Nondevelopment of resistance by bacteria during hospital use of povidone-iodine.

Since the bacterial ability to develop resistance against various factors of their surroundings is a well-known phenomenon, resistance against iodine and specifically against povidone-iodine (PVP-I) has been widely investigated. Yet there is little known about bacterial resistance in long-term daily use of disinfectants in continuous ambulatory peritoneal dialysis (CAPD) patients. The aim of our study was to investigate whether on daily use of PVP-I over a period of at least 6 months coagulase-negative staphylococci (CNS)--the predominant infective organisms of peritonitis--developed resistance against PVP-I. At the catheter exit site of 40 CAPD patients we isolated 36 CNS. 23 CNS (CNS + PVP) orginate from patients using PVP-I, 13 CNS (CNS + CI) from patients using sodium hypochlorite (NaOCl) as disinfectant. The strains were biotyped, antibiotic resistance patterns were determined and resistance against PVP-I or NaOCl was calculated as reduction factor using the quantitative suspension test combined with a turbidimetric standardization. Resistance against PVP-I 0.01% and against NaOCl 0.005% was determined at two contact times (30 and 300 s) for each patient group. In addition, we investigated the effects of plasmid loss on sensitivity to PVP-I. Out of 5 multiple-antibiotic-resistant CNS, 3 strains showed no difference in reduction factor against PVP-I before and after curing. There was no significant difference in reduction factor against NaOCl. CNS + PVP were even significantly more sensitive to PVP-I than CNS + Cl. Taken together, our results demonstrate that long-term use of PVP-I does not cause any bacterial resistance in CNS of CAPD patients.