Test 1 Flashcards
What is microbiology?
test q
study of microscopic organisms such as bacteria, viruses, archaea, fungi (yeast) and protozoa
note: all of these examples are cellular besides viruses
Who made the first microscope with magnification of 50x-300x?
Antoni Van Leeuwenhoek
Who was the first to discover the bacterial world?
Antoni Van Leeuwenhoek
Who introduced the first systemic method of vaccination and used cow pox virus (vaccinia virus) to cross immunize against human small pox virus (variola virus)?
Edward Jenner
Whats the year of vaccines?
1796 (when Edward Jenner introduced small pox vax)
Who saved the silk and wine industry in France?
Louis Pasteur
Who introduced the first vaccine for the rabies virus?
Louis Pasteur
Who introduced the first vaccine for Bacillus anthracis (the bacteria causing anthrax), a disease of cows, sheep, etc. and can be fatal to man?
Louis Pasteur
Who introduced the principles of pasteurization?
Louis Pasteur
Who was the pioneer of aseptic (no dirt= clean) in obstetrics?
Ignaz Philipp Semmelweiss
He directed his medical students to wash their hands in chlorine water before helping laboring mothers and the birth death rate greatly dropped
Who proved germ theory?
Robert Koch
who introduced postulates named after himself, which provided a way to identify a specific microorganism as causing a specific infectious disease?
Robert Koch
Who introduced agar to nutrient medium to provide it with a solid substratum?
Robert Koch
Who first isolated bacillus anthracis (bacteria that causes anthrax) in pure culture?
Robert Koch
Microbiology of air (air-bone) is that air has no ______ in and of itself. Microbes are found in the air temporarily as a result of coughing, sneezing, sweeping, etc
flora
What are some common human viruses spread by air?
-common cold (rhinovirus, adenovirus)
-measles (rubeola = true measles)
-rubella (German measles)
-Influenza (flu)
-mumps (infectious parotitis)
-small pox (Variola virus, extinct)
*for sure know Rubeola, Rubella, and Variola
What are some common bacterial infections spread by air?
-Streptococcal pharyngitis (strep throat, Streptococcus pyogenes)
-Diphtheria (Corynebacterium diphtheria)
-Pertussis or whooping cough (Bordetella pertussis)
-Tuberculosis (Mycobacterium tuberculosis)
What are the routes of transmission for microorganisms?
-air-borne
-blood borne
-food borne
-water borne (fecal-oral transmission)
-vector-borne
-STDs
What is the difference between horizontal and vertical transmission?
in horizontal transmission viruses are transmitted among individuals of the same generation, while vertical transmission occurs from mothers to their offspring
define endemic
-illness/disease within population
-relatively small scale (low number of cases)
-not usually associated with outbreaks
define epidemic
illness/disease in more than one population, an outbreak of something
define pandemic
-illness/disease in all people/populations
-larger than an epidemic/more specific
-more than 2 continents are involved
What are the 3 shape classifications of bacteria?
1) coccus (spherical, plural= cocci, means like a berry)
2) rods (cylindrical, aka bacillus)
3) helicoidal (spiral, special type of rods)
define diplococcus
spherical pairs
define streptococcus
spherical chains
define staphylococcus
spherical irregular grape-like clusters
define gaffkya
spherical arrangement in packets of 4 (tetrads)
define sarcina
spherical arrangements in packets of 8
What are the characteristics of rods/bacillus?
-straight, sausage shaped, cylindrical shaped, cigar shaped (fusiform)
-outnumber all other forms of bacteria
-coryneform bacillus can be in V or L type structures
What type of bacteria is a shape intermediate between cocci and bacilli?
coccobacillus
define vibrio
curved rod, comma shaped
define spirillum
helical shape with a thick rigid cell wall
define spirochete
thin flexible cell wall
What are bacterial cells usually measured in?
micrometers
What is flagellum?
organ of motility
ATP and cell wall are needed for flagella to function (functions in a rotary fashion)
define atrichous
-a= no/without flagella= no motility
-trichous= hair
define monotrichous
single polar flagellum (1 flagellum)
define amphitrichous
1 flagellum on each end
define lophotrichous
multiple polar flagella, tuft (threads of hair) on one or both ends
loph= tuft
define peritrichous
flagella distributed over the entire cell
What is another name for pili?
fimbria
What are pili?
protein fibers that originate from the cell membrane that are not flagella (smaller shorter and more numerous than flagella)
present on mostly gram negative bacteria
What is the function of pili?
