Free-living amoebae promote Candida auris survival and proliferation in water.

Candida auris is an emerging species responsible for life-threatening infections. Its ability to be resistant to most systemic antifungal classes and its capacity to persist in a hospital environment have led to health concerns. Currently, data about environmental reservoirs are limited but remain essential in control of C. auris spread. The aim of our study was to explore the interactions between C. auris and two free-living amoeba (FLA) species, Vermamoeba vermiformis and Acanthamoeba castellanii, potentially found in the same water environment. Candida auris was incubated with FLA trophozoites or their culture supernatants. The number of FLA and yeasts was determined at different times and transmission electron microscopy (TEM) was performed. Supernatants of FLAs promoted yeast survival and proliferation. Internalization of viable C. auris within both FLA species was also evidenced by TEM. A water environmental reservoir of C. auris can therefore be considered through FLAs and contamination of the hospital water networks would consequently be possible.

In vitro activity of isavuconazole against three species of Acanthamoeba.

Acanthamoeba keratitis due to a genus of free-living amoebae is a severe corneal infection. Treatment of this disease is based on the combined use of antiseptics and other drugs, including azoles. We tested isavuconazole, the latest marketed azole, in vitro, against A. castellanii, A. lenticulata and A. hatchetti. Our results show that isavuconazole presents slight amoebistatic activity against A. castellanii trophozoites but no cysticidal activity. Isavuconazole could be used only in association for management of AK due to A. castellanii.

Free-living amoebae: what part do they play in healthcare-associated infections?

Free-living amoebae (FLA) are ubiquitous protozoa that do not require a host organism for survival. They are found in natural environments such as water or soil, and man-made environments including tap water or swimming pools, where they may interact with other micro-organisms, including bacteria, fungi and viruses. FLA can harbour micro-organisms including those found in hospital water systems, offering them protection against hostile conditions, providing a vehicle of dissemination, and enabling them to prepare for subsequent survival in macrophages. The interaction between Legionella pneumophila and FLA has been studied extensively; subsequent investigations have shown that FLA may serve as a reservoir for other bacteria including mycobacteria, Pseudomonas aeruginosa, Acinetobacter baumannii, or even fungi and viruses. Amoebae found in hospital water systems can serve as a reservoir of potential pathogens and thus be indirectly related to healthcare-associated infections.

[Detection of Aspergillus antigen galactomannan using ELISA method: validation of the performances of the method for accreditation]. / Validation d'une méthode Elisa pour la recherche de l'antigène aspergillaire galactomannane en vue de l'accréditation.

Diagnosis of invasive aspergillosis for patients with high risk of infection is based on the monitoring of Aspergillus antigenemia assessed by the detection of galactomannan in serum by a sandwich-type ELISA (Biorad(®)). The validation of the method was displayed according to the guide COFRAC SH GTA 04. The internal quality control system settled, involves two quality control samples made of pools of sera (negative and positive). The repeatability of the measurements, as estimated by the coefficients of variation (CV), obtained by two different technicians was found from 9 to 13.7% for the positive control. The CV of the negative control, for which the provider indicates it is not useful in the analytical process, was found from 7.1 to 30%. In our experience it could be an indicator of environmental contamination. The evaluation of the intermediary fidelity was 15.7% for the positive control and 22.5% for the negative one. In the lack of reference material (International Standard) and recommendation from scientific societies, performances obtained will be discussed according to the results reported in the technical form of the supplier and those obtained by 39 laboratories participating in the only available external quality assessment program organized in France by ProBioQual(®) where the CV of reproducibility are 44.7% of unit (mean index 0.131) for the negative control and 18% (mean index 1.089) for the positive one in 2011.

Hartmanella vermiformis can be permissive for Pseudomonas aeruginosa.

