Evaluation of free or anchored antimicrobial peptides as candidates for the prevention of orthopaedic device-related infections.

The prevention of implant-associated infection, one the most feared complications in orthopaedic surgery, remains a major clinical challenge and urges development of effective methods to prevent bacterial colonization of implanted devices. Alpha-helical antimicrobial peptides (AMPs) may be promising candidates in this respect due to their potent and broad-spectrum antimicrobial activity, their low tendency to elicit resistance and possible retention of efficacy in the immobilized state. The aim of this study was to evaluate the potential of five different helical AMPs, the cathelicidins BMAP-27 and BMAP-28, their (1-18) fragments and the rationally designed, artificial P19(9/G7) peptide, for the prevention of orthopaedic implant infections. Peptides were effective at micromolar concentrations against 22 Staphylococcus and Streptococcus isolates from orthopaedic infections, while only BMAP-28 and to a lesser extent BMAP-27 were active against Enterococcus faecalis. Peptides in solution showed activities comparable to those of cefazolin and linezolid, on a molar basis, and also a variable capacity to neutralize bacterial lipopolysaccharide, while devoid of adverse effects on MG-63 osteoblast cells at concentrations corresponding to the MIC. The (1-18) BMAP fragments and P19(9/G7) were selected for further examination, based on better selectivity indices, and showed effectiveness in the presence of hyaluronic acid and in synovial fluid, while human serum affected their activity to variable extents, with BMAP-27(1-18) best retaining activity. This peptide was immobilized on streptavidin-resin beads and retained activity against reference Staphylococcus epidermidis and Staphylococcus aureus strains, with negligible toxicity towards osteoblasts, underlining its potential for the development of infection-resistant biomaterials for orthopaedic application. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Antifungal activity of cathelicidin peptides against planktonic and biofilm cultures of Candida species isolated from vaginal infections.

Vulvovaginal candidiasis (VVC) is a frequent gynecological condition caused by Candida albicans and a few non-albicans Candida spp. It has a significant impact on the quality of life of the affected women also due to a considerable incidence of recurrent infections that are difficult to treat. The formation of fungal biofilm may contribute to the problematic management of recurrent VVC due to the intrinsic resistance of sessile cells to the currently available antifungals. Thus, alternative approaches for the prevention and control of biofilm-related infections are urgently needed. In this regard, the cationic antimicrobial peptides (AMPs) of the innate immunity are potential candidates for the development of novel antimicrobials as many of them display activity against biofilm formed by various microbial species. In the present study, we investigated the in vitro antifungal activities of the cathelicidin peptides LL-37 and BMAP-28 against pathogenic Candida spp. also including C. albicans, isolated from vaginal infections, and against C. albicans SC5314 as a reference strain. The antimicrobial activity was evaluated against planktonic and biofilm-grown Candida cells by using microdilution susceptibility and XTT [2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide] reduction assays and, in the case of established biofilms, also by CFU enumeration and fluorescence microscopy. BMAP-28 was effective against planktonically grown yeasts in standard medium (MIC range, 2-32µM), and against isolates of C. albicans and Candida krusei in synthetic vaginal simulated fluid (MIC range 8-32µM, depending on the pH of the medium). Established 48-h old biofilms formed by C. albicans SC5314 and C. albicans and C. krusei isolates were 70-90% inhibited within 24h incubation with 16µM BMAP-28. As shown by propidium dye uptake and CFU enumeration, BMAP-28 at 32µM killed sessile C. albicans SC5314 by membrane permeabilization with a faster killing kinetics compared to 32µM miconazole (80-85% reduced biofilm viability in 90min vs 48h). In addition, BMAP-28 at 16µM prevented Candida biofilm formation on polystyrene and medical grade silicone surfaces by causing a >90% reduction in the viability of planktonic cells in 30min. LL-37 was overall less effective than BMAP-28 against planktonic Candida spp. (MIC range 4-≥64µM), and was ineffective against established Candida biofilms. However, LL-37 at 64µM prevented Candida biofilm development by inhibiting cell adhesion to polystyrene and silicone surfaces. Finally, Candida adhesion was strongly inhibited when silicone was pre-coated with a layer of BMAP-28 or LL-37, encouraging further studies for the development of peptide-based antimicrobial coatings.

Qualidade microbiológica da água utilizada para consumo humano na região do extremo oeste de Santa Catarina, Brasil / Microbiological quality of water used for human consumption in the extreme western region of Santa Catarina, Brazil

No presente estudo, foi avaliada a qualidade microbiológica da água consumida pela população na região do extremo oeste do estado brasileiro de Santa Catarina. Essa região é essencialmente agrícola, com atividades de bovinocultura e suinocultura, fatores que podem influenciar na qualidade microbiológica da água – principalmente porque, muitas vezes, esses mananciais não são adequadamente protegidos e os dejetos são incorretamente descartados. Foram avaliadas 298 amostras de águas de diversas propriedades dessa região entre os anos de 2007 a 2010. As análises microbiológicas (coliformes totais e termotolerantes) foram realizadas pela técnica de fermentação em tubos múltiplos, conforme a metodologia prescrita pela APHA (1998), segundo a Instrução Normativa 62 de 26 de agosto de 2003, do Ministério da Agricultura Pecuária e Abastecimento. Das 298 amostras avaliadas, 191 (64,1%) estavam impróprias para o consumo humano, conforme os padrões bacteriológicos estabelecidos pela portaria 518/2004 do Ministério da Saúde. Das amostras analisadas, 191 (64,1%) continham coliformes totais e 168 (56,4%) coliformes totais e termotolerantes. Esses resultados são preocupantes, e mostram a necessidade de ferramentas como a adoção de medidas preventivas e o tratamento adequado das águas comprometidas, para evitar a ocorrência de enfermidades de veiculação hídrica.