H. Trabelsi

Pathogenic free-living amoebae: Epidemiology and clinical review

Free-living amoebae are widely distributed in soil and water. Small number of them was implicated in human disease: Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris and Sappinia diploidea. Some of the infections were opportunistic, occurring mainly in immunocompromised hosts (Acanthamoeba and Balamuthia encephalitis) while others are non opportunistic (Acanthamoeba keratitis, Naegleria meningoencephalitis and some cases of Balamuthia encephalitis). Although, the number of infections caused by these amoebae is low, their diagnosis was still difficult to confirm and so there was a higher mortality, particularly, associated with encephalitis. In this review, we present some information about epidemiology, ecology and the types of diseases caused by these pathogens amoebae.

Clinical utility and prognostic value of galactomannan in neutropenic patients with invasive aspergillosis

UNLABELLED Invasive aspergillosis (IA) is a major cause of morbidity and mortality in profoundly neutropenic patients. Delayed diagnosis and therapy may lead to poor outcomes. AIMS The objective of this study was to assess the performance characteristics of the galactomannan (GM) assay in serum and bronchoalveolar lavage specimens for the diagnosis of IA in neutropenic patients with hematological malignancies. We also evaluated the prognostic outcome. PATIENTS AND METHODS A total of 1198 serum samples and 42 BAL from 235 neutropenic patients were tested with a GM elisa platelia test. We used Cox modeling of time to 6- and 12-week mortality for GM level at the time of diagnosis (GM0) and GM decay in the week following diagnosis in proven and probable IA patients with more than two GM values. RESULTS There were three proven, 55 probable, and four possible cases of IA. The sensitivity and specificity of the GM test were 96.8% and 82.4% respectively. In BAL samples, sensitivity was 86% and the specificity 93%. BAL GM was more sensitive than microscopy (22.2%) and BAL culture (38.9%). Among patients with proven/probable IA, serum and BAL GM were in agreement for 92.8% of paired samples. The hazard ratio (HR) of GM0 and 1-week GM decay per unit increase in Aspergillus enzyme immunoassay (EIA) was 1.044 (95% CI, 0.738 to 1.476) and 0.709 (95% CI, 0.236 to 2.130) respectively. CONCLUSION We found good correlation between the GM0 and GM decay combination and outcome of IA patients. The GM is a useful tool for diagnosis and monitoring of IA.

Invasive fungal infections in renal transplant recipients: About 11 cases

UNLABELLED Invasive fungal infections are a major complication and an important cause of morbidity and mortality among solid organ transplant recipients. Their diagnosis is difficult and their prognosis is often pejorative. OBJECTIVE The aim of this study was to report the cases of invasive fungal infections in renal transplant recipients in Habib Bourguiba Sfax university hospital and to identify the main fungal agents. MATERIALS AND METHODS It is a retrospective study of invasive fungal infections in renal transplant recipient reported in our hospital from January 1995 to February 2013. RESULTS Invasive fungal infections were diagnosed in 11 cases (3.4%) among 321 renal transplant recipients. These infections included four cases of pneumocystosis, two cases of candidiasis, two cases of aspergillosis, two cases of cryptococcosis and one case of mucormycosis. There were six men and five women. The mean age was 37 years. The infection was late in 63% of cases (>3 months after transplantation). The prolonged corticosteroid and immunosuppressive therapy were the main risk factors (100%) followed by renal failure (45%), graft rejection (45%), broad spectrum antibiotics (45%), CMV infection (36%), neutropenia (36%) and dialysis (18%). The evolution under treatment was favourable only in two cases (18%). CONCLUSION Invasive fungal infections are not common among kidney transplant recipients. However, they remain an important cause of morbidity and mortality in this group of patients. Prevention, early diagnosis and appropriate management are necessary to improve prognosis and reduce mortality rate.

Epidemiological profile of fungal keratitis in Sfax (Tunisia).