-serve as attachment sites to viruses and cells of body
-some bacteria contain a specialized “F pilus” which serves as a conjugation tube for transfer of DNA (F stands for fertility, but remember that bacteria is asexual)
-pili act as virulence factor (enhance attachment to host cells)
What are the 3 major modes of genetic exchange between bacteria ?
1) conjugation
2) transduction
3) transformation
What is conjugation?
genetic exchange between bacteria, involves cell-to-cell contact
What is transduction?
foreign DNA is introduced into a cell by a virus or viral vector
define transformation
genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane(s)
What is another name for the capsule of bacterial cells?
glycocalyx or slime layer
The capsule of a bacterial cell is a gelatinous, sticky substance that surrounds the outside of the cell. It is usually _________________ in nature. The layer can be thick and covalently bound to cell and is referred to as a “capsule.” A thinner, loosely attached layer is referred to as a “slime layer”
polysaccharide
What does the capsule of a bacterial cell protect the cell from?
-from desiccation and other environmental factors
-against phagocytosis by macrophages and phagocytic WBCs
What are the SHiNE SKiS encapsulated organisms (bacteria w/ capsule)?
-strep pneumonia (S)
-haemophilus influenza (h i)
-Neisseria meningitis (N)
-E. coli (E)
-Strep algalacticae (Group B strep) (S)
-Klebsiella (K)
-Salmonella (S)
What does Quellung reaction positive mean?
when microorganisms are mixed with specific anti-microbial serum, the capsule swells
Bacterial cell walls help maintain shape and protect the cell membrane from rupture. What differentiates gram positive bacteria from gram negative bacteria?
test q
the amount of peptidoglycan in the cell wall
What is endotoxin?
potentially fatal toxin released from the lipopolysaccharide layer of the dead and dying gram-negative bacteria
LPS (endotoxin) of gram negative bacteria are the bacterial cell outer membrane components
What is exotoxin?
a bacterial posion composed of protein that may be excreted by a microorganism or released upon lysis
acts on a tissue site
categorized by tissues they affect
many gram positive and gram negative organisms produce exotoxins
-enterotoxin
-neurotoxin
What bacteria has the cell wall with a thicker layer of peptidoglycan?
test q
gram positive
What bacteria has the cell wall with a thinner layer of peptidoglycan?
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gram negative
What is found in the LPS of gram negative bacteria that is responsible for fever toxicity?
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Lipid A
on cell death, lipid A is released and is related to endotoxins!!!!
How many layers does gram positive bacteria have?
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3 layers
How many layers does gram negative bacteria have?
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5 layers
T/F: most bacteria are haploid because they have only one chromosome that contains the cell’s essential genetic info
true
What is the nucleoid?
-localized region of the cytoplasm which contains double stranded, circular DNA molecule
-NOT membrane bound
What are plasmids?
-present in some but not all bacteria (nonessential genetic info, comprised of 1-2% of total cell DNA)
-small circular double stranded DNA
-codes like nucleus, for cell products like enzymes
What part of the bacterial cell is responsible for antibiotic resistance?
plasmids
What are the vehicles for genetic engineering?
plasmids
What are ribosomes?
-spherical structures made up of protein and ribosomal RNA
-involved in protein synthesis
-built from RNA and protein and are composed of a large subunit (50S) and a small subunit (30S)
-for proteins to be synthesized, the 2 subunits come together and form a 70S functional ribosome (50S + 30S= 70S)
-their relative size is measured in Svedburg units by how fast they settle when spun in a centrifuge
What is the function of ribosomes?
translate RNA and make protein
What are inclusions (volutin/metachromatic granules)?
nutrient storage granules that stain red with methylene blue and are composed of polyphosphate used for energy like ATP
What are endospores?
-organelles for survival
-produced when nutrients are limited
-extremely resistant dormant cell produced by some gram positive bacterial species (some may live 60+ years)
-main reason for sterilization in canning process is to kill endospores (especially those of clostridium botulinum)
-under ideal conditions, they germinate into vegetative cells
What 2 genera of bacteria produce spores (endospores)?
