Morrison Shauna, Singh Ameet, Rousseau Joyce, Walker Meagan, Nazarali Alim, Crawford Evan, Brisson Brigitte, Sears William C, Weese J Scott
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Am J Vet Res. 2015 May;76(5):395-401. doi: 10.2460/ajvr.76.5.395.
To evaluate the impact of gentamicin, silver, or both additives in polymethylmethacrylate (PMMA) beads on methicillin-resistant Staphylococcus pseudintermedius (MRSP) biofilm formation in vitro.
4 preparations of PMMA beads (formed with no additive [control], gentamicin, silver, and gentamicin and silver).
Beads from each group were exposed to 10 MRSP isolates known to be strong biofilm formers. Following incubation, the beads were rinsed to remove planktonic bacteria, then sonicated to dislodge biofilm-associated bacteria. Resulting suspensions were serially diluted, plated on blood agar, and incubated overnight; CFUs were counted. Variance of mean CFU counts following log10 transformation was analyzed among PMMA groups.
None of the PMMA additives tested completely inhibited MRSP biofilm formation. There was a significant effect of gentamicin and gentamicin plus silver on this variable, compared with controls, but not of silver alone. There was no difference between gentamicin and gentamicin plus silver. When only isolates not susceptible to gentamicin were evaluated, there were no significant differences among PMMA additive groups. Within gentamicin-susceptible isolates, there was an impact of gentamicin and gentamicin plus silver, but no impact of silver alone and no difference between gentamicin and gentamicin plus silver.
Gentamicin-impregnated PMMA was effective at reducing biofilm formation of gentamicin-susceptible MRSP isolates but had no effect on isolates not susceptible to gentamicin. Silver-impregnated PMMA had no effect on MRSP biofilm formation. Results suggested that gentamicin-impregnated PMMA may not be effective in vivo against MRSP isolates not susceptible to gentamicin. Antibacterial efficacy of silver should not be assumed without proper testing of the target bacteria and specific silver compound.
评估庆大霉素、银或二者同时添加到聚甲基丙烯酸甲酯（PMMA）微珠中对体外耐甲氧西林中间型葡萄球菌（MRSP）生物膜形成的影响。
4种PMMA微珠制剂（分别为无添加剂[对照]、含庆大霉素、含银以及含庆大霉素和银）。
将每组微珠暴露于10株已知为强生物膜形成菌的MRSP分离株。孵育后，冲洗微珠以去除浮游细菌，然后进行超声处理以去除与生物膜相关的细菌。将所得悬浮液进行系列稀释，接种于血琼脂平板上并孵育过夜；计算菌落形成单位（CFU）。对PMMA各实验组经log10转换后的平均CFU计数的方差进行分析。
所测试的PMMA添加剂均未完全抑制MRSP生物膜的形成。与对照组相比，庆大霉素以及庆大霉素加银对该变量有显著影响，但单独银无此影响。庆大霉素与庆大霉素加银之间无差异。当仅评估对庆大霉素不敏感的分离株时，PMMA添加剂组之间无显著差异。在对庆大霉素敏感的分离株中，庆大霉素以及庆大霉素加银有影响，但单独银无影响，且庆大霉素与庆大霉素加银之间无差异。
含庆大霉素的PMMA可有效减少对庆大霉素敏感的MRSP分离株的生物膜形成，但对庆大霉素不敏感的分离株无效。含银的PMMA对MRSP生物膜形成无影响。结果表明，含庆大霉素的PMMA在体内可能对庆大霉素不敏感的MRSP分离株无效。在未对目标细菌和特定银化合物进行适当测试的情况下，不应假定银具有抗菌效力。