UNLABELLED Fungal keratitis is responsible for a significant burden of blinding disease in the developing world. OBJECTIVE The aim of this study was to determine the etiological agents, predisposing factors and therapy of keratomycosis in our region. METHODS Retrospective study of 60 patients with clinically and cultured confirmed fungi keratitis, who were attended at department of mycology in Sfax (1995 to 2012). RESULTS The mean age of patients was 47.2 years (sex ratio: 1.58). At least, one presumed predisposing factor was identified in 83.3% of cases. Corneal traumatism was established as the most common predisposing factor (61.6%) with vegetative matter (42.4%). Patients had corneal ulcer in 40% or abscess in 47.6%. All cases were positive on direct microscopy and 93% of cultures were positive. Filamentous fungi form the major etiologic agents (83%): Fusarium species (49% with F. solani [66%]), Aspergillus sp. (22%), Alternaria (5%), Scedosporium sp. (2%); and non-identified mold in (5%). Yeast were identified in 17% of cases. Topical agents were used in 97% of cases: ketoconazole 2%, amphotericin B (0.5%). Fluconazole per os was administrated for 11% of cases, itraconazole (2 cases) and voriconazole (one case). Keratoplasty was indicated for 27% of cases. The outcome was favorable in 16% of patients. Among the patients, 71% had persistent corneal deposit sequelae. Four patients lost the eyeball. CONCLUSION Corneal traumatism was the principal risk factor for fungal keratitis in young and middle-aged farmers. Fusarium solani is the predominant cause in Sfax. Early diagnosis, coupled with appropriate treatment, is crucial for increasing the chance of complete recovery.

Molecular characterization of strains of the Trichophyton verrucosum complex from Tunisia

Trichophyton verrucosum is the most frequent etiologic agent of cattle dermatophytosis. Throughout the world, it was the second most common agent of zoophilic dermatophytes in human. The aim of our study was to evaluate the efficacy of the PCR- RFLP and PCR-sequencing methods for the identification and differentiation of T. verrucosum strains.Thirty-six clinical strains identified by morphological characteristics as T. verrucosum were isolated from patients referred to parasitology-mycology laboratory of Sfax University Hospital. Identification of our strains by conventional methods was confirmed by molecular methods in 94.4% of cases. Two strains were reclassified as T. violaceum PCR products digested with HinfI produced three profiles and two patterns with MvaI. Sequence analysis revealed a polymorphism in the ITS1and 5.8S regions. Analysis and alignment of consensus sequences has distinguished two types of genotypes among our T. verrucosum strains. The ITS type I was the dominant genotype (93.7%). Phylogenetic study showed that one cluster comprised T. verrucosum strains with ITS type I and species of T. mentagrophytes complex. It was related to Arthroderma vanbreuseghemii complex. The other cluster contained the two T. verrucosum strains with ITS type II, and was related to Arthroderma benhamiae complex. In this study, most of T. verrucosum isolates were type I, dissimilar to others rare studies where type II has been the most common. Specie and strain differentiation is relevant because it helps in prescribing the correct treatment and determining the source of the infection.

Analysis of virulence factors and in vivo biofilm-forming capacity of Yarrowia lipolytica isolated from patients with fungemia

Abstract Yarrowia lipolytica is ubiquitous in the environment, opportunistic, and might be considered as one of the causative agents of catheter‐related candidemia. Our work aimed to study some virulence factors of Y. lipolytica such as hydrolases production and biofilm formation with comparison to the most frequent Candida specie in human disease. In sum, 58 clinical isolates of Y. lipolytica, 16 C. glabrata, and 12 C. albicans were collected from Intensive care unit (ICU). All were tested for enzymatic production and biofilm formation. All tested isolates of C. albicans and C. glabrata were able to degrade casein, and 98.2% of Y. lipolytica showed caseinase activity but no gelatinase activity was detected in all isolates. Y. lipolytica strains showed significantly lower (3.4%) in vitro phospholipase activity than C. albicans and C. glabrata (P < .05). No significant differences of the hemolytic activity were detected between the three species (P > .05). Concerning biofilm formation, and unlike the results obtained on polystyrene plate, the number of adhered and biofilm cultivable cells obtained by Y. lipolytica after 168 hours of catheter subcutaneous implantation is significantly greater and tends to be more compact and structured hyphal layer. Although C. albicans remains the most pathogenic yeast, development of selective ability of Y. lipolytica to adhere, to form a biofilm on catheter medical devices, and to produce phospholipase and hemolytic enzyme is of particular interest, and it is strongly recommended to be vigilant in the use of medical implanted medical devices, particularly in ICU.

