Microbiology Culture Media Master

Comprehensive vocabulary flashcards covering microbiology culture media types, full media names, mechanism of action, target organisms, and diagnostic colony appearances based on the master summary notes.

Enriched medium

Culture medium containing added blood, serum, growth factors, or extra nutrients to grow fastidious organisms.

Enrichment broth

Liquid medium that creates conditions favoring a target organism while suppressing competitors, used to increase desired organisms when outnumbered by normal flora.

Selective medium

Culture medium containing inhibitors that suppress unwanted organisms to recover a particular bacterial group from mixed flora.

Differential medium

Culture medium containing substrates and indicators that change colony or medium appearance to visually distinguish organisms.

Selective and differential medium

Culture medium that combines selective inhibitors to isolate a group with substrates and indicators to visually distinguish metabolic reactions.

Reducing medium

Culture medium containing reducing agents that lower oxidation-reduction potential to recover oxygen-sensitive organisms or determine oxygen relationships.

Transport medium

Low-nutrient, buffered culture formulation designed to keep organisms alive between collection and lab processing without major multiplication.

Blood agar plate (BAP)

Primary isolation medium containing a nutrient agar base and usually 5% sheep blood, used to isolate routine bacteria and evaluate hemolysis (alpha, beta, gamma).

Chocolate agar

Enriched medium made by heating blood until red cells lyse, releasing hemin (X factor) and nicotinamide adenine dinucleotide (V factor) to cultivate fastidious bacteria like Haemophilus and Neisseria.

Phenylethyl alcohol agar (PEA)

Selective medium containing phenylethyl alcohol, which inhibits many gram-negative rods by interfering with DNA synthesis/membranes, selecting for gram-positive organisms and anaerobes.

Colistin-nalidixic acid agar (CNA)

Selective blood-containing medium in which colistin disrupts gram-negative membranes and nalidixic acid inhibits gram-negative DNA replication to isolate gram-positive bacteria.

Mueller-Hinton agar

Standardized nonselective agar with controlled pH and cation content, used for standard antimicrobial susceptibility testing (Kirby-Bauer disk diffusion) of nonfastidious bacteria.

Thioglycollate broth

Enriched broth containing sodium thioglycollate/cysteine and a small amount of agar to reduce oxygen and slow diffusion, demonstrating organism oxygen relationships.

MacConkey agar (MAC)

Selective and differential medium containing bile salts and crystal violet to inhibit gram-positives, with lactose and neutral red indicator to differentiate lactose-fermenting gram-negative enteric rods.

Eosin methylene blue agar (EMB)

Selective and differential medium containing Eosin Y and methylene blue to inhibit gram-positives and differentiate lactose fermenters, on which Escherichia coli forms a metallic green sheen.

Hektoen enteric agar (HE)

Selective stool medium containing bile salts, carbohydrates, and H2S indicators; Salmonella forms blue-green colonies with black centers, while Shigella forms green/blue-green colonies without black.

Xylose lysine deoxycholate agar (XLD)

Selective stool agar using deoxycholate, phenol red, xylose, lysine, and thiosulfate/iron to differentiate Salmonella (red colonies with black center) from Shigella (red/pink colonies without black).

Salmonella-Shigella agar (SS)

Highly selective stool medium using bile salts, brilliant green, citrate, lactose, and thiosulfate/iron; Salmonella forms colorless colonies with black centers and Shigella forms colorless colonies.

Bismuth sulfite agar

Selective medium containing bismuth sulfite, brilliant green, and iron, used specifically for isolating Salmonella Typhi, which forms black colonies often with a metallic sheen.

Brilliant green agar

Selective medium containing brilliant green dye to suppress normal enteric flora, yielding red/pink/white Salmonella colonies surrounded by red medium.

Selenite enrichment broth

Enrichment broth containing selenite that inhibits competing intestinal flora to increase recovery of Salmonella from stool prior to subculture.

Gram-negative enrichment broth (GN broth)

Enrichment broth containing citrate, deoxycholate, and mannitol to favor recovery of low numbers of Salmonella and Shigella from stool.

Tetrathionate enrichment broth

Selective broth containing tetrathionate and bile salts used to enrich Salmonella from fecal material or food samples before plating.

Sorbitol MacConkey agar (SMAC)

Selective medium substituting sorbitol for lactose to screen for Escherichia coli O157:H7, which produces colorless colonies because it is sorbitol-negative.

Cefixime-tellurite sorbitol MacConkey agar (CT-SMAC)

Selective SMAC medium formulation with added cefixime and tellurite to further suppress competing organisms when screening for E. coli O157:H7.

