Novel antimicrobial ointment for infected wound healing in an in vitro and in vivo porcine model.

Microbial contamination of wounds is a significant problem that delays healing, particularly when bacterial biofilms are present. A novel combination of pectinic acid (PG) + caprylic acid (CAP) was previously found in vitro to be highly effective in eradicating various pathogens in biofilms with minimal cytotoxicity. In this study, a novel wound ointment was formulated with PG + CAP and first assessed in vitro using a well-established biofilm eradication model. In vitro, the PG + CAP ointment was shown to be efficacious in reducing the microbial biofilms. This ointment was then tested in vivo in two pilot porcine wound healing models, with and without Staphylococcus aureus microbial challenge. Ointments were applied to each wound daily, and healing by wound closure area measurement was assessed weekly over 4 weeks. After 4 weeks, pigs were sacrificed and wounds were scored for reepithelialization, inflammation, granulation tissue, and collagen deposition. We compared PG + CAP to hydroxyethylcellulose + glycerol ointment base (control) and MediHoney (comparator). In the porcine microbial challenge model, the novel antimicrobial PG + CAP wound ointment rapidly eradicated bacterial organisms embedded in wounds, was safe and well-tolerated, and was associated with enhanced healing compared to ointment base and MediHoney. Specifically, the cumulative histopathology, reepithelialization of epidermis, and mature granulation tissue in the wound bed was significantly better with PG + CAP than with control and MediHoney treatments. This ointment warrants further study as a non-antibiotic ointment for use in treating a wide array of infected wounds.

Minocycline-EDTA-Ethanol Antimicrobial Catheter Lock Solution Is Highly Effective In Vitro for Eradication of Candida auris Biofilms.

Candida auris is an emerging pathogen that can cause virulent central-line-associated bloodstream infections. Catheter salvage through the eradication of biofilms is a desirable therapeutic option. We compared taurolidine and minocycline-EDTA-ethanol (MEE) catheter lock solutions in vitro for the eradication of biofilms of 10 C. auris strains. MEE fully eradicated all C. auris biofilms, while taurolidine lock partially eradicated all of the C. auris biofilms. The superiority was significant for all C. auris strains tested (P = 0.002).

Assessment of the Potential for Inducing Resistance in Multidrug-Resistant Organisms from Exposure to Minocycline, Rifampin, and Chlorhexidine Used To Treat Intravascular Devices.

To assess the potential for the induction of antimicrobial resistance following repeated subinhibitory exposures to the combination minocycline (MIN), rifampin (RIF), and chlorhexidine (CHX), a total of 29 clinical microbial pathogenic isolates were repeatedly exposed to subinhibitory concentrations of MIN, RIF, and CHX for 20 passages. MICs of the MIN, RIF, and CHX combination were assessed at each passage to evaluate the potential for resistance to have been induced. The combination of MIN, RIF, and CHX showed significant antimicrobial efficacy and synergy against organisms resistant to all 3 individual components (MIC of ≥16 µg/ml for MIN or MIC of ≥4 µg/ml for RIF or CHX). Among the organisms originally resistant to 2 or more individual components and the organisms originally susceptible to 2 or more individual components, there was no evidence that organisms became resistant following 20 repeated subinhibitory exposure cycles to the triple combination. The risk of resistance developing to the triple combination is extremely low because microbes are inhibited or killed before resistance can simultaneously emerge to all three agents. Surveillance studies monitoring the development of resistance should be conducted in a clinical setting.

Nitroglycerin-Citrate-Ethanol Catheter Lock Solution Is Highly Effective for In Vitro Eradication of Candida auris Biofilm.

Candida auris poses emerging risks for causing severe central line-associated bloodstream infections. We tested in vitro the ability of antifungal lock solutions to rapidly eradicate C. auris biofilms. Liposomal amphotericin B, amphotericin B deoxycholate, fluconazole, voriconazole, micafungin, caspofungin, and anidulafungin failed to completely eradicate all 10 tested C. auris biofilms. Conversely, nitroglycerin-citrate-ethanol (NiCE) catheter lock solution completely eradicated all replicates for all of C. auris biofilms tested.

