Earlier we reported that the peptide corresponding to the first eleven N-terminal amino acids of human lactoferrin (hLF1-11) is active against multi-drug resistant pathogens in mice. The mechanisms... Show moreEarlier we reported that the peptide corresponding to the first eleven N-terminal amino acids of human lactoferrin (hLF1-11) is active against multi-drug resistant pathogens in mice. The mechanisms underlying this anti-infective activity remain unclear. Since hLF1-11 is ineffective against pathogens at physiological salt concentrations and hLF1-11 directs differentiation of monocytes toward a macrophage subset with enhanced effector functions, we investigated the effects of hLF1-11 on human and murine monocytes. Results revealed that human and murine monocytes exposed for 1 h to hLF1-11 and then stimulated with the Toll-like receptor (TLR)-ligand LPS for 18 h, displayed enhanced cytokine and chemokine production as compared to control (peptide-treated) monocytes. We also found that expression of mRNA, cell-surface receptor expression, and NF-kappa B activation by hLF1-11-exposed human monocytes were enhanced as compared to control (peptide-treated) monocytes. Furthermore, the kinetics of the cytokine production was unchanged as mRNA levels and protein levels paralleled the enhanced response of hLF1-11-exposed monocytes to LPS. The cytokine production by human monocytes in response to TLR4, TLR5, and TLR7 stimulation, but not to TLR2 stimulation, was elevated by hLF1-11. In concordance, translocation of NF-kappa B subunits to the nucleus was enhanced in hLF1-11-exposed monocytes after TLR stimulation, except for TLR2, as compared to control (peptide-exposed) monocytes. In conclusion, monocytes were primed by hLF1-11 for an enhanced inflammatory response upon TLR4, TLR5, and TLR7 stimulation, but not TLR2 stimulation. Such effects of hLF1-11 on monocyte reactivity should be taken into account when considering the clinical development of this peptide for a therapeutic intervention in patients. Show less
Maggots of the blowfly Lucilia sericata are used for the treatment of chronic wounds. Previously we reported that maggot excretions/secretions (ES) break down Staphylococcus aureus biofilms but do... Show moreMaggots of the blowfly Lucilia sericata are used for the treatment of chronic wounds. Previously we reported that maggot excretions/secretions (ES) break down Staphylococcus aureus biofilms but do not kill the bacteria. As many antibiotics are not effective against biofilms we assessed the effect of combinations of ES and antibiotics on S. aureus biofilms and on the survival of the bacteria released from the biofilms. Effects of ES, antibiotics (vancomycin, daptomycin or clindamycin) and combinations thereof on S. aureus ATCC 29 213 biofilms and bacterial viability were determined using microtitre plates and in vitro killing assays. Vancomycin and daptomycin dose-dependently enhanced biofilm formation, whereas clindamycin reduced S. aureus biofilm size. Adding ES to antibiotic incubations caused a complete biofilm breakdown. After a lag time the bacteria derived from biofilms became susceptible to vancomycin and clindamycin, provided that the medium was refreshed. Daptomycin dose-dependently eliminated the biofilm-derived bacteria immediately. Furthermore, it was significantly more effective against bacteria derived from ES-exposed biofilms than those from control biofilms. ES did not affect the activity of the antibiotics against log-phase S. aureus. Combinations of maggot ES and antibiotics eliminate S. aureus biofilms and the bacteria derived therefrom. Show less
The human lactoferrin-derived peptide hLF1-11 displays antimicrobial activities in vitro and is effective against infections with antibiotic-resistant bacteria and fluconazole-resistant Candida... Show moreThe human lactoferrin-derived peptide hLF1-11 displays antimicrobial activities in vitro and is effective against infections with antibiotic-resistant bacteria and fluconazole-resistant Candida albicans in animals. However, the mechanisms underlying these activities remain largely unclear. Since hLF1-11 is ineffective in vitro at physiological salt concentrations, we suggested modulation of the immune system as an additional mechanism of action of the peptide. We investigated whether hLF1-11 affects human monocyte-macrophage differentiation and determined the antimicrobial activities of the resulting macrophages. Monocytes were cultured for 7 days with GM-CSF in the presence of hLF1-11, control peptide, or saline for various intervals. At day 6, the cells were stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or heat-killed C. albicans for 24 h. Thereafter, the levels of cytokines in the culture supernatants, the expression of pathogen recognition receptors, and the antimicrobial activities of these macrophages were determined. The results showed that a short exposure of monocytes to hLF1-11 during GM-CSF-driven differentiation is sufficient to direct differentiation of monocytes toward a macrophage subset characterized by both pro-and anti-inflammatory cytokine production and increased responsiveness to microbial structures. Moreover, these macrophages are highly effective against C. albicans and Staphylococcus aureus. In conclusion, hLF1-11 directs GM-CSF-driven differentiation of monocytes toward macrophages with enhanced effector functions. Show less
Rapid identification and antimicrobial susceptibility profiling of the bacteria in blood cultures can result in clinical and financial benefits. Addition of saponin to the fluid from blood culture... Show moreRapid identification and antimicrobial susceptibility profiling of the bacteria in blood cultures can result in clinical and financial benefits. Addition of saponin to the fluid from blood culture bottles promotes the recovery of the bacteria and thus may shorten the turnaround time of the microbiological analyses. In this study we compared the identification and susceptibility profiles of saponin-treated and untreated (standard method) blood cultures monomicrobial for Gram-positive cocci using Vitek 2. We concordantly identified 49 (89%) of 55 monobacterial cultures using the results with the standard method as reference. Complete categorical agreement between the susceptibility profiles with the new and the standard method was found for 26 (53%) of 49 isolates, while discrepancies were seen for 23 (47%) cultures. E-tests indicated that the new method resulted in a correct susceptibility profile for 8 (35%) of these 23 blood cultures. Therefore, 34 (69%) of 49 cultures showed a concordant/correct susceptibility profile for all antimicrobials with an overall error rate of 2.3%. Thus, addition of saponin to the fluid from blood culture bottles of the Bactec 9240 leads to the rapid (results available a parts per thousand yen12 hours earlier) and reliable identification and susceptibility profiling of Gram-positive cocci in blood cultures with Vitek 2. Show less
