Evaluation of Bacteria Reducing Efficiency Using Bactericide Under Full Scale Field Study-A Negative Pressure Pattern testing

• Main Authors: Yun-Ting Wang, 王韻婷
• Other Authors: 賴全裕
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/xr798k

碩士 === 中山醫學大學 === 職業安全衛生學系碩士班 === 103 === Many nosocomial infections of patients are derived from secondary infections during their hospital stay via pathogens or by its toxins, thereby causing local or systemic adverse reactions in them that are not present prior to admission or not at a latency stage. The major nosocomial infection route can be divided into two pathways, via airborne and contact transmission. According to recent researches, general disinfection methods are direct contact to pathogens but seldom relat to airborne disinfection method. Our research first conducted the paper disk diffusion test to initially understand the effectiveness of the bactericides. Then, in a full-scale test ventilation laboratory equipped with stable(ΔP=0 pa), negative(ΔP=-8 pa), or positive(ΔP=+8 pa)pressure ventilation. The dimensions of laboratory were 3 x 3 x 3 meters, that could provide different dilution ventilation flow patterns, included the short-circuit and displacement pattern. Moreover, the operation parameter also compared the different air change rate per hour (ACH). The experimental procedure was to deploy bacteria and bactericides and test their effective bacteria reducing rate under different flow patterns and pressure drop(negative, stable, positive)setting. For experimental comparison, the bacteria of Bacillus subtilis was used as challenge aerosol while the Collison Atomizer was used for producing the bioaerosol and the bactericide. The bioaerosol disinfection efficiency was compared via the Andersen Single Stage Microbial Sampler. As for the bactericides, different proportions of diluted bactericides were atomized and sprayed in the full scale test laboratory with the selection of hypochlorous acid, terpinen-4-ol, and lemon grass oil. The research results indicated that most bactericides worked most effectively under negative pressured airflow field environments. There was a significant reducing in bactericidal effect under positive or stable pressured environments. In particular, the hypochlorous acid still showed a high bactericidal effect under different pressure drops. Under the short circuit airflow field, the terpinen-4-ol and lemon grass oil both also showed significant bactericia reducing effect. The resulted bactericidal rates were also related to the particle sizes of the bactericides and the experimental bacteria used. The greater the difference of the particle sizes between the bactericides and experimental bacteria used, the greater was their coagulation, which may produce a better bactericia reducing effect.