0.5 McFarland turbidity standard is used to standardize the inoculum for performing antimicrobial susceptibility test. Before antibiotic disks are placed on Muller Hinton agar plate, the bacterial suspension should be matched with the turbidity of 0.5 McFarland turbidity standard. It contains 1.5 X 108 CFU/ml of bacteria. Note: If we skip matching the turbidity of […]
While reading bacterial structures, you might have known that flagella are the organ of locomotion in bacteria. If bacteria do not possess flagella then they are non motile. For example, Klebsiella spp Shigella spp do not possess flagella hence they are nonmotile while those psoosessing flagella are Bacteria (especially gram negative bacilli) possess flagella with […]
Colony characteristics are observed after the primary isolation bacteria in solid culture medium. The appearance of bacterial colony on culture medium is usually characteristic and helps in preliminary identification. It is described under following headings: Size: diameter of the colony is measured in millimeters Shape: Shape refers to the general form of the colony which […]
INTRODUCTION : Rapid plasma reagin is commonly abbreviated as RPR. RPR test is a macroscopic, nontreponemal, flocculation test. It is a non-specific screening test for diagnosis of syphilis. Syphilis is a venereal disease caused by the spirochete Treponema pallidum. After acquiring infection, the host forms antibodies to Treponema pallidum, in addition, the host also forms […]
Mycoplasma colonies can be identified by observing typical fried egg colonies on culture medium. Visualization is facilitated by application of Diene’s stain directly to the agar surface. Diene’s stain is a nonspecific stain that imparts a contrasting appearance to Mycoplasma colonies on agar. It allows easy visualization of colony morphology and characteristics. Composition of Diene’s […]
Wuchereria bancrofti, Brugia malayi and Brugia timori are the causative agents of Lymphatic filariasis (Elephantiasis). Microfilariae of these nematodes show nocturnal periodicity. They appear in peripheral blood at night time between 9 pm and 2 am. This periodicity is due to biological and evolutionary co-adaptation of the microfilariae to the feeding habit of the mosquito […]
Potassium hydroxide (KOH) mount is a very useful test for the laboratory diagnosis of fungal infection of tissues especially skin, hair and nails. KOH separates the fungal elements from intact cells as it digests the protein debris and dissolves cement substances that holds the keratinized cells together and makes it easy to visualize under the […]