Association between biomass formation and the prognosis of infective endocarditis due to Staphylococcus aureus / Asociación entre la formación de biomasa y el pronóstico de la endocarditis infecciosa causada por Staphylococcus aureus

INTRODUCTION: The aim of this study was to evaluate the association between biomass formation and the clinical characteristics and prognosis of Staphylococcus aureus infective endocarditis (IE). METHODS: We prospectively studied 209 S. aureus strains causing IE. Biomass formation was examined using the crystal violet assay and quantified spectrophotometrically. The average (SD) optical density of the biomass was compared for each clinical, microbiological (methicillin-resistance, vancomycin MIC≥1.5μg/ml) and molecular (clonal complex, agr type and agr dysfunction) variable according to their presence or absence. The primary clinical endpoints studied were in-hospital death, severe sepsis, persistent bacteraemia, symptomatic peripheral embolisms and prosthetic valve IE. RESULTS: Mean age was 66.1 years, 61.5% of patients were male and the median age-adjusted Charlson comorbidity index was 5 points (IQR 3-8). In-hospital mortality was 37.3%. Strains belonging to CC5 and CC22 had optical biomass densities [mean (SD) 1.573 (1.14) vs 0.942 (0.98) p < 0.001 and 1.720 (0.94) vs 1.028 (1.04) p = 0.001, respectively]. Strains belonging to CC5 and CC22 had significantly higher optical biomass densities [1.369 (1.18) vs 0.920 (0.93) p = 0.008]. No statistically significant differences were found in the clinical endpoints studied. CONCLUSIONS: High biomass production was associated with CC5 and CC22 but not with higher hospital mortality, septic complications, type of endocarditis, methicillin-resistance, elevated vancomycin MIC or agr dysfunction

INTRODUCCIÓN: La bacteriemia por Staphylococcus aureus es un problema de salud importante asociado a una elevada mortalidad. El objetivo de este estudio fue evaluar la asociación entre la capacidad de formación de biomasa y las características clínicas y el pronóstico de la endocarditis infecciosa (EI) por Staphylococcus aureus. MÉTODOS: Se estudiaron de forma prospectiva 209 cepas de S. aureus causantes de episodios de EI. La formación de biomasa se estudió mediante la técnica de cristal violeta y se cuantificó por espectrometría. La media (DE) de la densidad óptica de la biomasa se comparó para cada variable clínica, microbiológica (resistencia a la meticilina, CMI de vancomicina ≥1,5μg/ml) y molecular (complejo clonal, tipo y disfunción de agr) según su presencia o ausencia. El criterio principal de valoración fue la mortalidad hospitalaria. Otras variables clínicas evaluadas fueron: septicemia grave, bacteriemia persistente, embolias periféricas sintomáticas y EI sobre válvula protésica. RESULTADOS: La edad media (DE) fue de 66,1 (16,2) años, el 61,5% eran varones y la mediana del índice de comorbilidad de Charlson ajustado a la edad fue de 5 puntos (RIC 3-8). La mortalidad hospitalaria fue del 37,3%. Las cepas pertenecientes a CC5 y CC22 presentaron densidades ópticas de biomasa significativamente más elevadas (media [DE] 1,573 [1,14] frente a 0,942 [0,98] p < 0,001 y 1,720 [0,94] frente a 1,028 [1,04]; p = 0,001, respectivamente). Las cepas pertenecientes a los grupos agrII mostraron mayores densidades ópticas de biomasa (1,369 [1,18] frente a 0,920 [0,93]; p = 0,008). No se observaron diferencias estadísticamente significativas en las variables clínicas estudiadas. CONCLUSIONES: La producción elevada de biomasa se asoció a determinados linajes clonales (CC5 y CC22), pero no se asoció a una mayor mortalidad hospitalaria, complicaciones sépticas, tipo de endocarditis, resistencia a la meticilina, CMI de vancomicina elevada o disfunción del agr

Association between biomass formation and the prognosis of infective endocarditis due to Staphylococcus aureus.

INTRODUCTION: The aim of this study was to evaluate the association between biomass formation and the clinical characteristics and prognosis of Staphylococcus aureus infective endocarditis (IE). METHODS: We prospectively studied 209 S. aureus strains causing IE. Biomass formation was examined using the crystal violet assay and quantified spectrophotometrically. The average (SD) optical density of the biomass was compared for each clinical, microbiological (methicillin-resistance, vancomycin MIC≥1.5µg/ml) and molecular (clonal complex, agr type and agr dysfunction) variable according to their presence or absence. The primary clinical endpoints studied were in-hospital death, severe sepsis, persistent bacteraemia, symptomatic peripheral embolisms and prosthetic valve IE. RESULTS: Mean age was 66.1 years, 61.5% of patients were male and the median age-adjusted Charlson comorbidity index was 5 points (IQR 3-8). In-hospital mortality was 37.3%. Strains belonging to CC5 and CC22 had optical biomass densities [mean (SD) 1.573 (1.14) vs 0.942 (0.98) p<0.001 and 1.720 (0.94) vs 1.028 (1.04) p=0.001, respectively]. Strains belonging to CC5 and CC22 had significantly higher optical biomass densities [1.369 (1.18) vs 0.920 (0.93) p=0.008]. No statistically significant differences were found in the clinical endpoints studied. CONCLUSIONS: High biomass production was associated with CC5 and CC22 but not with higher hospital mortality, septic complications, type of endocarditis, methicillin-resistance, elevated vancomycin MIC or agr dysfunction.

