Marcela Sabou

Comparison between the Biflex III-Biotyper and the Axima-SARAMIS Systems for Yeast Identification by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

ABSTRACT Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is emerging in laboratories as a new diagnostic tool for microorganism identification. We prospectively compared the performances of the Biflex III-Biotyper (Bruker Daltonics) and the Axima (Shimadzu)-SARAMIS (AnagnosTec) systems for the identification of 312 yeasts isolated from clinical specimens (249 Candida spp., including 19 C. albicans and 230 non-albicans species and 63 isolates belonging to different species of the genera Saccharomyces [20 isolates], Rhodotorula [8 isolates], Cryptococcus [8 isolates], Trichosporon [7 isolates], Pichia [7 isolates], Geotrichum [12 isolates], and Sporopachydermia cereana [1 isolate]). Species were identified by using routine conventional phenotypical methods and internal transcribed spacer (ITS) sequencing in case of discrepancy. We used expanded thresholds for species identification (log score of ≥1.7 with 3 identical consecutive propositions and no discrepancy between the duplicates for the Bruker Daltonics system and similitude of ≥40% with 5 successive identical propositions and no discrepancy between the duplicates for the Shimadzu system). Of the 312 isolates, 272 (87.2%) and 258 (82.7%) were successfully identified by the Bruker Daltonics and Shimadzu systems, respectively. All isolates were successfully identified within the most frequent and clinically relevant Candida species by the two systems. Nonvalid results corresponded mainly to species not or poorly represented in the databases. Major misidentifications were observed for 2 isolates (0.6%) by the Bruker Daltonics system and 4 isolates (1.3%) by the Shimadzu system. In conclusion, the performances of the Bruker Daltonics and the Shimadzu systems for yeast identification were good and comparable under routine clinical conditions, despite their differences in sample preparation, database content, and spectrum analysis.

New clinical and experimental insights into Old World and neotropical ocular toxoplasmosis

Retinal lesions or other ocular manifestations are serious consequences of infection with the protozoan parasite Toxoplasma gondii. Whilst classically considered a consequence of congenital transmission, recent screening studies estimated that 2% of T. gondii seropositive persons in Europe and North America have retinal lesions, most of them persisting unnoticed. The situation is more dramatic in South America, probably due to the predominance of virulent strains. Some of these strains seem to exhibit ocular or neuronal tropism and are responsible for severe ocular lesions. Despite the medical importance, the physiopathological mechanisms have only recently begun to be elucidated. The particular immune-privileged situation in the eye has to be considered. Studies on French patients showed low or undetectable ocular parasite loads, but a clear Th1/Th17 type immune reaction. Suitable mouse models have appeared in the last few years. Using such a model, IL-17A proved to impair parasite control and induce pathology. In contrast, in South American patients, the parasite seems to be much less efficiently controlled through a Th2 type or suppressive immune response that favors parasite replication. Finally, several host genetic markers controlling immune response factors have been associated with ocular involvement of T. gondii infection, mainly in South America.

The local immune response to intraocular Toxoplasma re-challenge: Less pathology and better parasite control through Treg/Th1/Th2 induction

Ocular toxoplasmosis is a major cause of blindness world-wide. Ocular involvement is frequently seen following congenital infection. Many of these infections are quiescent but pose a life-time risk of reactivation. However, the physiopathology of ocular toxoplasmosis reactivation is largely unexplored. We previously developed a Swiss-Webster outbred mouse model for congenital toxoplasmosis by neonatal injection of Toxoplasma gondii cysts. We also used a mouse model of direct intraocular infection to show a deleterious local T helper 17 type response upon primary infection. In the present study, our two models were combined to study intravitreal re-challenge of neonatally infected mice, as an approximate model of reactivation, in comparison with a primary ocular infection. Using BioPlex proteomic assays in aqueous humour and reverse transcription-PCR for T helper cell transcription factors, we observed diminished T helper 17 type reaction in reinfection, compared with primary infection. In contrast, T helper 2 and T regulatory responses were enhanced. Interestingly, this was also true for T helper 1 markers such as IFN-γ, which was paralleled by better parasite control. Secretion of IL-27, a central cytokine for shifting the immune response from T helper 17 to T helper 1, was also greatly enhanced. We observed a similar protective immune reaction pattern in the eye upon reinfection with the virulent RH strain, with the notable exception of IFN-γ. In summary, our results show that the balance is shifted from T helper 17 to a less pathogenic but more effective anti-parasite Treg/T helper 1/T helper 2 pattern in a reactivation setting.

Interleukin-6-Driven Inflammatory Response Induces Retinal Pathology in a Model of Ocular Toxoplasmosis Reactivation

ABSTRACT Ocular inflammation is one of the consequences of infection with the protozoan parasite Toxoplasma gondii. Even if lesions are self-healing in immunocompetent persons, they pose a lifetime risk of reactivation and are a serious threat to vision. As there are virtually no immunological data on reactivating ocular toxoplasmosis, we established a model of direct intravitreal injection of parasites in previously infected mice with a homologous type II strain. Two different mouse strains with variable ability to control retinal infection were studied in order to describe protective and deleterious reaction patterns. In Swiss-Webster mice, which are already relatively resistant to primary infection, no peak of parasite load was observed upon reinfection. In contrast, the susceptible inbred strain C57BL/6 showed high parasite loads after 7 days, as well as marked deterioration of retinal architecture. Both parameters were back to normal on day 21. C57BL/6 mice also reacted with a strong local production of inflammatory and Th1-type cytokines, like interleukin-6 (IL-6), IL-17A, and gamma interferon (IFN-γ), while Swiss-Webster mice showed only moderate expression of the Th2 cytokine IL-31. Interestingly, rapid intraocular production of anti-Toxoplasma antibodies was observed in Swiss-Webster but not in C57BL/6 mice. We then localized the cellular source of different immune mediators within the retina by immunofluorescence. Finally, neutralization experiments of IFN-γ or IL-6 demonstrated the respective protective and deleterious roles of these cytokines for parasite control and retinal integrity during reinfection. In conclusion, we developed and immunologically characterized a promising mouse model of reactivating ocular toxoplasmosis.

