Kidney dialysis equipment

A case has been reported from Colombia of the infection of at least nine patients who seroconverted within a four-month period during 1992 after kidney dialysis treatment at the same centre. The risk was eventually narrowed down to inadequate disinfection of dialysis equipment, including reusable needles. It was noted by investigators that all those who had seroconverted had received treatment with needles soaked in the same disinfecting tray as the index case, in a solution of 0.16% benzalkonium chloride. The solution was changed only once a week, allowing considerable opportunities for cross-infection. Dialyser filters and bloodlines were sterilised between each patient with a solution of approximately 1.5% formaldehyde. What is surprising about this case is the viability of HIV in such a disinfectant solution and the relatively small quantities of blood likely to have been involved. The authors note that the anti-microbial activity of benzalkonium chloride is likely to decline over time, especially in the presence of organic matter from a large number of instruments.¹