In Vitro Study of Antimicrobial Percutaneous Nephrostomy Catheters for Prevention of Renal Infections.

Percutaneous nephrostomy (PCN) catheters are the primary method for draining ureters obstructed by malignancy and preventing a decline of renal function. However, PCN catheter-related infections, such as pyelonephritis and urosepsis, remain a significant concern. Currently, no antimicrobial PCN catheters are available for preventing infection complications. Vascular catheters impregnated with minocycline-rifampin (M/R) and M/R with chlorhexidine coating (M/R plus CHD) have previously demonstrated antimicrobial activity. Therefore, in this study, we examined whether these combinations could be applied to PCN catheters and effectively inhibit biofilm formation by common uropathogens. An in vitro biofilm colonization model was used to assess the antimicrobial efficacy of M/R and M/R-plus-CHD PCN catheters against nine common multidrug-resistant Gram-positive and Gram-negative uropathogens as well as Candida glabrata and Candida albicans Experimental catheters were also assessed for durability of antimicrobial activity for up 3 weeks. PCN catheters coated with M/R plus CHD completely inhibited biofilm formation for up to 3 weeks for all the organisms tested. The reduction in colonization compared to uncoated PCN catheters was significant for all Gram-positive, Gram-negative, and fungal organisms (P < 0.05). M/R-plus-CHD PCN catheters also produced significant reductions in biofilm colonization relative to M/R PCN catheters for Enterobacter spp., Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, C. glabrata, and C. albicans (P < 0.05). M/R-plus-CHD PCN catheters proved to be highly efficacious in preventing biofilm colonization when exposed to multidrug-resistant pathogens common in PCN catheter-associated pyelonephritis. M/R-plus-CHD PCN catheters warrant evaluation in a clinical setting to assess their ability to prevent clinically relevant nephrostomy infections.

Pilot Ex Vivo and In Vitro Evaluation of a Novel Foley Catheter with Antimicrobial Periurethral Irrigation for Prevention of Extraluminal Biofilm Colonization Leading to Catheter-Associated Urinary Tract Infections (CAUTIs).

CAUTI remains a serious healthcare issue for incontinent patients whose urine drainage is managed by catheters. A novel double-balloon Foley catheter was developed which was capable of irrigating the extraluminal catheter surfaces within the periurethral space between the urethral-bladder junction and meatus. The catheter has a retention cuff that is inflated to secure the catheter in the bladder and a novel irrigation cuff proximal to the urethral-bladder junction capable of providing periurethral irrigation from the urethral-bladder junction to the meatus. Uniform periurethral irrigation was demonstrated in an ex vivo porcine model by adding a dye to the antimicrobial urethral irrigation solution. An in vitro biofilm colonization model was adapted to study the ability of periurethral irrigation with a newly developed antimicrobial combination consisting of polygalacturonic acid + caprylic acid (PG + CAP) to prevent axial colonization of the extraluminal urethral indwelling catheter shaft by common uropathogens. The extraluminal surface of control catheters that were not irrigated formed biofilms along the entire axial urethral tract after 24 hours. Significant (p < 0.001) inhibition of colonization was seen against multidrug-resistant Pseudomonas aeruginosa (PA), carbapenem-resistant Escherichia coli (EC), and carbapenem-resistant Klebsiella pneumoniae (KB). For other common uropathogens including Candida albicans (CA), Proteus mirabilis (PR), and Enterococcus faecalis (EF), a first irrigation treatment completely inhibited colonization of half of the indwelling catheter closest to the bladder and a second treatment largely disinfected the remaining intraurethral portion of the catheter towards the meatus. The novel Foley catheter and PG + CAP antimicrobial irrigant prevented biofilm colonization in an in vitro CAUTI model and merits further testing in an in vivo CAUTI prevention model.

In vitro activity of tedizolid and comparator agents against clinical Gram-positive isolates recovered from patients with cancer.

