An Improved Slide Culture Technique for the Study and Identification of Pathogenic Fungi

Abstract

The microscopic identification of many pathogenic fungi still depends almost wholly upon morphology, especially upon the size, location, and arrangement of individual spores or groups of spores. The usual procedure is to examine teased wet-mount preparations. These have a number of disadvantages, however. The structures depended upon for the recognition of such fungi as Blastomyces dermatitidis or Sporotrichum 8chenkii, for example, are often so distorted or disarranged in these teased mounts that identification is made difficult or impossible, particularly for persons unfamiliar with this technique. Slide cultures, on the other hand, when suitably prepared, make possible the definite recognition of these genera, and also help materially with the classification of other varieties of fungi. Use of the available slide culture techniques (Henrici, 1930; Brown, 1942; Lewis and Hopper, 1943), however, is beset with numerous difficulties. None of these methods is suitable for rapid identification of pathogenic fungi. The present paper describes an improved slide culture technique which is relatively easy to oarry out and is useful for practical diagnostic work in mycology, as well as for classroom teaching. Since pathogenic fungi grow slowly, and hence may easily be crowded out by more rapidly developing contaminants, provision has been made to exclude such contaminating organisms. The method also makes possible the direct inoculation of the culture slide with a large inoculum. This has been found to be necessary to insure growth of pathogenic species. Special attention also has been given to the nature of the medium for the microculture. Since identification depends to a large degree upon the presence of typical spores, it is important that the medium used stimulate early and abundant sporulation. Lastly, this improved slide culture technique is designed to permit the easy preparation from the culture of stained slides which preserve intact the morphological features of the fungus. These slides are valuable for making photomicrographs and are especially useful for teaching purposes. MICROCULTURE TECHNIQUE Culture media. After some experimentation it has been found that best results in forcing early sporulation of pathogenic fungi are obtained with the specially prepared potato glucose agar described below. Cut 250 grams of whole potato into pieces about the size of walnuts, place in 500 ml of distilled water, and steam for 2 hour. Pour through a wet towel, make 1 Presented before the Texas Branch of the Society of American Bacteriologists, Austin,

Trehalose 6‐phosphate phosphatase is required for cell wall integrity and fungal virulence but not trehalose biosynthesis in the human fungal pathogen Aspergillus fumigatus

“…A modified slide culture method adapted from Johnson (Johnson, 1946) and Harris (Harris, 1986) was used to visualize the conidia and conidiophores of the orlA mutant compared with the wild‐type and reconstituted strains with light microscopy. Briefly, a thin layer of solid media was cut in blocks approximately 10 mm 2 , aseptically removed and placed on the glass slide, which was placed on a support in a sterile 60 mm plastic Petri dish.…”

Endophytic fungi isolated from plants present in a mine tailing facility show a differential growth response to lead

“…2004). The visualization of the mycelium was done by slide culture samples according to Johnson (1946) in an optical microscope (Carl Zeiss LSM 510).…”

Evaluation of Indigenous Fungal Pathogens from Horse Purslane (Trianthema portulacastrum) for Their Relative Virulence and Host Range Assessments to Select a Potential Mycoherbicidal Agent

“…Morphological studies were carried out using slide-culture techniques with PDA. The fungi were identified based on their morphological growth characteristics, sporulation, conidial measurement, and ability to produce pigmentation on growth media, using available literature (Barnett 1960;Booth 1977;Domsch et al 2007;Ellis 1971Ellis , 1976Gilman 1959;Holliday 1993;Sivanesan 1987;Sutton 1980) and slide-culture techniques (Johnson 1946).…”