Predominance of Cryptococcus neoformans Var. grubii in Ahvaz, Molecular Identification and Evaluation of Virulence Factors

Background: Cryptococcus neoformans is an encapsulated yeast pathogen with worldwide distribution, and the highest incidence of cryptococcosis was attributed to C. neoformans (var. grubii. The pathogenicity of Cryptococcus species is associated with several factors, including capsule and melanin production, growth at 37 ºC, and secretion of extracellular enzymes. Objectives: The present study aimed to isolate and identify Cryptococcus species from pigeon guano in Ahvaz, Iran and investigate important virulence factors in the isolates. Methods: Seventy-three isolates of C. neoformans var. grubii were identified based on classical and molecular microbiology methods. Capsule size was measured by the grow yeasts in the presence of 5% CO2. Specific media demonstrated the activity of extracellular enzymes (phospholipase, hemolysin, proteinase, esterase, urease, catalase, and gelatinase). Besides, melanin production was evaluated by the niger seed agar medium. Results: Two hundred and seventeen samples were examined for the presence of Cryptococcus over 165 days in Ahvaz. All tested isolates were contained capsules with variable sizes under 5% CO2 concentration. Moreover, 100% of isolates were produced extracellular enzymes (urease, hemolysin, and catalase), whereas no proteinase and gelatinase activities were observed among isolates. Furthermore, most isolates had phospholipase (93.1%) and esterase activities (86.3%). Also, melanin was produced by all of the isolates. Conclusions: Although two methods were used for recovery of Cryptococcus, only Cryptococcus was isolated from pigeon guano, and swabs from the cage walls were negative. Cryptococcus neoformans var. grubii was the only species from pigeon droppings from Ahvaz with more pathogenic factors. Owing to the high pathogenicity of the isolates, the frequency of the disease is expected to be higher.

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Phenotypic plasticity in the productions of virulence factors within and among serotypes in the Cryptococcus neoformans species complex

10.21203/rs.3.rs-282607/v1 ◽

2021 ◽

Author(s):

Yajur Iyengar ◽

J. P. Xu

Keyword(s):

Phenotypic Plasticity ◽

Cryptococcus Neoformans ◽

Virulence Factors ◽

Species Complex ◽

Nitrosative Stress ◽

Capsular Polysaccharide ◽

Melanin Production ◽

Oxidative And Nitrosative Stress ◽

Polysaccharide Production ◽

Fungal Meningitis

Abstract The Cryptococcus neoformans species complex (CNSC) is a common opportunistic human fungal pathogen and the most frequent cause of fungal meningitis. There are three major serotypes in CNSC: A, D, and their hybrids AD, and they have different geographic distributions and medical significance. Melanin pigment and a polysaccharide capsule are the two major virulence factors in CNSC. However, the relationships between serotype and virulence factor production and how environmental factors might impact their relationships are not known. This study investigated the expressions of melanin and capsular polysaccharide in a genetically diverse group of CNSC strains and how their phenotypic expressions were influenced by oxidative and nitrosative stress levels. We found significant differences in melanin and capsular polysaccharide productions among serotypes and across stress conditions. Under oxidative stress, the laboratory hybrids exhibited the highest phenotypic plasticity for melanin production while serotype A showed the highest for capsular polysaccharide production. In contrast, serotype D exhibited the highest phenotypic plasticity for capsular polysaccharide production and clinical serotype AD the highest phenotypic plasticity for melanin production under nitrosative stress. These results demonstrated that different serotypes have different environmental condition-specific mechanisms to modulate the expression of virulence factors.

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Evaluation the efficacy of some culture media in melanin production by Cryptococcus neoformans

Materials Today Proceedings ◽

10.1016/j.matpr.2021.07.184 ◽

2021 ◽

Author(s):

Israa Mahmood Kadhim AL-Zubaidy ◽

Raed Ali Hussain Shabaa

Keyword(s):

Cryptococcus Neoformans ◽

Culture Media ◽

Melanin Production

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Environmental Status of Cryptococcus neoformans and Cryptococcus gattii in Colombia

Journal of Fungi ◽

10.3390/jof7060410 ◽

2021 ◽

Vol 7 (6) ◽

pp. 410

Author(s):

Briggith-Nathalia Serna-Espinosa ◽

Diomedes Guzmán-Sanabria ◽

Maribel Forero-Castro ◽

Patricia Escandón ◽

Zilpa Adriana Sánchez-Quitian

Keyword(s):

Cryptococcus Neoformans ◽

Species Complex ◽

Columba Livia ◽

Systematic Investigation ◽

Cryptococcus Gattii ◽

Eucalyptus Species ◽

Environmental Niche ◽

Worldwide Distribution ◽

Bird Droppings ◽

The Central Nervous System

The genus Cryptococcus comprises more than 80 species, including C. neoformans and C. gattii, which are pathogenic to humans, mainly affecting the central nervous system. The two species differ in geographic distribution and environmental niche. C. neoformans has a worldwide distribution and is often isolated from bird droppings. On the contrary, C. gattii is reported in tropical and subtropical regions and is associated with Eucalyptus species. This review aims to describe the distribution of environmental isolates of the Cryptococcus neoformans species complex and the Cryptococcus gattii species complex in Colombia. A systematic investigation was carried out using different databases, excluding studies of clinical isolates reported in the country. The complex of the species of C. gattii is recovered mainly from trees of the genus Eucalyptus spp., while the complex of the species of C. neoformans is recovered mainly from avian excrement, primarily Columba livia (pigeons) excrement. In addition, greater positivity was found at high levels of relative humidity. Likewise, an association was observed between the presence of the fungus in places with little insolation and cold or temperate temperatures compared to regions with high temperatures.

