A Five-Year Survey of Dematiaceous Fungi in a Tropical Hospital Reveals Potential Opportunistic Species

Dematiaceous fungi (black fungi) are a heterogeneous group of fungi present in diverse environments worldwide. Many species in this group are known to cause allergic reactions and potentially fatal diseases in humans and animals, especially in tropical and subtropical climates. This study represents the first survey of dematiaceous fungi in Malaysia and provides observations on their diversity as well as in vitro response to antifungal drugs. Seventy-five strains isolated from various clinical specimens were identified by morphology as well as an internal transcribed spacer (ITS)-based phylogenetic analysis. The combined molecular and conventional approach enabled the identification of three classes of the Ascomycota phylum and 16 genera, the most common being Cladosporium, Cochliobolus and Neoscytalidium. Several of the species identified have not been associated before with human infections. Among 8 antifungal agents tested, the azoles posaconazole (96%), voriconazole (90.7%), ketoconazole (86.7%) and itraconazole (85.3%) showed in vitro activity (MIC ≤1 µg/mL) to the largest number of strains, followed by anidulafungin (89.3%), caspofungin (74.7%) and amphotericin B (70.7%). Fluconazole appeared to be the least effective with only 10.7% of isolates showing in vitro susceptibility. Overall, almost half (45.3%) of the isolates showed reduced susceptibility (MIC >1 µg/mL) to at least one antifungal agent, and three strains (one Pyrenochaeta unguis-hominis and two Nigrospora oryzae) showed potential multidrug resistance.     

Identification and Characterization of a Rare Fungus,Quambalaria cyanescens,Isolated from the Peritoneal Fluid of a Patient after Nocturnal Intermittent Peritoneal Dialysis

Peritonitis is the leading complication of peritoneal dialysis, which is primarily caused by bacteria rather than fungi. Peritonitis is responsible for approximately 18% of the infection-related mortality in peritoneal dialysis patients. In this paper, we report the isolation of a rare fungus, Quambalaria cyanescens, from the peritoneal fluid of a man after he switched from continuous ambulatory peritoneal dialysis to nocturnal intermittent peritoneal dialysis. Based on the morphological examination and multigene phylogeny, the clinical isolate was confirmed as Q. cyanescens. This pathogen exhibited low sensitivity to all tested echinocandins and 5-flucytosine. Interestingly, morphological characterization revealed that Q. cyanescens UM 1095 produced different pigments at low temperatures (25°C and 30°C) on various culture media. It is important to monitor the emergence of this rare fungus as a potential human pathogen in the tropics. This study provides insight into Q. cyanescens UM 1095 phenotype profiles using a Biolog phenotypic microarray (PM). Of the 760 nutrient sources tested, Q. cyanescens UM 1095 utilized 42 compounds, and the fungus can adapt to a broad range of osmotic and acidic environments. To our knowledge, this is the first report of the isolation of Q. cyanescens from peritoneal fluid, revealing this rare fungus as a potential human pathogen that may be misidentified using conventional methods. The detailed morphological, molecular and phenotypic characterization of Q. cyanescens UM 1095 provides the basis for future studies on its biology, lifestyle, and potential pathogenicity.     

Draft genome sequence of Daldinia eschscholzii isolated from blood culture

Daldinia eschscholzii is an invasive endophyte that is most commonly found in plant tissues rich in secondary metabolites. We report the draft genome sequence of D. eschscholzii isolated from blood culture. The draft genome is 35,494,957 bp in length, with 42,898,665 reads, 61,449 contigs, and a G+C content of 46.8%. The genome was found to contain a high abundance of genes associated with plant cell wall degradation enzymes, mycotoxin production, and antifungal drug resistance.     

Sequencing of Cladosporium sphaerospermum, a Dematiaceous fungus isolated from blood culture

Cladosporium sphaerospermum is one of the most widely distributed allergens causing serious problems in patients with respiratory tract disease. We report the 26,644,473-bp draft genome sequence and gene annotation of C. sphaerospermum UM843. Analysis of the genome sequence led to the finding of genes associated with C. sphaerospermum's melanin biosynthesis, allergens, and antifungal drug resistance.     

