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.

In Vitro Assessment of the Antimicrobial Efficacy of Optimized Nitroglycerin-Citrate-Ethanol as a Nonantibiotic, Antimicrobial Catheter Lock Solution for Prevention of Central Line-Associated Bloodstream Infections.

The rapid, broad-spectrum, biofilm-eradicating activity of the combination of 0.01% nitroglycerin, 7% citrate, and 20% ethanol and its potential as a nonantibiotic, antimicrobial catheter lock solution (ACLS) were previously reported. Here, a nitroglycerin-citrate-ethanol (NiCE) ACLS optimized for clinical assessment was developed by reducing the nitroglycerin and citrate concentrations and increasing the ethanol concentration. Biofilm-eradicating activity was sustained when the ethanol concentration was increased from 20 to 22% which fully compensated for reducing the citrate concentration from 7% to 4% as well as the nitroglycerin concentration from 0.01% to 0.0015% or 0.003%. The optimized formulations demonstrated complete and rapid (2 h) eradication of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate Staphylococcus aureus (VISA), methicillin-resistant Staphylococcus epidermidis (MRSE), vancomycin-resistant enterococci (VRE), multidrug-resistant (MDR) Pseudomonas aeruginosa, MDR Klebsiella pneumoniae, MDR Enterobacter cloacae, MDR Acinetobacter baumannii, MDR Escherichia coli, MDR Stenotrophomonas maltophilia, Candida albicans, and Candida glabrata biofilms. The optimized NiCE lock solutions demonstrated anticoagulant activities comparable to those of heparin lock solutions. NiCE lock solution was significantly more effective than taurolidine-citrate-heparin lock solution in eradicating biofilms of Staphylococcus aureus and Candida glabrata The optimized, nonantibiotic, heparin-free NiCE lock solution demonstrates rapid broad-spectrum biofilm eradication as well as effective anticoagulant activity, making NiCE a high-quality ACLS candidate for clinical assessment.

Caprylic acid and glyceryl trinitrate combination for eradication of biofilm.

There is a growing need for biocompatible, broad-spectrum, nonantibiotic, antimicrobial treatments because of the frequent ineffectiveness of antibiotics against biofilms and the increasing incidence of antibiotic resistance. In this study, we demonstrate rapid and complete biofilm eradication in an in vitro model with synergistic combinations of glyceryl trinitrate and caprylic acid against resistant Gram-positive, Gram-negative, and fungal biofilms.

Improved antibiotic-impregnated catheters with extended-spectrum activity against resistant bacteria and fungi.

Minocycline-rifampin-impregnated central venous catheters (M/R CVCs) have been shown to be efficacious in reducing catheter-related bloodstream infections (CRBSI) and inhibiting the biofilm adherence of resistant Gram-positive and Gram-negative pathogens, with the exception of Pseudomonas aeruginosa and Candida spp. To expand the spectrum of antimicrobial activity, a novel second-generation M/R catheter was developed by adding chlorhexidine (CHX-M/R). CVCs and peripherally inserted central catheters (PICCs) were impregnated with CHX-M/R and compared with first-generation M/R catheters, CHX-silver sulfadiazine-treated CVCs (CHX/SS-CVCs), chlorhexidine-treated PICCs, and uncoated catheters. A biofilm catheter colonization model was used to assess the efficacy of catheters against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), P. aeruginosa, Candida albicans, and Candida glabrata. CHX-M/R-impregnated CVCs were the only antimicrobial catheters that completely inhibited the biofilm colonization of all resistant bacterial and fungal organisms tested at all time intervals, and they were significantly superior to uncoated catheters (all P values were ≤0.003). Furthermore, CHX-M/R-coated CVCs had a significantly more effective and prolonged (up to 3 weeks) antimicrobial activity against MRSA and P. aeruginosa than M/R, CHX/SS, and uncoated CVCs (P < 0.0001). Similarly, CHX-M/R-coated PICCs were also superior to M/R-coated and CHX-coated PICCs in preventing biofilms of MRSA, VRE, P. aeruginosa, and Candida species (P value = 0.003 for all). Our study shows that novel CHX-M/R-coated catheters have unique properties in completely inhibiting biofilm colonization of MRSA, VRE, P. aeruginosa, and fungi in a manner superior to that of M/R- and chlorhexidine-treated catheters.

Review of allergic reactions from use of chlorhexidine on medical products in clinical settings over 40 years: Risks and mitigations.

