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Abstract：
BACKGROUND: The study aims to investigate the effect of combining silver nanoparticles (AGNPs) with different antibiotics on multi-drug resistant (MDR) and extensively drug resistant (XDR) isolates of Pseudomonas aeruginosa (P. aeruginosa) and to investigate the mechanism of action of AGNPs.
METHODS: AGNPs were prepared by reduction of silver nitrate using trisodium citrate and were characterized by transmission electron microscope (TEM) in addition to an assessment of cytotoxicity. Clinical isolates of P. aeruginosa were collected, and antimicrobial susceptibility was conducted. Multiple Antibiotic Resistance (MAR) index was calculated, and bacteria were categorized as MDR or XDR. Minimum inhibitory concentration (MIC) of gentamicin, ciprofloxacin, ceftazidime, and AGNPs were determined. The mechanism of action of AGNPs was researched by evaluating their effect on biofilm formation, swarming motility, protease, gelatinase, and pyocyanin production. Real-time PCR was performed to investigate the effect on the expression of genes encoding various virulence factors.
RESULTS: TEM revealed the spherical shape of AGNPs with an average particle size of 10.84 ± 4.64 nm. AGNPS were safe, as indicated by IC50 (42.5 µg /ml). The greatest incidence of resistance was shown against ciprofloxacin which accounted for 43% of the bacterial isolates. Heterogonous resistance patterns were shown in 63 isolates out of the tested 107. The MAR indices ranged from 0.077 to 0.84. Out of 63 P. aeruginosa isolates, 12 and 13 were MDR and XDR, respectively. The MIC values of AGNPs ranged from 2.65 to 21.25 µg /ml. Combination of AGNPs with antibiotics reduced their MIC by 5-9, 2-9, and 3-10Fold in the case of gentamicin, ceftazidime, and ciprofloxacin, respectively, with synergism being evident. AGNPs produced significant inhibition of biofilm formation and decreased swarming motility, protease, gelatinase and pyocyanin production. PCR confirmed the finding, as shown by decreased expression of genes encoding various virulence factors.
CONCLUSIONS: AGNPs augment gentamicin, ceftazidime, and ciprofloxacin against MDR and XDR Pseudomonas isolates. The efficacy of AGNPs can be attributed to their effect on the virulence factors of P. aeruginosa. The combination of AGNPs with antibiotics is a promising strategy to attack resistant isolates of P. aeruginosa.
METHODS: AGNPs were prepared by reduction of silver nitrate using trisodium citrate and were characterized by transmission electron microscope (TEM) in addition to an assessment of cytotoxicity. Clinical isolates of P. aeruginosa were collected, and antimicrobial susceptibility was conducted. Multiple Antibiotic Resistance (MAR) index was calculated, and bacteria were categorized as MDR or XDR. Minimum inhibitory concentration (MIC) of gentamicin, ciprofloxacin, ceftazidime, and AGNPs were determined. The mechanism of action of AGNPs was researched by evaluating their effect on biofilm formation, swarming motility, protease, gelatinase, and pyocyanin production. Real-time PCR was performed to investigate the effect on the expression of genes encoding various virulence factors.
RESULTS: TEM revealed the spherical shape of AGNPs with an average particle size of 10.84 ± 4.64 nm. AGNPS were safe, as indicated by IC50 (42.5 µg /ml). The greatest incidence of resistance was shown against ciprofloxacin which accounted for 43% of the bacterial isolates. Heterogonous resistance patterns were shown in 63 isolates out of the tested 107. The MAR indices ranged from 0.077 to 0.84. Out of 63 P. aeruginosa isolates, 12 and 13 were MDR and XDR, respectively. The MIC values of AGNPs ranged from 2.65 to 21.25 µg /ml. Combination of AGNPs with antibiotics reduced their MIC by 5-9, 2-9, and 3-10Fold in the case of gentamicin, ceftazidime, and ciprofloxacin, respectively, with synergism being evident. AGNPs produced significant inhibition of biofilm formation and decreased swarming motility, protease, gelatinase and pyocyanin production. PCR confirmed the finding, as shown by decreased expression of genes encoding various virulence factors.
