1Sf1Ep mediumCulturing Treponema pallidum, the bacteria that causes syphilis, in vitro is a challenge. T. pallidum is not routinely cultured in the laboratory for diagnostic purposes, in part because it cannot be grown on artificial media. However, a breakthrough in culturing T. pallidum was reported in 2018 when researchers managed to grow the bacterium in a rabbit epithelial cell line (Sf1Ep) using a medium called 'Sf1Ep medium'. It's not used for routine diagnostic purposes, but for research only. The diagnosis involves direct microscopic examination, serologic tests, molecular tests and histopathology.
2Mannitol Salt Agar (MSA), or Chapman AgarThis is a selective and differential medium. The high concentration of NaCl (~7.5%) selects for halophiles, organisms that can tolerate high salt concentrations, thereby favouring the growth of Staphylococcus species. Mannitol is the differential component: S. aureus ferments mannitol, lowering the pH of the medium, which results in a color change of the pH indicator from red to yellow. Thus, growth of S. aureus is indicated by yellow colonies.
3Sauton’s MediumA liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
4BACTECThis is not a traditional medium but a system for detecting the growth of M. tuberculosis by monitoring the release of C14O2 from C14 palmitic acid, which the bacteria metabolize. An increase in radioactive counts in the BACTEC instrument indicates the growth of bacteria.
5Loeffler MediumA serum-based medium. M. tuberculosis colonies on Loeffler medium are small, dry, wrinkled, and off-white to yellow.
6Tarshis MediumA blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
7Violet Red Bile Agar (VRBA)E. coli colonies are red (pink to red) and may show bluish fluorescence under UV light.
8m-ENDO AgarE. coli colonies appear as green with a metallic sheen, indicating lactose fermentation.
9Eosin Methylene Blue (EMB) AgarA selective and differential medium where E. coli forms distinctive metallic green sheen colonies due to vigorous lactose fermentation.
10Blood Agar (BA)E. coli colonies on this differential medium are large, circular, gray, moist, and can show β-hemolysis.
11Nickerson’s Medium or Bismuth Sulfite Glucose Glycine Yeast (BSGG)This medium is used to stimulate the production of germ tubes, a characteristic of Candida albicans.
12CHROMagar CandidaThis differential medium allows for the isolation and identification of Candida species based on colony color. Candida albicans usually forms green colonies on this medium.
13Sabouraud Dextrose Agar (SDA)It is composed of peptone, dextrose (glucose), and agar. The high dextrose concentration promotes fungal growth, while the acidic pH inhibits bacterial growth.
1Middlebrook 7H9 BrothThis is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
2Brilliant Green Agar (BGA)A selective medium that is used to isolate Salmonella species, but E. coli can grow on it, albeit not as well.
3Nutrient Agar (NA)A non-selective medium. E. coli colonies are usually large, circular, grayish-white, moist, and smooth.
1BACTECThis is not a traditional medium but a system for detecting the growth of M. tuberculosis by monitoring the release of C14O2 from C14 palmitic acid, which the bacteria metabolize. An increase in radioactive counts in the BACTEC instrument indicates the growth of bacteria.
2Proskauer and Beck’s MediumA liquid medium. The growth of M. tuberculosis causes turbidity.
3Pawlowsky MediumA potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
4Liquid Media (such as Nutrient Broth)E. coli exhibits homogenous turbid growth within 12-18 hours. After prolonged incubation, pellicles may form on the surface of the media.
5Violet Red Bile Agar (VRBA)E. coli colonies are red (pink to red) and may show bluish fluorescence under UV light.
6CHROMagar CandidaThis differential medium allows for the isolation and identification of Candida species based on colony color. Candida albicans usually forms green colonies on this medium.
7Bile Esculin Agar (BEA)A selective and differential medium that differentiates group D Streptococci and Enterococci based on the ability to hydrolyze esculin in the presence of bile. E. faecalis hydrolyzes esculin, leading to the formation of a dark brown or black precipita
1Blood Agar (BA)This is a nutrient-rich, differential medium that supports the growth of many organisms. S. aureus forms colonies that are round, smooth, and golden-yellow. This bacterium typically demonstrates β-hemolysis, which is complete lysis of red blood cells, resulting in a clear zone around the colonies. This hemolysis is due to the production of hemolysins by S. aureus.
2Sauton’s MediumA liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
3BACTECThis is not a traditional medium but a system for detecting the growth of M. tuberculosis by monitoring the release of C14O2 from C14 palmitic acid, which the bacteria metabolize. An increase in radioactive counts in the BACTEC instrument indicates the growth of bacteria.
4Dorset MediumAn egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
5Urea Agar/BrothE. coli is typically urease negative, so no color change would be expected in this medium.
6Potato Dextrose Agar (PDA)Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.
7Azide Dextrose BrothA selective medium inhibiting Gram-negative bacteria, used for the isolation of streptococci and staphylococci from mixed samples. E. faecalis will show a positive growth resulting in a turbid appearance of the broth.
8Tryptic Soy Broth or Agar (TSB/TSA)A general-purpose medium that supports the growth of a broad spectrum of bacteria. E. faecalis on TSA will typically form small, round, and white colonies, indicating a positive growth.
1Blood Agar (BA)This is a nutrient-rich, differential medium that supports the growth of many organisms. S. aureus forms colonies that are round, smooth, and golden-yellow. This bacterium typically demonstrates β-hemolysis, which is complete lysis of red blood cells, resulting in a clear zone around the colonies. This hemolysis is due to the production of hemolysins by S. aureus.
2Sauton’s MediumA liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
3BACTECThis is not a traditional medium but a system for detecting the growth of M. tuberculosis by monitoring the release of C14O2 from C14 palmitic acid, which the bacteria metabolize. An increase in radioactive counts in the BACTEC instrument indicates the growth of bacteria.
4Middlebrook 7H9 BrothThis is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
5Tarshis MediumA blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
6Potato Dextrose Agar (PDA)Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.
1DNase Test AgarS. aureus produces the enzyme DNase which hydrolyses DNA. When S. aureus grows on this medium, the DNA is broken down, which can be visualised using a hydrochloric acid (HCl) solution: clear zones around the colonies indicate DNA breakdown.
2Sauton’s MediumA liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
3Proskauer and Beck’s MediumA liquid medium. The growth of M. tuberculosis causes turbidity.
4Middlebrook 7H11 AgarThis is a nutrient-rich medium similar to 7H10 but includes additional pyruvate for energy source, promoting more luxurious growth. The colonies of M. tuberculosis appear small, slightly domed, and rough with a butyrous consistency.
5Petragnini MediumAn egg-based medium enriched with additional nutrients to promote the growth of Mycobacterium tuberculosis. Colonies of M. tuberculosis are small, round, buff-colored, and typically take 3-4 weeks to appear.
6Urea Agar/BrothE. coli is typically urease negative, so no color change would be expected in this medium.
7Tryptic Soy Agar (TSA)A general purpose medium. E. coli colonies are medium to large, with a shiny moist appearance.
8Violet Red Bile Agar (VRBA)E. coli colonies are red (pink to red) and may show bluish fluorescence under UV light.
1Sorbitol-MacConkey agarA variant of MacConkey agar, used in detecting E. coli O157:H7, which does not ferment sorbitol, unlike most strains of E. coli.
2Potato Dextrose Agar (PDA)Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.
3MacConkey AgarTraditionally used to isolate and differentiate Gram-negative bacilli, E. faecalis can grow on this medium, producing small, round, magenta pink colonies due to lactose fermentation, indicating a positive result.
4Brain-Heart Infusion (BHI) Broth or AgarThis is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.