細菌產生CMY-2水解酵素對頭孢子黴素類(cephalosporins)抗生素產生水解作用,是造成抗藥性的主因之一。與該酵素有關的基因可在不同菌株和菌種間相互傳播,造成抗藥質體的散布。為解決醫療院所中燒燙傷、皮膚潰爛或面積損傷病人感染問題,發展能抗菌且能被生物分解的敷材,具有其重要意義。本研究開發以幾丁聚醣為基材包覆奈米銀離子的敷材,分別以大腸桿菌和沙門氏菌的標準菌株評估與此敷材有關的特性,包括:(1)奈米銀離子是否可以被釋出並產生優異的殺菌效果;(2)奈米銀離子需要多久的時間才能釋出;(3)對於常見具CMY-2水解酵素的格蘭氏陰性菌是否有殺菌效果;(4)釋出多少濃度的奈米銀離子可達到殺菌或抑菌效果;(5)奈米銀離子釋出濃度是否對人體產生危害。實驗結果顯示:對於大腸桿菌的標準菌株,大約包覆100 ppm奈米銀離子的敷料會有顯著的殺菌及抑菌,但需到200 ppm 才有統計上顯著差異(p<0.05);而對於沙門氏菌的標準菌株,需包覆200 pmm奈米銀離子的敷料,才能達到統計上顯著的殺菌及抑菌效果(p<0.05)。而對於具有CMY-2水解酵素的大腸桿菌菌株,則需包覆200 ppm奈米銀離子的敷料,才會有統計上顯著的殺菌及抑菌效果(p<0.05) ;但具有CMY-2水解酵素的沙門氏菌菌株,包覆200 ppm奈米銀離子的敷料,則沒有達到顯著的抑菌及殺菌效果。由此推論,以幾丁聚醣為基材包覆奈米銀離子的最佳濃度為200 ppm。進ㄧ步對包覆奈米銀離子200 ppm的敷料實施48小時萃取物對L929纖維母細胞毒性試驗,實驗結果並未觀察到任何無毒性反應。敷料奈米銀離子在24hr一直持續至48hr的釋出時間,均有良好的抑菌及殺菌反應。本研究僅對格蘭氏陰性菌進行測試,包覆奈米銀離子的幾丁聚醣敷材是否對多數的菌株有效,於未來後續更多的菌株測試將可確認此敷材適用的範圍。
CMY-2 β -lactamase distributed throughout bacteria has a hydrolytic effect on cephalosporin antibiotics which is one of the leading causes of drug resistance. Genes related to CMY-2 β lactamase are able to distribute between and among different strains and types of strain breeding and initiate the distribution of drug resistance plasmid. It is essential, thus, to develop wound dressings that are bacteria-resistant and biodegradable for patients treated in medical institutions for inflammation caused by burning, skin ulcers, or other injuries. This study developed a chiston wound dressing coated with Ag nanoparticles and used the standard strains of pathogenic E. coli and Salmonella to evaluate the proposed wound dressing to examine relevant characteristics including: (1) Could the Ag nanoparticles be released to create an exceptional bacteria elimination effect; (2) How long did it take for the wound dressing to release the Ag nanoparticles? (3) Was it possible to eliminate commonly seen Gram-negative bacteria with blaCMY-2? (4) What concentration of the Ag nanoparticles was needed to kill or inhibit bacteria? (5) Was the concentration of the released Ag nanoparticles harmful to human health? The results of the experiments indicated that the wound dressing coated with a concentration of 100 ppm Ag nanoparticles had significant bacteria elimination and inhibiting effects on E. coli (p<0.05); the concentration had to reach 200 ppm to significantly kill and inhibit the bacteria of Salmonella (p<0.05). However, the pathogenic strain of E. coli with blaCMY-2 needed to be coated with a concentration of 200 ppm Ag nanoparticles to reach the significant bacteria elimination and inhibiting effects (p<0.05); for Salmonella with blaCMY-2, even a concentration of 200 ppm failed to kill and inhibit bacteria significantly (p<0.05). In short, the optimal concentration of Ag nanoparticles coated on the wound dressing was 200 ppm. A further study on the wound dressing coated with a concentration of 200 ppm Ag nanoparticles was conducted for 48 hours to examine the toxicity for L929 fibroblast. The result did not exhibit any toxic effect on the L929 fibroblast. During the release time of the Ag nanoparticles of the wound dressing starting from 24 to 48 hours after application, good bacteria inhibiting and elimination effects were always observed. In this study only Gram-negative bacteria were tested. Whether the wound dressing coated with Ag nanoparticles work effectively on multiple bacteria strains should be explored in future studies.