Showing papers by "Wieland Meyer published in 2012"

Clinical manifestations of Cryptococcus gattii infection: determinants of neurological sequelae and death

Abstract: Background: Longer-term morbidity and outcomes of Cryptococcus gattii infection are not described. We analyzed clinical, microbiological, and outcome data in Australian patients followed for 12 months, to identify prognostic determinants. Methods: Culture-confirmed C. gattii cases from 2000 to 2007 were retrospectively evaluated. Clinical, microbiological, radiological, and outcome data were recorded at diagnosis and at 6 weeks, 6 months, and 12 months. Clinical and laboratory variables associated with mortality and with death and/or neurological sequelae were determined. Results: Annual C. gattii infection incidence was 0.61 per 10⁶ population. Sixty-two of 86 (72%) patients had no immunocompromise; 6 of 24 immunocompromised hosts had idiopathic CD4 lymphopenia, and 1 had human immunodeficiency virus/AIDS. Clinical and microbiological characteristics of infection were similar in immunocompromised and healthy hosts. Isolated lung, combined lung and central nervous system (CNS), and CNS only disease was reported in 12%, 51% and 34% of the cases, respectively. Complications in CNS disease included raised intracranial pressure (42%), hydrocephalus (30%), neurological deficits (27%; 6% developed during therapy) and immune reconstitutionlike syndrome (11%). Geometric mean serum cryptococcal antigen (CRAG) titers in CNS disease were 563.9 (vs 149.3 in isolated lung infection). Patient immunocompromise was associated with increased mortality risk. An initial cerebrospinal fluid CRAG titer of >= 256 predicted death and/or neurological sequelae (P = .05). Conclusions: Neurological C. gattii disease predominates in the Australian endemic setting. Lumbar puncture and cerebral imaging, especially if serum CRAG titers are >= 512, are essential. Long-term follow up is required to detect late neurological complications. Immune system evaluation is important because host immunocompromise is associated with reduced survival.

MALDI-TOF MS enables the rapid identification of the major molecular types within the Cryptococcus neoformans/C. gattii species complex.

Abstract: Background: The Cryptococcus neoformans/C. gattii species complex comprises two sibling species that are divided into eight major molecular types, C. neoformans VNI to VNIV and C. gattii VGI to VGIV. These genotypes differ in host range, epidemiology, virulence, antifungal susceptibility and geographic distribution. The currently used phenotypic and molecular identification methods for the species/molecular types are time consuming and expensive. As Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) offers an effective alternative for the rapid identification of microorganisms, the objective of this study was to examine its potential for the identification of C. neoformans and C. gattii strains at the intra- and inter-species level. Methodology: Protein extracts obtained via the formic acid extraction method of 164 C. neoformans/C. gattii isolates, including four inter-species hybrids, were studied. Results: The obtained mass spectra correctly identified 100% of all studied isolates, grouped each isolate according to the currently recognized species, C. neoformans and C. gattii, and detected potential hybrids. In addition, all isolates were clearly separated according to their major molecular type, generating greater spectral differences among the C. neoformans molecular types than the C. gattii molecular types, most likely reflecting a closer phylogenetic relationship between the latter. The number of colonies used and the incubation length did not affect the results. No spectra were obtained from intact yeast cells. An extended validated spectral library containing spectra of all eight major molecular types was established. Conclusions: MALDI-TOF MS is a rapid identification tool for the correct recognition of the two currently recognized human pathogenic Cryptococcus species and offers a simple method for the separation of the eight major molecular types and the detection of hybrid strains within this species complex in the clinical laboratory. The obtained mass spectra provide further evidence that the major molecular types warrant variety or even species status.

Correlation of antifungal susceptibility and molecular type within the Cryptococcus neoformans/C. gattii species complex.

Abstract: Members of the Cryptococcus neoformans/C. gattii species complex are grouped into eight molecular types, differing in their epidemiology, disease severity and geographic range. Recent in vitro antifungal susceptibility studies of isolates of the complex revealed contradictory results. The objective of the present study was to assess if this variation is random or correlates with different molecular types by testing the in vitro antifungal susceptibility of 18 C. neoformans (VNI), 11 C. gattii (VGI) and 38 C. gattii (VGII) strains from Brazil to eight antifungal drugs using the CLSI microdilution method. We herein report that the molecular type VGII is the least susceptible genotype, followed by VGI and VNI. This indicates a clear correlation between antifungal susceptibilities and genotypes of the causative cryptococcosis agents, emphasizing the importance of determining the molecular type as part of the clinical diagnostic process to enable an informed decision as to the most appropriate antifungal treatment.

Identification of Novel Hybrids Between Cryptococcus neoformans var.grubii VNI and Cryptococcus gattii VGII

Abstract: Cryptococcusneoformans and Cryptococcusgattii are pathogenic yeasts causing meningoencephalitis in immunocompromised and immunocompetent hosts. The fungus is typically haploid, and sexual reproduction occurs normally between individuals with opposite mating types, α and a. C. neoformans var. grubii (serotype A) is comprised of molecular types VNI, VNII, and VNB, and C. neoformans var. neoformans (serotype D) contains the molecular type VNIV. Additionally, diploid or aneuploid AD hybrids (VNIII) have been reported. C. gattii contains the molecular types VGI, VGII, VGIII, and VGIV, which encompass both serotypes B and C. To identify possible hybrid strains, URA5-RFLP analysis was performed on 350 globally obtained clinical, environmental, and veterinary isolates. Four clinical isolates from cerebrospinal fluid showed combination patterns of C. neoformans var. grubii and C. gattii: Brazil (n = 2), Colombia (n = 1), and India (n = 1). These strains were monokaryotic and diploid or aneuploid. M13 PCR fingerprinting showed that they contained fragments of both proposed parental groups. Luminex IGS genotyping identified these isolates as hybrids with two different molecular type combinations: three VNI/VGII and one VNI/VGI. Blue color development on CGB agar was delayed in three isolates and absent in one. C. gattii-specific PCR confirmed the presence of C. gattii in the hybrids. CAP59 allele-specific PCR revealed that all the hybrids contained both serotype A and B alleles. Determination of mating-type allelic patterns by PCR revealed that the isolates were αA aB. This is the first study discovering novel natural hybrids between C.neoformans molecular type VNI and C. gattii molecular type VGII.

Preshipment testing success: resolution of a nasal sinus granuloma in a captive koala (Phascolarctos cinereus) caused by Cryptococcus gattii.

Abstract: A 3-yr-old female koala (Phascolarctos cinereus) was diagnosed with a nasal sinus granuloma caused by Cryptococcus gattii after a pre-shipment examination revealed a latex cryptococcal agglutination titer of 1:512. Successful medical and surgical treatment of the granuloma was monitored using serial latex cryptococcal agglutination titers, serum levels of antifungal drugs, and advanced imaging.