Sterilization Procedure for Temperature-Sensitive Hydrogels Loaded with Silver Nanoparticles for Clinical Applications.

Hydrogels (HG) have recognized benefits as drug delivery platforms for biomedical applications. Their high sensitivity to sterilization processes is however one of the greatest challenges regarding their clinical translation. Concerning infection diseases, prevention of post-operatory related infections is crucial to ensure appropriate patient recovery and good clinical outcomes. Silver nanoparticles (AgNPs) have shown good antimicrobial properties but sustained release at the right place is required. Thus, we produced and characterized thermo-sensitive HG based on Pluronic® F127 loaded with AgNPs (HG-AgNPs) and their integrity and functionality after sterilization by dry-heat and autoclave methods were carefully assessed. The quality attributes of HG-AgNPs were seriously affected by dry-heat methods but not by autoclaving methods, which allowed to ensure the required sterility. Also, direct sterilization of the final HG-AgNPs product proved more effective than of the raw material, allowing simpler production procedures in non-sterile conditions. The mechanical properties were assessed in post mortem rat models and the HG-AgNPs were tested for its antimicrobial properties in vitro using extremely drug-resistant (XDR) clinical strains. The produced HG-AgNPs prove to be versatile, easy produced and cost-effective products, with activity against XDR strains and an adequate gelation time and spreadability features and optimal for in situ biomedical applications.

Safety and effectiveness of sodium colistimethate-loaded nanostructured lipid carriers (SCM-NLC) against P. aeruginosa: in vitro and in vivo studies following pulmonary and intramuscular administration.

The usefulness of nanotechnology to increase the bioavailability of drugs and decrease their toxicity may be a tool to deal with multiresistant P. aeruginosa (Mr-Pa) respiratory infections. We describe the preparation and the in vivo efficacy and safety of sodium colistimethate-loaded nanostructured lipid carriers (SCM-NLC) by the pulmonary and intramuscular routes. Nanoparticles showed 1-2 mg/L minimum inhibitory concentration against eight extensively drug-resistant P. aeruginosa strains. In vivo, SCM-NLC displayed significantly lower CFU/g lung than the saline and similar to that of the free SCM, even the dose in SCM-NLC group was lower than free SCM. There was no tissue damage related to the treatments. Biodistribution assessments showed a mild systemic absorption after nebulization and a notorious absorption after IM route. Altogether, it could be concluded that SCM-NLC were effective against P. aeruginosa in vivo, not toxic and distribute efficiently to the lung and liver after pulmonary or intramuscular administrations.

Efficacy of liposomal amphotericin B and anidulafungin using an antifungal lock technique (ALT) for catheter-related Candida albicans and Candida glabrata infections in an experimental model.

OBJECTIVE: The aims of this study were as follows. First, we sought to compare the in vitro susceptibility of liposomal amphotericin B (LAmB) and anidulafungin on Candida albicans and Candida glabrata biofilms growing on silicone discs. Second, we sought to compare the activity of LAmB versus anidulafungin for the treatment of experimental catheter-related C. albicans and C. glabrata infections with the antifungal lock technique in a rabbit model. METHODS: Two C. albicans and two C. glabrata clinical strains were used. The minimum biofilm eradication concentration for 90% eradication (MBEC90) values were determined after 48h of treatment with LAmB and anidulafungin. Confocal microscopy was used to visualize the morphology and viability of yeasts growing in biofilms. Central venous catheters were inserted into New Zealand rabbits, which were inoculated of each strain of C. albicans and C. glabrata. Then, catheters were treated for 48h with saline or with antifungal lock technique using either LAmB (5mg/mL) or anidulafungin (3.33mg/mL). RESULTS: In vitro: anidulafungin showed greater activity than LAmB against C. albicans and C. glabrata strains. For C. albicans: MBEC90 of anidulafungin versus LAmB: CA176, 0.03 vs. 128 mg/L; CA180, 0.5 vs. 64 mg/L. For C. glabrata: MBEC90 of anidulafungin versus LAmB: CG171, 0.5 vs. 64 mg/L; CG334, 2 vs. 32 mg/L. In vivo: for C. albicans species, LAmB and anidulafungin achieved significant reductions relative to growth control of log10 cfu recovered from the catheter tips (CA176: 3.6±0.3 log10 CFU, p≤0.0001; CA180: 3.8±0.1 log10 CFU, p≤0.01). For C. glabrata, anidulafungin lock therapy achieved significant reductions relative to the other treatments (CG171: 4.8 log10 CFU, p≤0.0001; CG334: 5.1 log10 CFU, p≤0.0001). CONCLUSIONS: For the C. albicans strains, both LAmB and anidulafungin may be promising antifungal lock technique for long-term catheter-related infections; however, anidulafungin showed significantly higher activity than LAmB against the C. glabrata strains.

