The incidence and prevalence of serious fungal diseases in Tunisia.

With increasing concern about the negative health impact of fungal disease, there is a need to survey what is and is not known about the epidemiology of these infections in Tunisia. We have estimated the incidence and prevalence of the most serious fungal diseases in Tunisia for the first time. Using published literature from Tunisia, or if absent other countries, we have estimated the burden of life-threatening fungal infections and those causing significant morbidity, using deterministic modeling, based on populations at greatest risk. An estimated 250,494 (2.12% of the Tunisian population) are affected by a serious fungal disease annually. Invasive and chronic pulmonary aspergillosis are relatively common with 708 and 2090 patients affected, partly linked to the prevalence of chronic obstructive pulmonary disease (COPD). Fungal asthma (allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitization) have an estimated prevalence of 38,264 (5.8% of the adult asthma population). Fungal keratitis probably affects 1,761 eyes annually, often leading to uniocular blindness. Candidaemia and Candida peritonitis probably affect at least 680 people annually, with a high mortality. Recurrent vulvovaginal candidiasis probably affects over 200,000 women. While fungal diseases are regularly diagnosed in Tunisia, epidemiological studies with denominators are uncommon. Some fungal diseases are poorly addressed with the current diagnostic portfolio, and surveillance is lacking. Studies on these diseases and the implementation of a national program of surveillance are required.

Tuning the electronic and optical properties of small organic acenedithiophene molecular crystals for photovoltaic applications: First principles calculations.

Periodic density functional theory was employed to investigate the impact of chemical modifications on the properties of π-conjugated acenedithiophene molecular crystals. Here, we highlight the importance of the ß-methylthionation effect, the position of the sulfur atoms of the thiacycle group and their size, and the number of central benzene rings in the chemical modification strategy. Our results show that the introduction of the methylthio groups at the ß-positions of the thiophene and the additional benzene ring at the center of the BDT crystal structure are a promising strategy to improve the performance of organic semiconductors, as observed experimentally. We found that ß-MT-ADT exhibits large charge carrier mobility, which is in good agreement with the experimental results and comparable to that of rubrene. In addition, the electronic and optical properties of these ambipolar materials suggest promising performances with ß-MT-ADT > ADT >ß-MT-NDT > NDT > BEDT-BDT >ß-MT-BDT > BDT. Moreover, functionalization with thiacycle-fused sulfur atoms of different sizes and numbers improve the properties of BDT but is still less efficient than the methylthionation effect. Overall, our findings suggest a promising molecular modification strategy for possibly high performance ambipolar organic semiconducting materials.

First-principles study of the structural and electronic properties of tetragonal ZrOX (X = S, Se, and Te) monolayers and their vdW heterostructures for applications in optoelectronics and photocatalysis.

Using first-principles calculations, we have studied the structural and electronic properties of ZrOX (X = S, Se, and Te) monolayers and their van der Waals heterostructures in the tetragonal structure. Our results show that these monolayers are dynamically stable and are semiconductors with electronic bandgaps ranging from 1.98 to 3.16 eV as obtained with the GW approximation. By computing their band edges, we show that ZrOS and ZrOSe are of interest for water splitting applications. In addition, the van der Waals heterostructures formed by these monolayers show a type I band alignment for ZrOTe/ZrOSe and a type II alignment for the other two heterostructures, making them potential candidates for certain optoelectronic applications involving electron/hole separation.

Dipeptidyl peptidase III as a DNA marker to investigate epidemiology and taxonomy of Old World Leishmania species.

