Exp. No. 6 Isolation and identification of clinically important fungi: Candida sp., and Aspergillus sp.,

 

Isolation and identification of clinically important fungi: Candida sp.,

Introduction

Candida are the members of the normal flora of skin. More than 100 species are available in Candida. Among these Candida albicans cause most of the human infections. The germ tube test provides a simple, reliable and economical procedure for the presumptive identification of Candida albicans. About 95% of the clinical isolates produce germ tubes when incubated in serum at 35°C for 2.5-3 hours. A germ tube represents the initiation of a hypha directly from the yeast cell. They have parallel walls at their point of origin. Germ tube formation is influenced by the medium inoculum size and temperature of incubation. Fresh normal pooled human sera or a commercially available germ tube solution to be used as the medium for the test. The inoculum should result in a very faintly turbid serum suspension. Over-inoculation will inhibit the development of germ tubes. Incubate in at 35°C-37°C for 2.5-3 hours.

Aim

To identify Candida albicans.

Materials and Methods

Wooden applicator stick, Serum, Test tubes, Incubator, microscope, Culture of Candida albicans on SDA medium

Procedure

·         Using a Pasteur pipette, dispense 3 drops of fresh pooled human serum into the tubes. With a sterile wooden applicator stick, lightly touch a yeast colony and place the stick into the serum. Suspend the yeast in the serum. Discard the stick in a discard container. Incubate the tubes at 35°C for 2.5-3 hours. Placed a drop of the suspension on a clean microscopic slide. Placed a clean cover glass over the suspension and then examine it with a microscope using the low power objective. Use high power objective to confirm the presence or absence of germ tubes. Read control and record results.

 Result

Tube like outgrowth is identified as germ tube. The given culture was found to be Candida albicans.

 Isolation and identification of clinically important fungi: Aspergillus sp.,

Introduction

Fungi are significant, sometimes overlooked, human pathogens. Infection caused by the fungus ranges from procedure includes Demonstration of fungi by microscopy, Identification by culture, Detection of specific humoral mild to life threatening. Diagnosis is based on a combination of clinical and laboratory investigations. Laboratory response and Detection of fungal antigens and metabolites in body fluids.

Aim

To collect proper specimen for the isolation of fungal pathogens and to perform fungal isolation techniques.

Materials and Methods

Czapek dox agar and culture.

Procedure

Fungal species may sub cultured on different commercially available mycological media. On selective and differential medium fungal species grown initially as white/multicolored mycelium. Fruiting bodies / asexual are formed during growth, which is considered as a selective character for identification. Conidium are usually identified by making use of any one of the following methods. Block inoculation, Scarification are the subculture inoculation methods. Slide culture technique, tease preparation and cellophane tape mount are used to identify conidial structures. All these techniques use Lactophenol Cotton Blue as a clarity stain for clear visualization of fungal elements. Size and shape of the conidia will vary depends up on the genus. The following are different types of conidia present in different fungal species.

Result

Fungal species can be identified based on microscopic morphology and culture as Aspergillus sp.

 

Aspergillus sp.,