In vitro susceptibility of Candida albicans to four disinfectants and their combinations.
Waltimo TM, Orstavik D, Sirén EK, Haapasalo MP.
Source
NIOM, Scandinavivan Institute of Dental Materials, Haslum, Norway. tuomas.waltimo@helsinki.fi
Abstract
AIM:
The aim of this study was to evaluate the susceptibility of seven strains of Candida albicans to four disinfectants: iodine potassium iodide, chlorhexidine acetate, sodium hypochlorite and calcium hydroxide. In addition, all possible pairs of the disinfectants were tested in order to compare the effect of the combination and its components.
METHODOLOGY:
Filter paper discs were immersed in standardized yeast suspensions and then transferred to disinfectant solutions of different concentrations and incubated at 37 degrees C for 30 s, 5 min, 1 h and 24 h. After incubation the filter paper discs were transferred to vials with PBS and glass beads that were then vigorously shaken for dispersal of the yeast cells. PBS with resuspended yeasts was serially diluted 10-fold. Droplets of 25 microL from each dilution were inoculated on TSB agar plates and incubated in air at 37 degrees C for 24 h. The number of colony-forming units was then calculated from appropriate dilutions.
RESULTS:
C. albicans cells were highly resistant to calcium hydroxide. Sodium hypochlorite (5% and 0.5%) and iodine (2%) potassium iodide (4%) killed all yeast cells within 30 s, whilst chlorhexidine acetate (0.5%) showed complete killing after 5 min. Combinations of disinfectants were equally or less effective than the more effective component. All C. albicans strains tested showed similar susceptibility to the medicaments tested.
CONCLUSIONS:
This study indicates that sodium hypochlorite, iodine potassium iodide and chlorhexidine acetate are more effective than calcium hydroxide against C. albicans in vitro. However, combining calcium hydroxide with sodium hypochlorite or chlorhexidine may provide a wide-spectrum antimicrobial preparation with a long-lasting effect.

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In 1953 Dr. Orian Truss discovered the devastating effects of antibiotics in an Alabama (USA) hospital. During a hospital round Truss was intrigued by a gaunt, apparently elderly man who was obviously dying. However, he was only in his forties and in hospital for four months. No specialist had been able to make a diagnosis. Out of curiosity Truss asked the patient when be was last completely well. The man answered that he was well until six months before when he had cut his finger He had received antibiotics for this. Shortly afterwards he developed diarrhea and his health deteriorated. Truss had seen before how antibiotics cause diarrhea. It was known that Candida was opportunistic and thrived in debilitated patients, but now Truss wondered if it might not be the other way round, that Candida actually caused the debilitated condition.
Truss had read that potassium iodide solution could be used to treat Candida infestation of the blood. So he put the patient on six to eight drops of Lugol’s solution four times a day and soon the patient was again completely well. Soon afterwards he had a female patient with a stuffy nose, a throbbing headache, vaginitis and severe depression. To his amazement all her problems immediately cleared with Candida treatment.