BACKGROUND: Dipeptidyl peptidase III (DPPIII) member of M49 peptidase family is a zinc-dependent metallopeptidase that cleaves dipeptides sequentially from the N-terminus of its substrates. In Leishmania, DPPIII, was reported with other peptidases to play a significant role in parasites' growth and survival. In a previous study, we used a coding sequence annotated as DPPIII to develop and evaluate a PCR assay that is specific to dermotropic Old World (OW) Leishmania species. Thus, our objective was to further assess use of this gene for Leishmania species identification and for phylogeny, and thus for diagnostic and molecular epidemiology studies of Old World Leishmania species. METHODOLOGY: Orthologous DDPIII genes were searched in all Leishmania genomes and aligned to design PCR primers and identify relevant restriction enzymes. A PCR assays was developed and seventy-two Leishmania fragment sequences were analyzed using MEGA X genetics software to infer evolution and phylogenetic relationships of studied species and strains. A PCR-RFLP scheme was also designed and tested on 58 OW Leishmania strains belonging to 8 Leishmania species and evaluated on 75 human clinical skin samples. FINDINGS: Sequence analysis showed 478 variable sites (302 being parsimony informative). Test of natural selection (dN-dS) (-0.164, SE = 0.013) inferred a negative selection, characteristic of essential genes, corroborating the DPPIII importance for parasite survival. Inter- and intra-specific genetic diversity was used to develop universal amplification of a 662bp fragment. Sequence analyses and phylogenies confirmed occurrence of 6 clusters congruent to L. major, L. tropica, L. aethiopica, L. arabica, L. turanica, L. tarentolae species, and one to the L. infantum and L. donovani species complex. A PCR-RFLP algorithm for Leishmania species identification was designed using double digestions with HaeIII and KpnI and with SacI and PvuII endonucleases. Overall, this PCR-RFLP yielded distinct profiles for each of the species L. major, L. tropica, L. aethiopica, L. arabica and L. turanica and the L. (Sauroleishmania) L. tarentolae. The species L. donovani, and L. infantum shared the same profile except for strains of Indian origin. When tested on clinical samples, the DPPIII PCR showed sensitivities of 82.22% when compared to direct examination and was able to identify 84.78% of the positive samples. CONCLUSION: The study demonstrates that DPPIII gene is suitable to detect and identify Leishmania species and to complement other molecular methods for leishmaniases diagnosis and epidemiology. Thus, it can contribute to evidence-based disease control and surveillance.

Electronic properties of several two dimensional halides from ab initio calculations.

Using density functional theory, we study the electronic properties of several halide monolayers. We show that their electronic bandgaps, as obtained with the HSE hybrid functional, range between 3.0 and 7.5 eV and that their phonon spectra are dynamically stable. Additionally, we show that under an external electric field some of these systems exhibit a semiconductor-to-metal transition.

Microsatellite Typing of Aspergillus flavus Strains in a Tunisian Onco-hematology Unit.

Aspergillus flavus is the most common species associated with invasive aspergillosis in Tunisia. The molecular epidemiology of the species is poorly documented. We used five highly discriminative microsatellite markers for the genotyping of clinical and hospital environmental A. flavus strains to assess whether IA could be hospital-acquired in the onco-hematology unit of the Farhat Hached teaching hospital of Sousse, Tunisia. The genotyping of 18 clinical isolates, collected from sputa of 17 acute leukemia patients, and 81 isolates, collected in these patients' hospital environment and food, identified 57 isolates that were grouped in 10 clones, each of them including 2-17 isolates. The remaining 42 isolates showed a unique genotype. Two main transmission scenarios were observed: (1) the same clone was isolated from different patients; (2) the same clone was isolated from a patient, its hospital environment and/or food. These findings strongly suggest the occurrence of hospital-acquired A. flavus infection/colonization in the investigated onco-hematology unit.

Hospital environment fungal contamination and aspergillosis risk in acute leukaemia patients in Sousse (Tunisia).

Hospital environment is considered the main source of invasive aspergillosis (IA) in leukemic patients. This study aimed to describe Aspergillus colonisation in leukemic patients and their hospital environment and to test whether Aspergillus environmental contamination was associated with IA. For a 2-year period including 14-month renovation work, 91 acute leukaemia inpatients at the hematology department of University hospital in Sousse (Tunisia) were prospectively included. The incidence of probable IA (EORTC/MSG criteria) was 9.9%. Fifty-six Aspergillus were isolated from 53 (6.5%) of 811 sputa collected from 35 (38.5%) patients. Aspergillus spp. were isolated in 59.7% of 494 air samples and in 52.8% of 1579 surface samples taken in the patients' room. Aspergillus section Nigri (72.7%) was the most frequent. Aspergillus contamination peaked in autumn and winter on surface and in summer and autumn in air samples and was higher (P = 0.03) during the renovation work period. Multivariate analysis showed that for each Aspergillus section Nigri CFU airborne contamination IA risk increased by 1.05 (P = 0.04). In Tunisia, Aspergillus section Nigri and Flavi, but not Fumigati, are chiefly involved in IA. Our findings support swift implementation of airborne fungal contamination control measures in areas where immunocompromised patient are hospitalised.

