Department of Pathology, Biofilm Laboratory, Medical School, West Virginia University, Morgantown, West Virginia, USA.
Wound Repair Regen. 2011 Nov;19(6):767-74. doi: 10.1111/j.1524-475X.2011.00739.x. Epub 2011 Oct 19.
In this study our objectives were (1) to investigate whether meticillin-resistant Staphylococcus aureus (MRSA) showed an increased tolerance to silver wound dressings compared with meticillin-sensitive S. aureus (MSSA); and (2) to evaluate the effects of bacterial phenotypic states of MRSA and MSSA, and pH, on the activity of silver wound dressings and two antibiotics, ampicillin and clindamycin. Twenty MRSA strains and 10 MSSA strains isolated from burns patients in South Africa were evaluated for their susceptibility to a silver alginate and a silver carboxymethyl cellulose wound dressing, employing a corrected zone of inhibition assay, conducted on Mueller Hinton agar and a poloxamer-based biofilm model. When exposed to the two silver dressings, all 30 S. aureus strains showed susceptibility. Possible enhanced antimicrobial efficacy of the silver dressings occurred when pH was lowered to 5.5, compared with a pH of 7.0. When all S. aureus were grown in the biofilm phenotypic state and exposed to both silver dressings and antibiotics, enhanced tolerance was noted. Susceptibility to silver was overall higher for MRSA when compared with MSSA. This study showed that the effect of pH and bacterial phenotypic state must be considered when the antimicrobial activity of silver wound dressings is being investigated. It is evident from the data generated that both pH and the bacterial phenotypic state are factors that induce changes that affect both antimicrobial performance and bacterial susceptibility.
在这项研究中，我们的目的是：（1）研究耐甲氧西林金黄色葡萄球菌（MRSA）与甲氧西林敏感金黄色葡萄球菌（MSSA）相比，对银质伤口敷料是否表现出更高的耐受性；（2）评估 MRSA 和 MSSA 的细菌表型状态以及 pH 值对银质伤口敷料和两种抗生素（氨苄西林和克林霉素）活性的影响。本研究评估了南非烧伤患者分离的 20 株 MRSA 菌株和 10 株 MSSA 菌株对银藻酸盐和银羧甲基纤维素伤口敷料的敏感性，采用校正抑菌圈测定法，在 Mueller Hinton 琼脂和基于泊洛沙姆的生物膜模型上进行。当所有 30 株金黄色葡萄球菌菌株接触两种银敷料时，均表现出敏感性。与 pH 值为 7.0 相比，当 pH 值降低至 5.5 时，银敷料的可能具有增强的抗菌功效。当所有金黄色葡萄球菌在生物膜表型状态下生长并接触两种银敷料和抗生素时，观察到增强的耐受性。与 MSSA 相比，MRSA 对银的敏感性总体更高。本研究表明，在研究银质伤口敷料的抗菌活性时，必须考虑 pH 值和细菌表型状态的影响。从生成的数据中可以明显看出，pH 值和细菌表型状态都是诱导影响抗菌性能和细菌敏感性变化的因素。
