What is the time required for the iodine special stain?
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1 minute.
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What is the time required for the iodine special stain?
1 minute.
What are the disadvantages of using 10% KOH for direct examinations of specimen for fungi?
Background material may cause confusion.
What is the pH range for alkaliphiles?
pH = 9.
What is the decolorizer used in the Gram stain technique?
Acetone.
What is the purpose of Thioglycolate broth?
Enrichment broth for anaerobic bacteria; Determines aerotolerance – ability to live at a particular level of oxygen.
What is the purpose of Buffered Charcoal Yeast Extract (BCYE) agar?
It is used for the recovery of Legionella and Nocardia, and it is specialized for aerobic organisms and fastidious.
What is the purpose of TCBS agar?
It is used for the recovery of Vibrio species.
What is the stain used for the detection of Pneumocystis organisms in respiratory specimens?
Toluidine blue O stain.
What is the principle of the simple wet mount technique?
Direct clinical examination of stool, vaginal discharge, urine sediment, aspirates.
What is the application of the simple wet mount technique?
Determining the cellular composition of a sample in terms of its morphology, gross and microscopic biological activity, and motility.
What is the function of phenol in Lactophenol Cotton Blue?
It acts as a disinfectant and destroys some of the surrounding contaminants.
What is the special stain used for rapid detection of fungi?
Lactophenol cotton blue.
What is the role of lactic acid in Lactophenol Cotton Blue?
It preserves the structure and prevents deformation.
What component does Cotton Blue stain in Lactophenol Cotton Blue?
Chitin component.
What is the role of mordant in staining?
Assist the attachment of the dye, particularly the primary stain, to the cellular component and make the primary stain more stable by forming a complex.
What is the purpose of selective media?
To inhibit the growth of some bacteria but allow others to grow.
What are the advantages of using 10% KOH for direct examinations of specimen for fungi?
Rapid detection of fungi.
What are the characteristics of basic stains?
They are positively charged (cation).
What is the function of the decolorizing agent in staining?
Assist the removal of the primary stain if it can be removed.
What is the purpose of differential media?
To allow visualization of metabolic differences between groups or species of bacteria.
What is the most used differential stain?
Gram stain.
What is the charge of acid stains?
Negatively charged (anion).
What is the primary stain used in the Gram stain technique?
Crystal violet or methylene blue.
What is the pH range for neutrophiles' optimal growth?
pH = 7.2-7.4.
What is the basis for separating major groups of bacteria in the Gram stain?
Gram-positive and Gram-negative.
What is the role of chromophore in a dye?
It is the functional group of the dye that gives color to the stain.
What is the secondary stain used in the Gram stain technique?
Safranin red.
What is the primary stain used in the Gram stain technique?
Crystal violet.
What does the auxochrome component do in a dye?
It gives ionic property to the stain.
What is the charge of the secondary stain used in the Gram stain technique?
Basic.
What is the pH range for acidophiles?
pH = 3.
What is the mordant used in the Gram stain technique?
Iodine.
What does the secondary stain differentiate between in the Gram stain technique?
Cells that retain the primary stain and those that are being removed by the decolorizing agents.
What temperature range do psychrophiles prefer?
-10-20°C.
What temperature range do mesophiles prefer?
10-40°C.
What is the secondary stain used in the Gram stain technique?
Safranin red.
What temperature range do thermophiles prefer?
40-70°C.
What is the primary stain used in the Acid-fast stain technique?
Carbolfuchsin.
What temperature range do hyperthermophiles prefer?
70-110°C.
What is the decolorizer used in the Acid-fast stain technique?
Acid alcohol.
What is the secondary stain used in the Acid-fast stain technique?
Methylene blue.
What is the stain primarily used for the detection of fungal elements in tissue?
Methenamine silver stain.
What is the purpose of Regan-Lowe agar?
It is used for the recovery of Bordetella pertussis.
What is the purpose of Blood agar?
