The treatment of invasive fungal infections remains challenging and the emergence of new fungal pathogens as well as the development of resistance to the main antifungal drugs highlight the need for ...novel therapeutic strategies. Although in vitro antifungal susceptibility testing has come of age, the proper evaluation of therapeutic efficacy of current or new antifungals is dependent on the use of animal models. Mammalian models, particularly using rodents, are the cornerstone for evaluation of antifungal efficacy, but are limited by increased costs and ethical considerations. To circumvent these limitations, alternative invertebrate models, such as
, have been developed. Larvae of
have been widely used for testing virulence of fungi and more recently have proven useful for evaluation of antifungal efficacy. This model is suitable for infection by different fungal pathogens including yeasts (
,
,
) and filamentous fungi (
, Mucorales). Antifungal efficacy may be easily estimated by fungal burden or mortality rate in infected and treated larvae. The aim of the present review is to summarize the actual data about the use of
for testing the in vivo efficacy of licensed antifungal drugs, new drugs, and combination therapies.
Candida albicans chronically colonizes the respiratory tract of patients with Cystic Fibrosis (CF). It competes with CF-associated pathogens (e.g. Pseudomonas aeruginosa) and contributes to disease ...severity. We hypothesize that C. albicans undergoes specific adaptation mechanisms that explain its persistence in the CF lung environment. To identify the underlying genetic and phenotypic determinants, we serially recovered 146 C. albicans clinical isolates over a period of 30 months from the sputum of 25 antifungal-naive CF patients. Multilocus sequence typing analyses revealed that most patients were individually colonized with genetically close strains, facilitating comparative analyses between serial isolates. We strikingly observed differential ability to filament and form monospecies and dual-species biofilms with P. aeruginosa among 18 serial isolates sharing the same diploid sequence type, recovered within one year from a pediatric patient. Whole genome sequencing revealed that their genomes were highly heterozygous and similar to each other, displaying a highly clonal subpopulation structure. Data mining identified 34 non-synonymous heterozygous SNPs in 19 open reading frames differentiating the hyperfilamentous and strong biofilm-former strains from the remaining isolates. Among these, we detected a glycine-to-glutamate substitution at position 299 (G299E) in the deduced amino acid sequence of the zinc cluster transcription factor ROB1 (ROB1G299E), encoding a major regulator of filamentous growth and biofilm formation. Introduction of the G299E heterozygous mutation in a co-isolated weak biofilm-former CF strain was sufficient to confer hyperfilamentous growth, increased expression of hyphal-specific genes, increased monospecies biofilm formation and increased survival in dual-species biofilms formed with P. aeruginosa, indicating that ROB1G299E is a gain-of-function mutation. Disruption of ROB1 in a hyperfilamentous isolate carrying the ROB1G299E allele abolished hyperfilamentation and biofilm formation. Our study links a single heterozygous mutation to the ability of C. albicans to better survive during the interaction with other CF-associated microbes and illuminates how adaptive traits emerge in microbial pathogens to persistently colonize and/or infect the CF-patient airways.
Azole resistance in
(Af) has become a widespread threat and a major concern for optimal management of patients with invasive aspergillosis (IA). Combination of echinocandins with azoles is an ...attractive alternative option for the treatment of IA due to azole-resistant Af strains. The aim of this study was to evaluate the
and
combination of caspofungin (CAS) with either voriconazole (VRZ) or posaconazole (PSZ).
interactions were assessed by two methods, and an animal model of IA in
was used for
evaluation. Assessment of efficacy was based on larvae mortality. Groups of 10 larvae were infected by 3 clinical strains of Af (azole susceptible, AfS; PSZ resistant, AfR1; VRZ and PSZ resistant strain, AfR2).
, combination of CAS and azoles was indifferent against AfS, and AfR2, and a synergy was found for AfR1. When compared to VRZ monotherapy, the combination of VRZ at 4 µg/larva with CAS at 4 µg/larva improved survival of AfR2-infected larvae (p=0.0066). Combination of PSZ at 4µg/larva with CAS at 4 µg/larva improved survival of AfR1-infected larvae compared to CAS (p=0.0002) and PSZ (0.0024) monotherapy. Antagonism was never observed. In conclusion, the combination of caspofungin with azoles is a promising alternative for the treatment of azole resistant strains of Af.
