Microbiology Media Quiz: MSA, EMB, HE

Endotoxins are released by Gram-negative bacteria upon cell death. They are also known as lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria.

Exotoxins are proteins produced by both Gram-positive and Gram-negative bacteria, but are released during bacterial growth. They can be found in three main types: cytotoxins, neurotoxins, and enterotoxins.

Mycobacterium have a thick, waxy cell wall that protects them from harsh environments, while Mycoplasma lack a cell wall altogether, making them susceptible to osmotic stress.

Alpha hemolysis shows a greenish or brownish zone around the bacterial colony, indicating partial destruction of red blood cells. Beta hemolysis creates a clear, yellow zone, signifying complete destruction of red blood cells. Gamma hemolysis shows no visible change, meaning no disturbance of red blood cells.

Sporulation is the process of forming a resistant, dormant spore within a bacterial cell. Bacteria sporulate under unfavorable conditions like nutrient depletion or environmental stress. Bacillus and Clostridium can both sporulate. Clostridium sporulates anaerobically, while Bacillus sporulates aerobically or facultatively.

The breath test diagnoses Helicobacter pylori by detecting the presence of carbon dioxide (CO2) in the breath, which is produced by the bacteria's urease enzyme.

Tc cells (cytotoxic T cells) are CD8+ cells that bind to MHC I molecules on infected or cancerous cells. Their job is to destroy infected or cancerous cells by releasing cytotoxic substances like perforin and granzyme. Memory Tc cells are responsible for recognizing and responding to reinfection with the same pathogen.

T helper (Th) cells are CD4+ cells that bind to MHC II molecules on antigen-presenting cells (APCs). They regulate the immune response by activating other immune cells, like Tc cells and macrophages. Memory Th cells store the memory of an infection and can quickly activate the immune response upon reinfection with the same pathogen.

Thioglycolate media is used to determine the oxygen tolerance of bacteria. Aerobic bacteria grow at the top of the tube, anaerobic bacteria grow at the bottom of the tube, and facultative anaerobes grow throughout the tube.

Coliforms are a group of gram-negative, facultatively anaerobic, lactose-fermenting bacteria commonly found in the intestines of humans and animals. Non-coliforms are gram-negative bacteria that do not ferment lactose.

MSA (Mannitol Salt Agar) is a selective and differential medium used to isolate and differentiate Staphylococcus aureus from other bacteria. It's selective due to its high salt concentration (7.5% NaCl), which inhibits the growth of most bacteria except staphylococci. It's differential because it contains mannitol, a sugar that S. aureus can ferment, leading to a yellow color change due to the production of acid, while non-mannitol fermenting bacteria produce pink growth.

EMB (Eosin Methylene Blue Agar) is differential, meaning it distinguishes bacteria based on their ability to ferment lactose. Pink/lavender growth indicates a weak lactose fermenter, red growth indicates a non-lactose fermenter, and metallic green growth indicates a rapid lactose fermenter. EMB is commonly used for identifying fecal coliforms, gram-negative bacteria that ferment lactose.

HE (Hektoen Enteric Agar) is a differential medium that utilizes lactose fermentation, sulfur reduction, and protein breakdown for bacterial differentiation. Yellow growth indicates fermentation of sugars such as lactose, blue/green growth indicates breakdown of proteins to alkali products, and black colonies signify sulfur reduction. HE can differentiate between Salmonella and Shigella, which EMB cannot.

B cells (B lymphocytes) originate and mature in the bone marrow. They are responsible for humoral immunity, which involves the production of antibodies. Regulatory B cells help suppress autoimmune responses. B cells are activated when their antigen receptors bind to specific antigens presented by MHC (Major Histocompatibility Complex) molecules.

T cells (T lymphocytes) originate in the bone marrow but mature in the thymus. They are responsible for cell-mediated immunity. Regulatory T cells help suppress autoimmune responses. T cells are activated when their antigen receptors bind to specific antigens presented by MHC molecules on antigen-presenting cells.