High-Dose Daptomycin Is Effective as an Antibiotic Lock Therapy in a Rabbit Model of Staphylococcus epidermidis Catheter-Related Infection.

Long-term catheter-related bloodstream infections (CRBSIs) involving coagulase-negative staphylococci are associated with poor patient outcomes, increased hospitalization, and high treatment costs. The use of vancomycin lock therapy has been an important step forward in treatment of these biofilms, although failures occur in 20% of patients. In this study, we report that a high dose of daptomycin lock therapy may offer a therapeutic advantage for these CRBSIs in just 24 h of treatment.

Efficacy of anidulafungin in the treatment of experimental Candida parapsilosis catheter infection using an antifungal-lock technique.

OBJECTIVES: The effectiveness of anidulafungin versus liposomal amphotericin B (LAmB) for treating experimental Candida parapsilosis catheter-related infection by an antifungal-lock technique was assessed. METHODS: Two clinical strains of C. parapsilosis (CP12 and CP54) were studied. In vitro studies were used to determine the biofilm MICs (MBIC50 and MBIC90) by XTT reduction assay and LIVE/DEAD biofilm viability for anidulafungin and LAmB on 96-well microtitre polystyrene plates and silicone discs. An intravenous catheter was implanted in New Zealand white rabbits. Infection was induced by locking the catheter for 48 h with the inoculum. The 48 h antifungal-lock treatment groups included control, 3.3 mg/mL anidulafungin and 5.5 mg/mL LAmB. RESULTS: Anidulafungin showed better in vitro activity than LAmB against C. parapsilosis growing in biofilm on silicone discs. MBIC90 of LAmB: CP12, >1024 mg/L; CP54, >1024 mg/L. MBIC90 of anidulafungin: CP12, 1 mg/L; CP54, 1 mg/L (P ≤ 0.05). Moreover, only anidulafungin (1 mg/L) showed >90% non-viable cells in the LIVE/DEAD biofilm viability assay on silicone discs. No differences were observed between the in vitro susceptibility of anidulafungin or LAmB when 96-well plates were used. Anidulafungin achieved significant reductions relative to LAmB in log10 cfu recovered from the catheter tips for both strains (P ≤ 0.05). Only anidulafungin achieved negative catheter tip cultures (CP12 63%, CP54 73%, P ≤ 0.05). CONCLUSIONS: Silicone discs may be a more reliable substrate for the study of in vitro biofilm susceptibility of C. parapsilosis. Anidulafungin-lock therapy showed the highest activity for experimental catheter-related infection with C. parapsilosis.

Daptomycin is effective as antibiotic-lock therapy in a model of Staphylococcus aureus catheter-related infection.

BACKGROUND: The effectiveness of daptomycin versus vancomycin for treating experimental methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) catheter-related infection by antibiotic-lock technique was assessed. METHODS: One MSSA strain and one clinical MRSA isolate were used. A preliminary in vitro study determined the minimum biofilm eradication concentration (MBEC) of vancomycin and daptomycin. An intravenous catheter was implanted in New Zealand white rabbits. Infection was induced by 24 h locking the catheter with 0.3 mL of broth culture containing MSSA or MRSA. The 24 h of antibiotic-lock treatment groups were: control, vancomycin 10 mg/mL, daptomycin 5 mg/mL and daptomycin 50 mg/mL. RESULTS: Daptomycin showed greater in vitro activity than vancomycin against biofilm bacteria (MBECs of vancomycin and daptomycin for MSSA, >2000 mg/L and 7 mg/L; MRSA, >2000 mg/L and 15 mg/L). Daptomycin 5 mg/mL achieved significant reductions relative to vancomycin 10 mg/mL in log10 cfu recovered from catheter tips for both strains (P < 0.05). Only daptomycin 50 mg/mL achieved negative catheter tip cultures (up to 75% in MSSA and 85% in MRSA, P < 0.05), showing the greatest median log10 cfu reduction compared to controls (6.07 in MSSA and 6.59 in MRSA, P < 0.05). CONCLUSIONS: Daptomycin 50 mg/mL showed the highest activity against both strains biofilms.