AIMS: The amoebae of the genus Hartmanella are frequently recovered from hospital water taps, whereas Pseudomonas aeruginosa is often implicated in nosocomial infections. Previous works suggested that free living amoebae can act as vehicles of bacterial transmission. The present work investigates the relationships between a strain of Hartmanella vermiformis and three strains of P. aeruginosa: a reference strain, a strain from a patient and an environmental strain. METHODS AND RESULTS: In a saline medium, H. vermiformis is not able to favour for the development of P. aeruginosa. In a rich co-cultivation medium, only the environmental strain has shown a growth. CONCLUSIONS: We showed that P. aeruginosa is not a good nutrient source for H. vermiformis. SIGNIFICANCE AND IMPACT OF THE STUDY: Nevertheless, in particular conditions and with particular strains, the presence of H. vermiformis could represent a possibility of growth for P. aeruginosa.

Paranasal sinus fungus ball: epidemiology, clinical features and diagnosis. A retrospective analysis of 173 cases from a single medical center in France, 1989-2002.

Over the last decade, we have observed a high frequency of Aspergillus rhinosinusitis in french medical centers. The epidemiological data, clinical presentations, radiology, mycology and histology results of 173 consecutive patients with paranasal sinus fungus balls who were admitted from 1989 to 2002 have been reviewed. The most common symptoms included purulent nasal discharges and nasal obstructions, with the maxillary sinus being the most common site of infection (152 cases, 87.8%). Computed tomography scans (CT scan) were performed in 92% (159/173) of the cases and heterogeneous opacities were observed in 132 patients (83%). Histology examinations were performed in all cases and proved positive in 162 patients. Fungi were recovered, mainly Aspergillus fumigatus, from samples of 50 patients, while specimens from the remaining 123 patients were negative. Since no specific clinical sign could be found, a diagnosis of fungus ball is frequently made after a long term symptomatic period. CT scan findings of metallic or calcified densities within an opacified sinus cavity are highly suggestive of a fungus ball, but mycological and histological studies are essential to confirm the diagnosis. Treatment consisted of functional endonasal sinus surgery and was successful in 172 out of 173 cases.

[Imported malaria: prevention should strengthened]. / Paludisme d'importation: il faut renforcer le message de prévention.

INTRODUCTION: The risk of acquiring malaria infection can largely be prevented by the regular use of chemoprophylactic drugs combined with protective measures against mosquito bites. In a retrospective study we had for aim to evaluate the compliance to malaria chemoprophylaxis in patients presenting with malaria infection. METHODS: We analyzed the compliance to the recommended malaria chemoprophylaxis of French travelers hospitalized in a department of infectious diseases because of malaria infection, between January 1999 and December 2003. RESULTS: Eighty-five patients, with a mean age of 34.1 years (16-65) were treated for malaria infection. Seventy-seven were due to Plasmodium falciparum. The outcome was favorable for all patients, despite four severe accesses. Forty-six patients (54%) did not take any chemoprophylaxis (CP), 19 (22%) had an inadequate CP for the risk, 13 (15%) badly complied with intermittent intake of CP and seven (8%) complied well with the recommended malaria CP. Among the 85 patients, 27 (32%) had come to the travelers' consultation and been given recommendations and a recommended malaria CP prescription before traveling. CONCLUSION: These results confirm that the majority of imported malaria cases is a consequence of bad compliance to CP. Understanding user profiles and factors predicting non-compliance may help us to improve pretravel counseling, thereby reducing the risk for travelers to acquire malaria infection.

Influence of sub-inhibitory concentrations of conventional antifungals on metabolism of Candida albicans and on its adherence to polystyrene and extracellular matrix proteins.

Five antifungal agents with different mechanisms of action were compared for their ability to affect mitochondrial dehydrogenase activity and adherence capacity of Candida albicans to polystyrene and extracellular matrix proteins. Only amphotericin B inhibited mitochondrial dehydrogenase activity when the culture medium was supplemented with galactose. 5-Fluorocytosine and terbinafine did not affect this activity, whereas itraconazole and fluconazole improved it. Furthermore, in these experimental conditions, the effect of sub-inhibitory concentrations of antifungals on adherence was dependent on the tested antifungal and the adherence surface: amphotericin B inhibited adherence to polystyrene and fibrinogen, but improved adherence to extracellular matrix. For all surfaces tested, when culture medium was supplemented with galactose, fluorocytosine did not affect adherence, and itraconazole, fluconazole and terbinafine inhibited adherence. Our results also confirmed the influence of the carbohydrates: sub-minimum inhibitory concentrations (MIC) of itraconazole increased or did not modify the mitochondrial metabolism of yeasts when the culture medium was supplemented with galactose, but this antifungal always decreased mitochondrial metabolism when the culture medium was supplemented with glucose. These data indicate that antifungals used below their MIC values can have various effects. It is important to distinguish the effects of antifungals on the metabolism of C. albicans from effects on its adherence capacity. The former effects are linked to the viability of the yeast and the latter depends on the colonization of cellular as opposed to inert surfaces.