CONCLUSIONS: AGNPs augment gentamicin, ceftazidime, and ciprofloxacin against MDR and XDR Pseudomonas isolates. The efficacy of AGNPs can be attributed to their effect on the virulence factors of P. aeruginosa. The combination of AGNPs with antibiotics is a promising strategy to attack resistant isolates of P. aeruginosa.
摘要：
背景：该研究旨在研究将银纳米颗粒（AGNPs）与不同抗生素结合对铜绿假单胞菌的多药耐药（MDR）和广泛耐药（XDR）分离株的影响（P。铜绿假单胞菌），并研究AGNP的作用机制。
方法:通过使用柠檬酸三钠还原硝酸银来制备AGNPs,并且通过透射电子显微镜(TEM)以及细胞毒性的评估来表征。收集临床分离的铜绿假单胞菌，和抗菌药物敏感性进行。计算多重抗生素耐药性（MAR）指数，细菌被分类为MDR或XDR。庆大霉素的最小抑制浓度(MIC),环丙沙星,头孢他啶,并确定了AGNP。通过评价AGNPs对生物膜形成的影响,研究了AGNPs的作用机理,成群的运动性，蛋白酶，明胶酶,和铜氰素生产。进行实时PCR以研究对编码各种毒力因子的基因表达的影响。
结果：TEM显示AGNP的球形，平均粒径为10.84±4.64nm。AGNPS是安全的,如IC50（42.5µg/ml）所示。对环丙沙星的耐药性最高，环丙沙星占细菌分离株的43％。在测试的107个分离株中，有63个分离株显示出异质抗性模式。MAR指数范围为0.077至0.84。在63株铜绿假单胞菌中，12和13是MDR和XDR，分别。AGNPs的MIC值范围为2.65至21.25µg/ml。在庆大霉素的情况下，AGNPs与抗生素的组合将其MIC降低了5-9、2-9和3-10倍，头孢他啶,还有环丙沙星,分别,协同作用明显。AGNPs对生物膜的形成产生了显著的抑制作用，并降低了成群运动，蛋白酶，明胶酶和绿脓苷的生产。PCR证实了这一发现，如编码各种毒力因子的基因表达降低所示。
结论：AGNP增强了庆大霉素，头孢他啶,和环丙沙星对抗MDR和XDR假单胞菌分离株。AGNP的功效可归因于它们对铜绿假单胞菌的毒力因子的影响。AGNPs与抗生素的组合是攻击铜绿假单胞菌抗性分离株的有希望的策略。
方法:通过使用柠檬酸三钠还原硝酸银来制备AGNPs,并且通过透射电子显微镜(TEM)以及细胞毒性的评估来表征。收集临床分离的铜绿假单胞菌，和抗菌药物敏感性进行。计算多重抗生素耐药性（MAR）指数，细菌被分类为MDR或XDR。庆大霉素的最小抑制浓度(MIC),环丙沙星,头孢他啶,并确定了AGNP。通过评价AGNPs对生物膜形成的影响,研究了AGNPs的作用机理,成群的运动性，蛋白酶，明胶酶,和铜氰素生产。进行实时PCR以研究对编码各种毒力因子的基因表达的影响。
结果：TEM显示AGNP的球形，平均粒径为10.84±4.64nm。AGNPS是安全的,如IC50（42.5µg/ml）所示。对环丙沙星的耐药性最高，环丙沙星占细菌分离株的43％。在测试的107个分离株中，有63个分离株显示出异质抗性模式。MAR指数范围为0.077至0.84。在63株铜绿假单胞菌中，12和13是MDR和XDR，分别。AGNPs的MIC值范围为2.65至21.25µg/ml。在庆大霉素的情况下，AGNPs与抗生素的组合将其MIC降低了5-9、2-9和3-10倍，头孢他啶,还有环丙沙星,分别,协同作用明显。AGNPs对生物膜的形成产生了显著的抑制作用，并降低了成群运动，蛋白酶，明胶酶和绿脓苷的生产。PCR证实了这一发现，如编码各种毒力因子的基因表达降低所示。
结论：AGNP增强了庆大霉素，头孢他啶,和环丙沙星对抗MDR和XDR假单胞菌分离株。AGNP的功效可归因于它们对铜绿假单胞菌的毒力因子的影响。AGNPs与抗生素的组合是攻击铜绿假单胞菌抗性分离株的有希望的策略。
