Three thermotolerant “Lichtheimia-like” isolates from patients suffering from mucormycosis (nasopharyngeal swab of a liver transplant recipient, gastric biopsy of a renal transplant recipient, and skin biopsy of a man with burn, respectively) were characterized. Phenotypic characteristics, including colony morphology, microscopic morphology and thiamine dependency, were determined. Microscopic examination of agar block smear preparations showed that most side branches of the three “Lichtheimia-like” isolates and Lichtheimia ramosa were circinate, with abundant pleomorphic giant cells with fingerlike projections commonly observed. Sequence analysis of four loci (internal transcribed spacer region of the ribosomal DNA, partial elongation factor 1-α gene, partial β-actin gene, and the D1-D2 region of 28S rRNA) showed that the three “Lichtheimia-like” isolates and L. ramosa formed a distinct cluster, and are closely related to, but distinct from, other Lichtheimia sp.. A new species, Lichtheimia hongkongensis (synonym of L. ramosa), was proposed to describe this fungus. It was also hypothesized that a proportion of “A. corymbifera (L. corymbifera)” reported in the literature could be L. hongkongensis. In this study, 13 fungal strains that were reported as “A. corymbifera (L. corymbifera)” in the literature in an 11-year period were collected. Microscopic examination of agar block smear preparations of these 13 strains revealed unique characteristics of L. hongkongensis, including circinate side branches and pleomorphic giant cell with finger-like projections. Phylogenetic analysis also showed that all 13 strains are closely related with L. hongkongensis. It was confirmed that a significant number of reported A. corymbifera (L. corymbifera) infections are L. hongkongensis infections which are of global distribution. In order to confirm the distinct phylogenetic position of L. hongkongensis, the mitochondrial genomes of three L. hongkongensis strains and a strain of L. corymbifera were sequenced. L. hongkongensis HKU21, HKU22 and HKU23 have circular mitochondrial genomes with sizes ranging from 31830 bp to 32167 bp, which contain 39 to 41 genes transcribed by both strands. L. corymbifera HKU25 has a circular mitochondrial genome of size 37262 bp, which contains 41 genes that are transcribed by both strands. All the four mitochondrial genomes contain a complete set of tRNAs, the small and the large rRNAs, as well as the basic 14 protein-coding genes. Analysis of gene order showed that the three L. hongkongensis strains are clustered together. It is also shown that the Lichtheimia group is also closely related to Rhizopus oryzae, which is a member of Mucorales. A mouse model was used to determine if there is a difference in virulence between L. hongkongensis and L. corymbifera. The groups of mice challenged with L. hongkongensis have a higher survival rate than those challenged with L. corymbifera. Intravenous administration of Lichtheimia spores resulted in an infection in livers and spleens as indicated by positive cultures. The number of spores that could be recovered from these organs was significantly lower in mice challenged with L. hongkongensis than those challenged with L. corymbifera, indicating that L. hongkongensis could be less virulent than L. corymbifera. / published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

Identification of pathogenic fungi isolated from clinical specimens in clinical microbiology laboratories is primarily based on observing fungal phenotypic structures under the microscope and performing biochemical tests for fungal cultures. This conventional method is very time-consuming and labor-dependent. It usually requires several weeks for the fungi to grow sufficiently on culture media, and the identification processes on fungal phenotypic structure rely very much on experienced staff. Therefore, a more accurate and rapid method for pathogenic fungal identification is necessary for clinical laboratories to get abreast of modern development. Gene sequencing and phylogenetic analysis targeting the internal transcribed spacer (ITS) region in the fungal genomes are the most commonly used molecular methods for fungal identification. Because of the optimal inter and intra-species variation property of the ITS region, it can act as the DNA barcode to identify fungi to the species level. In this study, 33 clinical fungal isolates were identified by both phenotypic method and ITS sequencing. The results showed that 23 isolates were successfully identified to thespecies level by both phenotypic and molecular methods. Moreover, five isolates were only identified to the genus level by phenotypic method, but they could be successfully identified to the species level by ITS sequencing. However, five isolates have not been differentiated because there were mismatched results from phenotypic and sequencing methods. It may be due to the limitation of sequencing method on some fungal species. Building up a more comprehensive database or setting up a standard platform to guide the molecular process may help improve the performance of molecular method. To conclude, molecular method is a rapid and reliable way for fungal identification because ITS region acts as the DNA barcode for pathogenic fungi. / published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Elizabethkingia spp. is a gram-negative, non-fermenting rod bacterium that is frequently implicated in hospital outbreaks. Elizabethkingia has a high rate of resistance to antibiotics and a shortage of effective parenteral antibiotics usually occurs in intensive care units. Infection includes neonatal sepsis and meningitis. Recently, a new species of Elizabethkingia, which is closely related to E. meningoseptica ATCC 13253 and E. miricola GTC862, was reported as a human pathogen in Central Africa and named E. anophelis. Our investigation involved 27 Elizabethkingia clinical isolates, which were fully identified through phenotypic and genotypic typing. The isolates were identified as E. meningoseptica by VITEK 2 (bioMereux) and Phoneix (Beckton Dickinson) automated bacterial identification systems. We then re-identified the isolates by 16S rRNA gene sequencing; 23 of the 27 strains were identified as E. anophelis and one was identified as E. miricola instead of E. meningoseptica. Subsequently, we evaluated the performance of the Bruker MALDI-TOF MS system for identification of the E. anophelis strains; many were misidentified as E. meningoseptica or were unidentified. All of the strains were correctly re-identified as E. anophelis when the original Bruker database was expanded with the inclusion of 10 E. anophelis clinical isolates and a standard 〖R26 〗^T strain. We also analysed 23 E. anophelis clinical isolates by biochemical tests, antimicrobial susceptibilities tests and pulsed-field gel electrophoresis. From the biochemical investigation of all isolates and type strain, showing that the conventional biochemical tests are not reliable to differentiate E. anophelis from other Elizabethkingia spp. More than 75% of the isolates tested were susceptible to cotrimoxazole, ciprofloxacin, and cefoperazone-sulbactam, however they were all resistant to aminoglycosides and beta-lactam drugs except one strain. At the PFGE investigation all the strains were not clonally related as shown by PFGE and displayed distinct PFGE fingerprints. / published_or_final_version / Medicine / Master / Master of Medical Sciences

No description available.

No description available.

Thesis (PhD)--University of South Australia, 2003.

iv, 135 leaves : ill., graphs, photos ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1976

Thesis (Ph. D. - Plant Pathology)--University of Arizona. / Includes bibliographical references.

Thesis (Ph.D.) -- Flinders University of South Australia, Department of Environmental Health, 2005. / Typescript (photocopy). Includes bibliographical references (leaves 255-266). Also available online.

Thesis (Ph.D.) -- University of Adelaide, Department of Plant Pathology, 1976.