Effect of matrix metalloprotease inhibitors on the 95 kDa metallopeptidase of Candida albicans.

A 95 kDa metallopeptidase of Candida albicans could be involved in the process of dissemination of the yeast. Matrix metalloproteases (MMPs) are also responsible for collagen breakdown in inflammatory and malignant processes. We tested six compounds on the C. albicans enzyme. Doxycycline, gentamicin, cefalothin, galardin, and elaidic and oleic acids are known for their capacity to inhibit some MMPs. Amongst these agents, only oleic acid was able to markedly inhibit the purified metallopeptidase at very low concentrations. Moreover, this fatty acid inhibited the secretion of the enzyme in the culture medium without altering the yeast viability.

Imported Plasmodium vivax malaria in France: geographical origin and report of an atypical case acquired in Central or Western Africa.

A total of 73 cases of Plasmodium vivax infections acquired in Western or Central Africa were diagnosed on microscopical criteria in French travellers from 1995 to 1998. We report a case of P. vivax infection in a non immune traveller confirmed by polymerase chain reaction and presenting an atypical P. ovale morphology. The infection was acquired in Western or Central Africa. These microscopical observations, together with the molecular evidence for P. vivax in Western and Central Africa suggest that P. vivax is transmitted in this area despite lacking the Duffy receptor in autochthonous population.

Toxoplasma gondii: purification and characterization of an immunogenic metallopeptidase.

A Toxoplasma gondii aminopeptidase specific for the fluorogenic substrate L-arginine 7-amino-4-methylcoumarin was identified in cell-free extract. This enzyme was purified by high-performance liquid chromatography using first size exclusion, then anion exchange, followed by a second size exclusion. The purified enzyme exhibited a pl of 4.7 by chromatofocusing and had an apparent molecular weight of 110 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. The purification factor was 80.9 and the yield was 14%. The optimal activity was at pH 7.4 and was strongly inhibited by EDTA and o-phenanthroline. Antibodies against this T. gondii metallopeptidase were detected by immunoprecipitation and immunoblotting in human sera obtained from patients undergoing toxoplasmosis.

Case report and review. Onychomycosis due to Candida parapsilosis.

We report a case of onychomycosis with melanonychia due to Candida parapsilosis alone. Candida parapsilosis is now identified in the great majority of candidal onychomycosis, mainly in association with other yeasts. The criteria allowing the distinction between invasion and colonization, the risk factors and the treatment of C. parapsilosis onychomycosis are discussed.

A Candida albicans metallopeptidase degrades constitutive proteins of extracellular matrix.

Among potential virulence factors of Candida albicans, enzymes seem to play an important role. Many studies concern the secreted aspartic proteinases (saps), and the degradation of some components of the subendothelial extracellular matrix by the isoenzyme sap2 has been proved. Nevertheless, other proteolytic enzymes could be involved in the pathogenicity of the yeast. We studied the degradation of four constitutive proteins of the extracellular matrix: type I and IV collagens, laminin and fibronectin, by a 95-kDa metallopeptidase, localised in the cell wall of C. albicans. Each of these constituents was incubated with the purified enzyme and its degradation products analysed by an electrophoretic method. We observed that type I collagen and fibronectin were totally degraded by the enzyme whereas type IV collagen and laminin were only partially degraded. The C. albicans metallopeptidase may play a role in the degradation of the subendothelial extracellular matrix components. This enzyme could facilitate the migration of the yeast in the tissues after crossing the endothelial layer, allowing the fungal invasion of target organs.

