MLT microbiology Questions and Answers

MLT microbiology Questions and Answers Autotrophs organisms that produce organic compounds from carbon dioxide as a carbon source, using either light or reaction of inorganic chemical compounds as a source of energy Phototrophs autotrophs that use photosynthesis to feed Chemolithotrophs autotrophs that obtain energy by oxidation of inorganic compounds Heterotrophs organisms that requires organic substrates as a source of carbon for growth and development Fastidious hard to grow, requires additional growth factors Psychrophiles bacteria that grow best at cold temperatures (optimal growth at 10°C to 20°C) Mesophiles an organism that grows best in moderate temperature neither hot nor cold ( 25°C to 40°C) Thermophiles bacteria that grow best at high temperatures (optimal growth at 50°C - 60°C) Obligate aerobes a microorganism that requires oxygen for growth Obligate anaerobes a microorganism that can live and reproduce only in a strict anaerobic environment (0% oxygen) Facultative anaerobes a microorganism that does not require oxygen for growth but will use oxygen and grow better if it is present Capnophilic term used to describe microorganisms that require an increased concentration of CO², usually between 5% and 10% Microaerophilic microorganism that grows with reduced oxygen and increased carbon dioxide Minimal media a laboratory growth medium whose contents are simple and completely defined; not usually used in the diagnostic microbiology laboratory Nutrient media culture media that are complex and made of extracts of meat or soybeans Enriched media media that contains nutritional enhancement to allow growth of fastidious microbes Selective media media that support the growth of one type or one group of microbes but not of another Differential media media that allows grouping of microbes based on different characteristics demonstrated on the medium Transport media liquid or semisolid medium meant to preserve and maintain the integrity of the specimen for the period between specimen collection and laboratory processing of the sample Generation/doubling time the time required for a microbial population to double in numbers prokaryotic cell A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea. eukaryotic cell A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Examples of organisms with these cells are protists, plants, fungi, and animals. gram positive cell wall very thick peptidoglycan layer; techoic acid, attaches to peptidoglycan layer; lipoteichoic acid, attached to cell membrane gram negative cell wall inner layer: thin peptidoglycan layer outer layer: outer membrane with LPS periplasmic space, (space between outer membrane and inner membrane) acid fast bacterial cell wall similar to gram-positive, the outer membrane or envelope of the cell wall contains a waxy layer of glycolipids, mycolic acid retains stain after an acid-alcohol decolorizer bacterial capsules A virulence factor that impedes phagocytosis and may enhance adherence to tissues bacterial slime layer gelatinous sheath; allows bacteria to stick to slick surfaces and host tissue; inhibits phagocytosis an easily removed, diffuse, unorganized layer of extracellular material that surrounds bacteria cells composed of polysaccharides bacterial appendage Includes flagella, pili/fimbriae Lipopolysaccharide (LPS) Composed of O antigen polysaccharide (outer) Core polysaccharide (middle) Lipid A (inner): also called endotoxin (responsible for fever and shock) found on outer membrane of gram negative cell wall diplococci Spherical bacteria that grow in pairs and cause diseases such as pneumonia streptococci Pus-forming bacteria arranged in curved lines that resemble a string of beads staphylococci Spherical shaped bacteria that form grape-like clusters bacillus rod shaped bacteria coccobacilli oval bacilli that looks similar to cocci fusiform Spindle-shaped or tapered at each end. pleomorphic when a species varies in size and shape within a pure culture Palisading Lining up of cells in a row side by side spirochetes spiral-shaped bacteria that have flexible walls and are capable of movement flagella exterior protein filaments that rotate and cause bacteria to be motile polar flagella flagella that may occur singly at one or both ends Lophotrichous flagella that occur in multiples (tufts) peritrichous flagella that occur on all sides of the bacterium pili aonmotile, long hollow protein tubes that connect two bacterial cells and mediate DNA exchange fimbriae non-flagellar, sticky proteinaceous, hairlike appendages that adhere some bacterial cells to one another and to environmental surfaces archaeobacteria literally means ancient bacteria, many are found in extreme environments. Closely related to eukaryotes. Examples include halophilic (salt-loving), thermoacidophilic (heat/acid loving), and methanogenic (methane loving) bacteria. cilia short structures projecting from a cell and containing bundles of microtubules that move a cell through its surroundings or move fluid over the cell's surface gram stain a method for the different staining of bacteria that involves fixing the bacteria cells to a slide and staining with crystal violet and iodine, then washing with alcohol, and counterstaining with safranin. Acid fast stain a differential stain technique that identifies bacterial that have a waxy material in their cell walls; uses Carbolfuchsin as its primary stain, Acid-alcohol as its decolorant, Methylene blue as its secondary stain lactophenol cotton blue used to stain the walls of medically important fungi india ink a negative stain used to visualize capsules surrounding certain yeast, such as cryptococcus Fermentation Anaerobic process of breaking down carbohydrates (obligate anaerobes and facultative anaerobes) respiration/oxidation Aerobic process of breaking down carbohydrates (obligate aerobes and facultative anaerobes) lag phase bacteria preparing to divide log phase bacteria activly dividing stationary phase number of bacteria remains constant death phase more dead cells than live cells bacteriostatic inhibits bacterial growth bactericidal kills bacteria antimicrobial substance used to prevent or treat an infection caused by bacteria and other pathogenic organisms antibiotic substance used to prevent or treat an infection caused by bacteria and other pathogenic organisms synergy the working together of two things to produce an effect greater than the sum of their individual effects antagonism interference in or inhibition of the physiological action of a chemical substance by another having a similar structure MIC Minimum Inhibitory Concentration Susceptible the patient's infecting organism should respond to therapy with the normal recommended dosage of the agent intermediate the patient's infecting organism may respond only to a level of this antimicrobial agent that cannot ordinarily be achieved in vivo resistant the patient's infecting organism should not respond to therapy with the normal recommended dosage of this agent MRSA Methicillin-resistant Staphylococcus aureas VRE Vancomycin-Resistant Enterococcus MBC Minimal bactericidal concentration ESBL Extended Spectrum Beta-Lactamase plasmid extra-chromosomal, circular DNA; often carry virulence and antibiotic resistance genes transformation uptake and incorporation of naked DNA from another bacteria that has died transduction bacteriophage inject their DNA into bacteria so they replicate and express viral products conjugation donor to recipient via sex pili exchange of DNA as well as plasmids sterilization distruction of all forms of life, including bacterial spores all or nothing process disinfection a process that eliminates a defined scope of microorganisms including some spores antiseptic a substance applied to the skin for the purpose of eliminating or reducing the number of bacteria present standard precautions infection-control precautions that assume that all patients are potentially infected and that implement practices to prevent contact with blood and body fluids quality control a system for detecting and correcting analytical errors by establishing performance limits and ensuring the maintenance of proper standards, especially by periodic random inspection of the product performance improvement Continuous analysis of processes or procedures and continual implementation of improvements customer concept the view or perception each laboratory customer holds in regard to quality and their own expectations benchmarking a reference point obtained by using an industry's or a profession's best practices to imitate and improve processes nonselective media media that support the growth of most nonfastidious aerobes enrichment broth liquid medium designed to encourage the growth of small numbers of a particular orgnism while suppressing other flora present. broth media liquid medium used as a supplement to agar plates to detect small numbers of most aerobes, anaerobes, and microaerophiles