Cefsulodin-irgasan-novobiocin agar (CIN agar)

Selective medium with antibiotics and mannitol fermentation indicators used to recover Yersinia enterocolitica from stool, producing characteristic 'bull's-eye' colonies with deep red centers.

Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

Selective and differential medium with high pH, bile salts, and sucrose used to isolate Vibrio species; V. cholerae forms yellow sucrose-positive colonies.

Alkaline peptone water

High-pH enrichment broth that favors the rapid growth of Vibrio species over competing flora prior to subculture on TCBS agar.

Campylobacter blood agar (Campy-BAP)

Selective blood agar base with antimicrobials incubated microaerophilically (often at 42°C) to isolate thermophilic Campylobacter jejuni and Campylobacter coli from stool.

Campylobacter CVA agar

Selective blood medium containing cefoperazone, vancomycin, and amphotericin B used to recover Campylobacter species while suppressing stool flora.

Charcoal cefoperazone deoxycholate agar (CCDA)

Blood-free selective medium utilizing charcoal to neutralize toxic compounds along with cefoperazone and deoxycholate to isolate Campylobacter species.

Skirrow selective medium

Classic Campylobacter selective medium composed of a blood agar base supplemented with vancomycin, polymyxin B, and trimethoprim.

Helicobacter pylori selective blood agar

Enriched blood medium with selective antibiotics, incubated microaerophilically at ~35-37°C to culture Helicobacter pylori from gastric biopsy specimens.

X, V, and XV factor disk test

Differential test using factor-deficient agar and impregnated paper disks to determine growth factor requirements for Haemophilus species (e.g., H. influenzae requires both X and V factors).

Haemophilus test medium (HTM)

Mueller-Hinton-based medium supplemented with growth factors, standardized specifically for antimicrobial susceptibility testing of Haemophilus influenzae.

Haemophilus satellitism test

Blood agar test where Staphylococcus aureus acts as a feeder organism releasing V factor and lysing RBCs for X factor, allowing tiny Haemophilus influenzae colonies to grow around it.

Thayer-Martin selective medium

Chocolate agar base supplemented with vancomycin, colistin, and nystatin to selectively isolate pathogenic Neisseria from sites containing normal flora.

Modified Thayer-Martin selective medium

Selective chocolate medium adding trimethoprim to Thayer-Martin medium to prevent Proteus swarming during Neisseria isolation.

Martin-Lewis medium

Chocolate-based selective medium with antimicrobials similar to modified Thayer-Martin, designed for selective isolation of Neisseria gonorrhoeae from nonsterile sites.

New York City medium (NYC medium)

Clear enriched agar with selective antimicrobials used to isolate Neisseria gonorrhoeae from genital specimens, allowing transparent visualization of small colonies.

Bordet-Gengou agar

Potato infusion, glycerol, and blood medium used for classic isolation of Bordetella pertussis, producing glistening pearl- or mercury-drop-like colonies.

Regan-Lowe charcoal agar

Charcoal medium with horse blood and cephalexin preferred for selective culture and transport of Bordetella pertussis.

Buffered charcoal yeast extract agar (BCYE)

Enriched medium containing yeast extract, charcoal, L-cysteine, and iron required for the primary culture of Legionella pneumophila, yielding ground-glass colonies.

Tinsdale cystine-tellurite agar

Selective and differential medium where tellurite is reduced to black material and cystinase activity produces a brown halo around Corynebacterium diphtheriae colonies.

Loeffler serum medium

Coagulated serum medium that promotes rapid growth of Corynebacterium diphtheriae and enhances microscopic development of metachromatic granules.

Oxford agar

Selective differential medium containing esculin and iron to isolate Listeria monocytogenes, forming small gray colonies with black halos from esculin hydrolysis.

PALCAM agar

Selective and differential medium containing selective agents, esculin, iron, and mannitol to isolate Listeria species, which yield gray-green colonies with black halos/centers.

Vaginalis agar / human blood bilayer Tween agar

Medium incorporating human blood to demonstrate diffuse beta-hemolysis of Gardnerella vaginalis.

Anaerobic blood agar

Enriched blood agar supplemented with hemin and vitamin K, incubated oxygen-free for primary isolation and colony evaluation of obligate anaerobes.

Bacteroides bile esculin agar (BBE)

Selective and differential medium containing high bile, esculin, ferric indicator, and antibiotics used to isolate and identify the bile-resistant Bacteroides fragilis group (brown-black colonies).