Magnetic Resonance Imaging of Cerebral Aspergillosis: Imaging and Pathological Correlations

Cerebral aspergillosis is associated with a significant morbidity and mortality rate. The imaging data present different patterns and no full consensus exists on typical imaging characteristics of the cerebral lesions. We reviewed MRI findings in 21 patients with cerebral aspergillosis and correlated them to the immune status of the patients and to neuropathological findings when tissue was available. The lesions were characterized by their number, topography, and MRI signal. Dissemination to the brain resulted from direct spread from paranasal sinuses in 8 patients, 6 of them being immunocompetent. Hematogenous dissemination was observed in 13 patients, all were immunosuppressed. In this later group we identified a total of 329 parenchymal abscesses involving the whole brain with a predilection for the corticomedullary junction. More than half the patients had a corpus callosum lesion. Hemorrhagic lesions accounted for 13% and contrast enhancement was observed in 61% of the lesions. Patients with hematogenous dissemination were younger (p = 0.003), had more intracranial lesions (p = 0.0004) and had a higher 12-week mortality rate (p = 0.046) than patients with direct spread from paranasal sinuses. Analysis of 12 aneurysms allowed us to highlight two distinct situations. In case of direct spread from the paranasal sinuses, aneurysms are saccular and located on the proximal artery portions, while the hematogenous dissemination in immunocompromised patients is more frequently associated with distal and fusiform aneurysms. MRI is the exam of choice for cerebral aspergillosis. Number and type of lesions are different according to the mode of dissemination of the infection.

Sinusitis caused by Scopulariopsis brevicaulis: Case report and review of the literature.

We report a case of non-invasive sinusitis caused by Scopulariopsis brevicaulis in a 70-year-old immunocompetent patient who had an antibiotic-resistant suppurative tooth infection evolving for seven months. The sinus endoscopy highlighted a foreign body at the bottom of the sinus, which led to the hypothesis of fungal ball sinusitis. Culture of excised tissue was positive for S. brevicaulis.

A First Human Case of Ocular Dirofilariosis due to Dirofilaria repens in Northeastern France

We report the first case of ocular dirofilariasis to be diagnosed in northeast France (Alsace region), in a man who presented with a suborbital mass after a journey to Senegal. Microscopic examination of the surgical specimen identified Dirofilaria repens.

Performance of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identifying Clinical Malassezia Isolates

ABSTRACT The genus Malassezia comprises commensal yeasts on human skin. These yeasts are involved in superficial infections but are also isolated in deeper infections, such as fungemia, particularly in certain at-risk patients, such as neonates or patients with parenteral nutrition catheters. Very little is known about Malassezia epidemiology and virulence. This is due mainly to the difficulty of distinguishing species. Currently, species identification is based on morphological and biochemical characteristics. Only molecular biology techniques identify species with certainty, but they are time-consuming and expensive. The aim of this study was to develop and evaluate a matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) database for identifying Malassezia species by mass spectrometry. Eighty-five Malassezia isolates from patients in three French university hospitals were investigated. Each strain was identified by internal transcribed spacer sequencing. Forty-five strains of the six species Malasseziafurfur, M. sympodialis, M. slooffiae, M. globosa, M. restricta, and M. pachydermatis allowed the creation of a MALDI-TOF database. Forty other strains were used to test this database. All strains were identified by our Malassezia database with log scores of >2.0, according to the manufacturers criteria. Repeatability and reproducibility tests showed a coefficient of variation of the log score values of <10%. In conclusion, our new Malassezia database allows easy, fast, and reliable identification of Malassezia species. Implementation of this database will contribute to a better, more rapid identification of Malassezia species and will be helpful in gaining a better understanding of their epidemiology.

Bed bugs reproductive life cycle in the clothes of a patient suffering from Alzheimer’s disease results in iron deficiency anemia

We report the case of an 82-year-old patient, hospitalized for malaise. Her clothes were infested by numerous insects and the entomological analysis identified them as being Cimex lectularius (bed bugs). The history of the patient highlighted severe cognitive impairment. The biological assessment initially showed a profound microcytic, aregenerative, iron deficiency anemia. A vitamin B12 deficiency due to pernicious anemia (positive intrinsic factor antibodies) was also highlighted, but this was not enough to explain the anemia without macrocytosis. Laboratory tests, endoscopy and a CT scan eliminated a tumor etiology responsible for occult bleeding. The patient had a mild itchy rash which was linked to the massive colonization by the bed bugs. The C. lectularius bite is most often considered benign because it is not a vector of infectious agents. Far from trivial, a massive human colonization by bed bugs may cause such a hematic depletion that severe microcytic anemia may result.

Pseudozyma aphidis fungemia after abdominal surgery: First adult case

Pseudozyma aphidis is an environmental Basidiomycete yeast, and has been involved in the ten past years in rare cases of invasive infection. Pseudozyma species are naturally resistant to caspofungin and often present decreased susceptibility or resistance to fluconazole. This fungus may be difficult to recognize and misidentifications are reported with conventional phenotypical methods. We report a case of P. aphidis invasive infection in an adult with a metastatic ampulloma who had gone through digestive surgery.