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis. Primary TB is confined to the lungs and usually asymptomatic. Secondary TB occurs when the tubercle breaks open, releasing bacteria, leading to symptoms. Tertiary TB develops in individuals who already had TB. Disseminated TB occurs when the bacterium spreads from the lungs to other parts of the body. Two commonly used antibiotics are Isoniazid and Rifampin. Rifampin can cause a reddish-orange discoloration of bodily fluids.

Plasma cells are effector B cells, specialized B lymphocytes that secrete antibodies. They are responsible for the humoral immune response, targeting and neutralizing specific antigens.

A glycocalyx is a sugar-based coating found on some bacteria. Two examples include capsules and slime layers. These structures help bacteria survive by providing a mechanical barrier against antibiotics and the host's immune system. A biofilm is a complex community of bacteria, often encased in a glycocalyx, which enhances their survival by protecting them from the host's defenses and antibiotic treatment.

MSA (Mannitol Salt Agar) is a selective and differential media used to isolate and differentiate Staphylococcus aureus from other bacteria. It's selective due to the high salt concentration (7.5% NaCl) which inhibits the growth of most bacteria except staphylococci. It's differential because it contains mannitol, a sugar that S. aureus can ferment, causing a yellow color change due to acid production, while other bacteria produce pink growth.

EMB (Eosin Methylene Blue Agar) is a differential media that distinguishes bacteria based on their ability to ferment lactose. It's used to identify fecal coliforms, gram-negative bacteria that ferment lactose. Pink/lavender growth indicates a weak lactose fermenter, red growth indicates a non-lactose fermenter, and metallic green growth indicates a rapid lactose fermenter.

HE (Hektoen Enteric Agar) is a differential media that utilizes lactose fermentation, sulfur reduction, and protein breakdown for bacterial differentiation. Yellow growth indicates fermentation of sugars such as lactose. Blue/green growth indicates breakdown of proteins to alkali products. Black colonies signify sulfur reduction. HE can differentiate between Salmonella and Shigella, which EMB cannot.

B cells (B lymphocytes) originate and mature in the bone marrow. They are responsible for humoral immunity, which involves the production of antibodies. Regulatory B cells help suppress autoimmune responses. B cells are activated when their antigen receptors bind to specific antigens presented by MHC (Major Histocompatibility Complex) molecules.

T cells (T lymphocytes) originate in the bone marrow but mature in the thymus. They are responsible for cell-mediated immunity. Regulatory T cells help suppress autoimmune responses. T cells are activated when their antigen receptors bind to specific antigens presented by MHC molecules on antigen-presenting cells.

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis. Primary TB is confined to the lungs and usually asymptomatic. Secondary TB occurs when the tubercle breaks open, releasing bacteria, leading to symptoms. Tertiary TB develops in individuals who already had TB. Disseminated TB occurs when the bacterium spreads from the lungs to other parts of the body. Two commonly used antibiotics are Isoniazid and Rifampin. Rifampin can cause a reddish-orange discoloration of bodily fluids.

Plasma cells are effector B cells, specialized B lymphocytes that secrete antibodies. They are responsible for the humoral immune response, targeting and neutralizing specific antigens.

A glycocalyx is a sugar-based coating found on some bacteria. Two examples include capsules and slime layers. This structure helps bacteria survive by providing a mechanical barrier against antibiotics and the host's immune system. A biofilm is a complex community of bacteria, often encased in a glycocalyx, which enhances their survival by protecting them from the host's defenses and antibiotic treatment.

Fungi that exhibit two forms depending on the environment: Yeast form (pathogenic) found in the human body (37°C) and Mold form (environmental) found in the soil or environment (25°C).

Asexual spores borne on specialized structures.

Spores formed inside a sporangium.

Sexual spores formed by the fusion of two hyphae.

Sexual spores contained in a sac called an ascus.

