WGU C453 Clinical Microbiology Exam guide Expert Verified Actual Questions And Answers Newest Update 2025

Bacteria - -Single-celled organism that do not have a cell nucleus and the membrane enclosed intracellular structures found in most other cells (Prokaryotic cell). Gram-positive Bacteria - -Thick layer of peptidoglycan (20-80nm across). The peptidoglycan layer is closely attached to the outer surface of the cell membrane. Retains crystal violet stains. Lack an outer membrane and a periplasmic space. Gram-negative Bacteria - -Cell wall is thinner, but more complex. Only 10-20% peptidoglycan. Contains an outer membrane, leaving a very narrow periplasmic space. Does not retain crystal violet stain because of large quantities of lipoproteins and lipopolysaccharides (endotoxin). Acid-fast Bacteria - -Cell wall is thick, but consists of 60% lipids. Lipids make acid-fast organisms impermeable to most other stains and protect them from acids and alkalis. Stain as gram-positive. Grow slowly because the lipids impeded entry of nutrients. Endotoxin - -Lipopolysaccharide (LPS). Part of the outer membrane of the cell wall of gram-negative bacteria. It can cause fever and dilates blood vessels- causing BP to drop. Bacteria typically release this when they are dying, so killing them increases the concentration of this toxic substance. Antibiotics given late in the infection can cause worsening of symptoms or even death. Wall-deficient Bacteria - -Protected by a strengthened cell membrane that contains sterols. Example: mycobacterium paratuberculosis with Crohn's disease- a chronic disorder of the intestine. Coccus - -Sphere shaped bacteria Coccobacillus - -Short rod shaped bacteria (between cocci and bacilli) Vibrio - -Comma shaped bacteria Bacillus - -Rod shaped bacteria Spirillum - -Rigid, wavy shaped bacteria WGU C453 WGU C453 Spirochete - -Corkscrew shape bacteria Function of cell membrane - -To regulate movement of materials into and out of the cell by transport mechanisms. It synthesizes cell wall components, assists with DNA replication, secretes proteins, carries on respiration, and captures energy as ATP. Function of the cell wall - -Helps maintain the characteristic shape of the cell and prevents the cell from bursting when fluids flow into the cell by osmosis. Lies outside the cell membrane. Peptidoglycan - -Single most important component of the bacterial cell wall. Capsule - -Discrete layer of polysaccharides that protects the cell. Promotes infection by protecting the bacterial cell from engulfment by predatory protozoa or WBC (phagocytes). Also mediates adherence of cells to surfaces. Pili - -Tiny, hallow projections that are used to attach bacteria to surfaces. Are NOT involved in movement. Promote infection by transferring DNA amount bacteria- which in turn can transfer antibiotic resistance. Can adhere to RBC and cause blood cells to clump. Flagella - -Long, thin, helical appendages that allow bacteria to move. Endospore - -Helps the organism survive, and is not a means of reproduction. They are formed within the cells, contain very little water and are highly resistant to heat, drying, acids, bases, certain disinfectants, and even radiation. They are capable of surviving adverse environmental conditions for long periods of time. Chemotaxis - -Process of bacteria moving toward or away from substances in their environment. Towards- positive, Away- Negative. Bacteria that produce spores - -Bacillus, Clostridium Helminths - -Worm-like organisms living in and feeding on live hosts, receiving nourishment and protection while disrupting their hosts' nutrient absorption, causing weakness and disease. Example: Flukes, tapeworms, adult round-worms of intestine, and roundworm larvae. Zygomycota - -Bread molds Ascomycota - -Sac fungi. Yeasts. Replication by sexual reproduction. Basidiomycota - -Club fungi. Amanita and other mushrooms. Deuteromycota - -Fungi imperfection. Soil organisms. WGU C453 WGU C453 Virus - -Tiny, non living particle that invades and then reproduces inside a living cell. Contain only one kind of nucleic acid- either DNA or RNA (never both). Naked virus - -Virus with only a nucleocapsid and no envelope. Enveloped virus - -Have