大蒜蒜瓣中细菌多样性分析及抑菌剂筛选

微生物的生长会限制大蒜蒜瓣的贮藏期。通过分离纯化,结合菌落形态、菌体形态和PCR序列比对,分析大蒜蒜瓣中细菌多样性;测定抑菌圈直径、最小抑菌浓度和最小杀菌浓度,比较常用生物抑菌剂和化学防腐剂对大蒜蒜瓣中常见细菌的抑菌能力。结果表明,从大蒜蒜瓣中分离得到的菌株主要有水生拉恩菌、土生拉乌尔菌、表皮葡萄球菌、肠膜明串珠菌、乳酸明串珠菌、苏云金芽孢杆菌、成团泛菌、柠檬酸杆菌。生物抑菌剂肉桂醛和化学防腐剂双乙酸钠对4种指示菌(大肠杆菌、金黄色葡萄球菌、土生拉乌尔菌和水生拉恩菌)的抑菌效果最好,肉桂醛和双乙酸钠联用对大蒜蒜瓣中菌落总数的抑菌率达到98.4%,对大肠菌群的抑菌率达到100%。

不同有机酸联用对大肠杆菌的抑制作用

有机酸在抑制致病菌方面具有重要的应用价值。该文以大肠杆菌ATCC25922为指示菌,使用微量稀释法和棋盘格法确定多种有机酸及其组合的最小抑菌浓度,半数有效抑菌浓度和联合抑菌指数。并通过对大肠杆菌细胞膜电位和微观形态的观察,研究不同有机酸组合的联合抑菌效应。结果表明,乙酸、乳酸和丁酸的最小抑菌浓度为2560μg/mL,柠檬酸和苹果酸的最小抑菌浓度为5120μg/mL;乙酸、乳酸、丁酸、柠檬酸和苹果酸的半数有效抑菌浓度分别为1004.90、1497.50、964.32、1406.02、1727.72μg/mL。乙酸和乳酸联用表现为相加作用,乙酸、乳酸和第3种有机酸(丁酸、柠檬酸、苹果酸)联用表现为协同作用;有机酸及其组合会导致大肠杆菌膜电位下降,多数菌体出现收缩、弯曲变形。

16种岭南特色道地药材对肺炎链球菌的抑菌作用研究

研究16种岭南特色道地药材对肺炎链球菌的体外抑菌活性。以肺炎链球菌为受试菌,采用24孔板培养法测定16种岭南特色道地药材醇提物的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)。结果显示,16种岭南特色药材中有11种对肺炎链球菌有抑菌性,分别为:火炭母、桂枝、长萼堇菜、岗梅、广藿香、扁桃斑鸠菊、破布叶、一点红、狗肝菜、三桠苦、地胆草。其中,长萼堇菜、广藿香、扁桃斑鸠菊、狗肝菜、三桠苦、地胆草的醇提物表现出较强的抑菌活性。部分岭南特色道地药材的乙醇提取物对肺炎链球菌具有良好的抑菌作用。

酮康唑-甲基-β-环糊精包合物的表征及抑菌活性研究

[目的]为了提高低水溶性抗真菌药物酮康唑(ketoconazole,KCZ)的水溶性及抑菌活性,减少临床应用限制。[方法]采用饱和溶液法制备酮康唑-甲基-β-环糊精包合物,高效液相色谱法(HPLC)检测其溶解度,通过傅里叶变换红外光谱(IR)法对其结构进行表征,用纸片扩散法(K-B法)和最小抑菌浓度(MIC)方法对比检验酮康唑原药与酮康唑-甲基-β-环糊精包合物对白色假丝酵母菌的体外抗菌活性。[结果]通过甲基-β-环糊精包合,酮康唑在包合物中的水溶性比单一酮康唑增加了约2 941倍,通过傅里叶变换红外光谱(IR)法证实了有新物相形成。酮康唑原药的抑菌圈为(22.00±1.63) mm,酮康唑-甲基-β-环糊精包合物的抑菌圈则提升至(28.00±1.63) mm。最低抑菌浓度结果显示,酮康唑原药的最低抑菌浓度为(0.125±0.029)μg/mL,酮康唑-甲基-β-环糊精包合物的最低抑菌浓度为(0.062 5±0.015 0)μg/mL。[结论]酮康唑-甲基-β-环糊精包合物不仅没有破坏酮康唑原药对白色假丝酵母菌原有的抑菌能力,还提高了其抑菌效果。