Recovery of bacteria and fungi; Detection of aerobic and facultative anaerobic organisms.
What is the purpose of Sabouraud dextrose agar?
Recovery for fungi; No bacterial growth; addition of antibiotics to allow fungal growth.
What are the different color changes observed in Xylose-Lysine deoxycholate agar for different bacteria?
Yellow: ferments lactose (e.g., E. coli); Red: ferments carbohydrates (e.g., Shigella); Black: H2S producing bacteria (e.g., Salmonella typhi).
What does a positive (+) Catalase test indicate?
Presence of enzyme producing catalase using H202, typically found in Staphylococcus spp.
What does a positive (+) Indole test indicate?
Organism can degrade amino acid (trp → indole) using Kovac reagent, producing a cherry red reaction; typically found in E. coli and Vibrio cholera.
What are the different types of hemolysis observed in Blood agar?
Beta hemolysis: complete; Alpha hemolysis: partial (peroxide producing bacteria); Gamma hemolysis: none.
What is the purpose of Mueller-Hinton agar?
Bacterial susceptibility test medium; Used for antibiotic susceptibility and resistance testing.
What is the purpose of Inhibitory mold agar?
Isolating pathogenic fungi, selective for molds, and uses chloramphenicol.
What is the purpose of Middlebrook agar?
Selective for mycobacteria; Solidified agar.
What does a positive (+) Oxidase test indicate?
Production of cytochrome oxidase (Indophenol oxidase), typically found in Pseudomonas and Vibrio cholera (purple color).
What does a positive (+) Urease test indicate?
Color change by hydrolyzing reaction for urea to ammonia and CO2 production, typically found in Proteus spp. and Morganella morganii.
What is the purpose of MacConkey agar?
Selective for gram (-) bacteria; differential for lactose-fermentation.
What color change is observed in Mannitol salt agar due to mannitol fermentation?
From RED (neutral or no acid) to PINK (acidic).
What is the purpose of MacConkey sorbitol agar?
It is used for the recovery of E. coli 0517, and it causes complications of Hemolytic Uremic Syndrome; lactose was previously replaced with sorbitol, and it does not ferment sorbitol (NO FERMENTATION=NO COLOR CHANGE).
What does a negative (-) Coagulase test indicate?
Absence of the clumping of cells causing coagulation, typically found in Staphylococcus epidermis or Staphylococcus saprophyticus.
What does a positive (+) Citrate test indicate?
Presence of citrate being used as a carbon source by bacteria, leading to a rise in pH, typically found in Klebsiella.
What does a negative (-) Citrate test indicate?
Absence of citrate being used as a carbon source by bacteria, typically found in E. coli.
What are the different color changes observed in MacConkey agar due to lactose fermentation?
Lactose fermenters turn PINK (acidic); Nonlactose fermenters do not change color.
What is the purpose of Mannitol salt agar?
Selective for Staphylococci; differential for Staphylococcus aureus.
What is the purpose of Xylose-Lysine deoxycholate agar?
Selective for Salmonella and Shigella in enteric cultures.
What is the purpose of CHROMagar?
Selective, differential for selected bacteria and yeasts.
What does a negative (-) Oxidase test indicate?
Absence of the production of cytochrome oxidase, typically found in E. coli, Klebsiella, and Salmonella (no color change).
What does a negative (-) Indole test indicate?
Absence of the ability to degrade amino acid using Kovac reagent, typically found in Klebsiella, Salmonella, and Shigella.
What is the purpose of Cysteine-tellurite agar?
It is used for the recovery of Corynebacterium diphtheriae, and it produces gray-black colonies against a red-brown background.
What does a negative (-) Catalase test indicate?
Absence of the enzyme producing catalase, typically found in Streptococcus bacteria.
What is the purpose of Lowenstein-Jensen medium?
Selective for mycobacterium; Provides definitive diagnosis.
What does a positive (+) Coagulase test indicate?
Production of clumping of cells causing coagulation, typically found in Staphylococcus aureus.
