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result(s) for
"Thakur, Rameshwari"
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Taxonomy of the Trichophyton mentagrophytes/T. interdigitale Species Complex Harboring the Highly Virulent, Multiresistant Genotype T. indotineae
by
Kandemir, Hazal
,
Nenoff, Pietro
,
Verma, Shyam B.
in
Analysis
,
Antifungal agents
,
Antifungal Agents - pharmacology
2021
A severe outbreak of highly virulent and multi-resistant dermatophytosis by species in the
Trichophyton mentagrophytes
/
T
.
interdigitale
complex is ongoing in India. The correct identity of the etiologic agent is a much-debated issue. In order to define species limits, a taxonomic study was undertaken combining molecular, morphological, and physiological characteristics as evidence of classification. Molecular characteristics show that
T. mentagrophytes s. str
. and
T. interdigitale s. str
. can be distinguished with difficulty from each other, but are unambiguously different from the Indian genotype,
T
.
indotineae
by sequences of the HMG gene. The entities were confirmed by multilocus analysis using tanglegrams. Phenotypic characters of morphology and physiology are not diagnostic, but statistically significant differences are observed between the molecular siblings. These properties may be drivers of separate evolutionary trends.
Trichophyton mentagrophytes
represents the ancestral, homothallic cloud of genotypes with a probable geophilic lifestyle, while
T
.
indotineae
and
T
.
interdigitale
behave as anthropophilic, clonal offshoots. The origin of
T
.
indotineae
, which currently causes a significant public health problem, is zoonotic, and its emergence is likely due to widespread misuse of antifungals.
Journal Article
Outbreaks And Epidemics Of Superficial Dermatophytosis Due To Trichophyton mentagrophytes Complex And Microsporum canis : Global And Indian Scenario
2019
Until recently, superficial dermatophytosis, also known as tinea, was considered as a minor skin infection, which was easy to treat. There used to be rare outbreaks and epidemics of superficial dermatophytosis. Lately, there is a sweeping change in the clinical presentation due to extensive, atypical and recalcitrant dermatophytosis. Treating such infections poses a great challenge to the clinicians. Dermatophytosis is a superficial fungal infection of keratinized tissue (skin, hairs and nails) by dermatophytes (fungus). It is caused by the three genera of dermatophytes:
and
. The conventional methods of laboratory diagnosis have now been substantiated by molecular characterization. Earlier epidemics were usually due to anthropophilic dermatophytes. Now, zoophilic dermatophytes are also responsible for many outbreaks and epidemics. We need to be equipped with the tools to face the current scenario, because this depends upon the competence of the staff working in the state-of-the-art laboratories, which is needed for the study of the epidemiology and appropriate treatment.
Journal Article
Evidence that the Human Pathogenic Fungus Cryptococcus neoformans var. grubii May Have Evolved in Africa
by
Rossouw, Jenny
,
Mitchell, Thomas G.
,
Carbone, Ignazio
in
Acquired immune deficiency syndrome
,
AIDS
,
Antibiotics
2011
Most of the species of fungi that cause disease in mammals, including Cryptococcus neoformans var. grubii (serotype A), are exogenous and non-contagious. Cryptococcus neoformans var. grubii is associated worldwide with avian and arboreal habitats. This airborne, opportunistic pathogen is profoundly neurotropic and the leading cause of fungal meningitis. Patients with HIV/AIDS have been ravaged by cryptococcosis--an estimated one million new cases occur each year, and mortality approaches 50%. Using phylogenetic and population genetic analyses, we present evidence that C. neoformans var. grubii may have evolved from a diverse population in southern Africa. Our ecological studies support the hypothesis that a few of these strains acquired a new environmental reservoir, the excreta of feral pigeons (Columba livia), and were globally dispersed by the migration of birds and humans. This investigation also discovered a novel arboreal reservoir for highly diverse strains of C. neoformans var. grubii that are restricted to southern Africa, the mopane tree (Colophospermum mopane). This finding may have significant public health implications because these primal strains have optimal potential for evolution and because mopane trees contribute to the local economy as a source of timber, folkloric remedies and the edible mopane worm.
