PMC:7796291 / 22189-26231
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/7796291","sourcedb":"PMC","sourceid":"7796291","source_url":"https://www.ncbi.nlm.nih.gov/pmc/7796291","text":"3.4. Bactericidal Performance of Disinfection Treatments\nTo investigate the disinfection efficacy, the number of survived colony on respirators after disinfection treatments was quantified. The E. coli culture was loaded on the respirators applying physical pressure; the bacteria culture penetrated up to the stiffener, and did not penetrate beyond this layer (Figure 5). Without the physical pressure, the loaded culture drop rolled around on the surface of coverweb. The number of loaded E. coli by each layer was correlated with OD470 measurement and expressed as CFU/cm2 substrate surface. Bacteria inactivation or removal efficiency was calculated by: (B0−Bn)B×100 (%), where B0 is the number of live bacteria in the untreated sample area, and Bn is the number of live bacteria in the treated sample area (n = 1~8, each number indicating the eight disinfection methods).\nBactericidal or bacteria removal efficiency of Resp. A is shown in Figure 6 and Figure S7. In the 2.5 cm × 2.5 cm designated area of each web, non-treated samples showed ~1.46 × 106 and ~2.53 × 106 CFUs on the coverweb and stiffener, respectively. Microwaving, oven-dry, and UV treatment showed similar bactericidal effect up to about 82%; in fact, this is inconsistent with previous studies [18,20], where 99.99% inactivation efficiency was achieved. This discrepancy can be attributed to the different treatment conditions, such as irradiation intensity, treatment time, and amount of bacteria loaded. In a previous study, 1.0 × 106 CFU of bacteria was loaded on the respirator with a nebulizer; and the UV irradiation (wavelength; 254 nm, 5 min) and microwaving (400 W, 10 min) resulted in complete inactivation of cells [18]. The case of an oven-dry treatment (100 °C, 15 min) also achieved 99.99% inactivation efficiency, when 5.0 × 104 CFU of bacteria was dropped onto the surface of the respirator [20]. Compared to previous studies, this study built a harsher experimental condition with a higher loading of bacteria (5.0 × 106 CFU). As a result, the intensity of microwaving (750 W, 2 min), UV irradiation (wavelength; 253.7 nm, 2 h), and oven-dry (90 °C, 1 h) of this study were insufficient for complete sterilization [51]. Chemical solvents (ClO−, EtOH, and IPA) and laundering treatments showed no color change with cell staining, indicating 100% bactericidal or bacteria removal efficiency (Figure 6 and Figure S7).\nThe morphological state of loaded bacteria after disinfection treatments was analyzed by FE-SEM (Figure 6C). With microwaving, oven-dry, and UV irradiation, disruption of E. coli membrane integrity was observed; on the contrary, IPA immersion and water-laundering resulted in both cell deformation and cell detachment. Remaining bacteria on water-laundered media was observed in a tangled structure of cells with contaminants on the fiber surface. Generally, microwaving and oven-drying rely solely on the heating effect to inactivate microorganisms [52], as heating triggers the denaturation of cell proteins [53]. Additionally, the UV irradiation breaks the strong bond of cell membranes, such as O-H, P-O, and N-H bonds of E. coli, or induces oxidation, leading to cell death [54]. The solvents and detergent laundering treatments have compound effect of bactericidal and bacteria removal activity, by accumulating in the lipid of membrane and degrading the membrane integrity while inducing suspension of bacterial droplet into the liquid [55,56]. Meanwhile, laundering effectively removed bacteria by detaching them from fibers, rather than sterilizing the cells.