Anti-microbial principles of selected remedial plants from Southern India

Objective:To examine the anti-bacterial activity of leaf extracts of Morus alba L.(Moraceae)and Piper betel L.(Piperaceae),and seed extracts of Bombax ceiba L.(Borabacaceae).Methods:We have partially purified plant extracts by solvent extraction method,and evaluated the effect of individual fractions on bacterial growth using Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa) and Staphylococcus aureus(S.aureus) bacterial strains.Results:Compared with Morus and Bombax fractions,Piper fractions showed significant growth inhibition on all the three types of bacteria studied.The EtOAc-hexane fractions of Piper leaves exhibited significant antibacterial activity with minimum inhibitory concentrations(MIC) of 50 μg/mL culture against both gram-positive and gram-negative bacteria.The EtOAc-fractions Ⅰ,Ⅱ,and Ⅳ inhibited bacterial colony formation on soft agar in addition to growth inhibition.A combination treatment of piper fractions with ampicillin resulted in significant growth inhibition in E.coli and P.aeruginosa,and combination with anticancer drug geldanamycin(2 μg/mL) showed selective growth inhibition against P.aeruginosa and S.aureus.Three major compounds,i.e.,eugenol,3-hexene-ol and stigmasterol,were primarily identified from Piper betel leaf extractions.Among the individual compounds,eugenol treatment showed improved growth inhibition compared with stigmasterol and 3-hexene-ol.Conclusions:We are reporting potential anti-bacterial compounds from Piper betel against both gram-positive and gram-negative bacteria either alone or in combination with drug treatment.

Antimicrobial activities of the rhizome extract of Zingiber zerumbet Linn

Objective:To investigate antimicrobial effects of ethanolic extract of Zingiber zerumbet(Z.zerumbet)(L.)Smith and its chloroform and petroleum ether soluble fractions against pathogenic bacteria and fungi.Methods:The fresh rhizomes of Zingiber zerumbet were extracted in cold with ethanol(4.0 L)after concentration.The crude ethanol extract was fractionated by petroleum ether and chloroform to form a suspension of ethanol extract(15.0 g),petroleum ether fraction(6.6 g)and chloroform soluble fraction(5.0 g).The crude ethanol extract and its petroleum ether and chloroform fractions were evaluated for antibacterial and antifungal activity against thirteen pathogenic bacteria and three fungi by the disc diffusion method.Commercially available kanamycin(30μg/disc)was used as standard disc and blank discs impregnated with the respective solvents were used as negative control.Results:At a concentration of 400μg/disc,all the samples showed mild to moderate antibacterial and antifungal activity and produced the zone of inhibition ranging from 6 mm to 10 mm.Among the tested samples,the crude ethanol extract showed the highest activity against Vibrio parahemolyticus(V.parahemolyticus).The minimum inhibitory concentration(MIC)of the crude ethanol extract and its fractions were within the value of 128-256μg/mL against two Gram positive and four Gram negative bacteria and all the samples showed the lowest MIC value against V.parahemolyticus(128μg/mL).Conclusions:It can be concluded that,potent antibacterial and antifungal phytochemicals are present in ethanol extract of Z.zerumbet(L.).

Aqueous and organic extracts of Trigonella foenum-graecum L.inhibit the mycelia growth of fungi

Aqueous extracts from various plant parts of fenugreek(3%)(aerial parts:leaves and stems(LS),roots(R),ground seeds(GS)and not ground seeds(NGS))and petroleum ether,ethyl acetate and methanolic fractions of the aerial parts were assayed to determine their antifungal potential against Botrytis cinerea,Fusarium graminearum,Alternaria sp.,Pythium aphanidermatum,and Rhizoctinia solani.All fenugreek plant parts showed antifungal potential and the magnitude of their inhibitory effects was species and plant parts d...