1) clostridium (terminal spores, anaerobic- air is toxic)
2) bacillus (central spores, aerobic- need air to grow)
What is the difference between eukaryotic and prokaryotic cells?
What is the bright-field/compound light microscope? What are its characteristics?
-possess 2 lens system: objective lens near the specimen and the ocular lens near your eye
-objective lens produces a magnified image of the object and the ocular lens magnifies the image produced by the objective lens
3 basic magnifications of objective lens=
-low power = 10x
-high dry= 43x
-oil immersion= 100x
magnification of ocular lens is usually 10-20x
final magnification= objective x ocular
-lower power 10x x ocular 10x= 100x
-high dry 43x x ocular 10x= 430x
-oil immersion 100x x ocular 10x= 1000x
principle= light passes through a colored stained object
stain provides contrast
objects observed= arrangement, shape, size of killed microorganisms (except viruses)
What is a dark field microscope?
used to view live, unstained microorganisms and motility of live cells, such as Treponema pallidum (syphilis)
What is a flourescent microscope?
-image appears bright against a dark background
-uses fluorescent dyes called fluorochromes
-principle= UV light illuminates fluorescent coated objects
What is an immunofluorescent microscope?
a fluorescent dye is coupled to a specific antibody and this antibody can be used to stain the antigen
What is an electron microscope?
-uses beams of electrons to magnify and resolve specimens
-short wavelength of the beam of electrons dramatically increases the resolving power of the microscope and makes it possible to visualize viruses and detailed structures
2 types commonly used=
-transmission electron microscope (TEM) used to view and record detailed structures within cells
-scanning electron microscope (SEM) used to see the surfaces of objects in the natural state, provides vivid and undistorted views of an organism’s surface details
principle= a beam of electrons is passed through the specimen
What is a simple stain?
using one dye, to note the shape of the microbe
Who is gram stain named after?
Christian Gram
What is gram staining?
-differential staining procedure used to distingusih between gram pos (purple) or gram neg (red) cells (the color is due to the amount of peptidoglycan in their cell walls)
gram pos (purple) organisms are composed of a thick layer of peptidoglycan
gram neg (red) organisms have a thin layer of peptidoglycan and a thicker layer of LPS (lipid A endotoxin) and lipoprotein
Gram staining consists of 4 reagents, 2 of those being dyes. What are the 4 reagents?
1) crystal violet
2) iodine
3) alcohol 95% or alcohol acetone mixture
4) safranin (red)
For gram staining, what color would gram positive bacteria be when primary dye (crystal violet) is applied?
purple
For gram staining, what color would gram negative bacteria be when primary dye (crystal violet) is applied?
purple
For gram staining, what color would gram positive bacteria be when primary dye (crystal violet) is applied and then iodine?
purple
For gram staining, what color would gram negative bacteria be when primary dye (crystal violet) is applied and then iodine?
purple
For gram staining, what color would gram positive bacteria be when primary dye (crystal violet) is applied, then iodine and alcohol?
purple
For gram staining, what color would gram negative bacteria be when primary dye (crystal violet) is applied, then iodine and alcohol?
colorless
For gram staining, what color would gram positive bacteria be when primary dye (crystal violet) is applied, then iodine and alcohol, and finally safranin/carbol fuchsin?
purple
For gram staining, what color would gram negative bacteria be when primary dye (crystal violet) is applied, then iodine and alcohol, and finally safranin/carbol fuchsin?
pink or red
What is another name for acid fast stain? Who was it named after?
Ziehl-Neelsen stain
named after Paul Ehrlich
What organisms are identified in acid fast stains?
genus Mycobacterium
What is mycolic acid?
waxy lipid material in cell walls of mycobacteria that is associated with virulence (strongly disease capable) and the acid fast property (it sucks up the acid fast stain)
it has anti-phagocytic properties
What are the 3 reagents used in acid fast staining?
1) carbol fuchsin
2) acid/alcohol
3) methylene blue
What color is acid fast bacteria? What color is non-acid fast bacteria?
acid fast bacteria= red
non-acid fast bacteria= blue
What are the 2 main acid fast bacterias of clinical significance?
mycobacterium tuberculosis (TB) and mycobacterium leprae (leprosy)
What are the 3 nutritional types of cultivation based on carbon needs?