[Subconjunctival localization of a Wuchereria bancrofti adult female]. / Localisation sous-conjonctivale d'une femelle adulte de Wuchereria bancrofti.

The authors describe a case of conjunctival localization of a living adult Wuchereria bancrofti female observed in a 6 year old native Haitian girl, two years after her arrival in France. The adult was surgically removed from the conjunctiva. Microfilariae were evidenced in blood samples obtained at midnight. This is the first case of sub-conjunctival localization of W. bancrofti. This case stresses the necessity to identify the filaria by studying the microfilariae in blood samples obtained at different times of the nycthemere and/or by observing the adult after surgical extraction. The presence of a Loa, a Dirofilaria, a Mansonella, or a Wuchereria calls for different medical therapies.

[Comparison of two techniques for detection of anti-Plasmodium falciparum antibodies: Falciparum-spot IF (Biomérieux) and Malaria IgG Celisa (BMD). Preliminary results]. / Comparaison de deux techniques de détection des anticorps anti-Plasmodium falciparum: Falciparum-spot IF (Biomérieux) et Malaria IgG Celisa (BMD). Résultats préliminaires.

We compared a new Elisa assay to detect malaria antibodies: Malaria IgG Celisa (BMD) with the IFAT technique Falciparum-spot IF (Biomérieux): sensitivity, specificity, predictive positive and negative values were 81%, 99%, 95%, 95%, respectively. Eight patients had positive thick blood smear out of 23 performed. For these eight confirmed acute malaria cases, the Elisa assay was negative in five instances. For two recent malaria attacks both Elisa and IFI were negative. With blood donors, two sera were IFAT positive and Elisa negative; 16 were IFAT doubtful and Elisa negative. Doubtful results rose up to 13.5% by IFAT against 1.5% by Elisa assay. We preferred kappa coefficient instead of chi 2 test for data analysis, which measures the concordance degree between the two techniques. Here concordance is moderate. Choosing an Elisa assay to detect the transmission of malaria for at-risk blood donors collides with the method sensitivity compared with IFAT as reference.

Improved immunodiagnosis of human candidiasis by an enzyme-linked immunosorbent assay using a Candida albicans 52-kilodalton metallopeptidase.

An immunogenic aminopeptidase of Candida albicans was purified by high-performance liquid chromatography. It was then used for the development of an enzyme-linked immunosorbent assay to detect antibodies directed against this antigen in sera from patients with candidiasis. This enzyme specifically cleaves the L-Arg-7-amino-4-methyl-coumarin substrate at pH 7.4 and was detected in the crude extract of different C. albicans isolates. Sera used for this study were obtained from healthy blood donors or from patients with one of the following: systemic candidiasis, aspergillosis, cryptococcosis, toxoplasmosis, or malaria. The statistical analysis demonstrates significant differences between absorbency values obtained with sera from patients with candidiasis and with sera from the other groups (P = 0.000001). Diagnostic parameters show high diagnostic specificity of 97% and a sensitivity of 83% at a cutoff value of 0.425 and suggest the usefulness of this aminopeptidase for the diagnosis of systemic candidiasis.

Purification and characterization of N-acetylglucosaminidase from Trypanosoma cruzi.

N-Acetyl-beta-D-glucosaminidase activity was recovered in cell-free extracts of Trypanosoma cruzi epimastigotes. This enzyme was identified on the basis of its ability to hydrolyze the fluorogenic substrate 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide. This activity was purified to apparent homogeneity by anion exchange and molecular sieve high-performance liquid chromatography. It eluted at a native molecular weight of approximately 48,000 Da and migrated as a single band upon reducing or nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimum pH of the activity was around pH 5.4 and the enzyme gave a single peak of activity on a chromatofocusing column with an isoelectric point of 4.2. The enzyme hydrolyzed 4-methylumbelliferyl-GlcNAc, suggesting that it should be characterized as a N-acetyl-beta-D glucosaminidase, with a K(m) value of 1.5 mM from Lineweaver-Burk plots. Many inhibitors as potential enzyme effectors were investigated.