Pathogen characteristics and its sensitivity against antimicrobial agents in fatal bacterial granuloma after eyelid trauma in vitro

AIM: To understand the pathogen characteristics and its sensitivity against antimicrobial agents in fatal bacterial granuloma after eyelid trauma (FBGT) in vitro, and to provide laboratory evidence for diagnosis. METHODS: The FBGT pathogens were isolaated and cultured with reformed rabbit-brain anaerobic enriched broth (RRAB), and identified by ATB/API 20A system. The minimum inhibiting concentration (MIC) was determined by anaerobic broth dilution method. RESULTS: A total of 22 strains of pathogen were separated from 21 patients with FBGT and identified as Propionibacterium acnes (PA) by ATB/API 20A system. The MIC of ciprofloxacin for 22 PA strains was 0.0625-0.5mg/L, the MIC of penicillin, ampicillin, ampicillin/sulbactam, cefoperazone, lincomycin, and imipenem/cilastatin were 0.125-0.5mg/L, the MIC of ticarcillin/clavulanic acid was 0.250-1.000mg/L, and the MIC of metronidazole was 64-256mg/L. The pathogen of FBGT was strictly anaerobic PA, which growed slowly and better in nutritious RRAB broth. All PA were resistant to metronidazole, but susceptive to other routine antimicrobial agents, such as penicillin, ampicillin and lincomycin. CONCLUSION: FBGT should not be treated with metronidazole. Clinicians should choose combined use of drugs or operation to treat FBGT according to patients' individual condition and the results of drug sensitivity test.

Linear Thanatin Is an Effective Antimicrobial Peptide against Colistin-Resistant <i>Escherichia coli in Vitro</i>

Colistin has been regarded as the last line antibiotic for treatment of infections caused by multidrug resistant gram-negative bacteria. Therefore, the increasing emergence of colistin resistance among gram-negative bacteria represents a serious problem. The objective of this study was to characterize the effectiveness of the chemically synthesized thanatin in linear form against colistin-resistant E. coli isolated from a pig farm in China. Agar diffusion assay and broth microdilution test were employed to analyze the susceptibility of colistin-sensitive E. coli (ATCC25922) and colistin-resistant E. coli (SHP45) to linear thanatin (L-thanatin). Combinatory effect of linear thanatin and colistin against E. coli was also determined by fractional inhibition concentration index (FICI) analysis. The results showed that L-thanatin at a concentration of 1 mg/ml produced larger inhibition zone on agar against ATCC25922 than SHP45. In the quantitative microdilution test, L-thanatin had the same MIC of 3.2 μg/ml for ATCC25922 and SHP45. Based on the FICI analysis, additive effect was obtained with 1.56 μg/ml of L-thanatin and 0.125 μg/ml of colistin for ATCC25922;but with 1.56 μg/ml of L-thanatin and 0.25 μg/ml of colistin or with 2 μg/ml of colistin and 0.39 μg/ml of L-thanatin for SHP45. These data proved that L-thanatin is an effective antimicrobial peptide against colistin-resistant E. coli.