Identification of reference genes for real-time polymerase chain reaction gene expression studies in Nile rats fed Water-Soluble Palm Fruit Extract

Molecular Biology Reports - The Nile rat (Arvicanthis niloticus) is a novel diurnal carbohydrate-sensitive rodent useful for studies on type 2 diabetes mellitus (T2DM) and the metabolic syndrome....     

Full genome SNP-based phylogenetic analysis reveals the origin and global spread of Brucella melitensis

Background

Brucellosis is an important zoonotic disease that affects both humans and animals. We sequenced the full genome and characterised the genetic diversity of two Brucella melitensis isolates from Malaysia and the Philippines. In addition, we performed a comparative whole-genome single nucleotide polymorphism (SNP) analysis of B. melitensis strains collected from around the world, to investigate the potential origin and the history of the global spread of B. melitensis.

Results

Single sequencing runs of each genome resulted in draft genome sequences of MY1483/09 and Phil1136/12, which covered 99.85% and 99.92% of the complete genome sequences, respectively. The B. melitensis genome sequences, and two B. abortus strains used as the outgroup strains, yielded a total of 13,728 SNP sites. Phylogenetic analysis using whole-genome SNPs and geographical distribution of the isolates revealed spatial clustering of the B. melitensis isolates into five genotypes, I, II, III, IV and V. The Mediterranean strains, identified as genotype I, occupied the basal node of the phylogenetic tree, suggesting that B. melitensis may have originated from the Mediterranean regions. All of the Asian B. melitensis strains clustered into genotype II with the SEA strains, including the two isolates sequenced in this study, forming a distinct clade denoted here as genotype IId. Genotypes III, IV and V of B. melitensis demonstrated a restricted geographical distribution, with genotype III representing the African lineage, genotype IV representing the European lineage and genotype V representing the American lineage.

Conclusion

We showed that SNPs retrieved from the B. melitensis draft full genomes were sufficient to resolve the interspecies relationships between B. melitensis strains and to discriminate between the vaccine and endemic strains. Phylogeographic reconstruction of the history of B. melitensis global spread at a finer scale by using whole-genome SNP analyses supported the origin of all B. melitensis strains from the Mediterranean region. The possible global distribution of B. melitensis following the ancient trade routes was also consistent with whole-genome SNP phylogeny. The whole genome SNP phylogenetics analysis, hence is a powerful tool for intraspecies discrimination of closely related species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1294-x) contains supplementary material, which is available to authorized users.     

Dissecting the fungal biology of Bipolaris papendorfii: from phylogenetic to comparative genomic analysis

Bipolaris papendorfii has been reported as a fungal plant pathogen that rarely causes opportunistic infection in humans. Secondary metabolites isolated from this fungus possess medicinal and anticancer properties. However, its genetic fundamental and basic biology are largely unknown. In this study, we report the first draft genome sequence of B. papendorfii UM 226 isolated from the skin scraping of a patient. The assembled 33.4 Mb genome encodes 11,015 putative coding DNA sequences, of which, 2.49% are predicted transposable elements. Multilocus phylogenetic and phylogenomic analyses showed B. papendorfii UM 226 clustering with Curvularia species, apart from other plant pathogenic Bipolaris species. Its genomic features suggest that it is a heterothallic fungus with a putative unique gene encoding the LysM-containing protein which might be involved in fungal virulence on host plants, as well as a wide array of enzymes involved in carbohydrate metabolism, degradation of polysaccharides and lignin in the plant cell wall, secondary metabolite biosynthesis (including dimethylallyl tryptophan synthase, non-ribosomal peptide synthetase, polyketide synthase), the terpenoid pathway and the caffeine metabolism. This first genomic characterization of B. papendorfii provides the basis for further studies on its biology, pathogenicity and medicinal potential.