1) autotrophs (self-feeding)
2) heterotrophs (feed on others)
3) saprobe (a type of heterotroph that feeds on the dead)
What are autotrophs?
-self feeders
-synthesize their own foods from simple carbon sources such as CO2
-carbohydrates are their main source of energy
-found in many places like soil, water, etc (human body is not their normal habitat- speaking of bacteria)
What are heterotrophs?
-feed on others
-derives its nutritional requirements from complex organic substances
-cannot synthesize its own food and relies on other organisms (both plant and animals for nutrition)
-obtain carbon by feeding on organic material present in other organisms
What are saprobes?
-a specific type of heterotroph that requires dead organic matter as a source of energy
-found in large intestine, manure, dead decaying animals, etc
What is enriched media?
-media that enhances growth
-contains substances which will enhance the growth of fastidious organisms (complex nutritional requirements)
-may contain blood, serum, heat treated blood, etc
What is selective media?
-media that selects whats to grow
-contains ingredients to inhibit the growth of certain microbes while allowing the growth of others (crystal violet inhibits gram positive organisms without inhibiting gram negative organisms)
What is differential media?
-media that can differentiate between different bacteria
-contains one or more compounds that allow one to differentiate between similar species based on specific biochemical or physiological properties
-can easily distinguish colonies from each other based on color, hemolytic patterns, etc
define optimum growth temp
temp which allows for the most growth within a short period of time
What is one of the most important physical factors for governing growth in bacteria?
optimum growth temp
What are psychrophiles?
psychro= cold
-able to grow at 0 degrees celsius (ideally) but can also grow between 15-20 degrees celsius
What are mesophiles?
meso= middle
-like temp between 20-40 degrees celsius, or body temp of humans (37 degrees celsius)
What are thermophiles?
thermo= hot
-multiply best at temps around 60 degrees celsius but can still grow between 40-70 degrees celsius
What are aerobes?
organisms that require oxygen like humans (approx 21.5% oxygen)
What are microaerophiles?
organisms that like lower conc. of oxygen (less than 21.5%)
What are anerobes?
-do not or cannot use oxygen
-fail to process an enzyme which is able to breakdown hydrogen peroxide (H2O2) which is toxic
define facultative
grow in the presence or reduced conc. of oxygen
-there 2 types: anaerobe and aerobe
What are facultative anaerobes?
can grow anaerobically but prefers aerobic growth
What are facultative aerobes?
can grow aerobically but prefers to grow anaerobically
Do bacteria cells reproduce sexually or asexually? Explain
-asexual reproduction or cell division of 2 daughter cells
-called binary fission
What is binary fission?
how bacteria reproduces
-occurs after a period of growth in which the cell doubles in mass
-DNA replicates and the 2 DNA molecules separate
-population of bacteria grows in a geometric progression (exponentially, doubles)
define generation time
time interval for the bacterial cell to divide/double (average is 20-60 min depending on species)
note: useful in determining the amount of time that passes before symptoms appear in an infected individual (faster division means shorter incubation time for a disease)
What are the 4 parts of a growth curve?
1) lag phase (preparation for division, period of adjustment, slow cell growth but no division)
2) log (exponential) phase (steady division at a constant rate)
3) stationary phase (organisms dying = organisms being produced, population is in a plateau)
4) decline or death phase (number of dying cells exceeds the number being reproduced, the numbers begin to decrease because of environmental changes like pH, decrease in nutrients, toxic by-product build up, etc)
T/F: microbial growth can be measured by direct and indirect methods
true
What is the direct method for measuring microbial growth?
viable cell count enumeration (samples of a broth cultures from a serial dilution are poured into agar plates, after incubation the number of viable cells can be estimated)
What is the indirect method for measuring microbial growth?
turbidometric enumeration (increase in growth is measured by turbidity in optical density (OD) or precent transmission units on a spectrophotometer
T/F: bacteria occur in nature as single species
true but RARELY (usually occur in mixed culture)
What are the 2 lab tests that can be done to diagnose pt with S. aureus?
1) coagulase test (positive test= blood serum coagulates= s. aureus)
2) mannitol salt agar (s. aureus will grow and agar will change from pink to yellow)
