Department of Orthopedics and Physical Rehabilitation, Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, Massachusetts 01655, United States.
ACS Appl Mater Interfaces. 2024 May 15;16(19):24421-24430. doi: 10.1021/acsami.4c06002. Epub 2024 May 1.
Periprosthetic infections caused by () pose unique challenges in orthopedic surgeries, in part due to the bacterium's capacity to invade surrounding bone tissues besides forming recalcitrant biofilms on implant surfaces. We previously developed prophylactic implant coatings for the on-demand release of vancomycin, triggered by the cleavage of an oligonucleotide (Oligo) linker by micrococcal nuclease (MN) secreted by the Gram-positive bacterium, to eradicate surrounding the implant in vitro and in vivo. Building upon this coating platform, here we explore the feasibility of extending the on-demand release to ampicillin, a broad-spectrum aminopenicillin β-lactam antibiotic that is more effective than vancomycin in killing Gram-negative bacteria that may accompany infections. The amino group of ampicillin was successfully conjugated to the carboxyl end of an MN-sensitive Oligo covalently integrated in a polymethacrylate hydrogel coating applied to titanium alloy pins. The resultant Oligo-Ampicillin hydrogel coating released the β-lactam in the presence of and successfully cleared nearby in vitro. When the Oligo-Ampicillin-coated pin was delivered to a rat femoral canal inoculated with 1000 cfu , it prevented periprosthetic infection with timely on-demand drug release. The clearance of the bacteria from the pin surface as well as surrounding tissue persisted over 3 months, with no local or systemic toxicity observed with the coating. The negatively charged Oligo fragment attached to ampicillin upon cleavage from the coating did diminish the antibiotic's potency against and () to varying degrees, likely due to electrostatic repulsion by the anionic surfaces of the bacteria. Although the on-demand release of the β-lactam led to adequate killing of but not in the presence of a mixture of the bacteria, strong inhibition of the colonization of the remaining on hydrogel coating was observed. These findings will inspire considerations of alternative broad-spectrum antibiotics, optimized drug conjugation, and Oligo linker engineering for more effective protection against polymicrobial periprosthetic infections.
由 （）引起的假体周围感染在骨科手术中带来了独特的挑战，部分原因是这种细菌除了在植入物表面形成顽固的生物膜外，还能够侵袭周围的骨组织。我们之前开发了一种预防性植入物涂层，用于在微球菌核酸酶 (MN) 切割寡核苷酸 (Oligo) 接头时按需释放万古霉素，这种接头由革兰氏阳性菌分泌，以在体外和体内消灭植入物周围的 。在此涂层平台的基础上，我们探索了将按需释放扩展到氨苄西林的可行性，氨苄西林是一种广谱氨基青霉素 β-内酰胺抗生素，在杀死可能伴随 感染的革兰氏阴性菌方面比万古霉素更有效。氨苄西林的氨基成功地与 MN 敏感的 Oligo 的羧基末端共价偶联，该 Oligo 整合在涂覆在钛合金销上的聚甲基丙烯酸酯水凝胶涂层中。所得的 Oligo-氨苄西林水凝胶涂层在存在 时释放出β-内酰胺，并成功清除了体外的 。当 Oligo-氨苄西林涂层的销被输送到用 1000 cfu 接种的大鼠股骨管中时，它通过及时按需释放药物来防止假体周围感染。从销表面以及周围组织中清除细菌持续了 3 个月，没有观察到涂层的局部或全身毒性。从涂层上切割下来并附着在氨苄西林上的带负电荷的 Oligo 片段在不同程度上降低了抗生素对 （）和 （）的效力，这可能是由于细菌的阴离子表面的静电排斥。尽管β-内酰胺的按需释放导致了足够的杀菌作用，但在存在细菌混合物的情况下，对 （）的杀伤作用不足，但观察到对水凝胶涂层上剩余的 （）的定植有强烈的抑制作用。这些发现将激发对替代广谱抗生素、优化药物偶联和 Oligo 接头工程的考虑，以更有效地防止多微生物假体周围感染。