\nThe results of bactericidal performance test imply the chemical solvents and hypochlorite solution are effective disinfection agents, as they concurrently inactivate the cell and detach bacteria. Even if it is not complete sterilization, UV irradiation, and oven-dry methods seem fairly applicable for inactivating cells to some extent. Laundering treatment removed a considerable amount of loaded bacteria; additionally, even the remaining bacteria was inactivated.","divisions":[{"label":"title","span":{"begin":0,"end":56}},{"label":"p","span":{"begin":57,"end":876}},{"label":"p","span":{"begin":877,"end":2406}},{"label":"p","span":{"begin":2407,"end":3575}}],"tracks":[{"project":"LitCovid-PubTator","denotations":[{"id":"222","span":{"begin":194,"end":201},"obj":"Species"},{"id":"223","span":{"begin":491,"end":498},"obj":"Species"},{"id":"228","span":{"begin":924,"end":928},"obj":"Gene"},{"id":"229","span":{"begin":2231,"end":2235},"obj":"Chemical"},{"id":"230","span":{"begin":2237,"end":2241},"obj":"Chemical"},{"id":"231","span":{"begin":2247,"end":2250},"obj":"Chemical"},{"id":"240","span":{"begin":2578,"end":2585},"obj":"Species"},{"id":"241","span":{"begin":3133,"end":3140},"obj":"Species"},{"id":"242","span":{"begin":2636,"end":2639},"obj":"Chemical"},{"id":"243","span":{"begin":2654,"end":2659},"obj":"Chemical"},{"id":"244","span":{"begin":2748,"end":2753},"obj":"Chemical"},{"id":"245","span":{"begin":2840,"end":2845},"obj":"Chemical"},{"id":"246","span":{"begin":3332,"end":3337},"obj":"Chemical"},{"id":"247","span":{"begin":3180,"end":3185},"obj":"Disease"},{"id":"249","span":{"begin":3653,"end":3665},"obj":"Chemical"}],"attributes":[{"id":"A222","pred":"tao:has_database_id","subj":"222","obj":"Tax:562"},{"id":"A223","pred":"tao:has_database_id","subj":"223","obj":"Tax:562"},{"id":"A228","pred":"tao:has_database_id","subj":"228","obj":"Gene:13897326"},{"id":"A229","pred":"tao:has_database_id","subj":"229","obj":"MESH:D006997"},{"id":"A230","pred":"tao:has_database_id","subj":"230","obj":"MESH:D000431"},{"id":"A231","pred":"tao:has_database_id","subj":"231","obj":"MESH:D019840"},{"id":"A240","pred":"tao:has_database_id","subj":"240","obj":"Tax:562"},{"id":"A241","pred":"tao:has_database_id","subj":"241","obj":"Tax:562"},{"id":"A242","pred":"tao:has_database_id","subj":"242","obj":"MESH:D019840"},{"id":"A243","pred":"tao:has_database_id","subj":"243","obj":"MESH:D014867"},{"id":"A244","pred":"tao:has_database_id","subj":"244","obj":"MESH:D014867"},{"id":"A245","pred":"tao:has_database_id","subj":"245","obj":"MESH:D004043"},{"id":"A246","pred":"tao:has_database_id","subj":"246","obj":"MESH:D008055"},{"id":"A247","pred":"tao:has_database_id","subj":"247","obj":"MESH:D003643"},{"id":"A249","pred":"tao:has_database_id","subj":"249","obj":"MESH:D006997"},{"subj":"222","pred":"source","obj":"LitCovid-PubTator"},{"subj":"223","pred":"source","obj":"LitCovid-PubTator"},{"subj":"228","pred":"source","obj":"LitCovid-PubTator"},{"subj":"229","pred":"source","obj":"LitCovid-PubTator"},{"subj":"230","pred":"source","obj":"LitCovid-PubTator"},{"subj":"231","pred":"source","obj":"LitCovid-PubTator"},{"subj":"240","pred":"source","obj":"LitCovid-PubTator"},{"subj":"241","pred":"source","obj":"LitCovid-PubTator"},{"subj":"242","pred":"source","obj":"LitCovid-PubTator"},{"subj":"243","pred":"source","obj":"LitCovid-PubTator"},{"subj":"244","pred":"source","obj":"LitCovid-PubTator"},{"subj":"245","pred":"source","obj":"LitCovid-PubTator"},{"subj":"246","pred":"source","obj":"LitCovid-PubTator"},{"subj":"247","pred":"source","obj":"LitCovid-PubTator"},{"subj":"249","pred":"source","obj":"LitCovid-PubTator"}],"namespaces":[{"prefix":"Tax","uri":"https://www.ncbi.nlm.nih.