First genotype identification of Trichosporon asahii in Sfax, Tunisia

Purpose. The objectives of our study were species identification and genotyping of Trichosporon isolates collected at the Parasitology and Mycology Laboratory in Sfax, Tunisia. Methodology. Molecular identification was carried out by analysing the IGS1 regions of the rDNA of 30 Trichosporon isolates. Results. Trichosporon asahii was the most frequent species detected. Furthermore, four genotypes were identified in Tunisia: 1 (46.4%), 4 (35.7%), 7 (14.3%) and 3 (3.6%). In vitro antifungal susceptibility testing of the isolates showed that voriconazole exhibited the highest activity. Conclusion. This is the first reported study of genotype identification of T. asahii in Tunisia and even in the African continent.

Highly Discriminatory Variable-Number Tandem-Repeat Markers for Genotyping of Trichophyton interdigitale Strains

ABSTRACT Trichophyton interdigitale is the second most frequent cause of superficial fungal infections of various parts of the human body. Studying the population structure and genotype differentiation of T. interdigitale strains may lead to significant improvements in clinical practice. The present study aimed to develop and select suitable variable-number tandem-repeat (VNTR) markers for 92 clinical strains of T. interdigitale. On the basis of an analysis of four VNTR markers, four to eight distinct alleles were detected for each marker. The marker with the highest discriminatory power had eight alleles and a D value of 0.802. The combination of all four markers yielded a D value of 0.969 with 29 distinct multilocus genotypes. VNTR typing revealed the genetic diversity of the strains, identifying three populations according to their colonization sites. A correlation between phenotypic characteristics and multilocus genotypes was observed. Seven patients harbored T. interdigitale strains with different genotypes. Typing of clinical T. interdigitale samples by VNTR markers displayed excellent discriminatory power and 100% reproducibility.

Real-Time PCR Identification of Six Malassezia Species

Lipophilic yeast Malassezia species is widely found on the skin surface of humans and other animals. This fungus can cause pityriasis versicolor, Malassezia folliculitis, and seborrheic dermatitis. Still now, there is a problem with species identification of Malassezia with conventional methods. We developed a real-time polymerase chain reaction (PCR) assay with multiple hybridization probes for detecting M. globosa, M. furfur, M. restricta, M. sympodialis, M. slooffiae, and M. pachydermatis. The amplification curves and specific melting peaks of the probes hybridized with real-time PCR product were used for species identifications. The assay was further evaluated on 120 samples which were performed by swabbing from 60 domestic animals (23 goats, 10 dogs, 15 cows, 3 cats, 8 rabbits, and 1 donkey) and in 70 human samples (28 patients with pityriasis versicolor, 17 breeders, and 25 control group). Fifteen M. pachydermatis were identified from animals. From human, 61 isolates were identified as M. globosa (28), M. furfur (15), M. restricta (6), M. sympodialis (8), M. slooffiae (2), and M. pachydermatis (2). Eight cases of co-detection from 6 patients and 2 breeders were revealed. Our findings show that the assay was highly effective in identifying Malassezia species. The application of multiplex real-time PCR provides a sensitive and rapid identification system for Malassezia species, which may be applied in further epidemiological surveys from clinical samples.

Changes in Genotype and Fluconazole Susceptibility of Isolates from Patients with Candida glabrata in Tunisia

UNLABELLED Candida glabrata has emerged as an opportunistic pathogen of considerable importance in invasive and superficial infections. AIMS To analyze the development of fluconazole resistance in patients under treatment through epidemiological survey in our hospital. PATIENTS AND METHODS Twenty two patients (89 clinical strains) were collected. Molecular typing of isolates was performed by polymorphic markers. Analysis of gene expression was realized by reverse transcriptase-real time polymerase chain reactions (RT-qPCR). RESULTS Genetic analysis showed that 63% persists with apparently unchanged strains (n=14). Among them, four showed fluconazole resistance development. A strain replacement was observed in 6 patients and two patients selected more resistant isolates during the course of treatment. An analysis of Candida glabrata cerebellar degeneration-related protein 1 (CgCDR1), Candida glabrata cerebellar degeneration-related protein 2 (CgCDR2) and Candida glabrata sterol 14 alpha-demetylase Erg 11 (CgERG11) expression revealed an over-expression in 10 resistant isolates. CONCLUSION This study demonstrated that C. glabrata strain undergo frequent changes in vivo. The increase in CgCDR1 and CgCDR2 expression was the most mechanism associated with fluconazole resistance.