A total of 248 Gram-positive isolates from cancer patients were tested for in-vitro susceptibility to tedizolid and 3 comparator agents using CLSI broth microdilution methodology. Tedizolid inhibited 97% of isolates at ≤0.5µg/ml. It was active against all Gram-positive species and consistently had 8 fold lower MICs than linezolid, although based on % susceptibility using CLSI breakpoints, most isolates were also susceptible to the comparators. Tedizolid was active against MRSA isolates with vancomycin MICs of ≥1.0µg/ml.

Caprylic and Polygalacturonic Acid Combinations for Eradication of Microbial Organisms Embedded in Biofilm.

There is a need for non-antibiotic, antimicrobial compositions with low toxicity capable of broad-spectrum eradication of pathogenic biofilms in food preparation and healthcare settings. In this study we demonstrated complete biofilm eradication within 60 min with synergistic combinations of caprylic and polygalacturonic (PG) acids in an in vitro biofilm eradication model against representative hospital and foodborne infectious pathogen biofilms (methicillin-resistant Staphylococcus aureus, multidrug-resistant Pseudomonas aeruginosa, Candida albicans, Escherichia coli, and Salmonella enteritidis). Antimicrobial synergy against biofilms was demonstrated by quantifying viable organisms remaining in biofilms exposed to caprylic acid alone, PG acid alone, or combinations of the two. The combinations also synergistically inhibited growth of planktonic organisms. Toxicity of the combination was assessed in vitro on L929 fibroblasts incubated with extracts of caprylic and PG acid combinations using the Alamar Blue metabolic activity assay and the Trypan Blue exclusion cell viability assay. The extracts did not produce cytotoxic responses relative to untreated control fibroblasts.

Sodium Mercaptoethane Sulfonate Reduces Collagenolytic Degradation and Synergistically Enhances Antimicrobial Durability in an Antibiotic-Loaded Biopolymer Film for Prevention of Surgical-Site Infections.

Implant-associated surgical-site infections can have significant clinical consequences. Previously we reported a method for prophylactically disinfecting implant surfaces in surgical pockets, where an antibiotic solution containing minocycline (M) and rifampin (R) was applied as a solid film in a crosslinked biopolymer matrix that partially liquefied in situ to provide extended prophylaxis. Here we studied the effect of adding sodium 2-mercaptoethane sulfonate (MeSNA) on durability of prophylaxis in an in vitro model of implant-associated surgical-site infection. Adding MeSNA to the M/R biopolymer, antimicrobial film extended the duration for which biofilm formation by multidrug-resistant Pseudomonas aeruginosa (MDR-PA) was prevented on silicone surfaces in the model. M/R films with and without MeSNA were effective in preventing colonization by methicillin-resistant Staphylococcus aureus. Independent experiments revealed that MeSNA directly inhibited proteolytic digestion of the biopolymer film and synergistically enhanced antimicrobial potency of M/R against MDR-PA. Incubation of the MeSNA containing films with L929 fibroblasts revealed no impairment of cellular metabolic activity or viability.

Comparative Efficacies of Antimicrobial Catheter Lock Solutions for Fungal Biofilm Eradication in an in Vitro Model of Catheter-Related Fungemia.

Fungal catheter-related bloodstream infections (CRBSIs)-primarily due to Candida species-account for over 12% of all CRBSIs, and have been progressively increasing in prevalence. They present significant health and economic burdens, and high mortality rates. Antimicrobial catheter lock solutions are an important prophylactic option for preventing fungal CRBSIs. In this study, we compared the effectiveness of two FDA-approved catheter lock solutions (heparin and saline) and three experimental antimicrobial catheter lock solutions-30% citrate, taurolidine-citrate-heparin (TCH), and nitroglycerin-citrate-ethanol (NiCE)-in an in vitro model of catheters colonized by fungi. The fungi tested were five different strains of Candida clinical isolates from cancer patients who contracted CRBSIs. Time-to-biofilm-eradication was assessed in the model with 15, 30, and 60 min exposures to the lock solutions. Only the NiCE lock solution was able to fully eradicate all fungal biofilms within 60 min. Neither 30% citrate nor TCH was able to fully eradicate any of the Candida biofilms in this time frame. The NiCE lock solution was significantly superior to TCH in eradicating biofilms of five different Candida species (p = 0.002 for all).