A new IgG immunoblot kit for diagnosis of toxoplasmosis in pregnant women.

The determination of the accurate immune status of pregnant women is crucial in order to prevent congenital toxoplasmosis. Equivocal results with conventional serological techniques are not uncommon when IgG titers are close to the cut-off value of the test, so that a confirmatory technique is needed. For this purpose, we developed a homemade immunoblot (IB) using soluble extract of Toxoplasma gondii tachyzoites and assessed it by testing 154 positive, 100 negative, and 123 equivocal sera obtained from pregnant women. In order to select the more valuable bands in terms of sensitivity and specificity, we used the Youden Index (YI). The highest YIs were those given by the 32, 36, 98, 21, and 33 bands. The simultaneous presence on the same blot of at least 3 bands showed a much higher YI (0.964) and was adapted as the positivity criterion. The analysis of results showed that our homemade IB correlated well with the commercial LDBIO Toxo II IgG® kit recently recommended as a confirmatory test (96.7% of concordance).

Characteristics of invasive aspergillosis in neutropenic haematology patients (Sousse, Tunisia).

Although scarce, available data suggest that the epidemiology of invasive aspergillosis (IA) in North Africa differs from northern countries, where more than 80 % is caused by Aspergillus fumigatus. This study aimed at describing the epidemiology of IA in the region of Sousse, Tunisia, and at assessing the usefulness of the available diagnostic tools. For 2 years, clinical and mycological data were prospectively collected from 175 neutropenia episodes of 91 patients hospitalised in the haematology department at the Farhat Hached hospital in Sousse (Tunisia). Screening for galactomannan antigen was positive in 40 % of neutropenia episodes; Aspergillus PCR was positive in 42 % of the tested sera. Nine patients were classified as probable and two as possible IA according to the EORTC/MSG criteria. Twelve patients who prematurely died, had no CT scan and could not be classified. Fifty-six Aspergillus spp. were isolated in 53 (6.5 %) sputa collected from 35 (20 %) patients. The following species were identified with MALDI-TOF mass spectrometry and DNA sequencing: A. niger, 35 %; A. flavus, 38 %; A. tubingensis, 19 %; A. fumigatus, 4 %; A. westerdijkiae, 2 % and A. ochraceus, 2 %. Our findings highlight the epidemiological features of IA in Tunisia, which is characterised by the predominance of Aspergillus spp. from sections Nigri and Flavi.

Etiology of Acute Diarrhea in Tunisian Children with Emphasis on Diarrheagenic Escherichia coli: Prevalence and Identification of E. coli Virulence Markers.

BACKGROUND: Diarrheal diseases can be caused by viral, bacterial and parasitic infections. This paper provides a preliminary image of diarrhea with regards to etiology and epidemiologic factors in Tunisian children less than five years of age. METHODS: Overall, 124 diarrhoeal stools were collected from patients suffering from acute diarrhea and 54 stool samples from healthy children. All stools were examined for the presence of enteric pathogens. RESULTS: In diarrheagenic children, 107 pathogenic bacteria were isolated (12 Salmonella spp. (9.7%) and 95 diarrheagenic Escherichia coli strains (76.6%): 29 enteroaggregative E.coli (EAEC) (23.4%), 15 enteroinvasive E.coli (EIEC) (12.1%), 17 enteropathogenic E.coli (EPEC) (13.7%), 26 enterotoxigenic E.coli (ETEC) (21%) and 2 enterohemoragic E.coli (EHEC) (1.6%). However, in the control group, 23 pathogenic E.coli strains were isolated (42.6%): 8 EAEC (14.8%), 12 EIEC (22.2%) and 3 EPEC (5.5%). Among diarrheagenic E.coli (DEC), only ETEC strains were significantly recovered from diarrheagenic children than from healthy controls (P < 0.0003). Group A rotavirus was identified in 33.9% (n=42) of diarrheagenic children and in 11.1% among the control group (n=6). Concerning norovirus, 8.9% (n=11) of the samples collected from diarrheagenic children and 9.2% (n=5) from the control group were positive. The prevalence of rotaviruses and Salmonella spp were also significantly higher in patients with diarrhea than in controls (P = 0.002 and P < 0.019, respectively). Finally, enteropathogenic parasites (Entamoeba coli and cryptosporidium Oocystes) were isolated from 4.8% and 9.2% of diarrheagenic and control children, respectively. CONCLUSION: These results provide baseline data about the relative importance of different enteropathogens in Tunisian children.