Allergic bronchopulmonary aspergillosis (ABPA) is an immunological pulmonary disorder caused by hypersensitivity to
Aspergillus
which colonizes the airways of patients with asthma and cystic ...fibrosis. Its diagnosis could be difficult in some cases due to atypical presentations especially when there is no medical history of asthma. Treatment of ABPA is frequently associated to side effects but cumulated drug toxicity due to different molecules is rarely reported. An accurate choice among the different available molecules and effective on ABPA is crucial. We report a case of ABPA in a woman without a known history of asthma. She presented an acute bronchitis with wheezing dyspnea leading to an acute respiratory failure. She was hospitalized in the intensive care unit. The bronchoscopy revealed a complete obstruction of the left primary bronchus by a sticky greenish material. The culture of this material isolated
Aspergillus fumigatus
and that of bronchial aspiration fluid isolated
Pseudomonas aeruginosa
. The diagnosis of ABPA was based on elevated eosinophil count, the presence of specific IgE and IgG against
Aspergillus fumigatus
and left segmental collapse on chest computed tomography. The patient received an inhaled treatment for her asthma and a high dose of oral corticosteroids for ABPA. Her symptoms improved but during the decrease of corticosteroids, the patient presented a relapse. She received itraconazole in addition to corticosteroids. Four months later, she presented a drug-induced hepatitis due to itraconazole which was immediately stopped. During the monitoring of her asthma which was partially controlled, the patient presented an aseptic osteonecrosis of both femoral heads that required surgery. Nine months after itraconazole discontinuation, she presented a second relapse of her ABPA. She received voriconazole for nine months associated with a low dose of systemic corticosteroid therapy with an improvement of her symptoms. After discontinuation of antifungal treatment, there was no relapse for one year follow-up.
is an environmental filamentous fungus responsible for life-threatening infections in humans and animals. Azoles are the first-line treatment for aspergillosis, but in recent years, the emergence of ...azole resistance in
has changed treatment recommendations. The objective of this study was to evaluate the efficacy of voriconazole (VRZ) in a
model of invasive infection due to azole-susceptible or azole-resistant
isolates. We also sought to describe the pharmacokinetics of VRZ in the
model.
larvae were infected with conidial suspensions of azole-susceptible and azole-resistant isolates of
. Mortality curves were used to calculate the lethal dose. Assessment of the efficacy of VRZ or amphotericin B (AMB) treatment was based on mortality in the lethal model and histopathologic lesions. The pharmacokinetics of VRZ were determined in larval hemolymph. Invasive fungal infection was obtained after conidial inoculation. A dose-dependent reduction in mortality was observed after antifungal treatment with AMB and VRZ. VRZ was more effective at treating larvae inoculated with azole-susceptible
isolates than larvae inoculated with azole-resistant isolates. The concentration of VRZ was maximal at the beginning of treatment and gradually decreased in the hemolymph to reach a C
(24 h) between 0.11 and 11.30 mg/L, depending on the dose. In conclusion,
is a suitable model for testing the efficacy of antifungal agents against
.
Microsporidiosis is an emerging opportunistic infection causing severe digestive disorders in immunocompromised patients. The aim of this study was to investigate the prevalence of intestinal ...microsporidia carriage among immunocompromised patients hospitalized at a major hospital complex in the Tunis capital area, Tunisia (North Africa), and perform molecular epidemiology and population structure analyses of
, which is an emerging fungal pathogen. We screened 250 stool samples for the presence of intestinal microsporidia from 171 patients, including 81 organ transplant recipients, 73 Human Immunodeficiency Virus (HIV)-positive patients, and 17 patients with unspecified immunodeficiency. Using a nested PCR-based diagnostic approach for the detection of
spp., we identified 18 microsporidia-positive patients out of 171 (10.5%), among which 17 were infected with
. Microsporidia-positive cases displayed chronic diarrhea (17 out of 18), which was associated more with HIV rather than with immunosuppression other than HIV (12 out of 73 versus 6 out of 98, respectively,
= 0.02) and correlated with extended hospital stays compared to microsporidia-negative cases (60 versus 19 days on average, respectively;
= 0.001). Strikingly, internal transcribed spacer (ITS)-based genotyping of
strains revealed high-frequency occurrence of ITS sequences that were identical (
= 10) or similar (with one single polymorphic site,
= 3) to rare genotype WL12. Minimum-spanning tree analyses segregated the 17
infection cases into four distinct genotypic clusters and confirmed the high prevalence of genotype WL12 in our patient population. Phylogenetic analyses allowed the mapping of all 17
strains to zoonotic group 1 (subgroups 1a and 1b/1c), indicating loose host specificity and raising public health concern. Our study suggests a probable common source of
genotype WL12 transmission and prompts the implementation of a wider epidemiological investigation.