a bilayer membrane outside their capsids. Retrovirus: Single-stranded positive-sense RNA virus - -Viral group that produces reverse transcriptase. Mechanical Vector - -parasite does not go through any part of its life cycle during transit. Flies that carry parasite eggs, bacteria, or viruses from feces to human food are mechanical vectors. Mutualism - -Both members of the association living together benefit from the relationship. Parasitism - -One organism, the parasite, benefits from the relationship, whereas the other organisms, the host, is harmed by it. Commensalism - -Two species live together in a relationship such that one benefits and the other one neither benefits nor is harmed. Antagonism - -An interaction between organisms so that one organism benefits at the expense of another. Incubation period - -The time between infection and the appearance of signs and symptoms. Prodromal phase - -Short period during which nonspecific, often mild, symptoms such as malaise and headache sometimes appear. Invasive phase - -The period during which the individual experiences the typical sings and symptoms of the disease. pyrogens that act on a center in the hypothalamus sometimes referred to as the body's "thermostat." Invasive: Acme - -Time when signs and symptoms reach their greatest intensity. Invasive: Fulminating - -Sudden or severe Decline phase - -Symptoms begin to subside. The period of illness during which host defenses and the effects of treatment finally overcome the pathogen. WGU C453 WGU C453 Convalescence period - -Tissues are repaired, healing takes place, and the body regains strength and recovers. Physical barriers - -Skin and mucus membranes and the chemicals they secrete. Prevent approach and deny access to pathogens. Chemical barriers - -Antimicrobial substances in body fluids such as tears, saliva, mucus, gastric juices, and the iron limitation mechanisms. Lysozyme- in tears, saliva, and mucus. Interferon - -A small, soluble protein that is responsible for viral interference. It can also stimulate adaptive immune defenses. Increases resistance of cells to infection, slow the spread of disease. Fever - -Body temperature rises in response to pryogens. This mobilizes defenses, accelerates repairs, and inhibits pathogens. Complement system - -1. Enhance phagocytosis by phagocytes; 2. Lyse microorganisms, bacteria, and enveloped viruses directly; 3. generate peptide fragments that regulate inflammation and immune responses. Goes to work as soon as invading microbe is detected. Attacks and breaks down cell walls, attract phagocytes, and stimulates inflammation. Protozoa - -one-celled organisms that have a nucleus and live in water or as parasites. Fungi - -A special eukaryotic organism that lives by decomposing and absorbing nutrients. Dimorphic - -Fungus can grow as both yeast and molds. Hyphae - -The branching, threadlike tubes that make up the bodies of multicellular fungi. Positive sense single-stranded RNA viruses - -RNA genomes ready for immediate translation into proteins Negative sense single-stranded RNA viruses - -other RNA genomes that have to be converted into proper form to be made into proteins Classical pathway - -antibodies bind pathogen's antigens Lectin pathway - -Lectin binds to carbs on pathogen surface Reaction cascade Alternate pathway - --activation is by the presence of endotoxin. WGU C453 WGU C453 -causes an inflammatory reaction Dendritic cells - -Phagocytic cells that re involved in initiating the adaptive defense response. Langerhans cells produce immune tolerance to good bacteria, preventing overreaction of our immune system. Neutrophils - -Phagocytic cells that guard blood, skin, and mucus membranes against infection. Most aggressive WBC in cases where bacteria attempt to destroy tissue. Eosinophils - -Help turn off inflammatory reactions by releasing histamine-degrading enzymes from their granules. Destroy parasitic organisms and play a major role in allergic reactions Basophils - -Release histamine, a chemical that helps initiate the inflammatory response. Phagocytes - -Attack and remove dangerous microorganisms by eating or engulfing them. Monocyte Innate immunity - -1. In place since birth (genetic)