Sexual spores produced on a basidium.

Culture medium used for growing fungi. It is slightly acidic (pH ~5.6), inhibiting bacterial growth and promoting fungal growth.

Most fungal infections are not contagious.

Fungal infections caused by invasive growth of fungi. Examples include Candida and Aspergillus.

Toxins produced by fungi. Aflatoxins from Aspergillus are an example.

Hypersensitivity reactions to fungal spores.

A test that dissolves keratin, making fungal elements visible under a microscope.

A stain that highlights fungal cells in tissue samples.

Antifungal medication that inhibits ergosterol synthesis, which is essential for fungal cell membrane formation.

Antifungal medication that binds to ergosterol in fungal cell membranes, disrupting their structure and function.

The process by which bacteria form a resistant, dormant spore within their cell to survive unfavorable conditions.

Gram-positive bacteria retain the crystal violet stain, appearing purple under a microscope. Gram-negative bacteria lose the stain and are visualized after a counterstain is applied, often appearing pink.

Mycobacterium have a thick, waxy cell wall that protects them from harsh environments, while Mycoplasma lack a cell wall altogether, making them susceptible to osmotic stress.

Alpha hemolysis shows a greenish or brownish zone around the bacterial colony, indicating partial destruction of red blood cells. Beta hemolysis creates a clear, yellow zone, signifying complete destruction of red blood cells. Gamma hemolysis shows no visible change, meaning no disturbance of red blood cells.

A breath test diagnoses Helicobacter pylori by detecting the presence of carbon dioxide (CO2) in the breath, which is produced by the bacteria's urease enzyme.

Tc cells (cytotoxic T cells) are CD8+ cells that bind to MHC I molecules on infected or cancerous cells. Their job is to destroy infected or cancerous cells by releasing cytotoxic substances like perforin and granzyme.

T helper (Th) cells are CD4+ cells that bind to MHC II molecules on antigen-presenting cells (APCs). They regulate the immune response by activating other immune cells, like Tc cells and macrophages.

Thioglycolate media is used to determine the oxygen tolerance of bacteria. Aerobic bacteria grow at the top of the tube, anaerobic bacteria grow at the bottom of the tube, and facultative anaerobes grow throughout the tube.

Hyaluronidase breaks down hyaluronic acid, a component of connective tissue. Kinase adds phosphate groups to molecules, often modifying cell proteins or signaling pathways. Coagulase triggers the conversion of fibrinogen into fibrin, causing blood clotting. Collagenase breaks down collagen, a major protein in connective tissue.

Sulfas, like Bactrim and Gantrisin, are competitive inhibitors of PABA (para-aminobenzoic acid). This prevents bacteria from producing folic acid, which is essential for their growth.

Margination is the process of white blood cells (WBCs) migrating to the site of tissue injury and adhering to the endothelium of blood vessels. Diapedesis is the movement of WBCs between endothelial cells and into the interstitial fluid. Chemotaxis is the directed movement of WBCs towards the site of injury guided by chemical signals.

A type of protozoan infection that is caused by the parasitic protozoa Plasmodium. It is transmitted by the bite of an infected female Anopheles mosquito.

The stage of the malaria parasite's life cycle that occurs in humans, characterized by asexual reproduction.

The stage of the malaria parasite's life cycle that occurs in mosquitoes, characterized by sexual reproduction.

A type of protozoan infection that is caused by the parasite Toxoplasma gondii. It is commonly found in cats and can be transmitted to humans through various routes.

A type of protozoan infection that is caused by the parasite Balantidium coli. It is transmitted through the fecal-oral route and is often associated with contaminated water or food.

A type of protozoan infection that is caused by the parasite Giardia lamblia. It is commonly known as "beaver fever" and is transmitted through the fecal-oral route.

A type of protozoan infection that is caused by the parasite Trichomonas vaginalis. It is a sexually transmitted infection (STI) that affects the vagina and urethra.

