Assessment of the types of catheter infectivity caused by Candida species and their biofilm formation. First study in an intensive care unit in Algeria

Sidi Mohammed Lahbib Seddiki,1 Zahia Boucherit-Otmani,1 Kebir Boucherit,1 Souad Badsi-Amir,2 Mourad Taleb,3 Dennis Kunkel41Laboratory: Antifungal Antibiotic, Physico-Chemical Synthesis and Biological Activity, University of Tlemcen, Algeria; 2Department of Anesthesiology, 3Department of Epidemiology, University Hospital of Sidi Bel Abbes, Algeria; 4Dennis Kunkel Microscopy Inc, Kailua, HI, USAAbstract: Nosocomial candidiasis remains a potential risk in intensive care units (ICUs), wherein Candida albicans is most responsible for its occurrence. Equally, non-C. albicans species, especially C. glabrata, are also involved. These infections are frequently associated with biofilms that contaminate medical devices, such as catheters. These biofilms constitute a significant clinical problem, and cause therapeutic failures, because they can escape the immune response and considerably decrease sensitivity to antifungal therapy. The diagnosis of catheter-related candidiasis is difficult; however, the differentiation between an infection of the catheter (or other medical implant) and a simple contamination is essential to start an antifungal treatment. Among the methods used for this type of study is the Brun-Buisson method, but this method only examines the infectivity of catheters caused by bacteria. For this reason, we wanted to adapt this method to the yeast cells of Candida spp. To assess the various types of infectivity of catheters (contamination, colonization, or infection) and their corresponding rates, as well as the responsible yeast species, we conducted our study, between February 2011 and January 2012, in the ICU at the University Hospital Center of Sidi Bel Abbes, Algeria; during this study, we took photographic images of the tongue of one patient and of that patient's implanted orobronchial catheter. In addition, catheters contaminated by C. albicans biofilms were observed by scanning electron microscopy.Keywords: ICU, contamination, colonization, infectio

Optimum Inhibition of Amphotericin-B-Resistant Candida albicans Strain in Single- and Mixed-Species Biofilms by Candida and Non-Candida Terpenoids

Candida albicans is one of the most common human fungal pathogens and represents the most important cause of opportunistic mycoses worldwide. Surgical devices including catheters are easily contaminated with C. albicans via its formation of drug-resistant biofilms. In this study, amphotericin-B-resistant C. albicans strains were isolated from surgical devices at an intensive care center. The objective of this study was to develop optimized effective inhibitory treatment of resistant C. albicans by terpenoids, known to be produced naturally as protective signals. Endogenously produced farnesol by C. albicans yeast and plant terpenoids, carvacrol, and cuminaldehyde were tested separately or in combination on amphotericin-B-resistant C. albicans in either single- or mixed-infections. The results showed that farnesol did not inhibit hyphae formation when associated with bacteria. Carvacrol and cuminaldehyde showed variable inhibitory effects on C. albicans yeast compared to hyphae formation. A combination of farnesol with carvacrol showed synergistic inhibitory activities not only on C. albicans yeast and hyphae, but also on biofilms formed from single- and mixed-species and at reduced doses. The combined terpenoids also showed biofilm-penetration capability. The aforementioned terpenoid combination will not only be useful in the treatment of different resistant Candida forms, but also in the safe prevention of biofilm formation

Hydrolytic activity and biofilm formation in clinical isolates of Candida albicans: the effect of changing pH and temperature

<p>Candida albicans is the most frequently isolated opportunistic yeast in hospitals; consistently responsible for invasive fungal infections. The formation of biofilms and the activity of hydrolytic enzymes are two major virulence factors contributing to the pathogenicity of this species. This study aimed to highlight the activity of hydrolytic enzymes in isolated strains of C. albicans which form biofilms, as well as the effect of the change in pH and temperature on their synthesis.The capacity to form biofilms was determined using the crystal violet technique. The synthesis of phospholipase was determined by the plate method using egg yolk culture medium. For the proteinase activity, agar plates containing bovine albumin serum was used. However, esterase, coagulase and hemolysin were evaluated using the opacity test, the condifventional tube test and the sheep blood plaque test, respectively. In addition, phospholipase, proteinase and esterase activities were assessed under different conditions of temperature and pH. The isolated strains of C. albicanswere able to form biofilms and synthesize phospholipase, proteinase, esterase, coagulase and hemolysin; the activities of these enzymes vary differently from one strain to another. C. albicans further exhibited hydrolytic activities. The interaction significance between the strains, pH and temperature depends on the type of enzymes. This draws attention to the importance of these enzymes to better understand the relationship between the pathogenesis and the virulent process of this species.</p&gt

Ex vivo decontamination of yeast-colonized dentures by iodine–thiocyanate complexes

Sarra Sebaa,1,2 Maxime Faltot,1 Sandra De Breucker,3 Zahia Boucherit-Otmani,2 Françoise Bafort,4 Jean-Paul Perraudin,5 Philippe Courtois1 1Laboratory of Physiology and Pharmacology, Université Libre de Bruxelles, Brussels, Belgium; 2Laboratory of Antibiotics and Antifungals: Physico-Chemistry, Synthesis and Biological Activity, University of Tlemcen, Tlemcen, Algeria; 3Department of Geriatrics, CUB – Hôpital Erasme, Brussels, Belgium; 4Integrated and Urban Plant Pathology Laboratory, Liège University, Gembloux, Belgium; 5Taradon Laboratory, Tubize, Belgium Introduction: Under well-defined experimental conditions, and in the presence of hydrogen peroxide, lactoperoxidase produces stable iodine–thiocyanate complexes that have antimicrobial properties. A novel process was developed to short circuit the consumption of hydrogen peroxide by microbial catalases by producing iodine–thiocyanate complexes prior to contact with microorganisms, with the aim of being able to decontaminate the ex vivo dentures colonized by yeasts. Materials and methods: Teabags containing lactoperoxidase adsorbed on inert clay beads were immersed for 1 minute in phosphate buffer solution (0.1 M pH 7.4) containing 5.2 mM potassium iodide, 1.2 mM potassium thiocyanate, and 5.5 mM hydrogen peroxide. After removing the adsorbed lactoperoxidase, the stability and efficacy of iodine–thiocyanate complexes for Candida-colonized denture decontamination were verified. Investigations were performed in vitro on Candida albicans ATCC 10231 and on clinical isolates from 46 dentures. A Candida plate count was performed after a 24-hour incubation at 37°C on Sabouraud–chloramphenicol or CHROMagar solid media; then, the yeast growth was evaluated in Sabouraud broth by turbidimetry and biofilm biomass by crystal violet staining. Results: In vitro tests demonstrated the effectiveness of the oxidant solution in sterilizing a suspension of 106 Candida cells per milliliter after a 5-minute incubation. A single ex vivo immersion of contaminated dentures in a solution of iodine–thiocyanate complexes led to a decrease of at least 1 log unit in the number of colony-forming units in 58.3% of the tested dentures, while immersing in water alone had no effect on denture colonization (significant X2: p = 0.0006). Conclusion: These data suggest a promising new strategy for decontamination of dentures. Keywords: biofilm, Candida, hygiene, lactoperoxidase, oral cavit