全国1200例VVC致病菌的常见抗真菌药物MIC分析

目的了解全国外阴阴道假丝酵母菌病(VVC)致病菌株的分布及其对常见抗真菌药物的敏感性。方法复苏2015年全国45家医院于妇科门诊就诊的VVC患者的VVC菌株1200例。用科玛嘉假丝酵母菌显色培养基进行培养鉴定。参照美国临床实验室标准化协会(CLSI)M27-A3方案,测定其对氟康唑、克霉唑、咪康唑、伊曲康唑及制霉菌素5种抗真菌药物的最低抑菌浓度(MIC)值情况。结果(1)在培养的1200例VVC致病菌株中,白假丝酵母菌占81.17%(974/1200),非白假丝酵母菌占18.83%(226/1200)。在非白假丝酵母菌中,光滑假丝酵母菌最多,占13.25%(159/1200)。(2)白假丝酵母菌与非白假丝酵母菌的氟康唑、克霉唑、咪康唑、伊曲康唑及制霉菌素不同MIC值分布比较差异均有统计学意义(χ^(2)值分别为175.220、66.912、217.150、281.004、21.175,P<0.0001)。(3)对于克霉唑,白假丝酵母菌的MIC低值比例更低,而非白假丝酵母菌的MIC高值比例更高。对于咪康唑,非白假丝酵母菌的MIC低值比例更低,而白假丝酵母菌的MIC高值比例更高。(4)白假丝酵母菌和非白假丝酵母菌对氟康唑的耐药性均较高,MIC≥64μg/mL比例分别为73.41%和50.88%;而白假丝酵母菌和非白假丝酵母菌对于制霉菌素MIC低值比例均较高,MIC≤1μg/mL比例分别为79.67%和76.11%。(5)白假丝酵母菌对于伊曲康唑耐药性高于非白假丝酵母菌,MIC≥16μg/mL比例分别为43.12%和25.66%。结论VVC的主要致病菌仍是白假丝酵母菌,光滑假丝酵母菌已成为白假丝酵母菌以外的VVC第2大致病菌。白假丝酵母菌和非白假丝酵母菌对5种抗真菌药物的MIC值分布具有明显差异。全国VVC患者对氟康唑耐药性较高,白假丝酵母菌致VVC患者对克霉唑和制霉菌素敏感度较高,非白假丝酵母菌致VVC患者对咪康唑和制霉菌素的敏感度较高。

Antimicrobial Effects of Berries on Listeria monocytogenes

The purpose of this study was to first evaluate the antimicrobial effects of powder and extracts of berries (rose-hip, aronia, sea buckthorn and hawthorn) on the development of antibiotic-resistant L. monocitogenes. Listeria monocytogenes is considered one of the most important pathogens responsible for food-borne infection. Antimicrobial properties were evaluated using the standard Kirby-Bauer disk diffusion method. Bacterial inactivation networks were determined and compared, as well as the possibility of using powders and extracts of berries to control the risk of Listeria monocytogees infestation in the milk and dairy industry as well as in the meat industry. The effect of pH (4.78 - 4.43) and water activity (0.90 - 0.80) on the relationship between optical density (OD) at 600 nm and the plate count (CFU ml-1) was investigated for Listeria monocytogenes. It was determined Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) of berries for L. monocytogenes. The most relevant bacteriostatic and bactericidal effect on L. monocytogenes in the tested berries demonstrated sea buckthorn and rosehip.

Antimicrobial activity of PVP from an Antarctic bacterium, Janthinobacterium sp. Ant5-2, on multi-drug and methicillin resistant Staphylococcus aureus

Multiple drug resistant(MDR)and methicillin-resistant Staphylococcus aureus(MRSA)have become increasingly prevalent as a community acquired infection.As a result limited treatment options are available with conventional synthetic antibiotics.Bioprospecting natural products with potent antimicrobial activity show promise for developing new drugs against this pathogen.In this study,we have investigated the antimicrobial activity of a purple violet pigment(PVP)from an Antarctic bacterium,Janthinobacterium sp.Ant5-2 on 15 clinical MDR and MRSA strains.The colorimetric resazurin assay was employed to determine the minimum inhibitory concentration(MIC90)of PVP against MDR and MRSA.The MIC90 ranged between 1.57μg/mL and 3.13μg/mL,which are significantly lower than many antimicrobials tested from natural sources against this pathogen.The spectrophotometrically determined growth analysis and total microscopic counts using Live/dead®BacLight™fluorescent stain exhibited a steady decrease in viability of both MDR and MRSA cultures following treatment with PVP at the MIC levels.In silico predictive molecular docking study revealed that PVP could be a DNA-targeting minor groove binding antimicrobial compound.The continued development of novel antimicrobials derived from natural sources with the combination of a suite of conventional antibiotics could stem the rising pandemic of MDR and MRSA along with other deadly microbial pathogens.