Background :
Healthcare-associated infections (HAIs) are with high rates of mortality and an additional cost, in onco-hematology patients.
Aim
:
The study aims to assess the prevalence trends of ...HAIs in the onco-hematology ward of the Tunisian National Bone Marrow Transplant Center (NBMTC), and to determine the principal associated risk factors.
Methods:
Six repeated point prevalence surveys were conducted, from May 2018 to March 2019, using a two months interval. All patients hospitalized in the day of the survey were included. Risk factors of HAIs were expressed as odds ratios (ORs) with 95% confidence intervals (CIs). They were assessed using a logistic regression model.
Results:
Nineteen patients out of a total of 74 patients have been diagnosed with 19 HAIs, representing a prevalence of 25.7%. No significant downward or upward trend of prevalence was revealed over time (p=0.3). The most common HAI was respiratory tract infection (57.9%) with a prevalence of 14.9%. Multiple logistic regression analysis revealed that HAI was significantly associated with neutropenia (Adjusted OR: 14; 95% CI: 1.5-127; p=0.01) and duration of central venous catheter (Adjusted OR: 1.1; 95% CI: 1-1.2; p=0.005).
Conclusion:
High prevalence of HAIs in our center with a high rate of mortality, requiring identifying potential problems in infection control practices.
Le paludisme est une complication inhabituelle de l’allogreffe de CSH dans les pays non endémiques. Nous rapportons le cas d’un paludisme survenu à J16 d’une allogreffe réalisée chez un patient ...atteint d’une aplasie médullaire sévère. Le paludisme a été suspecté devant une fièvre résistante aux antibiotiques et une hémolyse intravasculaire. Devant l’absence du séjour du patient et de son donneur de moelle dans une zone d’endémie et devant la négativité de la goutte épaisse et de la PCR chez le donneur de CSH, l’origine transfusionnelle a été suspectée.
L’enquête a été déclenchée par le CNTS après déclaration du cas par le CNGMO. La vérification des données figurant sur les fichiers informatiques des donneurs de sang, à la recherche d’un ou de plusieurs donneurs ayant séjourné dans des zones d’endémie, a révélé un seul donneur originaire de la côte d’Ivoire. Celui-ci a été convoqué pour réaliser un frottis sanguin, une goutte épaisse, une sérologie parasitaire et une PCR.
L’interrogatoire a révélé que ce donneur a présenté dans ces antécédents un accès palustre. La goutte épaisse ainsi que le frottis sanguin n’ont pas révélé le parasite. La sérologie parasitaire du paludisme est positive au 1/20e. La PCR à plasmodium falciparum est positive.
Ce cas illustre l’importance du diagnostic du paludisme chez le patient malgré l’absence de facteurs de risque chez le receveur et le donneur de CSH. Une remise en cause de la stratégie de la sélection des donneurs de sang et de dépistage du paludisme a été soulevée par les professionnels de la santé.
Docimology has allowed the development of evaluative processes assuring valid, reliable and objective assessments. It was adopted within the faculty of Medicine of Tunis since 2007. The aim of this ...study was to analyze the docimological survey results of hematology-oncology exams, to evaluate the interest of this analysis in the elaboration of exams and the construction of an item bank, and propose some corrections in order to improve assessment. Methods :We have analyzed the hematology-oncology exams of SCMS1 (Second cycle of Medical Studies 1) from educational year 2008-2009 to 2013-2014. The data input was already done with Excel. The test includes 4 disciplines (Hematology, Oncology, Genetics and the Anatomic Pathology). We have calculated docimological parameters allowing global analysis, by discipline and by item. Results : A total of 3281 papers and 1004 questions were analyzed. The average success rate per year was 91,54% ± 7,12. The highest average success rate was found in hematology (80,51% ± 10,18). The lowest rate was found in the anatomic pathology (51,61% ± 23,76). The average rate of students succeeding the test without having average note in hematology was 5,36%. It was 42,29% in the anatomic pathology. Average difficulty index was 0,57 ± 0,05. Items analysis showed that 38,04% were easy and 19,02% were difficult. Average discrimination index was 0,25 ± 0,02. Discrimination was very good in 20,51% of items and good in 17,13%. Useless and bad discrimination items were about 40,53%. The average of Cronbach Alpha coefficient was 0,84 ± 0,03, showing a good internal-consistency. Conclusion :This study allowed an objective evaluation of "contributive disciplines" in multidisciplinary evaluation and showed the interest of integrating questions. Question analysis with teachers would be important to reevaluate and improve these items.
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