In vitro susceptibility to amphotericin B, itraconazole, voriconazole, posaconazole and caspofungin of Aspergillus spp. isolated from patients with haematological malignancies in Tunisia.

The resistance of Aspergillus species to antifungal is increasingly reported and the knowledge of the local epidemiology and antifungal susceptibility pattern is pivotal to define adequate treatment policies. Our study aimed to: 1) describe the in vitro antifungal susceptibility profile of the Aspergillus species isolated from patients with haematological malignancies in Tunisia; 2) compare the E-test and Sensititre Yeast-One assays for the detection of paradoxical growth and trailing effect, both phenotypes commonly exhibited by Aspergillus spp. upon exposure to caspofungin and 3) to evaluate the mortality rate in patients according to the causative Aspergillus species and the antifungal treatment. We tested amphotericin B, itraconazole, voriconazole, posaconazole and caspofungin against 48 Aspergillus isolates (17, A. niger; 18, A. flavus; 9, A. tubingensis; 1, A. westerdijkiae; and 1, A. ochraceus) with the E-test. Minimal inhibition concentrations were above the epidemiological cut-off values for amphotericin B in 67% of A. flavus strains; for caspofungin in 22% of A. flavus strains; and for itraconazole in 22% of A. tubingensis strains, voriconazole and posaconazole MICs were below the epidemiological cut-off values for all strains. When exposed to caspofungin, 42% of the strains exhibited trailing effect and 38% paradoxical growth. Trailing effect occurred in 61% of A. flavus strains and paradoxical growth in 62% of Aspergillus section Nigri strains. E-test and Sensititre Yeast-One assays were only fairly concordant for the detection of these phenotypes. Repeatability of both assays was high for trailing effect but poor for paradoxical growth. The relatively high frequency of amphotericin B resistant strains makes voriconazole best adapted as a first-line treatment of invasive aspergillosis from amphotericin B to voriconazole in this hospital.

IgG western blot for confirmatory diagnosis of equivocal cases of toxoplasmosis by EIA-IgG and fluorescent antibody test.

The performance values of available techniques used in serodiagnosis of toxoplasmosis are satisfactory but they raise problems of equivocal and discordant results for very low IgG titers. Recently marketed, LDBio-Toxo II IgG Western blot (IB) showed an excellent correlation with the dye test. We estimated the proportion of equivocal and discordant results between the enzyme immunoassay Platelia Toxo IgG (EIA-IgG) and fluorescent antibody test (FAT) and assessed the usefulness of the IB as a confirmatory test. Out of 2,136 sera collected from pregnant women, 1,644 (77.0%) tested unequivocally positive and 407 (19.0%) were negative in both EIA-IgG and FAT. The remaining 85 (4%) sera showed equivocal or discordant results. Among them, 73 (85.9%) were positive and 12 (14.1%) were negative in IB. Forty-one (89.1%) equivocal sera in EIA-IgG and 46 (86.8%) equivocal sera in FAT were positive in IB. Reducing the cut-off values of both screening techniques improved significantly their sensitivity in detecting very low IgG titers at the expense of their specificity. In conclusion, equivocal results in routine-used techniques and their discordance in determination of the immune status in pregnancy women were not uncommon. IB test appeard to be highly useful in these situations as a confirmatory technique.

Cutaneous hyalohyphomycosis caused by Purpureocillium lilacinum in an immunocompetent patient: case report and review.