Journal Article
Multilocus Sequence Typing Reveals Three Genetic Subpopulations of Cryptococcus neoformans var. grubii (Serotype A), Including a Unique Population in Botswana
by
Litvintseva, Anastasia P
,
Vilgalys, Rytas
,
Thakur, Rameshwari
in
Botswana
,
Chromosomes
,
Cryptococcosis - microbiology
2006
We applied multilocus sequence typing (MLST) to investigate the population structure and mode of reproduction of Cryptococcus neoformans var. grubii (serotype A). This MLST system utilizes 12 unlinked polymorphic loci, which are dispersed on nine different chromosomes, and allows the unambiguous identification of closely related strains of serotype A. We compared MLST analyses with the conventional genotyping method of detecting amplified fragment length polymorphisms (AFLPs), and there was excellent correlation between the MLST and AFLP results. However, MLST differentiated a larger number of strains. We analyzed a global collection of isolates of serotype A using both methods, and the results identified at least three genetically distinct subpopulations, designated groups VNI, VNII, and VNB. Groups VNI and VNII are widespread, dominated by isolates with the MATα mating type, and predominantly clonal. Conversely, isolates of group VNB are unique to Botswana, include a significant proportion of fertile strains with the MATa mating type, and manifest compelling evidence of recombination. We have AFLP genotyped >1000 strains of serotype A from different parts of the world, including isolates from several African countries, and, to date, haploid serotype A isolates of group VNB have been found only in Botswana.
Journal Article
Updates on Genital Dermatophytosis
2020
Dermatophytes are a group of keratinophilic fungi, which normally cause superficial infection of skin, hair and nails. Based on ecology, they are classified into three groups: anthropophilic, zoophilic and geophilic. Superficial dermatophytic infection of the genital region is called genital dermatophytosis, tinea genitalis or pubo-genital dermatophytosis. In this review, we would like to discuss briefly, the various clinical presentations of genital dermatophytosis, current changes in the taxonomy and nomenclature, introduction of new diagnostic techniques and briefly describe some common dermatophytes and their sources. Also, there are serious concerns associated with the recent development of antifungal resistance among the dermatophytes. We are also facing the scenario of hard-to-treat dermatophytosis.
Journal Article
Spectrum of dermatophyte infections in Botswana
2015
Dermatophyte infections are a common cause of superficial fungal infection in different geographical locations of the world. Usually, it involves superficial invasion of keratinized tissue, eg, skin, nails, and hair, but in immunosuppressed individuals, it may cause atypical, extensive and deep lesions, which may pose serious diagnostic and therapeutic challenges.
To find out the causative dermatophyte species responsible for the various clinical types of dermatophyte infection.
Trichophyton violaceum was found to be the predominant species, being the causative organism responsible for all the clinical types.
T. violaceum was found to be the most common species responsible for most of the clinical forms of dermatophytosis (96; 80%). Tinea unguium was found to be the most frequent clinical type of dermatophytosis (33; 27.50%).
Journal Article
Tinea capitis in Botswana
2013
Tinea capitis (TC) is a common dermatophyte infection of the scalp that can also involve the eyebrows and eyelashes.
This study aimed to find the causative fungus responsible for TC in Botswana and determine its association with the clinical types of TC.
Samples for potassium hydroxide 10% mounts and fungal cultures were collected in a microbiology laboratory at the National Health Laboratory, Gaborone, Botswana. Dermasel agar and Sabouraud dextrose agar were inoculated with the samples. Lactophenol cotton blue mounts were prepared from the culture-positive samples to study the morphological characteristics.
Trichophyton violaceum was found to be the predominant causative organism of TC. Trichophyton tonsurans was isolated from one patient. Both are anthropophilic species.
TC was found to be most common in those aged 1-15 years (81%). Of 17 patients in this age group, 16 were younger than 10 years old and one was 14 years old. T. violaceum was the most common dermatophyte species isolated.