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Cryptococcus Species Other Than Cryptococcus neoformans and Cryptococcus gattii: Are They Clinically Significant?

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa527 ◽

2020 ◽

Vol 7 (12) ◽

Author(s):

Edison J Cano ◽

Zachary A Yetmar ◽

Raymund R Razonable

Keyword(s):

Cryptococcus Neoformans ◽

Opportunistic Infections ◽

Descriptive Analysis ◽

Laboratory Data ◽

Invasive Disease ◽

Cryptococcus Gattii ◽

Cryptococcus Laurentii ◽

Cryptococcus Species ◽

Clinically Significant ◽

Cryptococcus Spp

Abstract Background Cryptococcus spp is a major cause of opportunistic infections in immunocompromised patients, primarily due to Cryptococcus neoformans and Cryptococcus gattii. There are occasional reports of other Cryptococcus species causing invasive human disease. However, their epidemiology and clinical significance are not fully defined. We sought to describe cases with cultures positive for Cryptococcus species other than C neoformans and C gattii. Methods A retrospective descriptive analysis of clinical and laboratory data of patients with cultures growing Cryptococcus species other than C neoformans and C gattii from November 2011 to February 2019 was performed. Three Mayo Clinic sites in Arizona, Florida, and Minnesota were included. Results From 176 cases with a culture growing Cryptococcus spp, 54 patients (30%) had a culture for Cryptococcus other than C neoformans and C gattii in the study time frame. The most common species were Cryptococcus magnus, Cryptococcus laurentii, and Cryptococcus ater. The organisms were isolated and identified in culture of bronchoalveolar lavage (11), skin (11), urine (7), oral (4), sinus (3), intraoperative soft tissue (3), sputum (2), synovial fluid (2), cerebrospinal fluid (2), and intravenous catheter (2), among others (7). Only 8 (15%) cases were considered to be potentially pathogenic, with 1 case of invasive disease. Antifungal treatment was fluconazole, itraconazole, and griseofulvin, for a mean systemic antifungal duration of 42 days. Conclusions This large series of patients with Cryptococcus spp other than C neoformans and C gattii suggests that these species rarely cause clinically significant infection in humans. Only 1 case of invasive disease was found.

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Author Correction: Genetic Factors and Genotype-Environment Interactions Contribute to Variation in Melanin Production in the Fungal Pathogen Cryptococcus neoformans

Scientific Reports ◽

10.1038/s41598-021-91476-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Himeshi Samarasinghe ◽

David Aceituno-Caicedo ◽

Massimo Cogliati ◽

Kyung J. Kwon-Chung ◽

Volker Rickerts ◽

...

Keyword(s):

Cryptococcus Neoformans ◽

Fungal Pathogen ◽

Genetic Factors ◽

Melanin Production

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Cell Wall-Associated Virulence Factors Contribute to Increased Resilience of Old Cryptococcus neoformans Cells

Frontiers in Microbiology ◽

10.3389/fmicb.2019.02513 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 4

Author(s):

Erika P. Orner ◽

Somanon Bhattacharya ◽

Klea Kalenja ◽

Danielle Hayden ◽

Maurizio Del Poeta ◽

...

Keyword(s):

Cell Wall ◽

Cryptococcus Neoformans ◽

Virulence Factors

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Potential pathogenicity ofAeromonas hydrophilacomplex strains isolated from clinical, food, and environmental sources

Canadian Journal of Microbiology ◽

10.1139/cjm-2015-0466 ◽

2016 ◽

Vol 62 (4) ◽

pp. 296-306 ◽

Cited By ~ 10

Author(s):

Vicenta Albarral ◽

Ariadna Sanglas ◽

Montserrat Palau ◽

David Miñana-Galbis ◽

M. Carmen Fusté

Keyword(s):

Extracellular Enzymes ◽

The Elderly ◽

Secretion Systems ◽

Antibiotic Susceptibility Pattern ◽

Cytopathic Effects ◽

Pathogenic Factors ◽

High Prevalence ◽

Causative Agents ◽

Complete Lysis ◽

Potential Pathogenicity

Aeromonas are autochthonous inhabitants of aquatic environments, including chlorinated and polluted waters, although they can also be isolated from a wide variety of environmental and clinical sources. They cause infections in vertebrates and invertebrates and are considered to be an emerging pathogen in humans, producing intestinal and extra-intestinal diseases. Most of the clinical isolates correspond to A. hydrophila, A. caviae, and A. veronii bv. Sobria, which are described as the causative agents of wound infections, septicaemia, and meningitis in immunocompromised people, and diarrhoea and dysenteric infections in the elderly and children. The pathogenic factors associated with Aeromonas are multifactorial and involve structural components, siderophores, quorum-sensing mechanisms, secretion systems, extracellular enzymes, and exotoxins. In this study, we analysed a representative number of clinical and environmental strains belonging to the A. hydrophila species complex to evaluate their potential pathogenicity. We thereby detected their enzymatic activities and antibiotic susceptibility pattern and the presence of virulence genes (aer, alt, ast, and ascV). The notably high prevalence of these virulence factors, even in environmental strains, indicated a potential pathogenic capacity. Additionally, we determined the adhesion capacity and cytopathic effects of this group of strains in Caco-2 cells. Most of the strains exhibited adherence and caused complete lysis.

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