Purpureocillium lilacinum is a saprophytic fungus found in soil and decaying organic matter, but has been reported as an emerging pathogen in immunocompromised patients and following surgical procedures. Infections caused by this mold are often difficult to treat because of its intrinsic resistance to conventional antifungal agents and variable susceptibility to novel triazoles. In immunocompetent subjects, infections caused by P. lilacinum are unusual and mainly involve the skin. We describe herein a case of cutaneous hyalohyphomycosis due to this fungus in an immunocompetent girl without any predisposing risk factors and review the previously reported cases in immunocompetent hosts.

Identification of Tunisian Leishmania spp. by PCR amplification of cysteine proteinase B (cpb) genes and phylogenetic analysis.

Discrimination of the Old World Leishmania parasites is important for diagnosis and epidemiological studies of leishmaniasis. We have developed PCR assays that allow the discrimination between Leishmania major, Leishmania tropica and Leishmania infantum Tunisian species. The identification was performed by a simple PCR targeting cysteine protease B (cpb) gene copies. These PCR can be a routine molecular biology tools for discrimination of Leishmania spp. from different geographical origins and different clinical forms. Our assays can be an informative source for cpb gene studying concerning drug, diagnostics and vaccine research. The PCR products of the cpb gene and the N-acetylglucosamine-1-phosphate transferase (nagt) Leishmania gene were sequenced and aligned. Phylogenetic trees of Leishmania based cpb and nagt sequences are close in topology and present the classic distribution of Leishmania in the Old World. The phylogenetic analysis has enabled the characterization and identification of different strains, using both multicopy (cpb) and single copy (nagt) genes. Indeed, the cpb phylogenetic analysis allowed us to identify the Tunisian Leishmania killicki species, and a group which gathers the least evolved isolates of the Leishmania donovani complex, that was originated from East Africa. This clustering confirms the African origin for the visceralizing species of the L. donovani complex.

Investigation of a cluster of Candida albicans invasive Candidiasis in a neonatal intensive care unit by pulsed-field gel electrophoresis.

Nosocomial invasive candidiasis (IC) has emerged as a major problem in neonatal intensive care units (NICUs). We investigated herein the temporal clustering of six cases of neonatal IC due to Candida albicans in an NICU. Eighteen isolates obtained from the six neonates and two isolates from two health care workers (HCWs) working at the same unit and suffering from fingers' onychomycosis were genotyped by electrophoretic karyotyping (EK) and restriction endonuclease analysis of genomic DNA by using Sfi I (PFGE-Sfi I). PFGE-Sfi I was more effective in discriminating between temporally related isolates. It showed that (i) both HCWs had specific strains excluding them as a source of infections in neonates. (ii) Isolates collected from three neonates were identical providing evidence of their clonal origin and the occurrence of a horizontal transmission of C. albicans in the unit. (iii) The three remaining neonates had specific strains confirming that the IC cases were coincidental. (iv) Microevolution occurred in one catheter-related candidemia case. Our results illustrate the relevance of the molecular approach to investigate suspected outbreaks in hospital surveys and the effectiveness of PFGE-Sfi I for typing of epidemiologically related C. albicans isolates.

Temporal similarity between Candida albicans genotypes in a Tunisian neonatal intensive care unit suggests several nosocomial cross-contamination episodes.

The nosocomial transmission of Candida albicans in neonatal intensive care units (NICUs) is an increasing concern and understanding the route of this transmission is critical for adequate infection control measures. The aim of our study was to assess the likeliness of nosocomial acquisition of C. albicans in the NICU of Farhat Hached hospital in Sousse (Tunisia). We genotyped 82 isolates from 40 neonates and 7 isolates from 5 health care workers (HCWs) with onychomycosis, by using CDC3 microsatellite length polymorphism (MLP) and the high-resolution melting (HRM) analysis. Combined MLP and HRM CD3 analysis led to the delineation of 12 genotypes. Five temporal clustering caused by five genotypes occurred during the study period. Three of these genotypes were isolated in both neonates and HCWs. The first clustering included 28 isolates obtained between January 2003 and May 2004 from 16 neonates and 2 HCWs. The second clustering included three isolates collected in 2004 from three neonates and two HCWs. The third clustering included 11 isolates obtained from 6 neonates and 1 HCW in 2006. The two remaining clustering could not be associated with any HCW's contamination. These results argue for the nosocomial transmission of C. albicans in our NICU. The combined MLP and HRM analysis is a rapid first approach for tracking cross-contamination.

