CLINICAL MICROBIOLOGY ENTRANCE EXAM 2023 with Verified Solutions 100% Correct

CLINICAL MICROBIOLOGY ENTRANCE EXAM 2023 with Verified Solutions 100% Correct 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 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 imperfecti. Soil organisms. 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. 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. Acme *** Time when signs and symptoms reach their greatest intensity. 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. 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 protiens 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. -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) 2. Universal protection 3. Responds immediately Adaptive immunity *** The body's acquired resistance to a specific pathogen. Active immunity *** Immunity that develops as a result of natural or deliberate exposure to an antigen. Passive immunity *** Created when ready-made antibodies are introduced into the body- the host's own immune system does not make the antibodies. Naturally acquired active immunity *** Produced when a person is exposed to an infectious agent. Naturally acquired passive immunity *** Produced when antibodies made by a mother's immune system are transferred to her offspring. Artificially acquired active immunity *** Produced when a person is exposed to a vaccine. Artificially acquired passive immunity *** Produced when antibodies made by other hosts are introduced into a new host. Example: snake antivenin injection, rabies. Antigen *** A substance the body identifies as foreign and toward which it mounts an immune response. Antibody *** A protein produced in response to an antigen that is capable of binding specifically to an antigen. B cells *** Develop into plasma cells that make antibodies to attack bacteria and viruses. Memory B Cells *** B-cell product: Ready to produce specific antibodies in the future. Helper T cells *** Activate B and T cells: control or limit specific immune response. Cytotoxic T cells *** attack foreign or body cells infected by viruses & proved CELL mediated immunity. NK Cells *** destroy abnormal tissue cells Memory T Cells *** Remember antigen and quickly stimulate immune response on reexposure. IgG *** Goes across the placenta , and confers with the passive immunity Most abundant antibody IgM *** first antibody produced in an immune response IgA *** Abundant in colostrum where it helps protect infants from intestinal pathogens. Found in body secretions such as tears, milk, saliva, and mucous and is attached to the linings of the digestive, respiratory, and genitourinary systems. Does not cross the placenta. IgE *** Plays key role in allergenic response. Also elevated in patients harboring worm parasites. IgD *** Attached to B cells Activates B cells Hypersensitivity *** An exaggerated response by the immune system to a particular substance. Type I: Immediate *** Anaphylaxis. Results from prior exposure to a foreign substance. Type II: Cytotoxic *** Occurs when a patient receives the wrong blood type during a transfusion. Type III: Immune Complex *** Serum sickness, Arthus reaction Type IV: Cell-mediated/delayed *** Takes more than 12 hours to develop. Examples: Contact dermatitis, poison ivy reaction, tuberculin hypersensitivity (TB test). Myasthenia gravis *** Autoimmune neuromuscular disorder characterized by weakness of voluntary muscles Attenuated Vaccine *** Made from live viruses that can still replicate in a host cell Toxoid vaccine *** Inactivated toxin stimulates antibody production (ex. Tetanus) Dead vaccine *** Uses pieces of dead organism; ex. measles; need booster shots. Contains proteins of the organism. Rheumatoid Arthritis *** A disease characterized by the debilitating destruction of the joints due to inflammation, often causing deformation of the fingers. Systemic Lupus Erythematosus *** Chronic autoimmune inflammatory disease of collagen in skin, joints, and internal organs. Butterfly rash on sun exposed areas. Primary immunodeficiency *** resulting from a genetic defect ex.) defect of lymphocyte maturation/activation/function Secondary Immunodeficiency *** "acquired" resulting from an environmental cause ex. viral infection, cancer, etc. Agammaglobulinemia *** Patient lacks antibodies- this is a B cell defect DiGeorge Syndrome *** -Congenital absence of the thymus gland -T cell deficient, vulnerable to viral fungal and bacterial infections -Micro deletion of chromosome 22, multiple systematic problems AIDS *** a deadly disease that interferes with the body's natural ability to fight infection Penicillins- Mode of action *** Inhibition of cell wall synthesis Cephalosporins- Mode of Action *** Inhibition of cell wall synthesis Aminoglycosides- Mode of Action *** Inhibition of protein synthesis Tetracyclines- Mode of Action *** Inhibition of protein synthesis Chloramphenicol- Mode of Action *** Inhibition of protein synthesis Macrolides- Mode of Action *** Inhibition of protein synthesis Rifampin- Mode of Action *** Inhibition of nucleic acid synthesis Quinolones- Mode of Action *** Inhibition of nucleic acid synthesis Sulfonamides *** Inhibition of folate acid synthesis Isoniazid *** Inhibition of synthesis of mycolic acids. Amphotericin B *** Attaches to ergosterol in fungal membranes; cause lysis of cell. Griseofulvin *** Interferes with fungal microtubule function used for dermatophytes (Tinea) Flucytosine *** - interrupts nucleic acid synthesis and protein synthesis. - active against strains of Candida and Cryptococcus. Nystatin *** Binds to ergosterol. Forms pores in the membrane that lead to death of the fungus. Zidovudine (AZT) *** Interferes with reverse transcriptase making DNA from RNA. Is used in treating AIDS. Niclosamide *** Inhibits ATP production of the worm *- Treats tapeworm and flatworm infections* Synergism *** the effect of two drugs together is greater than the effect of either alone Addition of silver to a treatment regimen *** It can make an antibiotic resistant strain of bacteria sensitive to antibiotics again. Betalactamase *** Enzyme or toxin of staph that is resistance to penicillins and cephalosporins. Cross-resistance *** Is resistance to two or more similar antimicrobial agents via a common mechanism. Example: Beta lactamase. Sterilization *** Complete destruction of all forms of microbial life Disinfection *** Directly targets the removal of all pathogens, not necessarily all microorganisms. Sanitization *** The removal of microbes from eating utensils and food preparation areas Bacteriostatic agent *** An agent that inhibits the growth of bacteria. Viricide *** An agent that inactivates viruses. Germicide *** An agent capable of killing microbes rapidly. Some agents kill microorganisms, some only inhibit the growth. Bactericide *** An agent that kills bacteria- most do not kill spores. Fungicide *** An agent that kills fungi Sporocide *** An agent that kills bacteria endospores or fungal spores. Antiseptic *** are applied to living tissue Detergents *** Typically applied to inanimate objects. Uses: Hand washing (soap), laundering, sanitizing kitchen and dairy equipment. Phenols *** Denature proteins, inactivates enzymes, & disrupt membranes. Disinfect surfaces and destroy discarded cultures. Surgical scrub. Alcohols *** Denature proteins when mixed with water. Used to disinfect skin and can be used in aerosols Acids *** Lower pH and denature proteins. Uses: Food preservation Alkylating Agents *** Disrupt structure of proteins and nucleic acids. Uses: Disinfect and sterilize inanimate objects that would be harmed by high temperatures. Formaldehyde. Dyes *** May interfere with replication or block cell wall synthesis. Uses: Clean wounds. Crystal Violet used to treat some protozoan and fungal infections. Oxidizing Agents *** Disrupt disulfide bonds. Uses: clean puncture wounds, disinfect instruments. Halogens *** Chlorine- used in water. Iodine- used on skin. Heavy Metals *** Denature proteins. Example: Silver nitrite, Mercury, Copper Alkalis *** Raise pH and denature proteins. Found in soaps. Physical Antimicrobial Agents *** Filtration, irradiation, autoclave (moist heat), UV light, Pasteurization. ***