大蒜原汁对乳鸽腹泻大肠杆菌的抗菌效果研究

为检测大蒜汁对乳鸽腹泻大肠杆菌的抗菌作用,采用常量试管稀释法检测4种大蒜汁对乳鸽腹泻大肠杆菌的最小杀菌浓度(MBC)和最小抑菌浓度(MIC)。试验结果表明:37℃时紫皮多瓣蒜的MBC为2.5%,MIC为1.25%;白皮多瓣蒜、独头蒜和三瓣蒜的MBC均为5%,MIC均为2.5%。不同温度下,白皮多瓣蒜、三瓣蒜和独头蒜75℃时的MIC分别为2.5%、10%和10%,三者加热到85℃和95℃后均没有抗菌作用;紫皮多瓣蒜在85℃时有一定的抗菌作用,MIC为2.5%,加热到95℃后没有抗菌作用。4种大蒜汁在37℃时对乳鸽腹泻大肠杆菌均具有抗菌作用,对乳鸽腹泻大肠杆菌病具有良好的预防与治疗作用。

复配精油抑菌剂的制备及其对鲜切猪肉的抑菌作用

通过水蒸气蒸馏法提取肉桂精油(cinnamon essential oil,CEO)、紫苏精油(perilla essential oil,PEO)和牛至精油(oregano essential oil,OEO),采用微量二倍稀释法测定单一植物精油的最小抑菌浓度(minimal inhibitory concentration,MIC),用棋盘稀释法计算复配精油的分级抑菌浓度指数,并探究复配精油的抑菌效果及对鲜切猪肉的保鲜抑菌作用。结果表明,3种精油对大肠杆菌及金黄色葡萄球菌均有抑菌作用,抑菌能力的大小表现为肉桂精油>紫苏精油>牛至精油;精油复配后存在协同或相加现象,其中,肉桂-紫苏精油复配剂对2种供试菌种的抑菌效果显著优于肉桂-牛至精油复配剂和紫苏-牛至精油复配剂。肉桂-紫苏精油复配在一定程度上能有效抑制鲜切猪肉水分及蛋白质含量的损耗,抑制微生物生长并保持鲜猪肉的色泽,证明肉桂-紫苏精油复配剂对鲜切猪肉具有一定的保鲜抑菌作用。

抗水产病原非O1/O139霍乱弧菌的中草药筛选及抑菌效果分析

为筛选能有效抑制水产病原非O1/O139霍乱弧菌(non-O1/O139 Vibrio cholerae)生长的中草药,本研究通过水煎法获得黄柏、五倍子等23味中草药的提取物,采用琼脂打孔法测定其对非O1/O139霍乱弧菌的抑制作用,并用试管二倍稀释法测定了抑制效果较强的8种中草药对非O1/O139霍乱弧菌的最小抑菌浓度(Minimum Inhibitory Concentration,MIC)和最小杀菌浓度(Minimum Bactericidal Concentration,MBC)。结果表明:五倍子、白芍、黄柏、诃子、山楂、石榴皮、地榆、木瓜等8种草药对非O1/O139霍乱弧菌具有较强的抑制作用,其中非O1/O139霍乱弧菌对五倍子、白芍和黄柏高度敏感,其抑菌圈直径分别为(19.92±1.24)mm、(19.50±0.74)mm和(18.92±2.12)mm。五倍子抑菌和杀菌作用最强,MIC和MBC均为7.81 mg/mL,其次是白芍,MIC为15.63 mg/mL,MBC为31.25 mg/mL。本研究为中草药防治由非O1/O139霍乱弧菌引起的水产动物疾病提供了理论参考。

