Skin bacterial colonization/infection is a frequent cause of morbidity in patients with chronic wounds and allergic/inflammatory skin diseases. This study aimed to develop a novel approach to... Show moreSkin bacterial colonization/infection is a frequent cause of morbidity in patients with chronic wounds and allergic/inflammatory skin diseases. This study aimed to develop a novel approach to eradicate meticillin-resistant Staphylococcus aureus (MRSA) from human skin. To achieve this, the stability and antibacterial activity of the novel LL-37-derived peptide P10 in four ointments was compared. Results indicate that P10 is chemically stable and antibacterial in hypromellose gel and Softisan-containing cream, but not in Cetomacrogol cream (with or without Vaseline), at 4 degrees C for 16 months. Reduction in MRSA counts on Leiden human epidermal models (LEMs) by P10 in hypromellose gel was greater than that of the peptide in Cetomacrogol cream or phosphate buffered saline. P10 did not show adverse effects on LEMs irrespective of the ointment used, while Cetomacrogol with Vaseline and Softisan cream, but not hypromellose gel or Cetomacrogol cream, destroyed MRSA-colonized LEMs. Taking all this into account, P10 in hypromellose gel dose-dependently reduced MRSA colonizing the stratum corneum of the epidermis as well as biofilms of this bacterial strain on LEMs. Moreover, P10 dose-dependently reduced MRSA counts on ex-vivo human skin, with P10 in hypromellose gel being more effective than P10 in Cetomacrogol and Softisan creams. P10 in hypromellose gel is a strong candidate for eradication of MRSA from human skin. (C) 2019 Elsevier B.V. and International Society of Chemotherapy. All rights reserved. Show less
Infection of burn wounds remains the leading cause of death in burn patients. Topical treatment of such infections with conventional antibiotics is often unsuccessful due to the presence of... Show moreInfection of burn wounds remains the leading cause of death in burn patients. Topical treatment of such infections with conventional antibiotics is often unsuccessful due to the presence of drug-resistant bacteria and/or to the formation of bacterial biofilms. Taken together there is a clear need for novel antimicrobial agents with modes of action different that of current antibiotics. Identification of new synthetic peptide antibiotics for topical use holds a promising approach. In vitro skin models pose many similar properties as normal human skin, and are often used in laboratory settings. In this thesis in vitro models were used to study the effect of colonization and infection of healthy skin, (thermally) wounded skin (chapter 2), mucosal membranes (chapter 3) and skin with characteristics of atopic dermatitis (chapter 6). In addition, the difference in bacterial biofilm formation on biotic (in vitro skin models) versus a-biotic surfaces (polystyrene) was investigated (chapter 7). Finally, skin models were used to identify potent synthetic antimicrobial peptides against drug-resistant bacteria such as Staphylococcus aureus (chapter 3,4). These peptides proved to be effective when applied topically in saline, but also in a hydrogel (chapter 5). Show less
We previously found the LL-37-derived peptide P60.4Ac to be effective against methicillin-resistant Staphylococcus aureus (MRSA) on human epidermal models (EMs). The goal of this study was to... Show moreWe previously found the LL-37-derived peptide P60.4Ac to be effective against methicillin-resistant Staphylococcus aureus (MRSA) on human epidermal models (EMs). The goal of this study was to identify the preferred carrier for this peptide for topical application on skin and mucosal surfaces. We prepared P60.4Ac in three formulations, i.e., a water-in-oil cream with lanolin (Softisan 649), an oil-in-water cream with polyethylene glycol hexadecyl ether (Cetomacrogol), and a hydroxypropyl methylcellulose (hypromellose) 4000 gel. We tested the antimicrobial efficacy of the peptide in these formulations against mupirocin-resistant and -sensitive MRSA strains on EMs and bronchial epithelial models (BEMs). The cytotoxic effects of formulated P60.4Ac on these models were determined using histology and WST-1 and lactate dehydrogenase assays. Moreover, we assessed the stability of the peptide in these formulations with storage for up to 3 months. Killing of MRSA by P60.4Ac in the two creams was less effective than that by P60.4Ac in the hypromellose gel. In agreement with those findings, P60.4Ac in the hypromellose gel was highly effective in eradicating the two MRSA strains from EMs. We found that even 0.1% (wt/wt) P60.4Ac in the hypromellose gel killed >99% of the viable planktonic bacteria and >85% of the biofilm-associated bacteria on EMs. Hypromellose gels containing 0.1% and 0.5% (wt/wt) P60.4Ac effectively reduced the numbers of viable MRSA cells from BEMs by >90%. No cytotoxic effects of P60.4Ac in the hypromellose gel with up to 2% (wt/wt) P60.4Ac on keratinocytes in EMs and in the hypromellose gel with up to 0.5% (wt/wt) P60.4Ac on epithelial cells in BEMs were observed. High-performance liquid chromatography analysis showed that P60.4Ac was stable in the Softisan cream and the hypromellose gel but not in the Cetomacrogol cream. We conclude that P60.4Ac formulated in hypromellose gel is both stable and highly effective in eradicating MRSA from colonized EMs and BEMs. Show less
Reijer, P.M. den; Haisma, E.M.; Lemmens-den Toom, N.A.; Willemse, J.; Koning, R.A.; Demmers, J.A.A.; ... ; Wamel, W. van 2016
