Disinfecting activities of non-peroxide soft contact lens cold disinfection solutions.

The antimicrobial activities of three non-peroxide soft contact lens chemical disinfection systems--ReNu Multi-Purpose Solution (0.00005% polyaminopropyl biguanide), Opti-Soft Disinfecting Solution (0.001% polyquaternium-1), and Opti-Free Rinsing, Disinfecting & Storage Solution (0.001% polyquaternium-1)--were compared to Soft Mate Disinfecting Solution (0.005% chlorhexidine digluconate). Each product was separately inoculated with each of five microorganisms at approximately 10(6) microorganisms per mL. All of the solutions demonstrated excellent disinfecting activity against Pseudomonas aeruginosa and Staphylococcus epidermidis, with complete disinfection occurring within 4 hours. Only Soft Mate disinfected Serratia marcescens within 4 hours. ReNu reduced the microorganisms to 10-100 cells/mL and Opti-Soft and Opti-Free reduced the number to 10(2)-10(3) cells/mL. For the fungal species, Soft Mate showed excellent activity against Candida albicans (disinfection in 4 hours) and reduced Aspergillus fumigatus to 10(3) spores/mL in 4 hours. After 4 hours ReNu, Opti-Soft, and Opti-Free had reduced C. albicans only slightly, to 10(5) cells/mL and displayed virtually no disinfecting activity against A. fumigatus. For these newer chemical disinfection systems, diligent cleaning and rinsing of the soft contact lenses are the most important steps in the patient care regimen.

Surface interactions on hydrogel extended wear contact lenses: microflora and microfauna.

The microbial flora and fauna of 25 high water content nonionic "soft" contact lenses worn by patients on an extended wear basis, 4 hand-cleaned patient-worn lenses, and 4 improperly maintained lenses were compared. Almost all the patient-worn lenses (24 of 25) were free of viable microorganisms, whereas all the hand-cleaned lenses (4 of 4) were contaminated with different microorganisms. This study showed that hand contact is a major source of microbial contamination of a lens and that usually the hand-transported microorganisms do not survive permanently on the lens in a healthy, normal eye. Improperly maintained lenses demonstrated pathogenic microbial associations. Proof of the eye's potent antimicrobial environment was demonstrated. Thus, microorganism-lens associations are largely due to lens handling and inappropriate maintenance regimens. Typically there are few microorganisms on an extended wear soft lens while it is being worn.

Degradation of biochemical activity in soil sterilized by dry heat and gamma radiation.

The activities of three enzymes present in soil, phosphatases, urease, and decarboxylase, were monitered as indicators of the loss of biochemical information occurring when soil was sterilized by dry heat (0.08% relative humidity), gamma radiation, or a combination of both. More enzymatic activity was retained in soil sterilized by a long exposure to dry heat at relatively low temperature (8 weeks at 100.5 degrees C) than by a shorter exposure to a higher temperature (2 weeks at 124.5 degrees C). No enzymatic activity was detectable in soil sterilized by an even higher temperature (4 days at 148.5 degrees C). Soil sterilized with 7.5 Mrads of radiation retained much higher enzymatic activity than with heat sterilization. Combining sublethal doses of heat radiation effectively sterilized the soil and yielded enzymatic activities higher than those of soil sterilized by dry heat alone but lower than those of soil sterilized by radiation.

Chloramine mutagenesis in Bacillus subtilis.

Chloramine (which occurs widely as a by-product of sanitary chlorination of water supplies) is shown to be a weak mutagen, when reversion of trpC to trpC in Bacillus subtilis is used as an assay. Some DNA-repair mutants appear to be more sensitive to chloramine, suggesting the involvement of DNA targets in bactericide. The influence of plating media on survival of cells treated with chloramine suggests a bacterial repair system acting upon potentially lethal lesions induced by chloramine.