10%水合氯醛溶液剂与凝胶剂对5种菌株的体外抑菌效果研究

目的研究10%水合氯醛溶液剂与凝胶剂对金黄色葡萄球菌、铜绿假单胞菌、大肠埃希菌、枯草芽孢杆菌和沙门菌等5种菌株的体外抑菌活性。方法采用倍比稀释法结合平板划线法测定10%水合氯醛溶液剂与凝胶剂的最低抑菌浓度和最低杀菌浓度;采用牛津杯法及纸片扩散法测定其抑菌圈。结果(1)10%水合氯醛溶液剂对5种菌株均呈现不同程度的抑菌作用,铜绿假单胞菌的最低抑菌浓度为6.25 mg·ml^(-1),最低杀菌浓度为12.50 mg·ml^(-1);沙门菌和枯草芽孢杆菌的最低抑菌浓度均为12.50 mg·ml^(-1),最低杀菌浓度均为25.00 mg·ml^(-1);金黄色葡萄球菌和大肠埃希菌的最低抑菌浓度均为25.00 mg·ml^(-1),最低杀菌浓度均为50.00 mg·ml^(-1)。(2)10%水合氯醛凝胶剂对5种菌株也均呈现不同程度的抑菌作用,铜绿假单胞菌、枯草芽孢杆菌和沙门氏菌的最低抑菌浓度均为6.25 mg·ml^(-1),最低杀菌浓度均为12.50 mg·ml^(-1);金黄色葡萄球菌的最低抑菌浓度为12.50 mg·ml^(-1),最低杀菌浓度为25.00 mg·ml^(-1);大肠埃希菌的最低抑菌浓度为25.00 mg·ml^(-1),最低杀菌浓度为50.00 mg·ml^(-1)。(3)5种菌株对水合氯醛溶液剂与凝胶剂的敏感性均属于极度敏感,抑菌圈直径均大于20 mm。结论10%水合氯醛溶液剂与凝胶剂对金黄色葡萄球菌、铜绿假单胞菌、大肠埃希菌、枯草芽孢杆菌和沙门菌等5种菌株具有明显的体外抑菌活性。

中草药的抑菌活性及其对圣女果的保鲜效果

【目的】研究五倍子、油橄榄叶、虎杖和蒲公英4种中草药的抑菌活性及其对圣女果的保鲜效果,为开发绿色安全的圣女果保鲜剂,以及食品天然防腐保鲜剂的研究提供参考依据。【方法】采用醇提法制备五倍子、油橄榄叶、虎杖和蒲公英4种中草药提取液,以大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、啤酒酵母和黑曲霉为指示菌,利用牛津杯法考察提取液抑菌活性,以二倍稀释法考察最低抑菌浓度(MIC);将不同浓度(50.00和100.00 mg/mL)五倍子和油橄榄叶提取液喷洒于圣女果表面,以蒸馏水为空白对照(CK),通过感官评价、腐烂率、失重率、硬度、可滴定酸、可溶性固形物和维生素C(Vc)指标,考察对圣女果的保鲜效果。【结果】4种中草药提取液对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、啤酒酵母和黑曲霉均有不同程度的抑菌效果,五倍子和油橄榄叶抑菌效果最佳,抑菌圈直径分别为18.47和20.00 mm、17.77和22.00 mm、15.90和17.00 mm、14.83和13.00 mm、15.93和14.07 mm;MIC分别为62.50和15.63 mg/mL、31.25和7.81 mg/mL、31.25和15.63 mg/mL、62.50和31.25 mg/mL、62.50和62.50 mg/mL。从圣女果的保鲜测试指标结果可知,相较于CK,50.00和100.00 mg/mL五倍子和油橄榄叶提取液均可在不同程度上改善圣女果保鲜效果。贮藏至第10 d时,相较于其他处理组,100.00 mg/mL油橄榄叶提取液处理组的感官评分(46.15分)、腐烂率(16.67%)、失重率(4.50%)、硬度(1.20 kg/cm2)、可溶性固形物含量(6.18%)和Vc含量(31.50 mg/100 g)等保鲜指标最优,与CK存在显著(P<0.05)或极显著(P<0.01,下同)差异;而100.00 mg/mL五倍子提取液处理组的可滴定酸含量(0.48%)最高,与CK间差异极显著。【结论】100.00 mg/mL油橄榄叶提取液对圣女果的保鲜效果最佳,作为天然防腐保鲜剂具有良好的应用前景。

