Vancomycin-Loaded 3D-Printed Polylactic Acid-Hydroxyapatite Scaffolds for Bone Tissue Engineering.

The regeneration of bone remains one of the main challenges in the biomedical field, with the need to provide more personalized and multifunctional solutions. The other persistent challenge is related to the local prevention of infections after implantation surgery. To fulfill the first one and provide customized scaffolds with complex geometries, 3D printing is being investigated, with polylactic acid (PLA) as the biomaterial mostly used, given its thermoplastic properties. The 3D printing of PLA in combination with hydroxyapatite (HA) is also under research, to mimic the native mechanical and biological properties, providing more functional scaffolds. Finally, to fulfill the second one, antibacterial drugs locally incorporated into biodegradable scaffolds are also under investigation. This work aims to develop vancomycin-loaded 3D-printed PLA-HA scaffolds offering a dual functionality: local prevention of infections and personalized biodegradable scaffolds with osseointegrative properties. For this, the antibacterial drug vancomycin was incorporated into 3D-printed PLA-HA scaffolds using three loading methodologies: (1) dip coating, (2) drop coating, and (3) direct incorporation in the 3D printing with PLA and HA. A systematic characterization was performed, including release kinetics, Staphylococcus aureus antibacterial/antibiofilm activities and cytocompatibility. The results demonstrated the feasibility of the vancomycin-loaded 3D-printed PLA-HA scaffolds as drug-releasing vehicles with significant antibacterial effects for the three methodologies. In relation to the drug release kinetics, the (1) dip- and (2) drop-coating methodologies achieved burst release (first 60 min) of around 80-90% of the loaded vancomycin, followed by a slower release of the remaining drug for up to 48 h, while the (3) 3D printing presented an extended release beyond 7 days as the polymer degraded. The cytocompatibility of the vancomycin-loaded scaffolds was also confirmed.

Methicillin-resistant Staphylococcus aureus in swine housed indoors in Galicia, Spain.

INTRODUCTION: Livestock are known reservoirs of methicillin-resistant Staphylococcus aureus (MRSA) and this constitutes an important public health issue. The prevalence of nasal MRSA carriers in swine housed indoors in Galicia, Spain, was studied. METHODS: 197 samples from swine aged three, eight, 12, 16 and 24 weeks, and from adult pigs, were obtained from four farms. The cleaning procedures implemented to clean the barns and antimicrobial consumption were analyzed. Antimicrobial susceptibility and antimicrobial resistance genes were studied. PFGE, spa typing and MLST were used to classify the isolates. SCCmec, agr and pvl were analyzed. RESULTS: MRSA prevalence was 12.7%. Swine younger than 16 weeks had a higher colonization rate; 22.9% vs 3.5% (OR, 8.16; 95% CI, 2.47-29.79; p<0.01). The only farm found to be MRSA-free used disinfectants as part of its cleaning procedure. All MRSA were tetracycline-resistant (identifying the tetK and tetM genes), 80% were resistant to erythromycin and clindamycin and 16% were only clindamycin-resistant. The ermC and vgaA genes were identified in these two phenotypes. A single genotype (PFGE type A) and ST398 - spa t011 (84%) and t1451 (16%) were identified. SCCmec type V and agrI were identified in all isolates, and all were pvl-negative. CONCLUSION: A correlation between swine age and MRSA colonization was observed. Appropriate cleaning procedures could have an impact on MRSA colonization in farming. Resistance to antibiotics used in human health was identified. Clinicians should be aware if their patients have come into contact with farm animals.

Phenotypic and genetic characteristics of fluoroquinolone- and methicillin-resistant Staphylococcus aureus.

INTRODUCTION: Fluoroquinolone resistance in methicillin-resistant Staphylococcus aureus (MRSA) has increased in recent years. The objective of this study was to characterise two MRSA populations, one susceptible to fluoroquinolones and other resistant identifying the clonal types and the differential characteristics of both MRSA populations. METHODS: Molecular typing using PFGE, MLST, spa and SSCmec was performed on 192 MRSA strains isolated from 2009 to 2011, 49 only oxacillin-resistant (OX-R) and 143 oxacillin and levofloxacin-resistant (OX-R-LEV-R). Mutations that conferred resistance to fluoroquinolones, hypermutable phenotypes and the presence of eight microbial surface components recognising adhesive matrix molecules (MSCRAMMs) were also studied. RESULTS: A statistically significant increase in the OX-R-LEV-R phenotype was observed (p<0.05). The most common clone of the OX-R isolates was sequence type (ST) 8 (32.6%), followed by ST72 (26.5%) and ST5 (26.5%). In the OX-R-LEV-R phenotype, the ST5 clone was the most common (65.7%), followed by ST72 (15.4%), and ST125 (12.6%). All isolates except the ST398 clone carried the SCCmecIVc. Clones ST5, ST72, ST125, and ST30 had hypermutable phenotypes. The ST72 clone and the ST30 clone in the OX-R phenotype harboured the highest number of MSCRAMMs. CONCLUSION: ST5 and ST72 clones were the most frequent clones identified in OX-R-LEV-R phenotype. Both clones showed a hypermutable phenotype that favours their selection as the fluoroquinolone resistant clones. The genetic relationships identified indicate that OX-R-LEV-R clones have evolved from OX-R MRSA clones.

Molecular epidemiology of plasmid-mediated high-level mupirocin resistance in methicillin-resistant Staphylococcus aureus in four Spanish health care settings.

Mupirocin is used for the decolonization of methicillin-resistant Staphylococcus aureus (MRSA). High-level mupirocin resistance (Hi-Mup(R)) is of concern, having been associated with therapeutic failure. Our main objective was to assess the emergence and mode/s of spread of Hi-Mup(R) in the MRSA population recovered between 2002 and 2009 in four health care settings in the Pontevedra province, northwest Spain. Five hundred and fifty consecutive clinical MRSA isolates were obtained and screened for antimicrobial susceptibility. Isolates were stratified into multidrug-resistant (MDR) and non-MDR. High-level mupirocin resistant MRSA were characterized by genotyping and plasmid analysis. Thirty-one MRSA (5.6%) exhibited Hi-Mup(R). No association was detected between Hi-Mup(R) and MDR but isolates displaying Hi-Mup(R) were more likely to be resistant to gentamicin and tobramycin. Four main MRSA clones were identified: ST125/t067/PFGE A, ST36/t018/PFGE D, ST8/t008/PFGE B, and ST72/t148 or t3092/PFGE B. Each isolate carried the Hi-Mup(R)ileS2-encoding gene on plasmids and ten plasmid types were distinguished based on unique IS257-ileS2 configurations. Some plasmid types were successfully disseminated among the MRSA clones. Remarkably, six plasmid types were acquired by the predominant genotype ST125/t067/PFGE A. In conclusion, molecular characterization of MRSA isolates combined with the rapid typing of ileS2-encoding plasmids through determination of IS257-ileS2 configurations have proved to be a powerful strategy to address the molecular epidemiology of Hi-Mup(R). The transmission of a diverse set of ileS2-carrying plasmids promoted the emergence of the resistance, with a limited role of clonal expansion in its dispersion.