroquinolone antibiotics (3 days). Formalin (10%) was used to disinfect the needle tip after each biopsy core. All patients were monitored for post-biopsy infection. The rate of infection was compared to that of a historical series of 990 procedures. Two ex vivo experiments were conducted to test the disinfectant effectiveness of formalin against fluoroquinolone resistant Escherichia coli, and another experiment was performed to quantitate formalin exposure.

Results: Post-biopsy clinical sepsis with positive urine and blood cultures (quinolone resistant E. coli) developed in 2 patients (0.122%). Both patients were hospitalized, treated with intravenous antibiotics and had a full recovery without long-term sequelae. Mild uncomplicated urinary infection developed in 3 additional patients (0.183%). All were treated with outpatient oral antibiotics and had a complete recovery. The overall rate of urinary infection and sepsis using formalin disinfection was approximately a third of that of a prior series (0.30% vs 0.80%, p=0.13). Ex vivo experiments showed a complete lack of growth of fluoroquinolone resistant E. coli on blood and MacConkey agars after exposure to formalin. The amount of formalin exposure was negligible and well within the safe parameters of the Environmental Protection Agency.

Conclusions: Formalin disinfection of the biopsy needle after each prostate biopsy core is associated with a low incidence of urinary infection and sepsis. This technique is simple, effective and cost neutral.