PubMed Health⌕ Search

Biomedical subjects

Rama Ramani

Publications and source records attributed to Rama Ramani.

6 recordsLinked to original sources
PubMed2006

Application of fluorescent probes to study structural changes in Aspergillus fumigatus exposed to amphotericin B, itraconazole, and voriconazole.

The broad objective of this study was to document patterns of structural changes following antifungal treatment, and to determine any relationship with minimum inhibitory concentration (MIC) of an antifungal. Three clinical isolates of Aspergillus fumigatus, with high, intermediate, and low amphotericin B (AB), itraconazole (IZ), and voriconazole (VZ) MICs were studied in 24-well plates with cover slips. The fluorescent probes used were Calcofluor White (cell wall), propidium iodide (nucleus), and MitoTracker Green FM (mitochondria). Fluorescent microscopy as early as 3-h after exposure revealed that AB treated hyphae had intact cell wall with deformed mitochondria and nuclei while IZ and VZ treated hyphae revealed no intact cell wall, and deformation of mitochondria and nuclei. At 48 h, AB treated cells revealed rupture of hyphae and disintegration of mitochondria, and nuclei, IZ treated hyphae were swollen with disintegration of mitochondria, and nuclei while VZ treated hyphae showed rupture and disintegration of mitochondria and nuclei. The structural changes for the three strains studied were similar in fluorescent microscopy as long as the incubation time and their respective MICs were used. Thus, AB, IZ, and VZ induced gross organelle defects in A. fumigatus nuclei, mitochondria, and cell wall, which were consistent with respective MICs of antifungals used.

Amphotericin B↗
PubMed2004

Collaborative study of the NCCLS and flow cytometry methods for antifungal susceptibility testing of Candida albicans.

One hundred clinical isolates of Candida albicans were tested for amphotericin B and fluconazole susceptibilities by the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution test at center 1 (C1). The same isolates were tested blinded at center 2 (C2) by NCCLS and flow cytometry (FC) methods. The agreement between NCCLS and FC methods ranged from 96 to 99%.

Amphotericin B↗
PubMed2003

Flow cytometry antifungal susceptibility testing of Aspergillus fumigatus and comparison of mode of action of voriconazole vis-à-vis amphotericin B and itraconazole.

Aspergillus fumigatus isolates were tested with three antifungals by flow cytometry (FC) and fluorescence-activated cell sorting. FC results after 4 h correlated well with MICs obtained by the NCCLS M38-A method; voriconazole exhibited fungicidal activity, albeit to a lesser extent than amphotericin B, but to a greater extent than itraconazole.

Amphotericin B↗
PubMed2003

Evaluation of new medium for identification of dermatophytes and primary dimorphic pathogens.

Only 25 of 77 dermatophytic isolates caused dermatophyte identification medium (DIM) to turn purple after incubation at the recommended temperature (37 degrees C); the accuracy of the results was improved at 30 degrees C (71 of 77 isolates yielded positive results). Many dimorphic pathogenic fungi also tested positive at both incubation temperatures. Thus, DIM has limited usefulness for presumptive identification of dermatophytes.

Arthrodermataceae↗
PubMed2003

Proficiency testing program for clinical laboratories performing antifungal susceptibility testing of pathogenic yeast species.

Antifungal susceptibility testing is expected to facilitate the selection of adequate therapy for fungal infections. The general availability of antifungal susceptibility testing in clinical laboratories is low, even though a number of standard methods are now available. The objective of the present study was to develop and evaluate a proficiency testing program (PTP) for the antifungal susceptibility testing of pathogenic yeasts in laboratories licensed by the New York State Department of Health. A number of quality control standards, and methods for documenting laboratory performance, were developed in consultation with the laboratory directors. The participating laboratories were provided with five American Type Culture Collection strains of pathogenic yeasts for which the minimum inhibitory concentrations (MICs) of amphotericin B and fluconazole were well defined. A majority of laboratories (14 of 17) used broth microdilution, and these were evenly split between the NCCLS M-27A protocol and the Sensititre YeastOne method. The other three laboratories performed susceptibility testing with Etest. Overall, the levels of agreement between MIC reference ranges and the reported MICs were 85 and 74% for amphotericin B and for fluconazole, respectively. All laboratories except one successfully detected fluconazole resistance in a Candida krusei strain. However, amphotericin B resistance in a Candida lusitaniae strain was not detected by any of the participating labs. It is concluded that a suitably designed PTP could adequately monitor the competence of clinical laboratories performing antifungal susceptibility testing.

Antifungal Agents↗