An in-vitro evaluation of the activity of povidone-iodine against nosocomial bacterial strains.

Two povidone-iodine (PVP-I) preparations, one, an antiseptic handwash and one, a skin disinfectant, were tested against 504 bacterial strains isolated from nosocomial infections in 12 French hospitals. In vitro bactericidal activity was determined by a micromethod, using specific interfering substances over a range of dilutions, after 1, 3 and 5 min exposure times. A 5 log10 reduction of the challenge inoculum was considered as the criterion of efficacy. Any resistant strains were tested with the French Standard (T72300). When the micromethod was carried out at 20 degrees C, 10.7% (54/504) of the strains were resistant to the PVP-I skin disinfectant (dilution 1:10) and 1.6% (8/504) were resistant to the handwashing formulations (dilution 1:3) after 1 min exposure. By increasing the temperature to 32 degrees C, the resistance rate to the skin disinfectant fell to 1.9% (10/504). All of the 18 strains found resistant with the micromethod were sensitive using the French standard.