精油与天然产物复配对阴道炎念珠菌的体外抑制作用

念珠菌性阴道炎(vulvovaginal candidiasis,VVC)是女性阴道感染中最常见的疾病之一,临床上一般采用作用于局部或全身的抗真菌药物,但这些药物常引起阴道微生态失调,治疗效果不佳。以精油和天然产物为原料,采用低能乳化法配制了复方微乳液,研究了复合配方对白色念珠菌和乳酸杆菌的抑菌作用。当精油和天然产物的复合配方含有柠檬香茅50 mg/mL、厚朴提取物0.3 mg/mL、白千层5 mg/mL、香桃木5 mg/mL和KHC20抑菌剂2 mg/mL时,白色念珠菌对10倍最小抑菌浓度(MIC)的复合配方表现为高度敏感,在24 h的抑菌试验中无菌落生长;对于乳酸杆菌,由于未达到其MIC,复合配方的抑菌效果不显著,乳酸杆菌可形成菌膜且生长良好。结果表明,该复合配方在体外环境下能有效抑制白色念珠菌生长并且保护有益菌群不受破坏,为维护阴道微生态平衡的药物开发提供理论基础。

谷胱甘肽辅助合成银纳米粒子及其抗菌活性研究

为了制备具有较好的理化性质以及抗菌活性的银纳米粒子,以硝酸银为银源,抗坏血酸为还原剂、谷胱甘肽(GSH)为模板剂,通过一步法制得谷胱甘肽-银纳米粒子(GSH-AgNPs)。此外,以GSH和硝酸银摩尔比、反应时间、pH为影响因素,以GSH-AgNPs的抗菌活性为评价指标,筛选GSH-AgNPs的最佳制备工艺。采用透射电子显微镜、傅里叶变换红外光谱仪和X射线光电子能谱仪等表征产物的形貌、光学性质和化学组成。结果表明,最佳制备条件为GSH/硝酸银摩尔比3∶5,反应体系pH=8,反应时间8h。最优条件下制备的GSH-AgNPs为高度分散的球形纳米粒,平均粒径为(3.1±0.66)nm。GSH-AgNPs表现出广谱的抗菌能力,对革兰氏阴性菌(大肠杆菌、铜绿假单胞菌)、革兰氏阳性菌(金黄色葡萄球菌、枯草芽孢杆菌)、真菌(白色念珠菌)均表现出良好的抗菌效果,其对革兰氏阴性菌和革兰氏阳性菌的最小抑制浓度均为31.25mg/mL,对真菌的最小抑菌浓度为125mg/mL。

体外诱导耐药及相关基因检测

[目的]了解常见致病菌产生耐药性后耐药基因和毒力基因的变化。[方法]采用微量肉汤二倍稀释法测定21种临床常见抗生素对大肠杆菌、金黄色葡萄球菌等5种标准菌株的最小抑菌浓度,选取敏感药物进行体外诱导耐药试验,采用PCR法检测耐药基因和毒力基因。[结果]5个标准菌株均对氨基糖苷类药物敏感;大肠杆菌对四环素类药物敏感;鼠伤寒沙门氏菌、多杀性巴氏杆菌和肺炎链球菌对喹诺酮类药物敏感;金黄色葡萄球菌对克林霉素敏感。与标准菌株相比,氨基糖苷类和四环素类耐药菌株中均检测出新出现的相关耐药基因;喹诺酮类耐药基因parE在多杀性巴氏杆菌的标准菌株和耐诺氟沙星菌株中检测出,gyrB基因仅在肺炎链球菌的标准菌株和耐氧氟沙星菌株中检测出。在大肠杆菌中均检测出CS31A毒力基因,此外标准菌株中检测出fimH基因,耐多西环素菌株中检测出afa基因;多杀性巴氏杆菌标准菌株未检测出毒力基因,耐药菌株中均检测出oma87和tbpA基因;而鼠伤寒沙门氏菌、金黄色葡萄球菌和肺炎链球菌仅在标准菌株中检测出毒力基因。[结论]说明氨基糖苷类抗生素更容易诱导菌株产生耐药基因,而毒力基因与耐药基因无明显的相关性。细菌获得耐药性后,其毒力基因变化因菌株不同存在差异。