Geotrichum capitatum septicemia in patients with acute myeloid leukemia. Report of three cases.

Geotrichum capitatum infection is uncommon, and has been exclusively reported in immunocompromised patients. The prognosis is poor with a mortality rate ranging from 50 to 90%. We report 3 cases of Geotrichum capitatum fungemia in neutropenic patients receiving chemotherapy for acute myeloblastic leukemia. The infection was successfully cured with voriconazole in 1 case and was fatal in the 2 remaining cases despite treatment with amphotericin B.

Tinea capitis in adults in Tunisia.

OBJECTIVE: To determine the pattern of infectious agents causing tinea capitis (TC) in adult patients in the center of Tunisia. METHODS: From January 1990 to December 2005, we have retrospectively collected all cases of adult TC, confirmed by the mycological examination. RESULTS: Sixty patients (18 male, 42 female) with a mean age of 34.5 years were diagnosed as having adult TC among a total number of 1137 cases of TC (5.27%). Clinical features were polymorphic and diagnosis was made on mycological examination. Culture identified Trichophyton violaceum in 36 cases (60%), Microsporum canis in 12 cases (20%), Trichophyton schoenleini in 7 cases (12%), Trichophyton verrucosum in two cases (3.5%), and Trichophyton mentagrophytes and Trichophyton rubrum in one case (each 1.77%). Culture was negative in one case (1.77%). Treatment consisted of administration of Griseofulvin(20­25 mg/kg/d) during 6­8 weeks associated with antifungal topics. A complete recovery was noted in 55 cases (92%) and a relapse occurred in two patients (3.5%). A scary alopecia was observed in one patient (1.77%) and two patients were lost to follow-up. CONCLUSION: Trichophyton violaceum remains the most common etiological agent of adult TC in Tunisia. Microsporum canis is rising rapidly most notably due to the high frequency of asymptomatic carriage by domestic animals [corrected].

[Acanthamoeba keratitis. Report of 3 cases diagnosed in central Tunisia]. / Les kératites a Acanthamoeba sp: a propos de 3 cas diagnostiqués au centre Tunisien.

BACKGROUND: Amoeba of the genus Acanthamoeba are ubiquitous free-living protozoa encountered in water and soil. They frequently cause sight-threatening keratitis. AIM: Report of the three first cases diagnosed at the laboratory of Parasitology of Sousse Hospital, (Tunisia). CASE REPORT: Our study concerned three lens-wearing female patients, aged 17, 20 and 29 years respectively. The patients originate from central Tunisia and presented with unilateral (2 cases) or bilateral (one case) keratitis. Diagnosis was made by demonstrating Acanthamoeba trophozoites and/or cysts on direct examination and/or culture (in agar - Escherichia coli medium) of contact lenses and/or lenses' solution. Direct examination of corneal swabs was negative in three cases but culture was positive in one. The three patients were treated with hexamidine and neomycine eye-drops for three months. Treatment led to scarring of lesions with however sequellar opacities that was minor to moderate in two cases and consisted of a central leucoma with a poor visual outcome in the last case. CONCLUSION: The need for systematic research of amoeba in lenses wearing patients with keratitis is emphasized.

Rapid detection of Mycobacterium tuberculosis in sputum by Patho-TB kit in comparison with direct microscopy and culture.

The usefulness of a new rapid diagnostic test (Patho-TB) using antibodies specific to mycobacterial antigens was evaluated for the rapid discrimination between pulmonary tuberculosis (TB) and non-TB pulmonary diseases on sputa. One hundred sputa collected from 79 active TB patients and from 21 patients with non-TB pulmonary diseases (asthma and chronic obstructive pulmonary disease) were enrolled into the study and tested for the presence of Mycobacterium tuberculosis by Ziehl-Neelsen smear, Patho-TB kit, and Löwenstein-Jensen culture. The sensitivity, specificity, positive predictive value, and negative predictive value of the Patho-TB test were 95%, 100%, 100%, and 84%, respectively. Patho-TB test is simple, quick, and easy to perform. Its sensitivity, specificity, and positive predictive value are satisfactory. Therefore, it could be used as a screening test in poorly equipped laboratories of TB endemic areas.