A type of protozoan infection that is caused by the parasite Trypanosoma cruzi. It is transmitted by the bite of an infected triatomine bug, also known as a "kissing bug."

A type of protozoan infection that is caused by the parasite Leishmania donovani. It is transmitted by the bite of an infected sandfly.

A type of protozoan infection that is caused by the parasite Entamoeba histolytica. It is transmitted through the fecal-oral route and can cause dysentery.

A type of amoebic infection that affects the cornea of the eye. It is often associated with contact lenses and contaminated water.

A type of amoebic infection that affects the brain. It is caused by the amoeba Naegleria fowleri and is often contracted through contaminated water.

A type of roundworm infection that is caused by the parasite Ascaris lumbricoides. It is transmitted through the fecal-oral route and involves a complex migration cycle within the human body.

A type of roundworm infection that is caused by the parasite Enterobius vermicularis. It is commonly known as "pinworm" and is transmitted through the fecal-oral route.

A type of roundworm infection that is caused by the parasite Necator americanus. It is transmitted through skin penetration by larvae in contaminated soil.

A type of passive transport where water moves across a semipermeable membrane from an area of high water concentration to an area of low water concentration. This movement is driven by the difference in water potential.

A type of vaccine that uses a deactivated or killed version of the pathogen to stimulate an immune response. They are generally considered safe for most individuals, including pregnant women and those with weakened immune systems.

A type of vaccine that uses a weakened or modified live version of the pathogen to stimulate an immune response. They are often more effective than inactivated vaccines, but may not be suitable for everyone.

A solution with a higher concentration of solutes compared to the inside of the cell. Water moves out of the cell, causing it to shrink.

A solution with a lower concentration of solutes compared to the inside of the cell. Water moves into the cell, causing it to swell.

A solution with the same concentration of solutes as the inside of the cell. There is no net movement of water.

A type of respiratory virus, primarily affecting infants and young children. It can cause bronchiolitis, a serious lung infection leading to shortness of breath and wheezing.

A measure of how common a disease or condition is in a population at a specific time. It is often expressed as a percentage or proportion.

A measure of the number of new cases of a disease or condition that occur within a specific period of time. It is often expressed as the number of new cases per 100,000 individuals over a year.

A method of determining the sensitivity or resistance of bacteria to specific antibiotics. It involves placing antibiotic disks onto an agar plate containing bacteria and measuring the zone of inhibition around each disk.

Transmission occurs through the bite of infected mosquitoes (Culex, Anopheles, or Aedes species).

Transmission occurs through ingestion of water contaminated with copepods carrying larvae.

Slender, elongated worms. Males have a gynecophoral canal to hold females.

Leaf-shaped, flatworm approximately 3 cm in length. It feeds on liver tissue and bile.

Taenia solium has hooks and suckers, while Taenia saginata has only suckers.

Dorsoventrally flattened, unsegmented (except tapeworms). Includes flukes (Schistosoma, Fasciola) and tapeworms (Taenia).

Cylindrical, unsegmented bodies. Dioecious (separate sexes).

Multicellular eukaryotes with specialized systems (nervous, digestive, etc.). Life cycles involve intermediate and definitive hosts.

Separate male and female organisms (e.g., Schistosoma).

Both male and female reproductive organs in one organism (e.g., Fasciola hepatica, Taenia species).

Acute symptoms include rash, fever, chills, and diarrhea. Chronic symptoms include liver fibrosis, portal hypertension, splenomegaly, and ascites.

Acute symptoms include fever, abdominal pain, and nausea. Chronic symptoms include jaundice, bile duct obstruction, and liver damage.

Intestinal infection symptoms include abdominal pain, weight loss, and diarrhea.

Effective against a broad spectrum of nematodes (Ascaris, hookworms, pinworms) and some cestodes.

Effective against Schistosomes (blood flukes), liver flukes (Fasciola), and tapeworms (Taenia).