Journal Article
Cutaneous cryptococcosis in an adult male of sub-saharan origin
by
Kushwaha, Pragya
,
Thakur, Rameshwari
,
Kalsi, Avneet Singh
in
Antifungal agents
,
Antiretroviral drugs
,
Case reports
2023
Cryptococcosis is caused by the inhalation of the desiccated encapsulated yeast or basidiospores, which are found in the environment. After the infectious particles reach the lungs, get disseminated hematogenously in various organs. Meningoencephalitis is one of the most common manifestations, especially in sub-Saharan Africa. The dermal lesions can be either primary due to the traumatic implantation of infectious propagule or secondary in patients with disseminated infection due to cryptococcus. The typical presentations of the cutaneous lesions are like umbilicated lesions of molluscum contagiosum. The dermal lesions can also be similar to Kaposi sarcoma or talaromycosis (formerly penicilliosis). Here, we present a 34-year-old male HIV-positive and antiretroviral therapy-naive. The patient had a very low CD4 cell count and a high viral load. The patient was referred to the dermatology clinic for multiple eruptions due to umbilicated skin colored lesions 3-5 mm in diameter on the nose.The patient was first treated for the opportunistic infection. The causes of the dermal umbilicated skin lesions are several. We must find out whether the dermal lesion is due to infection with a single organism or more than one. It can be colesional also. Punch biopsy, India ink, and culture on Sabouraud dextrose agar confirmed the diagnosis of
.
Journal Article
Early Versus Delayed Antiretroviral Therapy and Cerebrospinal Fluid Fungal Clearance in Adults With HIV and Cryptococcal Meningitis
by
Weissman, Drew
,
Bisson, Gregory P.
,
Rantleru, Tumelo
in
Adenine - analogs & derivatives
,
Adenine - therapeutic use
,
Adult
2013
Background. The burden of Cryptococcus neoformans in cerebrospinal fluid (CSF) predicts clinical outcomes in human immunodeficiency virus (HIV)—associated cryptococcal meningitis (CM) and is lower in patients on antiretroviral therapy (ART). This study tested the hypothesis that initiation of ART during initial treatment of HIV/CM would improve CSF clearance of C. neoformans. Methods. A randomized treatment-strategy trial was conducted in Botswana. HIV-infected, ART-naive adults aged ≥21 years initiating amphotericin B treatment for CM were randomized to ART initiation within 7 (intervention) vs after 28 days (control) of randomization, and the primary outcome of the rate of CSF clearance of C. neoformans over the subsequent 4 weeks was compared. Adverse events, including CM immune reconstitution inflammatory syndrome (CM-IRIS), and immunologic and virologic responses were compared over 24 weeks. Results. Among 27 subjects enrolled (14 control and 13 intervention), the median times to ART initiation were 7 (interquartile range [IQR], 5–10) and 32 days (IQR, 28–36), respectively. The estimated rate of CSF clearance did not differ significantly by treatment strategy (−0.32 log 10 colony-forming units [CFU]/mL/day ± 0.20 intervention and −0.52 log 10 CFUs/mL/day (± 0.48) control, P = .4). Two of 13 (15%) and 5 of 14 (36%) subjects died in the intervention and control arms, respectively (P = 0.39). Seven of 13 subjects (54%) in the intervention arm vs 0 of 14 in the control arm experienced CM-IRIS (P = .002). Conclusions. Early ART was not associated with improved CSF fungal clearance, but resulted in a high risk of CM-IRIS. Further research on optimal incorporation of ART into CM care is needed. Clinical Trials Registration. NCT00976040.
Journal Article
Prevalence of Clinical Isolates of Cryptococcus gattii Serotype C among Patients with AIDS in Sub-Saharan Africa
by
Reller, L. Barth
,
Mitchell, Thomas G.
,
Thakur, Rameshwari
in
Acquired Immunodeficiency Syndrome - microbiology
,
AIDS
,
Alleles
2005
Cryptococcus gattii is a group of exogenous, neurotropic yeasts that possess the capsular serotype B or C. Isolates of serotype C are extremely rare and, until recently, were known to infect only immunocompetent individuals. We genotyped 176 isolates of Cryptococcus from patients in sub-Saharan Africa who had AIDS; 22 (13.7%) of 161 isolates from Botswana and 2 (13.3%) of 15 isolates from Malawi were C. gattii serotype C strains. All of these serotype C strains belong to the rare VGIV genotype, possess the MATα mating-type allele, and exhibit little genetic diversity
Journal Article