Fig. 1. Efficacy of pouring versus instilling 500mL of disinfectants on recovery of gram-negative bacilli from proximal sink drains in a research laboratory sink (A) and in sinks in rooms of hospitalized patients (N=4) (B). For instillation, a stop valve was used to allow complete filling of the drainage system from the valve to just above the strainer for 1 hour. Quantitative cultures for gram-negative bacilli were collected from the proximal sink drain to depth of 2.5cm below the strainer before treatment and intermittently for 15 days post treatment. For the laboratory sink, the stop valve was just distal to the P trap, whereas for the patient room sinks it was just proximal to the P trap. Swabs collected before versus after instillation of disinfectant for 1 hour are shown in panel (C).