Chlorhexidine is an antimicrobial agent widely used for infection prevention in medical settings. Nevertheless, allergic reactions ranging from mild to severe have been reported following its use. In this review, we analyzed all case reports published between the introduction of chlorhexidine and the end of 2019 for allergic responses associated with the use of medical devices and or other medical products containing chlorhexidine (CHX) to ascertain the prevalence of severe CHX allergic reactions and what practices might best mitigate those risks.In total, 77 publications containing 124 reported cases of allergic reactions were grouped into 3 product categories, catheters, semisolids, and fluid products. The country, type of reaction, route of sensitization, allergy confirmation, and intervention or mitigation was extracted for each case. Overall, 30 cases were associated with catheters, 46 cases were associated with semisolid products, and 48 cases were associated with the use of other medical products. Severe cases were managed with intravenous fluids, steroids, and epinephrine (adrenaline). None of the reported cases were fatal. The allergy risks can be mitigated by better warning and training clinicians and by recording and screening patient histories for CHX presensitization from prior exposure. For patients undergoing pre-use blood tests, IgE antibody screens can also be performed. Finally, as a precaution in the event a rare severe allergic reaction occurs, procedure carts and rooms can be prestocked with injectable epinephrine and other rapidly acting anti-inflammatory medications.

Enhanced Biofilm Eradication and Reduced Cytotoxicity of a Novel Polygalacturonic and Caprylic Acid Wound Ointment Compared with Common Antiseptic Ointments.

Antiseptic wound ointments are widely used to treat dermal wounds that are microbially contaminated. Polygalacturonic acid (PG)+caprylic acid (CAP) is a novel combination that has been shown to eradicate biofilms. We developed a novel PG+CAP ointment and compared the biofilm eradication capability and cytotoxicity of PG+CAP with that of commercially available antiseptic wound ointments. We used a well-established biofilm model to quantitatively assess the eradication of organisms following exposure to the wound ointments for 2 hours. PG+CAP ointment completely eradicated Candida albicans, multidrug-resistant Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus biofilms, whereas MediHoney, polyhexamethylene biguanide (PHMB), and benzalkonium chloride (BZK) ointments failed to eradicate all biofilms within 2 hours. We assessed cytotoxicity by exposing L-929 fibroblasts to extracts of each ointment; Trypan blue exclusion was used to assess cell viability, and Alamar blue conversion was used to assess metabolic function. After exposure to PG+CAP and MediHoney, fibroblast viability was 96.23% and 95.23%, respectively (Trypan blue), and was comparable to untreated cells (98.77%). PHMB and BZK showed reduced viability (83.25% and 77.83%, respectively, p < 0.05). Metabolic activity results followed a similar pattern. Cytotoxicity of PG+CAP ointment towards erythrocytes was comparable to saline. PG+CAP ointment seems to be safe and can rapidly eradicate microbial biofilm; thus, PG+CAP ointment merits further in vivo testing as a potential antimicrobial wound ointment.

The potential for developing new antimicrobial resistance from the use of medical devices containing chlorhexidine, minocycline, rifampicin and their combinations: a systematic review.

BACKGROUND: Catheter infections remain one of the most persistent adverse events causing significant morbidity, economic impact and mortality. Several strategies have been proposed to reduce these infections including the use of catheters embedded with antibiotics and/or antiseptics. One reoccurring challenge is the fear that antimicrobial medical devices will induce resistance. The aim of this systematic review is to evaluate the evidence for induced antimicrobial resistance caused by exposure to antimicrobial medical devices. METHODS: Four electronic databases [MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Scopus] were screened for studies published between 1983 and 2019 regarding assessment of microbial resistance with use of medical devices containing chlorhexidine, minocycline, rifampicin or combinations thereof. Development of new resistance, selection for tolerant organisms and 'no change in resistance' were assessed. RESULTS: Forty-four publications, grouped by study type and stratified by drug assessed, were included for analyses. The majority of studies found no change in resistance after exposure to antimicrobial medical devices (13 in vitro, 2 in vivo, 20 clinical). Development of new resistance was commonly reported with the use of rifampicin as a single agent and only reported in one study assessing the minocycline/rifampicin combination (M/R); however, the increase in MIC was well below clinical relevance. CONCLUSIONS: Emergence of new resistance to combinations of M/R, minocycline/rifampicin/chlorhexidine (M/R/CH) and chlorhexidine/silver sulfadiazine (CHXSS) was rare. No clinical trials confirmed its occurrence and some refuted it. The risk of development of new resistance to these antimicrobial combinations appears more fear-based than substantiated by clinical and experimental evidence but warrants continued surveillance.

Epidemiology of Infectious and Noninfectious Catheter Complications in Patients Receiving Home Parenteral Nutrition: A Systematic Review and Meta-Analysis.

Patients receiving parenteral nutrition (PN) as their primary source of nutrition are at high risk for both infectious and noninfectious catheter complications (catheter-related infections, catheter occlusion, and venous thrombosis). The aim of this review was to synthesize and evaluate what is known about catheter complications and prevention strategies in the PN population. Three electronic databases (Medline, Embase, and CINAHL) were screened for studies published between January 2012 and February 2019 regarding infectious and noninfectious catheter complications in patients receiving PN. Rates of infectious and noninfectious catheter complications, prevalence of causative pathogens, potential risk factors, and prevention strategies via the use of antimicrobial lock therapy (ALT) were assessed. Fifty-three catheter complication studies and 12 ALT studies were included. Studies were grouped by definition of complication: catheter-related bloodstream infections (CRBSI) or central line-associated bloodstream infections (CLABSI). Random effects summary rates per 1000 catheter days were 0.85 CRBSI episodes (95% CI 0.27-2.64) and 1.65 CLABSI episodes (95% CI 1.09-2.48). Use of taurolidine or ethanol ALT was efficacious in reducing infectious catheter complications; however, several studies had concerns for adverse mechanical complications. Potential risk factors for catheter complications were highly varied and often contradictory between studies. The rates of catheter complications were higher among catheterized patients receiving PN compared with nationally reported rates of complications in all catheterized patients. Risk factors for catheter complications need to be better understood for targeted prophylactic use of ALT. Future studies are warranted; however, they should be conducted using more standardized definitions and criteria.