gov/taxonomy/"},{"prefix":"MESH","uri":"https://id.nlm.nih.gov/mesh/"},{"prefix":"Gene","uri":"https://www.ncbi.nlm.nih.gov/gene/"},{"prefix":"CVCL","uri":"https://web.expasy.org/cellosaurus/CVCL_"}]},{"project":"LitCovid-sentences","denotations":[{"id":"T180","span":{"begin":0,"end":4},"obj":"Sentence"},{"id":"T181","span":{"begin":5,"end":56},"obj":"Sentence"},{"id":"T182","span":{"begin":57,"end":189},"obj":"Sentence"},{"id":"T183","span":{"begin":190,"end":372},"obj":"Sentence"},{"id":"T184","span":{"begin":373,"end":469},"obj":"Sentence"},{"id":"T185","span":{"begin":470,"end":594},"obj":"Sentence"},{"id":"T186","span":{"begin":595,"end":876},"obj":"Sentence"},{"id":"T187","span":{"begin":877,"end":929},"obj":"Sentence"},{"id":"T188","span":{"begin":930,"end":967},"obj":"Sentence"},{"id":"T189","span":{"begin":968,"end":1124},"obj":"Sentence"},{"id":"T190","span":{"begin":1125,"end":1328},"obj":"Sentence"},{"id":"T191","span":{"begin":1329,"end":1480},"obj":"Sentence"},{"id":"T192","span":{"begin":1481,"end":1706},"obj":"Sentence"},{"id":"T193","span":{"begin":1707,"end":1887},"obj":"Sentence"},{"id":"T194","span":{"begin":1888,"end":2018},"obj":"Sentence"},{"id":"T195","span":{"begin":2019,"end":2211},"obj":"Sentence"},{"id":"T196","span":{"begin":2212,"end":2406},"obj":"Sentence"},{"id":"T197","span":{"begin":2407,"end":2515},"obj":"Sentence"},{"id":"T198","span":{"begin":2516,"end":2725},"obj":"Sentence"},{"id":"T199","span":{"begin":2726,"end":2854},"obj":"Sentence"},{"id":"T200","span":{"begin":2855,"end":3022},"obj":"Sentence"},{"id":"T201","span":{"begin":3023,"end":3191},"obj":"Sentence"},{"id":"T202","span":{"begin":3192,"end":3458},"obj":"Sentence"},{"id":"T203","span":{"begin":3459,"end":3575},"obj":"Sentence"},{"id":"T204","span":{"begin":3576,"end":3771},"obj":"Sentence"},{"id":"T205","span":{"begin":3772,"end":3912},"obj":"Sentence"},{"id":"T206","span":{"begin":3913,"end":4042},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"attributes":[{"subj":"T180","pred":"source","obj":"LitCovid-sentences"},{"subj":"T181","pred":"source","obj":"LitCovid-sentences"},{"subj":"T182","pred":"source","obj":"LitCovid-sentences"},{"subj":"T183","pred":"source","obj":"LitCovid-sentences"},{"subj":"T184","pred":"source","obj":"LitCovid-sentences"},{"subj":"T185","pred":"source","obj":"LitCovid-sentences"},{"subj":"T186","pred":"source","obj":"LitCovid-sentences"},{"subj":"T187","pred":"source","obj":"LitCovid-sentences"},{"subj":"T188","pred":"source","obj":"LitCovid-sentences"},{"subj":"T189","pred":"source","obj":"LitCovid-sentences"},{"subj":"T190","pred":"source","obj":"LitCovid-sentences"},{"subj":"T191","pred":"source","obj":"LitCovid-sentences"},{"subj":"T192","pred":"source","obj":"LitCovid-sentences"},{"subj":"T193","pred":"source","obj":"LitCovid-sentences"},{"subj":"T194","pred":"source","obj":"LitCovid-sentences"},{"subj":"T195","pred":"source","obj":"LitCovid-sentences"},{"subj":"T196","pred":"source","obj":"LitCovid-sentences"},{"subj":"T197","pred":"source","obj":"LitCovid-sentences"},{"subj":"T198","pred":"source","obj":"LitCovid-sentences"},{"subj":"T199","pred":"source","obj":"LitCovid-sentences"},{"subj":"T200","pred":"source","obj":"LitCovid-sentences"},{"subj":"T201","pred":"source","obj":"LitCovid-sentences"},{"subj":"T202","pred":"source","obj":"LitCovid-sentences"},{"subj":"T203","pred":"source","obj":"LitCovid-sentences"},{"subj":"T204","pred":"source","obj":"LitCovid-sentences"},{"subj":"T205","pred":"source","obj":"LitCovid-sentences"},{"subj":"T206","pred":"source","obj":"LitCovid-sentences"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"LitCovid-PubTator","color":"#c9ec93","default":true},{"id":"LitCovid-sentences","color":"#ec93e3"}]}]}}