Results of the investigation showed that there was a difference in the bacteria isolated from dogs, cats and their living environment. The number and species isolated from the hair and front paw samples from dogs kept outdoors and from cats were greater and more varied than those from the samples from dogs kept indoors. Staphylococcus, Micrococcus and Bacillus were frequently detected from skin surfaces. On the other hand, Escherichia, Pseudomonas, Proteus and others were detected on each sampling area on dogs kept outdoors and on cats. About 60% of the bacteria commonly causes infectious diseases and carries a risk of food poisoning. Moreover, Pasteurella multocida, which causes pasteurellasis, a kind of zoonosis, was isolated from dogs and cats. These pathogenic bacteria were transmitted from animals to humans by direct contact. This result suggests that direct contact with dogs and cats and contact with aerosols can possibly transmit infectious diseases. Most of the isolates (75.9%, 60/79) were resistant to antibacterial agents. We then investigated the effect of household detergents and pet care deodorant sprays containing antibacterial agents on isolates from dogs and cats. They were effective in preventing the transmission of pathogens from dogs and cats to humans.

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Nosocomial infections are a great problem in the health care facilities. The white uniforms of nurses are often washed to keep them clean, but the nurse's caps are not washed as frequently in comparison. It could be that the importance of these caps is being overlooked. If these caps are providing a residence for microorganisms causing nosocomial infection in the health care facility, then they should be washed as frequently as the uniforms. So far, the relationship between the contamination of the nurse's caps and nosocomial infection has not yet been studied. Therefore, this study was conducted to confirm if relationships exist among factors regarding the number of microorganisms on the nurse's caps, the period in which caps were used without being washed, and the individual characteristics of nurse wearing the caps. Results showed that the degree of contamination of the nurse's caps depended on individual characteristics and the period of use. Finally, results led to the conclusion that the nurse's caps should not be worn if their only purpose is to symbolize female workers in the health care facilities because, in actually, they provide a resistance for microorganisms causing nosocomial infections.

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The photocatalyst equipment consists of a titanium dioxide membrane and an ultraviolet lamp. The authors studied if the photocatalyst equipment is practically useful in sterilizing environmental microorganisms in the health care facility. The number of microorganisms was compared in the cases of no sterilization (control) and the photocatalyst sterilization. As a result, a statistical difference was observed between control and the photocatalyst sterilization against airborne microorganisms (p<0.01), but not against surface microorganisms (p>0.2). The photocatalyst uses an air sucking system, so it may be ineffective against microorgan isms tightly attached to surfaces. However, the effectiveness of the photocatalyst to sterilize airborne microorganisms in the health care facility was successfully confirmed. Concerning the humidity effect on the photocatalyst sterilization, the authors compared the number of airborne microorganisms in cases of the control, UV alone and photocatalyst sterilization when humidity was changed. A statistical difference was observed between UV and the photocatalyst sterilization (p<0.01) when humidity was increased to 60-70%, but not observed between UV and the photocatalyst sterilization (p>0.2) when humidity was not controlled and was around 10-20%. This indicates that maintaining high humidity levels will present satisfactory sterilization results due to a greater production of OH radicals. From data obtained, no effect of the adsorption on the TiO₂ membrane could be observed.

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Chitin, chitosan and quaternary chitosan films were prepared, and the mechanical properties and the antibacterial activities of chitosan and quaternary chitosan films were evaluated.
The tensile strength of chitin films was 30-40% lower than that of chitosan films, but the crystallinity of the former was much higher than those of the latter. A detailed analysis of the crystallinity and orientation of crystallites of chitosan films revealed that the cast film prepared with acetic acid provided a little lower crystallinity than the others.
The antibacterial activities of quaternary chitosan films against Staphylococcus aureus and Escherichia coil were stronger than those of chitosan films.
The antibacterial activities of neutralized chitosan films may be slightly inferior to those of un-neutralized chitosan films. The improvement in the antibacterial activity of chitosan films against E. coil was slightly inferior to that against S. aureus. This phenomenon was particularly observed on the neutralized chitosan films.
Though the antibacterial activity of chitosan was slightly inferior to that of the organic antibacterial compounds, we emphasize that chitosan would be a useful and suitable material with regard to its effect on the environmental ecosystem.

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A bis-quaternary ammonium compound (bis-QAC), N, N'-hexamethylenebis (4-carbamoyl-1-decylpyridinium bromide) (D-38), exhibited a wide antifungal spectrum and a strong activity against sixteen strains of fungi including nine strains isolated from various kinds of food. The antifungal activity was higher than that of N-dodecylpyridinium iodide, a typical mono-QAC, and that of the commonly used fungicide, 2-(4-thiazolyl) benzimidazole. The activity of D-38, however, was comparatively low when it was measured by the agar dilution method. It is considered that the hydrophobic D-38 molecules, having two long alkyl chains, interacted with the agar medium, and therefore showed lower activity results. On the other hand, the activity of D-38 against Aspergillus niger IFO 6342 was not significantly influenced by temperature, pH and the initial spore concentration. These results indicate that bis-QACs can exhibit a high antifungal activity whether or not the environmental conditions change.

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Five spore-forming bacterial strains were isolated as the most dominant microorganisms from five products of different types of cooked food. Three strains in particular were isolated as spoilage organisms causing acidity. These belonged to the genus Paenibacillus, and one of them was identified as Paenibacillus odorifer. All five strains grew at 10°C in brain heart infusion broth; furthermore, four strains grew at 4°C also. These strains grew optimally at 30 to 35°C. Psychrotrophic Paenibacillus spp. can easily be mistaken for lactic acid bacteria in routine analysis because of their colony characteristics. Because the measures that must be taken for bacterial control are different in the case of contamination by these two bacterial groups, psychrotrophic Paenibacillus spp. contamination must be distinguished from that caused by lactic acid bacteria.

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