Kanamycin-vancomycin laked blood agar (KVLB / LKV)

Selective medium containing kanamycin, vancomycin, and laked blood to isolate anaerobic gram-negative rods (Prevotella, Porphyromonas, Bacteroides) and enhance pigment and brick-red UV fluorescence.

Egg yolk agar

Differential medium containing egg yolk fats to detect lecithinase (opaque white precipitate) and lipase (pearly iridescent sheen) activity in anaerobic bacteria like Clostridium.

Nagler reaction on egg yolk agar

Diagnostic test using specific antitoxin on one half of an egg yolk agar plate to confirm neutralization of Clostridium perfringens alpha-toxin lecithinase.

Cycloserine-cefoxitin-fructose agar (CCFA)

Selective medium using cycloserine, cefoxitin, and fructose to isolate Clostridioides difficile from stool, producing flat yellow ground-glass colonies with a horse-stable odor.

Pre-reduced anaerobically sterilized media (PRAS media)

Media prepared and sterilized in oxygen-free environments to maintain low redox potential for cultivating strict anaerobes.

Lowenstein-Jensen medium (LJ medium)

Egg-based solid medium with malachite green used to isolate Mycobacterium tuberculosis, which forms rough, dry, buff, cauliflower-like colonies after weeks.

Middlebrook 7H10 agar

Defined clear agar base enriched with salts, vitamins, and oleic acid-albumin, used for mycobacterial isolation and susceptibility testing.

Mycobacteria growth indicator tube (MGIT)

Automated liquid detection system containing a fluorescent oxygen sensor that fluoresces as multiplying mycobacteria consume oxygen.

MacConkey agar without crystal violet

Specialized MacConkey agar formulation omitting crystal violet to allow growth and differentiation of rapid-growing Mycobacterium species within days.

Fletcher semisolid medium

Semisolid nutrient medium incubated at ~28-30°C to cultivate Leptospira species, which form a characteristic subsurface growth ring.

Ellinghausen-McCullough-Johnson-Harris medium (EMJH medium)

Semisynthetic medium containing long-chain fatty acids and albumin used to cultivate Leptospira species.

Barbour-Stoenner-Kelly medium (BSK medium)

Complex enriched medium formulated specifically for the cultivation of Borrelia burgdorferi.

Pleuropneumonia-like organism medium (PPLO medium)

Enriched medium supplemented with cholesterol/sterol used to grow cell-wall-deficient Mycoplasma species, forming classic 'fried-egg' colonies.

A7 / A8 genital mycoplasma agar

Selective medium with indicators used to recover Ureaplasma urealyticum (tiny brownish 'sea-urchin' colonies) and Mycoplasma hominis.

Sabouraud dextrose agar (SDA)

General fungal isolation medium with low pH and high dextrose content to favor yeast and mold growth while inhibiting bacteria.

Mycosel / Mycobiotic agar

Selective agar containing chloramphenicol (suppresses bacteria) and cycloheximide (suppresses saprophytic fungi) to isolate dermatophytes.

Dermatophyte test medium (DTM)

Differential screening medium with phenol red indicator that turns early RED as dermatophytes metabolize proteins and raise pH.

Cornmeal agar with Tween 80

Nutrient-limited medium used to induce characteristic diagnostic microscopic morphology (pseudohyphae and terminal chlamydoconidia) in Candida albicans.

Chromogenic Candida agar (CHROMagar Candida)

Differential medium utilizing enzyme-cleaved chromogenic substrates to differentiate Candida species by colony color (e.g., C. albicans green, C. tropicalis blue).

Birdseed / Niger seed agar

Selective medium containing caffeic acid converted into melanin by phenoloxidase/laccase, identifying Cryptococcus neoformans/gattii as brown-black colonies.

Stuart transport medium

Non-nutritive buffered semisolid medium that maintains organism viability on collection swabs during transit without allowing multiplication.

Amies transport medium

Improved Stuart-type swab transport medium using phosphate buffer and optional charcoal to neutralize toxic fatty acids and inhibitors.

Cary-Blair transport medium

Low-nutrient, semisolid, alkaline transport medium formulated to preserve enteric stool pathogens (Salmonella, Shigella, Vibrio, Campylobacter) during transport.

Anaerobic transport medium

Reduced oxygen-free transport tube containing reducing agents to protect strict anaerobes from oxygen exposure between collection and culture.

Lysis-centrifugation Isolator system

Blood culture processing method that lyses blood cells and centrifuges the specimen, allowing direct plating of concentrated sediment for fungi, mycobacteria, and fastidious organisms.

McCoy cell culture

Living host cell tissue culture system required for growing obligate intracellular Chlamydia trachomatis, which produces intracytoplasmic inclusions.