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.

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.

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.

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).

Novel in situ liquefying antimicrobial wrap for preventing tissue expander infections following breast reconstructive surgeries.

Breast reconstruction surgeries using tissue expanders (TEs) have highly reported infection rates. To decrease this, we developed a method for disinfecting TEs and surgical pockets, where an antimicrobial solution was applied as a solid film at implantation that subsequently liquefied in situ to provide extended prophylaxis. Silicone discs cut from TEs were covered with gelatin-based films containing minocycline (M) and rifampin (R). Discs and films soaked in saline were subsequently challenged with pathogen at days 1, 3, 7, and 10 and quantified for potential biofilm formation. Discs that were not harvested at each specific time points were refreshed with sterile saline. The discs were challenged with clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), and multidrug-resistant Pseudomonas aeruginosa (MDR-PA). Recoveries of adherent organisms from uncovered silicone discs and gelatin-wrapped discs without added antimicrobial agents were >5 × 10(4) CFU/disc for each organism at each time point. Experimental 0.1%M/0.05%R gelatin films completely inhibited all challenge organisms from attaching to the silicone (p < 0.05) at each time point through day 10. Cytotoxicity was assessed by incubating films with HEK-293T human fibroblasts. There were no significant differences in HEK-293T cell survival between controls and any of the antimicrobial films. The in situ liquefying, bioabsorable, antimicrobial wrap prevented biofilm formation by microorganisms on silicone surfaces in vitro with minimal cytotoxicity.

Evaluation of a multiplex polymerase chain reaction assay for simultaneous detection of Rhodococcus equi and the vapA gene.

OBJECTIVE: To evaluate sensitivity and specificity of a multiplex polymerase chain reaction (PCR) assay for simultaneous detection of Rhodococcus equi and differentiation of strains that contain the virulence-associated gene (vapA) from strains that do not. SAMPLE POPULATION: 187 isolates of R equi from equine and nonequine tissue and environmental specimens and 27 isolates of bacterial species genetically or morphologically similar to R equi. PROCEDURE: The multiplex PCR assay included 3 gene targets: a universal 311-bp bacterial 16S ribosomal RNA amplicon (positive internal control), a 959-bp R equi-specific target in the cholesterol oxidase gene (choE), and a 564-bp amplicon of the vapA gene. Duplicate multiplex PCR assays for these targets and confirmatory singleplex PCR assays for vapA and choE were performed for each R equi isolate. An additional PCR assay was used to examine isolates for the vapB gene. RESULTS: Results of duplicate multiplex and singleplex PCR assays were correlated in all instances, revealing high specificity and reliability (reproducibility) of the vapA multiplex assay. Of the pulmonary isolates from horses with suspected R equi pneumonia, 97.4% (76/78) yielded positive results for vapA. Seven of 50 (14%) human isolates of R equi yielded positive results for vapA. Six human R equi isolates and 1 porcine isolate yielded positive results for vapB. No isolates with vapA and vapB genes were detected. CONCLUSIONS AND CLINICAL RELEVANCE: The multiplex PCR assay is a sensitive and specific method for simultaneous confirmation of species identity and detection of the vapA gene. The assay appeared to be a useful tool for microbiologic and epidemiologic diagnosis and research.

Urinary catheterization of male rabbits: a new technique and a review of urogenital anatomy.

Rabbits are widely used as an animal model for urologic research studies in which urinary bladder catheterization is required. However, standard manual retrograde urinary catheterization proved to be difficult to perform on anesthetized male rabbits in a research study, with frequent misplacement of the catheter into the vesicular gland. Attempts to reposition the catheter into the bladder after initial entry into the vesicular gland frequently failed and resulted in exclusion of the animal from the study. We assessed the normal anatomy of the lower urinary tract of male rabbits to determine the cause of catheterization misdirection into the vesicular gland and to develop a more reliable technique for urinary bladder catheterization. A modified 'digital (finger) pressure' catheterization technique was developed for successful urinary catheterization of male rabbits. Retrospective statistical analysis of 45 rabbits used for urinary catheterization studies showed improvement in the success rate of catheterization by using the digital pressure technique over the standard method of retrograde urinary catheter insertion. In addition, we here review the relevant gross and histologic anatomy of the urogenital tract of male rabbits.