Saran's Learn Microbiology

GERM TUBE TEST AIM        To identify and differentiate Candida albicans from other Yeasts by Germ Tube Test or Reynold’s Brande Phenomena. PRINCIPLE         Germ Tube Test is the Confirmatory test which is used to differentiate  Candida albicans  from other yeast. Germ tube formation was first reported by Reynolds and Braude in 1956 so it is also called as Reynold’s - Brande Phenomenon. Germ tubes are short outgrowth, non-septate germinating hyphae. They are half the width and 3 – 4 times the length of the cell from which they arise. When Candida albicans is grown in human or sheep serum at 37 °C for 3 hrs, they forms a Germ tubes, which can be detected with a Wet films as filamentous outgrowth extending from yeast cells. It is positive for  Candida albicans  and  Candida dubliniensis (produce Germ tube after 3 hrs) .  Approximately 95 – 97 % of  Candida albicans  isolated develop Germ tub...

SLIDE CULTURE TECHNIQUE AIM        To identify the Fungi morphology without any disturbance by Slide culture technique. PRINCIPLE       Fungi are the group of Eukaryotic microorganisms and they are identified mostly by close examination of its morphology and the characteristics it possess. Identification of Fungi is often difficult by tease mount method because of the dislodgement of conidia and spores from the Conidiogenous cell. To overcome this, Slide cultures technique is considered best for preserving and observing the actual structure of a fungus without any disturbances. The method was first developed by Riddel in 1950 and currently, several modifications are in use.      In Slide cultures technique, fungi are inoculated in small blocks of Nutrient deficient agar medium (Cornmeal agar or Potato dextrose agar) (Fungi when grown in nutrition deficient medium develop spores rapidly and adhere to th...

 POTASSIUM HYDROXIDE (KOH) WET MOUNT AIM             To visualize the fungal element present in the Clinical specimens (Skin, Hair and Nail). PRINCIPLE               Potassium hydroxide (KOH) preparation is used for the rapid detection of fungal elements in a clinical specimens, as it clears the specimen making fungal elements more visible during Direct microscopic examination. Potassium hydroxide (KOH) solution is alkaline and has the ability to dissolve keratin that is scraped from the outer layer of the skin or nail or hair. As the KOH dissolves, the material binding the skin cells together, any fungus present is released. This allows for the identification of organisms such as Dermatophytes.             The affected Skin or Nail is gently scraped with a small Scalpel or the edge of a Glass slide. The...

 LACTOPHENOL COTTON BLUE (LPCB) STAINING AIM            To identify the Microscopic morphology of Fungi by Lactophenol Cotton Blue (LPCB) Staining. PRINCIPLE               Fungi are the Eukaryotic microorganisms which are classified into two main group viz ., (i) Molds (Multicellular) and (ii) Yeasts (Unicellular). The Lactophenol Cotton Blue (LPCB) is a stain used for making semi-permanent microscopic preparation of Fungi. The LPCB stain has three components: (i) Phenol – Act as a Disinfectant or Fungicide and kills any living microorganisms; (ii) Lactic acid – Preserves the Fungal structure and (iii) Cotton blue stain - Stains the chitin and cellulose of the fungal cell wall intensely blue. LPCB solution is a mounting medium and staining agent used in the preparation of slides for microscopic examination of fungi. In LPCB staining, fungal element...

EVALUATION OF DISINFECTANTS REQUIRED CONCENTRATIONS AND TIMES FOR CHEMICAL DESTRUCTION OF MICROORGANISMS Disinfectants Microorganisms Disinfectant concentration Time Chlorine Mycobacterium tuberculosis 50 ppm 50 sec Entamoeba cyst 0.1 ppm 150 min Hepatitis A Virus 3 ppm 30 min Ethyl alcohol Staphylococcus aureus 70 % 10 min Escherichia coli 70 % 2 min Poliovirus 70 % 10 min Hydrogen peroxide Staphylococcus aureus 3 % 12.5 sec Neisseria gonorrhoea 3 % 0.3 sec Herpes simplex virus 3 % 12.8 sec Quaternary Ammonium compounds Staphylococcus aureus 450 ppm 10 min Salmonella typhi 300 ppm ...